Minecraft Clone

# **Minecraft-style Web Clone — Full Design & Implementation Plan**

---

## 🧰 1. **High-Level Overview**

### **Goal**  
Develop a minimal web-based clone of Minecraft with the core mechanics:

- **Procedural world generation**
- **Block creation and destruction**
- **First-person perspective movement**
- **Basic terrain rendering via GPU-accelerated WebGL**
- **3D collision and interaction system**

### **Tech Stack Summary**
| Layer              | Tool/Library                        |
|--------------------|-------------------------------------|
| Rendering Engine   | **Three.js**                        |
| UI Framework       | **React**                           |
| State Management   | **Redux Toolkit**                   |
| Backend Optional   | **Node.js + Express** + **SQLite** or **IndexedDB** |
| Build System       | **Vite** (faster dev experience)    |

---

## 🗺️ 2. **Core Features Supported**

| Feature               | Included? |
|-----------------------|-----------|
| World Generation      | ✅ Procedural noise-based terrain |
| Block Placement/Removal | ✅ With raycast detection         |
| First Person Controls | ✅ WASD + Mouse look              |
| Simple Physics/Collision | ✅ No gravity, AABB collision     |
| Block Palette UI      | ✅ Grid selector at bottom        |
| Persistence Option    | ✅ Local IndexedDB support        |
| Multiplayer Support   | ⏱ Planned for future expansion   |

---

## 🔁 3. **System Architecture (Textual Diagram)**

```
┌─────────────────────────────┐
│         React UI            │
│ (UI Layer - HUD, Menus)     │
└─────────────┬───────────────┘
              │
     ┌────────▼────────────┐
     │     Redux Store     │
     │ (worldState, player) │
     └────────┬────────────┘
              │
  ┌───────────▼──────────────┐
  │  Three.js Renderer       │
  │ - Scene manager          │
  │ - Camera setup           │
  │ - Mesh generation        │
  └──────────┬───────────────┘
              │
  ┌───────────▼──────────────┐
  │ Input & Interaction      │
  │ - WASD controls          │
  │ - Mouse interaction      │
  │ - Raycasting logic       │
  └──────────┬───────────────┘
              │
  ┌───────────▼──────────────┐
  │ World Data Layer         │
  │ - Chunked storage        │
  │ - Noise generator        │
  │ - Block database         │
  └──────────────────────────┘
```

> ⚙️ Separation of concerns:
> - UI component layer communicates state.
> - Rendering engine observes store changes.
> - Interaction layer updates world state directly.

---

## 🧱 4. **Key Data Structures**

### **Chunk**
- Type: 3D array `[x][y][z]` → `blockId`
- Size: 16 × 16 × 16 voxels
- Stored in `worldMap`: an object map from chunk coordinates to chunks

### **Block Palette**
- Type: Object `{ blockId : { name, textureAtlasIndex, isSolid } }`
- Example:

```json
{
  "0": null,
  "1": {"name": "dirt", "textureIndex": 0, "solid": true},
  "2": {"name": "grass", "textureIndex": 1, "solid": true},
  ...
}
```

### **World Map**
- Key structure: `Map<String, Chunk>`
- Key format: `"x,y,z"`

### **Player Object**
```js
{
  position: Vector3,
  rotation: EulerRotation,
  selectedBlockType: int, // corresponds to block ID
}
```

---

## ⚙️ 5. **Core Algorithms**

### ✅ A1. **Terrain Generation (Perlin Noise Algorithm)**

Steps:
1. For each chunk (x,z):
2. Compute noise height = Perlin(x,z)
3. Fill up to that depth with stone
4. Top layer becomes grass
5. Place water layers if below sea level

### ✅ A2. **Face Culling for Efficient Rendering**

```text
For every visible block:
   If current block is solid:
     For each face (north/south/east/west/top/bottom):
        If neighbor block not present or non-solid:
            Add quad vertices to mesh
```

> ⚡ Reduces mesh complexity dramatically.

### ✅ A3. **Raycasting – Block Interaction**

Logic:
1. Cast a ray from camera using mouse coordinates
2. Traverse along the ray direction with small increments
3. If the current block is solid → register hit
4. Return block position + face normal + adjacent block for placement

Used by both left-click (destroy) and right-click (place).

### ✅ A4. **Updating Chunk Meshes Dynamically**

After placing/destroying a block:
1. Rebuild affected chunk's geometry/mesh
2. Potentially rebuild neighboring chunks (for face culling)
3. Update scene graph in Three.js

---

## 💼 6. **Development Roadmap (Sprint-Based Plan)**

| Sprint | Features Implemented                                        | Estimated Time |
|--------|-------------------------------------------------------------|----------------|
| S1     | Setup dev env (Vite + React + Redux + Three.js)              | 1 day          |
| S2     | Implement world data layer and per-chunk procedural gen       | 2 days         |
| S3     | Render single chunk using instancing or merged geometry       | 2 days         |
| S4     | FPS-style movement with WASD + mouse                      | 2 days         |
| S5     | AABB-based collision detection against nearest voxels         | 2 days         |
| S6     | Mouse picking: implement raycasting and block selection       | 2 days         |
| S7     | Implement UI block palette + HUD interface                   | 1 day          |
| S8     | Optimization + polishing (face culling, performance tweaks)  | 1–2 days       |
| S9     | Testing, end-to-end scenarios                                | 1 day          |
| S10    | Deploy on Vercel/Netlify + write documentation               | 1 day          |

> Total estimated time: **2 weeks**, ideal team of 2 engineers.

---

## 🖼️ 7. **User Interface / UI Specification**

### **Desktop Controls**
| Action       | Input       |
|--------------|-------------|
| Move         | WASD keys   |
| Look Around  | Mouse       |
| Select Block | Click on UI bar |
| Place Block  | Right-click |
| Destroy Block| Left-click  |

### **Mobile Adaptation Considerations**
| Action                  | UI Controls                                  |
|-------------------------|-----------------------------------------------|
| Movement                | Virtual joystick (bottom left)                |
| View Control            | Tap-and-hold gesture anywhere off controls    |
| Interact / Place        | Double-tap hold (long press), two-finger tap  |
| Block Selection         | Scrollable palette strip                      |

> Mobile design can be deferred until after desktop version is stable.

### **HUD Elements**
- Crosshair center screen
- Selected block icon + name top-left
- Block palette docked bottom bar

---

## 🧩 8. **Sample Assets Plan**

### **Block Types (Minimal Set)**
| ID | Name   | Texture Index |
|----|--------|----------------|
| 0  | Air    | -              |
| 1  | Dirt   | 0              |
| 2  | Grass  | 1              |
| 3  | Stone  | 2              |
| 4  | Water  | 3              |
| 5  | Wood   | 4              |

### **Texture Atlas**
- Single PNG with UV coordinates mapped per face.
- Each tile mapped to a 2D coordinate (e.g., 0,0 for dirt).
- Atlas reused across all block faces to reduce draw calls.

---

## ✅ 9. **Testing Strategy**

| Area                  | Test Type            | Tools/Methods                             |
|-----------------------|----------------------|-------------------------------------------|
| World generation       | Unit Test            | Check known terrain heights at fixed seeds |
| Block placement logic  | Unit                 | Assert face alignment on placement         |
| Raycasting precision   | Manual E2E           | Visual test clicking various surfaces      |
| Movement & collision   | Integration test     | Simulate inputs and assert expected paths  |
| UI responsiveness      | Interaction test     | Ensure clicks trigger correct actions      |

> For unit tests, suggest tools like Jest or Mocha integrated with headless browser testing where needed.

---

## 🚀 10. **Deployment Guide**

### **Build Process Steps**
```bash
npm run build
```

Output → `dist/` folder ready for deployment.

### **Host Suggestions**
- **Vercel:** Zero-config hosting with automatic CDNs
- **Netlify:** Good for lightweight static apps
- **GitHub Pages:** Simple free option for personal builds

### **Optional Steps**
- Use CDN for assets
- Enable HTTPS
- Set up domain alias

---

## 💡 11. **Optional Future Extensions**

| Extension         | Description                                                                 |
|-------------------|-----------------------------------------------------------------------------|
| Lighting Effects  | Directional light + simple per-chunk shadow maps                            |
| Dynamic Skybox    | Sun angle over day cycle                                                   |
| Biomes            | Add zones like desert, forest with different terrain generation rules      |
| Inventory/Crafting| Item drag-drop UI to manage blocks                                        |
| Multiplayer       | WebSocket server syncs shared chunks between users                          |
| Sound Effects     | Step sounds, place/remove effects                                          |
| Frustum Culling   | Reduce over-rendered distant chunks via view frustum                       |
| Mobile Optimization | Adaptive controls + touch-based UI                                        |

---

# ✅ Final Deliverables (Without Code)

## 1. ✨ Technical Specification
Complete overview of:
- Architecture layers
- Core algorithms (procedural gen, raycast, collision)
- Interaction flow
- Performance guidelines

## 2. 📐 Architecture Diagrams (ASCII Style)

```
┌─────────────────────────────┐
│         React UI            │
└─────────────┬───────────────┘
              │
      ┌───────▼────────┐
      │ Redux / Zustand│          [Shared state store]
      └───────┬────────┘
              │
   ┌──────────▼──────────────┐
   │ Three.js/WebGL Engine   │        [Scene + render loop]
   └──────────┬──────────────┘
              │
   ┌──────────▼──────────────┐
   │ Game Logic & Systems    │        [Controls, physics, interaction]
   └──────────┬──────────────┘
              │
   ┌──────────▼──────────────┐
   │ World Data Layer (Chunks)│      [In-memory or persisted]
   └─────────────────────────┘
```

## 3. 🗃 Sample Data Files

**blockPalette.json**
```json
{
  "0": null,
  "1": { "name": "dirt", "textureIndex": 0, "solid": true },
  "2": { "name": "grass", "textureIndex": 1, "solid": true }
}
```

**textureAtlas.json**
```json
[
  { "type": "dirt", "uv": [0, 0] },
  { "type": "grass", "uv": [0.25, 0] },
  ...
]
```

## 4. 🧪 Testing Strategy

| Module | Method | Tooling |
|--------|--------|---------|
| World Gen      | Unit     | Jest/TestCafe   |
| Raycasting     | Unit     | Manual assertion |
| Collision      | Unit / Integration | Simulated input + Assert collisions |
| UI Components  | Unit / E2E | Cypress or Playwright |
| Performance    | Profiling | Chrome DevTools |

## 5. 📦 Deployment Guide

- Instructions for building final bundle (`dist/`)
- Hosting options (Netlify/Vercel setup)
- CI/CD considerations
- SSL enforcement & CDN setup tips

---

## 🏁 Summary

This plan defines a fully functional, simplified Minecraft web clone suitable for individual or small-team development within a few weeks.

It balances technical scope with extensibility, focusing first on core block logic before expanding into features like UI polish, sound, multiplayer, or AI-driven terrain.

--- 

> Would you like an SVG/PlantUML version of the architecture diagram next?

────────────────────────────────────────────────────────
WEB-BASED “MICRO-CRAFT” – COMPLETE DESIGN PACKAGE
────────────────────────────────────────────────────────

0. Executive Summary
“Micro-Craft” is a lightweight, browser-native Minecraft-style sandbox that lets players explore a procedurally generated voxel world and freely place or remove blocks.  The first public milestone (v0.1) purposefully limits scope to single-player, five block types, no gravity, and local-only persistence so the entire product can be delivered by a small team in two calendar weeks.

────────────────────────────────────────────────────────
1. Technology Stack (Decisions & Rationale)
────────────────────────────────────────────────────────
Rendering engine          : Three.js  (mature, large community, fine-grained control)  
UI framework              : React 18  (ecosystem, JSX ergonomics, TypeScript support)  
State management          : Redux Toolkit  (predictable, debug-friendly)  
Build / dev server        : Vite 5  (fast HMR, tree-shaking, easy TS/React template)  
Local persistence         : IndexedDB via idb-keyval  (async, browser-native, no server)  
Testing                   : Vitest + React Testing Library + Playwright  
Hosting / CI              : GitHub Actions → Vercel static deployment  
Languages                 : TypeScript for all front-end code; Markdown for docs  

────────────────────────────────────────────────────────
2. Functional Specification
────────────────────────────────────────────────────────
2.1 Core Gameplay
• World is an endless grid of 16 × 16 × 16 chunks generated on demand from 2-D simplex noise (height range 0-64).  
• Five solid block types: air (id 0), grass (1), dirt (2), stone (3), water (4), wood (5).  
• Left-click ray-cast ≤ 3 blocks ⇒ remove target block (set id → 0, play sound).  
• Right-click ray-cast ≤ 3 blocks ⇒ add currently selected block on the outward face.  
• First-person movement: WASD strafe, space jump toggle (no gravity yet), mouse-look with pointer-lock.  
• Collision: axis-aligned player capsule (0.6 × 1.8 blocks) cannot interpenetrate solid blocks.

2.2 User Interface
• Crosshair (SVG) at screen centre.  
• Hot-bar (9 slots) pinned bottom-centre; arrow keys or scroll wheel cycle selection.  
• F-key toggles in-game help overlay (controls reference).  
• FPS counter (dev mode only) top-left.

2.3 Non-Functional
• Stable 60 fps on desktop Chrome/Edge with Intel UHD integrated GPU at 1920 × 1080.  
• Initial bundle ≤ 2 MB gzipped, runtime memory ≤ 300 MB after 5 minutes of exploration.  
• All assets (textures, sounds) are public-domain or CC-0.

────────────────────────────────────────────────────────
3. Macro Architecture (Layered)
────────────────────────────────────────────────────────
ASCII ABSTRACTION:

┌──────────────────────────────────────────────────────┐
│                      React UI                       │
│  Hot-bar • HUD • Overlays • Dev tools               │
└───────────────▲────────────────▲────────────────────┘
                │ UI dispatches  │ subscribes
┌───────────────┴──────────┐┌────┴─────────────────────┐
│  Redux Store (pure data) ││ Three.js Render System  │
│  world slices • player   ││  Scene • Camera • Chunks │
└────────▲─────────────────┘└────────▲─────────────────┘
         │ selectors / actions       │ dirty-mesh events
┌────────┴───────────────────────────┴─────────────────┐
│              Domain Logic Layer                      │
│  • Chunk generator • Ray-caster • Collision • Input  │
└────────▲─────────────────────────────────────────────┘
         │ read / write
┌────────┴─────────────────────────────────────────────┐
│            Persistence Adapter (IndexedDB)           │
└──────────────────────────────────────────────────────┘

Communication style:
• UI issues Redux actions (e.g., placeBlock).  
• Reducers mutate the canonical world/chunk data.  
• A “chunk dirty” middleware emits an event; Render System rebuilds that chunk’s mesh.  
• Render System operates 100 % read-only on Store snapshots (copy-on-write).

────────────────────────────────────────────────────────
4. Data Model (TypeScript-style but language-agnostic)
────────────────────────────────────────────────────────
BlockId            = 0 … 255 (uint8)  
BlockDef           = { id, name, isSolid, atlasUV: [u,v] }  
ChunkCoord         = { cx: int32, cy: int32, cz: int32 }  
Chunk              = { blocks: Uint8Array(16³), dirty: bool }  
WorldMap           = Map<string /*“cx,cy,cz”*/, Chunk>  
Player             = { pos: Vec3f, rot: Euler, vel: Vec3f, selectedId: BlockId }  
Store Slice        = { world: WorldMap, player: Player, ui: UIState }  

Texture Atlas: one 256 × 256 PNG divided into 16 × 16 sub-tiles (each 16 px).  
Face winding uses array index look-ups to obtain correct UV for each block type.

────────────────────────────────────────────────────────
5. Key Algorithms & Processes
────────────────────────────────────────────────────────
5.1 Terrain Generation per Chunk  
1. Seeded simplex noise (yScale = 32, octaves = 4) on (cx * 16 + x, cz * 16 + z).  
2. Result → integer height h.  
3. For y = 0‥h-4 set stone, h-3‥h-1 set dirt, h set grass; below waterLevel (32) fill water.  
4. Mark chunk “dirty” for initial mesh build.

5.2 Mesh Builder (run inside Web Worker for 0 GC)  
Iterate all 4 096 blocks, generate a quad only if neighbour is air or water (for transparent).  
Vertices pushed into typed arrays; single BufferGeometry per chunk (indexed).  
Adjacency fetches neighbouring chunks directly via atomic pointer (read-only).

5.3 Ray Casting on Click  
• Convert 2-D mouse position to normalized device coords.  
• Use Three.js Raycaster with custom “voxel step” algorithm (DDA) to traverse grid ≤ reach.  
• First solid block hit → return block coord and normal.  
• Left Button → dispatch removeBlock(blockCoord).  
• Right Button → compute adjacent = blockCoord + normal → dispatch placeBlock(adjacent).

5.4 Movement & Collision (per animation frame)  
• Update desired velocity from keyboard input.  
• Apply simple damping (0.9).  
• Sweep player capsule along velocity vector; if collision predicted with solid voxel, clamp movement.

────────────────────────────────────────────────────────
6. Two-Week Implementation Road-map
────────────────────────────────────────────────────────
Day 1  – Repository bootstrap (Vite + React + TS), lint/format, commit hooks.  
Day 2  – Texture atlas, block definitions JSON, placeholder UI.  
Day 3  – Chunk data structure, seeded noise terrain generator (unit-tested).  
Day 4  – Basic Three.js scene, single mesh chunk renderer, camera.  
Day 5  – Implement face-culling mesh builder; add 4 worker threads for generation.  
Day 6  – Infinite chunk streaming around player (spiral load radius 4).  
Day 7  – Input handler: pointer-lock, WASD locomotion, collision AABB.  
Day 8  – Ray casting, remove-block interaction; hot-reload mesh updates.  
Day 9  – Place-block logic, selected-block hot-bar UI, scroll to cycle.  
Day 10 – IndexedDB save/load middleware; dirty-chunk auto-flush every 5 s.  
Day 11 – Responsive HUD, mobile touch controls (on-screen dual joysticks).  
Day 12 – Performance pass: frustum culling, geometry merging, texture mip levels.  
Day 13 – Testing: headless Vitest for generators, Playwright E2E script (spawn, break, quit).  
Day 14 – Polish, accessibility tweaks, CI/CD pipeline, public Vercel deploy.

Buffer: 10 % of each day is reserved for unforeseen work; if unused, invest in docs.

────────────────────────────────────────────────────────
7. Testing Strategy
────────────────────────────────────────────────────────
Unit Tests  
• terrain.test.ts – deterministic noise output for known seed/chunk.  
• chunkOps.test.ts – place/remove idempotency, correct dirty flag.  
• collision.test.ts – capsule vs. voxel grid edge cases.

Integration / E2E  
• Playwright script “happy-path”: load site → move forward → remove block → place block → reload page → assert block persists.  
• Mobile viewport simulation (iPhone 12) for virtual joysticks.

Performance Regression  
• Lighthouse CI budget: main-thread blocking ≤ 100 ms, memory ≤ 350 MB.  
• Custom FPS monitor logs 10 s average; redline < 50 fps fails workflow.

────────────────────────────────────────────────────────
8. Deployment & Operations
────────────────────────────────────────────────────────
build          : `pnpm run build` – Vite outputs static dist/  
preview        : `pnpm run preview` – local HTTPS for pointer-lock  
hosting        : Vercel (static) – auto-invalidate cache on push to main  
fallback       : GitHub Pages optional (same artifacts)  
bug capture    : Sentry browser SDK (free tier)  
analytics      : Plausible (self-host) opt-in toggle in settings

────────────────────────────────────────────────────────
9. Possible Future Enhancements
────────────────────────────────────────────────────────
• Gravity + jumping & fall damage.  
• Dynamic day/night skybox and per-vertex light map.  
• Crafting & inventory screens (drag-and-drop React-DND).  
• Multiplayer: WebSocket room server with state diff-sync per chunk (Yjs CRDT).  
• Biomes: temperature & humidity noise, block palette swap, foliage decorator.  
• Shader-based water with reflection/refraction.  
• Level-of-detail (greedy meshing, octree impostors) for >128 fps on mobile.

────────────────────────────────────────────────────────
10. Appendices
────────────────────────────────────────────────────────
A. Block Palette JSON (sample)
[
  {"id":1,"name":"grass","isSolid":true,"uv":[0,0]},
  {"id":2,"name":"dirt","isSolid":true,"uv":[1,0]},
  {"id":3,"name":"stone","isSolid":true,"uv":[2,0]},
  {"id":4,"name":"water","isSolid":false,"uv":[3,0]},
  {"id":5,"name":"wood","isSolid":true,"uv":[4,0]}
]

B. Texture Atlas Layout  
Row 0 = primary blocks (grass→wood). Rows 1–15 reserved.

C. Player State Transition (simplified)  
IDLE → keyDown → WALK → (velocity≈0) → IDLE  
WALK + mouseMove alters rot continuously.  
WALK/IDLE + click → INTERACT (0.05 s) → prior state.

────────────────────────────────────────────────────────
END OF DESIGN DOCUMENT
────────────────────────────────────────────────────────

# Technical Specification and Implementation Plan for a Web-Based Minecraft Clone

## 1. Introduction
This document outlines the detailed design and implementation plan for a minimal, web-based Minecraft-style clone. The application will support a 3D voxel world with block creation and destruction, procedural terrain generation, first-person controls, and a simple user interface. The target platform is browser-based (desktop and mobile), and the project prioritizes performance and extensibility for future enhancements. No code is included; this is a comprehensive specification and roadmap.

## 2. High-Level Overview
### 2.1 Project Goal
Create a browser-based Minecraft clone with core functionalities of block placement and removal in a 3D voxel environment, mimicking the sandbox gameplay of the original game in a lightweight, accessible form.

### 2.2 Target Platform
- Desktop and mobile browsers.
- Responsive design for varying screen sizes and input methods (mouse/keyboard for desktop, touch controls for mobile).

### 2.3 Tech Stack
- **Front-End Rendering**: Three.js (chosen for its robust community support, extensive documentation, and suitability for voxel-based rendering via WebGL).
- **State Management**: Redux (for centralized state management, ideal for handling world data and player interactions).
- **UI Framework**: React (for its component-based architecture and ease of integration with Redux and Three.js).
- **Build Tool**: Vite (for fast development builds and modern ES module support).
- **Backend (Optional for Persistence)**: IndexedDB for local storage (prioritized over Node.js + Express for simplicity and offline capability in a minimal implementation).
- **Other**: CSS for basic styling, no external game engine beyond Three.js.

### 2.4 Core Features
1. Procedurally generated terrain using a noise-based heightmap.
2. Real-time block placement (right-click/tap) and destruction (left-click/tap).
3. First-person controls with WASD for movement and mouse/touch for looking.
4. Basic collision detection and physics (grounded movement, no gravity in initial version).
5. Minimal UI for selecting block types from a palette.

## 3. Detailed Feature Breakdown
### 3.1 World Generation
- **Description**: A 3D voxel world generated via a 2D heightmap using Perlin noise for natural terrain variation.
- **Implementation Points**:
  - World divided into chunks (16x16x16 blocks) for efficient data management.
  - Heightmap determines ground level per (x,z) coordinate; blocks below are filled as dirt/stone, top layer as grass.
  - Water blocks added at a fixed height in low areas if below a threshold.
  - Store chunk data as 3D arrays mapping to block IDs.

### 3.2 Block Types
- **Description**: A palette of 5 block types: Grass, Dirt, Stone, Wood, Water.
- **Implementation Points**:
  - Each type assigned a unique ID (0 for empty/air, 1-5 for blocks).
  - Texture atlas (single image with sub-regions) for rendering efficiency.
  - Properties per block: isSolid (for collision), texture coordinates.

### 3.3 Rendering
- **Description**: Efficiently render only visible block faces in a 3D scene.
- **Implementation Points**:
  - Use Three.js to create a mesh per chunk, combining visible faces into a single geometry.
  - Implement face culling: exclude faces adjacent to solid blocks.
  - Optimize by regenerating meshes only for modified chunks.

### 3.4 Controls
- **Description**: First-person perspective navigation.
- **Implementation Points**:
  - Keyboard (WASD): Forward, backward, strafe left/right; Space for potential jump (future).
  - Mouse: Look around (yaw/pitch) with pointer lock for immersive control.
  - Mobile: Virtual joystick for movement, swipe for looking.
  - Interaction: Left-click to destroy, right-click to place blocks.

### 3.5 Block Interaction
- **Description**: Place or destroy blocks within a short range (3-5 blocks).
- **Implementation Points**:
  - Raycasting from camera position along view direction to detect target block.
  - For placement, target adjacent empty space based on hit face normal.
  - Update chunk data and refresh mesh on interaction.

### 3.6 Collision Detection
- **Description**: Prevent player from passing through solid blocks.
- **Implementation Points**:
  - Player represented as an AABB (axis-aligned bounding box).
  - Check collisions with neighboring blocks during movement updates.
  - Restrict movement to ground level (no gravity/falling in initial version).

### 3.7 User Interface
- **Description**: Simple HUD and block selection.
- **Implementation Points**:
  - React overlay with crosshair at center.
  - Bottom bar showing block icons (click to select active type).
  - Optional health or status display area for future expansions.

### 3.8 Persistence (Optional)
- **Description**: Save world state locally for session continuity.
- **Implementation Points**:
  - Use IndexedDB to store modified chunks as serialized JSON.
  - Auto-save on significant changes or on tab close; load on startup.

## 4. System Architecture
### 4.1 Architecture Diagram (ASCII)
```
┌─────────────────────────────┐
│  Browser UI (React)         │
│  • HUD, Block Palette       │
└─────────────┬───────────────┘
              │
┌─────────────▼───────────────┐
│  State Management (Redux)    │
│  • Player State, World Data  │
└─────────────┬───────────────┘
              │
┌─────────────▼───────────────┐
│  Render Engine (Three.js)    │
│  • Scene, Camera, Chunk Mesh │
└─────────────┬───────────────┘
              │
┌─────────────▼───────────────┐
│  Input & Physics Layer       │
│  • Controls, Raycasting     │
│  • Collision Detection      │
└─────────────┬───────────────┘
              │
┌─────────────▼───────────────┐
│  World Data Layer            │
│  • Chunk Storage, Generation│
│  • Persistence (IndexedDB)  │
└─────────────────────────────┘
```

### 4.2 Module Descriptions
- **UI (React)**: Renders HUD and block selector; interacts with Redux for state updates.
- **State (Redux)**: Centralized store for player position, active block type, and world data.
- **Render Engine (Three.js)**: Manages 3D scene, builds chunk meshes with face culling, updates visuals based on state.
- **Input & Physics**: Handles user inputs, translates to movement/interaction, applies collision logic.
- **World Data**: Procedural generation, chunk storage as 3D arrays, optional save/load functionality.

## 5. Data Structures
### 5.1 Chunk
- **Type**: 3D Array `[x][y][z]` of integers (block IDs).
- **Size**: 16x16x16 blocks.
- **Notes**: Stored in a world map with chunk coordinates as keys (e.g., `"x:y"` string for chunk position).

### 5.2 Block Palette
- **Type**: Object mapping ID to block properties.
- **Structure**: `{ id: { name, textureCoord, isSolid } }`
- **Example Data**: `{ 1: { name: "Grass", textureCoord: [0,0], isSolid: true } }`

### 5.3 World Map
- **Type**: Map or Object.
- **Structure**: Key as chunk coordinate string (e.g., "0:0"), value as Chunk data.

### 5.4 Player State
- **Type**: Object.
- **Structure**: `{ position: {x, y, z}, rotation: {yaw, pitch}, velocity: {x, y, z} }`
- **Notes**: Updated per frame based on input and collision checks.

## 6. Algorithmic Details
### 6.1 Terrain Generation
- For each chunk, compute a 2D heightmap using Perlin noise over (x,z) coordinates scaled by chunk position.
- Iterate (x,z) within chunk; set block types up to height as ground (bottom stone, middle dirt, top grass).
- Add water blocks in areas below a global sea level if applicable.

### 6.2 Face Culling for Rendering
- For each block in a chunk, check all 6 adjacent positions.
- If adjacent block is solid or out of bounds, skip rendering that face.
- Combine visible faces into a single mesh with texture coordinates from atlas.

### 6.3 Raycasting for Interaction
- Generate a ray from camera position through view direction.
- Step along ray up to max distance (e.g., 5 blocks), checking world grid for solid block hits.
- Return hit block coordinate and face normal for placement/destruction logic.

### 6.4 Collision Detection
- On movement update, project player AABB to new position.
- Check overlap with neighboring blocks in grid; if overlap with solid block, cancel movement component (x/y/z separately for sliding effect).

## 7. Implementation Plan (2-Week Roadmap)
### Week 1
- **Day 1-2 (Setup)**: Initialize project with Vite, React, Three.js, and Redux; set up basic HTML canvas and React overlay.
- **Day 3-4 (World Data)**: Implement chunk storage, Perlin noise terrain generation, and basic block palette.
- **Day 5-7 (Rendering)**: Create Three.js scene with chunk mesh builder, implement face culling, render initial world.

### Week 2
- **Day 8-9 (Controls & Physics)**: Add first-person controls (WASD, mouse look with pointer lock), basic movement, and AABB collision.
- **Day 10-11 (Interaction)**: Implement raycasting for block selection, logic for place/destroy, mesh regeneration on updates.
- **Day 12 (UI)**: Build React HUD with crosshair and block selector bar, tie to Redux for active block state.
- **Day 13 (Polish & Test)**: Optimize chunk rendering, add mobile touch controls (basic), test across browsers.
- **Day 14 (Deployment)**: Bundle project, write deployment guide, host on Netlify or Vercel.

### Potential Pitfalls
- Performance issues with mesh updates on block changes (mitigate by optimizing culling and limiting render updates).
- Mobile input complexity (start with desktop, add touch as stretch goal).
- Browser compatibility for WebGL (test early on multiple devices).

## 8. Testing Strategy
### 8.1 Unit Tests
- **World Generation**: Verify heightmap noise output consistency and chunk data integrity.
- **Raycasting**: Test ray-block intersection accuracy with sample world grids.
- **Collision**: Simulate player movement against known block layouts, assert correct position clamping.

### 8.2 End-to-End Tests
- **Movement**: Ensure WASD/mouse moves player smoothly without clipping through blocks.
- **Interaction**: Confirm block placement/destruction updates world visibly and respects range limits.
- **UI**: Validate block selector changes active type and reflects in placement.

### 8.3 Tools
- Use Jest for unit testing React components and logic.
- Manual testing in Chrome, Firefox, and mobile browsers for rendering/input consistency.

## 9. Deployment Guide
### 9.1 Build Process
- Run `npm run build` with Vite to create optimized production bundle.
- Output will be in `dist/` folder with static assets.

### 9.2 Hosting Options
- **Netlify**: Drag-and-drop `dist/` folder or connect GitHub repo for auto-deploys.
- **Vercel**: Similar setup, link project for CI/CD pipeline.
- Ensure hosting supports static sites with no backend requirement (unless persistence layer expanded).

### 9.3 Requirements
- Modern browser with WebGL support (fallback message if unsupported).
- No server-side dependencies for base version.

## 10. Sample Data Files
### 10.1 Block Palette JSON (Conceptual)
```
{
  "1": { "name": "Grass", "textureCoord": [0, 0], "isSolid": true },
  "2": { "name": "Dirt", "textureCoord": [0.25, 0], "isSolid": true },
  "3": { "name": "Stone", "textureCoord": [0.5, 0], "isSolid": true },
  "4": { "name": "Wood", "textureCoord": [0.75, 0], "isSolid": true },
  "5": { "name": "Water", "textureCoord": [0, 0.25], "isSolid": false }
}
```

### 10.2 Texture Atlas Plan
- Single 1024x1024 image with 4x4 grid of textures (each 256x256).
- Map block IDs to grid positions for UV coordinates during rendering.

## 11. Optional Extensions for Future Work
- **Multiplayer**: Integrate WebSocket server (e.g., with Socket.io) for real-time player and world updates.
- **Inventory/Crafting**: Add UI panel for item management, recipes for combining blocks.
- **Biomes**: Extend terrain generation with biome-specific block palettes (desert, forest).
- **Lighting**: Implement basic ambient occlusion or per-chunk light maps for visual depth.
- **Performance**: Add chunk streaming (load/unload based on distance) and frustum culling.

## 12. Conclusion
This specification provides a complete blueprint for developing a minimal Minecraft clone in a web environment. By leveraging Three.js for rendering, Redux for state, and React for UI, the project ensures modularity and scalability. The 2-week roadmap focuses on core features while outlining testing and deployment strategies to ensure a functional deliverable. Future expansions can build upon this foundation to enhance gameplay and complexity.

Of course. As an experienced game-development AI, I will now produce the complete design and implementation plan as requested.

---

### **Project "VoxeLoom": A Web-Based Voxel Engine**
**Technical Specification & Implementation Plan**

---

### **1. Technical Specification**

#### **1.1. High-Level Goal & Scope**
This document outlines the design for **VoxeLoom**, a minimal, web-based 3D voxel sandbox built for modern browsers. The primary goal is to create a performant and extensible foundation that delivers the core Minecraft experience: exploring a procedurally generated world and modifying it by placing and destroying blocks.

-   **Core Experience:** First-person navigation, world interaction (block placement/removal).
-   **Platform:** Desktop and Mobile Web Browsers (Chrome, Firefox, Safari).
-   **Scope:** This initial version focuses on a single-player, client-side experience. Multiplayer, advanced physics, and crafting are designated as future extensions.

#### **1.2. Chosen Technology Stack**

-   **Rendering Engine: Three.js**
    -   **Justification:** Three.js is a mature, powerful, and well-documented WebGL library. Its flexible, lower-level API is ideal for building a custom voxel renderer, allowing for fine-grained control over geometry, materials, and performance optimizations like custom shaders and face culling.
-   **UI Framework: React**
    -   **Justification:** React's component-based architecture is a natural fit for managing the game's UI (HUD, menus). Its strong ecosystem and virtual DOM ensure that UI updates are efficient and decoupled from the main game loop.
-   **State Management: Redux Toolkit**
    -   **Justification:** Redux provides a single, predictable source of truth for the entire application state (player position, world seed, selected block, etc.). Redux Toolkit simplifies its use, reducing boilerplate and making state changes transactional and easy to debug, which is critical for game development.
-   **Build Tool: Vite**
    -   **Justification:** Vite offers a vastly superior developer experience with near-instantaneous hot module replacement (HMR) and a highly optimized production build process. Its speed is a significant quality-of-life improvement during iterative development.
-   **Persistence: IndexedDB**
    -   **Justification:** IndexedDB is the browser's standard client-side database, capable of storing large amounts of structured data (like chunk data). It is asynchronous and non-blocking, ensuring that saving and loading world data does not freeze the main game thread.

#### **1.3. World & Environment System**
The world is the central data entity, composed of discrete chunks.

-   **World Structure:** A grid of chunks, managed by a `World` class. The world will be finite but large enough to feel expansive (e.g., 32x32 chunks).
-   **Chunk Structure:** Each chunk is a 16x16x256 volume of blocks. The vertical height of 256 allows for mountains and deep caves. Chunk data will be stored in a `Uint8Array`, a memory-efficient typed array, where each byte represents a block ID.
-   **Procedural Generation:**
    -   A 2D heightmap will be generated using a simplex noise algorithm for the entire world upon initialization.
    -   Terrain features will be layered:
        1.  **Bedrock:** A flat layer of an unbreakable 'adminium' block at Y=0.
        2.  **Stone:** Fills from Y=1 to `height - 4`.
        3.  **Dirt:** Fills from `height - 3` to `height - 1`.
        4.  **Grass:** Placed at `Y = height`.
        5.  **Water:** A fixed sea level (e.g., Y=64) will be established. Any generated terrain below this level will be replaced by water blocks.
-   **Block Palette:** A central registry will define block properties.
    -   **ID:** A unique number (0-255). ID 0 will be reserved for 'Air' (empty space).
    -   **Properties:** Includes `isSolid` (for collision/culling), `isTransparent` (for rendering logic), and texture coordinates.
    -   **Initial Palette:** 1: Grass, 2: Dirt, 3: Stone, 4: Wood Planks, 5: Water.

#### **1.4. Rendering System**
The rendering system's primary challenge is drawing a massive number of blocks efficiently.

-   **Chunk Meshing:** Each chunk will be converted into a single `THREE.BufferGeometry` mesh instead of rendering individual block cubes. This drastically reduces the number of draw calls.
-   **Greedy Meshing & Face Culling:**
    -   **Initial Implementation (Face Culling):** For each block in a chunk, check its six neighbors. If a neighbor is not a solid block, generate a quad (two triangles) for that face and add its vertices, normals, and UVs to the chunk's geometry arrays. This is simple and effective.
    -   **Optimization (Greedy Meshing):** A more advanced version would merge adjacent faces of the same block type into larger rectangles to further reduce vertex count. This will be considered a post-MVP optimization.
-   **Texture Atlas:** All block face textures will be combined into a single image file (the "atlas"). UV coordinates for each vertex will map to the correct sub-region of this atlas. This enables the entire world to be rendered with a single material and texture, minimizing state changes on the GPU.
-   **Frustum Culling:** Three.js automatically performs frustum culling, ensuring that chunks outside the camera's view are not rendered. Our chunk-based architecture works synergistically with this feature.

#### **1.5. Player & Controls System**
-   **Representation:** The player will be represented by a `THREE.PerspectiveCamera` and a conceptual Axis-Aligned Bounding Box (AABB) for physics.
-   **First-Person Controls (Desktop):**
    -   **Movement:** `W` (forward), `S` (backward), `A` (strafe left), `D` (strafe right). `Space` for jumping (if gravity is added), `Shift` for descending (in flying mode).
    -   **Look:** Mouse movement will control camera pitch (up/down) and yaw (left/right), handled via the Pointer Lock API for a seamless experience.
-   **Interaction:**
    -   **Ray-casting:** On a mouse click, a ray will be cast from the center of the screen into the world.
    -   **Reach:** The ray will be checked for intersections with blocks up to a limited distance (e.g., 5 blocks).
    -   **Action:**
        -   **Left-Click (Destroy):** The intersected block's ID is set to 0 (Air).
        -   **Right-Click (Place):** A new block is placed in the air block adjacent to the intersected face. The type of block is determined by the player's currently selected item.
-   **Physics & Collision:**
    -   **No Gravity:** Initially, the player will be in a "flying" mode. Collision will only prevent movement through solid blocks.
    -   **Collision Detection:** The player's AABB is checked against the AABBs of the 26 neighboring blocks in the world grid.
    -   **Collision Response:** If a potential move would result in an intersection, the movement along that specific axis is negated. This "slide" effect is common in first-person games.

#### **1.6. User Interface (UI) & Heads-Up Display (HUD)**
The UI will be rendered as a 2D HTML overlay using React components.

-   **HUD:**
    -   A simple `+` or dot crosshair will be fixed at the center of the screen.
-   **Block Hotbar:**
    -   A horizontal bar at the bottom-center of the screen will display the available block types (Grass, Dirt, Stone, etc.).
    -   The currently selected block will be highlighted.
    -   Users can click an icon or use number keys (1-5) to select their active block.

#### **1.7. Persistence Layer**
-   **Trigger:** World state will be saved automatically upon block modification. To avoid performance hits, this will be throttled (e.g., once every 5 seconds).
-   **Storage:** The `World` module will serialize any modified chunks into a storable format (e.g., `[{ key: "x,y,z", data: Uint8Array }, ...]`).
-   **Mechanism:** This array of modified chunks will be saved to IndexedDB using a library like `idb` to simplify the API. On application load, the `World` will query IndexedDB for saved data and apply it before the initial render.

---

### **2. System Architecture & Data Flow**

#### **2.1. Component Diagram (ASCII)**

```text
 ┌──────────────────────────┐      ┌──────────────────────────┐
 │      React UI Layer      │      │     Input Manager        │
 │ (HUD, Hotbar Components) │      │ (Keyboard, Mouse, Touch) │
 └─────────────┬────────────┘      └─────────────┬────────────┘
               │                                │
               │ (Renders State)                │ (Dispatches Actions)
               ▼                                ▼
 ┌────────────────────────────────────────────────────────────┐
 │                  Redux Store (Single Source of Truth)      │
 │  - playerState: { position, velocity, rotation }           │
 │  - worldState:  { seed, modifiedChunks (dirty flag) }      │
 │  - uiState:     { selectedBlock, isMenuOpen }              │
 └─────────────────────────────┬──────────────────────────────┘
                               │ (State subscriptions trigger updates)
                               ▼
 ┌────────────────────────────────────────────────────────────┐
 │                       Main Game Engine                     │
 │────────────────────────────────────────────────────────────│
 │  ┌────────────────┐  ┌────────────────┐  ┌────────────────┐  │
 │  │ Physics Engine │  │ Render Engine  │  │  World Manager │  │
 │  │ - Collisions   │  │  - Three.js    │  │  - Chunk Gen   │  │
 │  │ - Player Move  │  │  - Chunk Mesher│  │  - Block Update│  │
 │  └───────┬────────┘  └───────┬────────┘  └───────┬────────┘  │
 │          └───────────────────┼───────────────────┘          │
 │                              │                              │
 │                              ▼                              │
 │             ┌────────────────────────────────┐              │
 │             │      World Data Representation │              │
 │             │ - Map("x,y,z" -> Chunk(Uint8Array))           │
 │             └────────────────┬───────────────┘              │
 │                              │ (Async Save/Load)            │
 │                              ▼                              │
 │                          ┌───────────┐                      │
 │                          │ IndexedDB │                      │
 │                          └───────────┘                      │
 └────────────────────────────────────────────────────────────┘
```

**Data Flow Example (Placing a Block):**
1.  User `Right-Clicks`.
2.  `Input Manager` captures the event and dispatches a Redux action: `{ type: 'player/interact', payload: 'place' }`.
3.  The `Main Game Engine`, subscribed to the store, sees this action.
4.  It calls the `Render Engine` to perform a ray-cast to find the target block and face.
5.  If a valid target is found, it calls the `World Manager` to update the block data in the appropriate `Chunk` array.
6.  The `World Manager` marks the chunk (and potentially its neighbors) as "dirty."
7.  The `Render Engine`'s `Chunk Mesher` regenerates the mesh for all dirty chunks.
8.  The `World Manager` triggers a throttled save to `IndexedDB`.


#### **2.2. Core Data Structures**

| Data Structure      | Type                                       | Description                                                                                             |
| ------------------- | ------------------------------------------ | ------------------------------------------------------------------------------------------------------- |
| **BlockPalette**    | `Map<number, BlockDefinition>`             | A global map from a block ID (`Uint8`) to its properties (`{ name, isSolid, textureCoords }`).          |
| **Chunk**           | `Uint8Array`                               | A 1D typed array of size 16\*16\*256 representing a 3D volume of block IDs. Fast, memory-efficient.     |
| **World**           | `Map<string, Chunk>`                       | A map where the key is a coordinate string like `"x,z"` and the value is the corresponding `Chunk` object. |
| **PlayerState**     | `{ position: Vec3, rotation: Euler }`      | Stores the player's 3D position and camera orientation. Managed in the Redux store.                     |
| **ChunkMeshCache**  | `Map<string, THREE.Mesh>`                  | A cache in the `Render Engine` that maps a chunk coordinate string to its generated `THREE.Mesh`.           |

---

### **3. Implementation Plan (2-Week Roadmap)**

This aggressive roadmap assumes a single developer with experience in the chosen stack.

**Week 1: The World and The Player**

*   **Day 1: Project Scaffolding**
    *   **Task:** Initialize project with Vite (React + TypeScript template). Install dependencies: `three`, `@react-three/fiber`, `@react-three/drei`, `redux-toolkit`, `react-redux`.
    *   **Goal:** Render a single `THREE.BoxGeometry` in a 3D scene using `@react-three/fiber`. Set up basic orbital controls for verification.
*   **Day 2: World Data Layer**
    *   **Task:** Implement the `Chunk` and `World` data structures. Create a `BlockPalette`. Write the simplex noise-based procedural generation algorithm.
    *   **Goal:** Programmatically generate the data for a single chunk and log its block ID array to the console.
*   **Day 3-4: Voxel Rendering**
    *   **Task:** Implement the chunk meshing algorithm (naive face culling). Write a `ChunkMesh` component that takes chunk data and generates a `BufferGeometry`. Load a basic texture atlas.
    *   **Goal:** Render a single, static chunk in the 3D scene.
*   **Day 5: Player Controls**
    *   **Task:** Implement first-person controls. Use the Pointer Lock API. Bind `WASD` and mouse movement to update the player's state in the Redux store.
    *   **Goal:** A "noclip" camera that can fly freely around the rendered chunk.

**Week 2: Interaction and Polish**

*   **Day 6-7: Collision Detection**
    *   **Task:** Implement the AABB-based collision detection and response algorithm. The player controller will now query the `World` for nearby blocks before finalizing a move.
    *   **Goal:** The player can no longer move through solid blocks and can "walk" on the generated terrain.
*   **Day 8-9: Block Interaction**
    *   **Task:** Implement ray-casting for block selection. Dispatch actions for destroying and placing blocks. Trigger chunk data updates and mesh regeneration.
    *   **Goal:** Player can point at a block (highlighting it) and successfully destroy/place blocks, with the world visually updating in real-time.
*   **Day 10: Dynamic World Loading**
    *   **Task:** Implement logic to load/unload and render/hide chunks based on the player's position.
    *   **Goal:** As the player moves, new chunks appear in front of them, creating the illusion of an infinite world.
*   **Day 11: UI/HUD**
    *   **Task:** Create the React components for the crosshair and the block hotbar. Connect the hotbar to the Redux store to update `uiState.selectedBlock`.
    *   **Goal:** The UI is functional and overlayed on the 3D canvas.
*   **Day 12: Persistence**
    *   **Task:** Integrate `IndexedDB`. Implement the logic to save modified chunks on an interval and load them on startup.
    *   **Goal:** World modifications persist between page reloads.
*   **Day 13-14: Polish, Testing & Bug Fixing**
    *   **Task:** Refine controls, fix visual artifacts, improve performance, add comments, and write a README.
    *   **Goal:** A stable, functional, and shareable MVP.

---

### **4. Testing and Deployment Strategy**

#### **4.1. Testing**
-   **Unit Tests (`vitest`):**
    -   Test the world generation algorithm with a fixed seed to ensure deterministic output.
    -   Test the chunk data manipulation logic (getting/setting a block at `x,y,z`).
    -   Test Redux reducers to ensure predictable state transitions.
-   **Integration Tests:**
    -   Test the full interaction loop: `Player Action -> State Change -> World Update -> Mesh Regeneration`.
    -   Test collision response logic by programmatically moving a player AABB into a known solid block.
-   **End-to-End (E2E) Tests (`Playwright`):**
    -   Simulate a user journey: load the page, move forward, destroy a block, place a block, verify the change.
    -   Take screenshots to check for rendering regressions.

#### **4.2. Deployment**
-   **Build Process:** Run `npm run build` using Vite. This will compile the TypeScript/React code, bundle all assets, and output a set of optimized static files (HTML, CSS, JS) into a `/dist` directory.
-   **Hosting:** The `/dist` directory can be deployed to any static web host.
    -   **Recommended:** Netlify or Vercel. Both offer seamless Git integration, continuous deployment, and a generous free tier.
    -   **Steps:**
        1.  Push the project to a GitHub repository.
        2.  Connect the repository to a new Netlify/Vercel site.
        3.  Configure the build command (`npm run build`) and the publish directory (`dist`).
        4.  Deploy.

---

### **5. Future Extensions**

1.  **Performance Optimization:**
    -   **Web Workers:** Offload chunk generation and meshing to a background worker thread to prevent freezing the main game loop.
    -   **Greedy Meshing:** Implement greedy meshing to significantly reduce the vertex count of chunk meshes.
2.  **Lighting & Atmosphere:**
    -   **Ambient Occlusion (AO):** Add subtle "contact shadows" in corners where blocks meet. This can be pre-calculated during the chunk meshing stage by checking occluding neighbors.
    -   **Skybox & Directional Light:** Add a skybox and a directional light to simulate a sun, casting simple shadows.
3.  **Advanced World Generation:**
    -   **Biomes:** Use a second noise map to define biomes (e.g., forest, desert), which would use different block palettes and terrain characteristics.
    -   **Caves & Structures:** Use 3D noise or other algorithms to carve out caves and place simple, pre-defined structures.
4.  **Multiplayer:**
    -   **Architecture:** A Node.js server with WebSockets (`ws` or `socket.io`) would act as the authoritative state manager.
    -   **State Sync:** The server would manage player positions and world state, broadcasting updates to all connected clients. Clients would send their inputs to the server for processing.

---

# **Web-Based Minecraft Clone: Complete Design & Implementation Plan**  
> *Prepared by an Experienced Game Development AI Architect*  

---

## **1. Technical Specification Document**

### **1.1 Overview**

This document defines a full technical blueprint for a lightweight, browser-based Minecraft-style 3D voxel game. The core goal is to deliver a functional, real-time interactive experience that mimics the fundamental mechanics of block placement and destruction in a procedurally generated voxel world. Built entirely for web deployment, the game emphasizes performance, extensibility, and usability on both desktop and mobile platforms.

The project follows a modular architecture with clear separation between data, rendering, input, and UI layers. It leverages modern web technologies to simulate a rich 3D environment while optimizing memory and rendering throughput via chunked geometry and mesh culling.

---

### **1.2 Core Features & Scope**

- **Procedural World Generation**: A heightmap-driven terrain system generates infinite flatland-like worlds using Perlin noise, divided into fixed-size chunks.
- **Dynamic Block Interaction**:
  - Left-click to destroy blocks within reach.
  - Right-click to place selected block types on adjacent faces.
- **First-Person Movement**: WASD for movement, mouse look for camera control, with collision against solid blocks.
- **Efficient 3D Rendering**: Only visible block faces are rendered per chunk using face culling techniques.
- **Minimal UI Overlay**:
  - Bottom-row block palette selector.
  - Center crosshair.
  - Current block indicator.
- **Extensible Architecture**: Designed to support future features like multiplayer, biomes, or tools.

---

### **1.3 Tech Stack Selection (Justified)**

| Layer | Technology | Justification |
|------|-----------|-------------|
| **Frontend Framework** | **React** | High component modularity, large ecosystem, excellent state integration with Redux. Preferred for structured UI development. |
| **State Management** | **Redux (with Redux Toolkit)** | Centralized, predictable state management essential for managing world changes, player state, and rendering updates. Enables time-travel debugging and scalable data flow. |
| **3D Rendering Engine** | **Three.js** | Industry-standard WebGL wrapper; extensive documentation, mature mesh and shader APIs, ideal for procedural geometry generation. Easier integration with React via `react-three-fiber` (if needed later). Babylon.js considered but rejected due to slightly steeper learning curve and less React synergy. |
| **Build Tool** | **Vite** | Superior dev-server speed, native ES module support, minimal configuration. Outperforms Webpack in HMR and startup time—critical for rapid iteration. |
| **Persistence (Optional)** | **IndexedDB** | More capable than `localStorage` for structured binary/object storage. Supports asynchronous operations and larger datasets, suitable for saving chunk grids and metadata. |
| **Physics & Collision** | Hand-rolled AABB logic | Avoid overhead of full physics engines (e.g., Cannon.js); simple collision with voxel-aligned blocks sufficient. |

---

### **1.4 Detailed Feature Descriptions**

#### **World Generation**
- **Algorithm**: Use Perlin noise to generate a 2D heightmap over a grid of chunks.
- **Chunk Size**: 16×16×16 blocks (configurable for future expansion).
- **Biome Simplicity**: Single biome initially—mix grass (top layer), dirt (below), stone (lower), and water (at Y=60 global).
- **Infinite Concept**: Generate new chunks as player moves outward (lazy loading in future). Initial version loads a 5×5 grid (25 chunks).

#### **Block Types**
Five core block types:
1. **Air (ID: 0)** – Empty space.
2. **Grass (ID: 1)** – Surface layer over dirt.
3. **Dirt (ID: 2)** – Below grass.
4. **Stone (ID: 3)** – Deep ground.
5. **Water (ID: 4)** – Shallow oceans at fixed elevation.

Each associated with texture coordinates from a 256×256 texture atlas (4×4 grid), where each tile = 64×64 px.

#### **Rendering Pipeline**
- **Mesh Per Chunk**: Each chunk generates one static `THREE.Mesh` with a custom `BufferGeometry` and shared material.
- **Face Culling**: Only render a face if adjacent block is air or outside bounds.
- **Geometry Generation**:
  - Iterate all non-air blocks in chunk.
  - For each face, check neighbor block (if null/air, add face vertices & UVs).
  - Use indexed faces to minimize vertex count.
- **Textures**: Shared material using a single `Texture` (atlas) and custom UV mapping per face.

#### **Player Controls**
- **Keyboard (WASD)**: Movement in XZ plane; speed capped.
- **Mouse Look**: Relative mouse mode (if enabled via pointer lock); pitch (Y-axis) limited to avoid gimbal lock.
- **Click Interaction**:
  - **Left**: Cast ray—destroy block on hit.
  - **Right**: Place block offset from hit face into free space.
- **Reach Distance**: 3 blocks maximum. Raycast performed at 0.1-block increments.

#### **Collision Detection**
- Player represented as AABB (0.6×1.8×0.6 units).
- On movement, predict next position and check all 8 vertical corners against block occupancy.
- If collision, clamp movement per-axis (sliding behavior).
- Ground detection: Check block directly under feet (Y−0.1) to allow jumping (planned later).

#### **UI System**
- 2D HTML/CSS overlay with React components.
- **Block Palette Bar**: Horizontal toolbar at screen bottom showing five block icons. Click to select active block ID.
- **Crosshair**: Centered `div` with border and background.
- **Active Block Indicator**: Small icon in corner reflecting current selection.

#### **Persistence (Optional)**
- Save entire world state (chunk map) to **IndexedDB**, key: `"world_v1"`.
- Load on game start if present.
- Auto-save delay: Debounced 500ms after any block change (to reduce I/O).

#### **Extensibility Hooks**
- Block registry as singleton `BlockRegistry` class: allows future plugins to add blocks.
- Chunk events: emit `'chunkChanged'`, `'chunkLoaded'`, etc.
- Modular phases: world gen → mesh gen → physics → input can be replaced or extended.

---

## **2. System Architecture Diagram**

```
┌──────────────────────────────────────────────────┐
│                   User Interface (React)         │
│  • Block Palette                                 │
│  • HUD Overlay (Crosshair, Indicator)            │
│  • Mobile Controls (Virtual Joystick - Phase 2)  │
└─────────────────────▲────────────────────────────┘
                      │ Dispatch Actions
                      │
         ┌────────────┴────────────┐
         │       Global State      │
         │      (Redux Store)      │
         │  • world: { chunks }    │
         │  • player: { pos, rot } │
         │  • ui: { selectedBlock }│
         └────────────┬────────────┘
                      │ Subscribes To Changes
                      │
         ┌────────────▼────────────┐
         │     Render Engine       │
         │       (Three.js)        │
         │  • Renderer & Scene     │
         │  • ChunkMeshManager       │
         │  • GeometryGenerator      │
         │  • TextureAtlasHandler    │
         └────────────┬────────────┘
                      │ Raycast Queries
                      │
         ┌────────────▼────────────┐
         │    Input Manager        │
         │  • KeyboardHandler       │
         │  • MouseLookHandler      │
         │  • PointerLockToggle     │
         │  • RaycastResolver       │
         └────────────┬────────────┘
                      │ Sends Events
                      │
         ┌────────────▼────────────┐
         │     World Data Layer    │
         │  • Chunk Manager         │
         │  • World Generator       │
         │  • Block Registry        │
         │  • Storage (IndexedDB)   │
         └─────────────────────────┘
```

### **Key Interfaces Between Layers**
- **Redux ↔ React UI**: State drives UI rendering; UI dispatches block selection actions.
- **Redux ↔ Input**: Input subscribes to player state and dispatches movement/interaction.
- **Input ↔ World**: Raycasting queries world data for block hits.
- **World ↔ Render**: Chunk changes trigger mesh regeneration.
- **World ↔ Storage**: Asynchronous save/load of chunk map.

---

## **3. Implementation Plan (2-Week Roadmap)**

| Sprint | Duration | Milestone | Key Tasks | Time Estimate | Risks & Mitigation |
|-------|----------|---------|-----------|---------------|---------------------|
| **1** | Day 1–2 | Project Bootstrap | • Initialize Vite + React project.<br>• Install Three.js, Redux Toolkit.<br>• Set up basic scene with camera, light, renderer.<br>• Render a placeholder cube. | 16 hrs | *Risk*: Build config issues.<br>*Mitigation*: Use Vite template with Three.js. |
| **2** | Day 3–4 | World Data & Generation | • Define `Chunk` class (16³ grid).<br>• Implement Perlin noise terrain generator (using `simplex-noise.js`).<br>• Build `World` class; generate 5×5 chunks.<br>• Define `BlockRegistry` with 5 types. | 16 hrs | *Risk*: Noise artifacts.<br>*Mitigation*: Normalize noise output and clamp height range. |
| **3** | Day 5–7 | Voxel Rendering Engine | • Write `GeometryGenerator` for chunk meshes.<br>• Implement face culling algorithm.<br>• Load texture atlas; assign UVs.<br>• Batch chunk meshes; update on world change.<br>• Implement `ChunkMeshManager` to handle updates. | 24 hrs | *Risk*: Poor performance with many meshes.<br>*Mitigation*: Merge chunk geometries, avoid per-block meshes. |
| **4** | Day 8–9 | First-Person Controls | • Implement `WASD` state tracking.<br>• Add `PointerLockControls` (mouse look).<br>• Integrate with player position/rotation in Redux.<br>• Add AABB collision: raycast down for ground, check corners on move. | 16 hrs | *Risk*: Janky movement.<br>*Mitigation*: Use delta-time smoothing and fixed speed cap (5 units/sec). |
| **5** | Day 10–12 | Block Interaction System | • Implement raycast from camera to max distance.<br>• Detect hit face and block coordinate.<br>• Dispatch actions to destroy/place blocks.<br>• Update chunk data and trigger mesh regeneration.<br>• Implement neighbor chunk checks for face culling update. | 24 hrs | *Risk*: Mesh update lag.<br>*Mitigation*: Debounce heavy regeneration; use worker threads (post-MVP). |
| **6** | Day 13  | UI & HUD Implementation | • Build block palette component (React).<br>• Add active block indicator.<br>• Implement crosshair.<br>• Connect UI to Redux store. | 8 hrs | *Risk*: UI blocks rendering.<br>*Mitigation*: Use lightweight HTML overlay with `position: fixed`. |
| **7** | Day 14  | Persistence & Polish | • Implement IndexedDB save/load of chunk map.<br>• Add debounced auto-save on block change.<br>• Test on mobile: touch controls via buttons (optional).<br>• Optimize memory: unload distant chunks.<br>• Bug squash, performance check. | 16 hrs | *Risk*: IndexedDB async race.<br>*Mitigation*: Throttle saves, use transaction queues. |

> **Total Estimated Effort**: ~120 hours (≈2 weeks full-time).

---

## **4. Testing Strategy**

### **Unit Tests (Jest + React Testing Library)**
- **World Generation Test**:
  - Verify heightmap returns plausible Y values (e.g., 50–70).
  - Test water layer placement at correct offset.
- **Chunk Logic Test**:
  - Confirm block set/get within bounds.
  - Ensure out-of-bounds access returns air (0).
- **Raycast Logic Test**:
  - Simulate ray hitting cube face; verify correct block and normal.
  - Validate block placement on opposite face works.
- **Collision Test**:
  - Simulate player moving into solid block; ensure position is corrected.
  - Test sliding behavior on diagonal wall.

### **End-to-End Tests (Cypress)**
- **User Interaction Flow**:
  - Start game → ground appears → player can move.
  - Left-click near block → block disappears.
  - Right-click on face → new block appears.
  - Selected block changes → next placement uses correct type.
- **Persistence Test**:
  - Place blocks → reload page → verify world state restored.

### **Performance Testing**
- Monitor FPS in Chrome DevTools with 25+ chunks.
- Check memory usage after 100+ block edits.
- Use `THREE.Mesh.frustumCulled = true` to prevent offscreen rendering.

---

## **5. Deployment Guide**

### **Build Process**
```bash
npm run build
# Output: /dist folder with static assets
```

### **Hosting Options**
| Platform | Setup |
|--------|-------|
| **Netlify** | Drag-and-drop `/dist`; set publish directory. Auto SSL, CDN, and atomic deploys. |
| **Vercel** | Connect Git repo; auto-deploys on push. Optimized for React+Vite. |
| **GitHub Pages** | Push `/dist` to `gh-pages` branch. Use `ngrok` for local testing. |

### **Requirements**
- Modern browser (Chrome, Firefox, Safari, Edge) with WebGL2 support.
- Pointer Lock API enabled (user click to engage mouse look).

---

## **6. Sample Data Files**

### **Block Palette (JSON)**
```json
{
  "blocks": [
    {
      "id": 0,
      "name": "air",
      "solid": false,
      "texture": null
    },
    {
      "id": 1,
      "name": "grass",
      "solid": true,
      "texture": { "top": [1,0], "side": [2,0], "bottom": [2,1] }
    },
    {
      "id": 2,
      "name": "dirt",
      "solid": true,
      "texture": { "all": [2,1] }
    },
    {
      "id": 3,
      "name": "stone",
      "solid": true,
      "texture": { "all": [0,1] }
    },
    {
      "id": 4,
      "name": "water",
      "solid": false,
      "transparent": true,
      "texture": { "all": [3,0] }
    }
  ]
}
```

### **Texture Atlas Layout (256×256)**
```
[0,0]=Stone     [1,0]=GrassTop  [2,0]=DirtSide  [3,0]=Water
[0,1]=Stone     [1,1]=GrassSide [2,1]=Dirt/DirtBot [3,1]=Sand
[0,2]=Bedrock   [1,2]=Cobble    [2,2]=Planks      [3,2]=Glass
[0,3]=IronOre   [1,3]=GoldOre   [2,3]=DiamondOre  [3,3]=Lava
```
- UV coordinates normalized: e.g., `[1,0]` → U: 0.25–0.5, V: 0.75–1.0.

---

## **7. Additional Considerations (Future Expansion)**

| Feature | Description | Implementation Notes |
|--------|-----------|-----------------------|
| **Multiplayer** | Add real-time sync via WebSocket | Server: Node.js + Socket.IO. Sync only block deltas. Use authoritative server model. |
| **Inventory & Crafting** | GUI-based inventory with crafting grid | Add `Inventory` slice in Redux. Drag-and-drop UI with React DnD. |
| **Biomes** | Region-based terrain variation | Noise blending (temperature/rainfall). Map biomes to block rules and colors. |
| **Lighting System** | Day/night cycle + block light | Per-chunk light map (byte array). Propagate light from sun (Y=255) downward. |
| **Performance Optimization** | For larger worlds | • Implement frustum culling.<br>• Stream chunks near player.<br>• Use Web Workers for mesh generation. |
| **Mobile Touch Support** | Virtual joystick and tap-to-interact | Use `react-joystick-component`. Two-finger tap for alternate action (e.g., menu). |
| **Modding API** | Allow custom scripts or blocks | Expose `BlockRegistry.register(...)` API. Load mods from JSON config. |

---

## **Final Notes**

This specification delivers a complete, production-grounded plan for a high-quality web-based voxel game. It prioritizes:
- **Performance** via chunked culling and batching.
- **Stability** through typed data and Redux state integrity.
- **Scalability** using event-driven architecture.
- **Cross-platform usability**, with mobile readiness via overlays.

The outcome will be a compelling, interactive 3D environment suitable for demos, educational use, or as a foundation for a full survival-crafting game.

Deployment is straightforward, and testing ensures robustness. Future enhancements are clearly scoped and modular.

**End of Document**

Certainly! Below is a comprehensive, code‑free technical specification and development plan for a web-based Minecraft-style clone, strictly following your prompt and requirements.

---

# 1. Technical Specification

## 1.1 Goal

Create a minimal, performant Minecraft-style game running in the browser, focused on:

- Procedurally generated 3D terrain (simple heightmap)
- Real-time block creation (placement) and destruction (removal)
- Chunked world storage
- Basic first-person controls (WASD + mouse look)
- Collision detection and physics (no gravity, ground collision)
- Minimal UI for block selection

**Technology Stack:**

- **Rendering:** Three.js (WebGL)
- **UI Framework:** React
- **State Management:** Redux
- **Build Tool:** Vite
- **Persistence (optional):** IndexedDB (browser local)
- **Browser Compatibility:** Desktop (primary), Mobile (optional touch controls for later sprints)

---

## 1.2 Core Features

### A. Procedural World Generation
- Uses Perlin or Simplex noise for generating a 2D heightmap that is mapped to a 3D grid of voxels.
- The world is divided into “chunks” (each 16x16x16 blocks for memory/performance).

### B. Block System
- Palette of at least 5 block types: grass, dirt, stone, water, wood.
- Each block has a unique ID, texture atlas coordinates, and a solidity property.

### C. Rendering
- Only visible block faces are rendered (faces exposed to air).
- Each chunk is rendered as a single mesh generated from its solid faces.
- Uses texture atlas mapping for efficiency.
  
### D. Player & Controls
- WASD movement and mouse for first-person look.
- Player can walk but not jump or fly.
- Mouse controls: Left-click to destroy, right-click to place a block within reach (3 blocks), block type comes from current selection in block palette.

### E. Interaction & Physics
- Raycast from camera under cursor determines block selection/add/removal.
- Collisions checked via AABB against world voxels—player cannot pass through blocks.

### F. User Interface
- Minimal HUD with crosshair, block palette (selectable bar), and current block indicator.
- HUD overlays on 3D scene.

### G. Persistence (Optional)
- Local storage of world/chunk data via IndexedDB for return visits/sessions.

---

# 2. System Architecture Diagram

```
┌────────────────────────────┐
│       User Interface       │
│  (React UI Components; HUD │
│   Block Palette, etc)      │
└───────────────┬────────────┘
                │
      ┌─────────▼────────┐
      │    Redux Store   │
      │(Player, World,   │
      │ UI State, etc)   │
      └────────┬─────────┘
               │
      ┌────────▼──────────┐
      │ World Management  │
      │(Chunk Data, Block │
      │ Palette, Noise)   │
      └────────┬──────────┘
               │
      ┌────────▼──────────┐
      │   Three.js Engine │
      │(Mesh Gen, Chunk   │
      │ Rendering, Atlas) │
      └────────┬──────────┘
               │
      ┌────────▼──────────┐
      │    Input Handler  │
      │(WASD, Mouse,      │
      │ Raycasting)       │
      └────────┬──────────┘
               │
      ┌────────▼──────────┐
      │Persistence (Opt.) │
      │(IndexedDB)        │
      └───────────────────┘
```

---

# 3. Data Structures

| Data Entity      | Structure/Format                        | Description                                              |
|------------------|----------------------------------------|----------------------------------------------------------|
| **Chunk**        | 3D array: `[x][y][z] → blockID`        | 16x16x16 per chunk; stores block ID at each position     |
| **Block Palette**| Map: `blockID → {type, texCoord, solid}` | Core dictionary for block metadata and rendering         |
| **World Map**    | Map: `chunkCoord → Chunk`              | Allows dynamic loading/unloading, supports large worlds  |
| **Player State** | `{position, rotation, velocity}`        | Controls movement, camera look, interaction              |
| **UI State**     | `{selectedBlockID}`                     | Which block is currently selected for placement          |

---

# 4. Algorithms

## 4.1 Chunk Generation
- On chunk load, generate perlin noise-based heightmap.
- Fill from bottom up:
  - Stone for deep levels.
  - Dirt for mid-levels.
  - Grass for surface.
  - (Optional) Water on low spots.

## 4.2 Chunk Mesh Building (Face Culling)
- For each block in the chunk:
  - If solid, for each face (6 directions):
    - Add to mesh only if adjacent block is empty.
- Store chunk mesh as one geometry per chunk for performance.

## 4.3 Player Interaction (Raycasting)
- On mouse click:
  - Project ray from camera through crosshair.
  - Step through world at small intervals to find first solid block.
  - Record the block hit and its face normal.

## 4.4 Block Place/Destroy Logic
- **Destroy:** Set blockID to zero (“air”) at hit position; update mesh.
- **Place:** Add block at adjacent position (in face-normal direction); update mesh.
- Notify and update only affected chunks.

## 4.5 Collision Handling
- Player bounding box checked against adjacent solid blocks each frame.
- If overlap detected, movement/position is clamped.

## 4.6 UI and Persistence
- Block palette shown in UI; selection updates current placement type.
- All chunk modifications are serialized and stored using IndexedDB.

---

# 5. Design Diagrams

## 5.1 Class/Data Diagram (Textual)

- **WorldManager**
  - Holds: Map of `chunkCoord → Chunk`
  - Methods: `loadChunk`, `unloadChunk`, `getBlock`, `setBlock`, `saveChunk`

- **Chunk**
  - Holds: 3D array of block IDs, current mesh object

- **Renderer**
  - Methods: `buildChunkMesh(chunk)`, `updateChunkMesh(chunk)`, `applyTextureAtlas()`

- **Player**
  - Fields: position (Vec3), rotation (Euler), velocity, bounding box
  - Methods: `move`, `look`, `interact`

- **BlockPalette**
  - Map: `blockID → {type, texCoord, solid}`

- **UI State**
  - selectedBlockID

## 5.2 Player State Diagram

```
Idle ──────► Moving ─────────► Interacting
  ▲             │                │
  └─────────────┴────────────────┘
```
- **Idle:** No movement input
- **Moving:** WASD input determines direction and speed (momentum can be ignored)
- **Interacting:** Raycasting and block placement/destruction actions

---

# 6. Implementation Plan & Roadmap

**2-Week Sprint Plan (10 days + 4 buffer/fix days)**

| Day | Tasks                                                                                 |
|-----|---------------------------------------------------------------------------------------|
| 1   | Set up Vite + React + Redux basic project scaffold (lint/test/format tooling).        |
| 2   | Integrate Three.js, create basic viewport, render test cube.                          |
| 3   | Design core data structures (Chunk, Block Palette). Build chunk generation module.     |
| 4   | Implement noise-based terrain for single chunk. Add block palette & texture atlas.    |
| 5   | Expand to multi-chunk world, chunk loading/unloading.                                 |
| 6   | Implement chunk mesh generator with face culling. Basic chunk rendering pipeline.      |
| 7   | Basic player controller (WASD movement, mouse look). Add AABB ground collision.        |
| 8   | Implement block raycasting for selection, removal, and placement (interaction logic). |
| 9   | Build minimal UI overlay (block palette, crosshair, selection).                       |
| 10  | Playtest, refine controls, chunk boundaries, and fix critical edge-cases.             |
| 11-13 | Optional tasks: persistence via IndexedDB, mobile/touch support.                    |
| 14  | Polish UI, optimize rendering, comprehensive bug fixes, prepare for deployment.       |

**Time Estimates:**

- Core system (days 1–10): ≈80–90%
- Optional/polish (days 11–14): buffer for optimization/testing/fixes

---

# 7. Sample Data Files

## 7.1. Block Palette (`block_palette.json`)
```json
[
  {"id": 1, "type": "grass", "texCoord": [0,0], "solid": true},
  {"id": 2, "type": "dirt", "texCoord": [1,0], "solid": true},
  {"id": 3, "type": "stone", "texCoord": [2,0], "solid": true},
  {"id": 4, "type": "water", "texCoord": [3,0], "solid": false},
  {"id": 5, "type": "wood", "texCoord": [4,0], "solid": true}
]
```

## 7.2. Texture Atlas Plan

- Single PNG (5 block textures, each 16x16 or 32x32 pixels)
- Arrange as a horizontal strip
- Map block types to UV coordinates using `texCoord` from palette

---

# 8. Testing & Deployment Strategy

## 8.1 Unit Tests

- **World Generation:** Validate output chunks for consistent heightmap; assert no invalid block IDs.
- **Mesh Generation:** Test that chunk mesh only contains faces adjacent to empty space.
- **Block Interaction:** Simulate raycasts, confirm correct block selection/removal/placement.

## 8.2 End-to-End Tests

- Simulate user actions (WASD + mouse); check world updates as expected.
- Assert correct block palette changes via UI.
- Regression tests for chunk boundaries and block persistence.

## 8.3 Deployment Guide

- **Build:** Use `vite build` for optimized static output.
- **Hosting:** Deploy to Netlify, Vercel, or any static hosting.
- **Recommended:** Automatic deploys from `main` branch.

---

# 9. Optional Extensions (Future Work)

- **Multiplayer:** Add Node.js server with WebSocket for world synchronization and multi-user editing.
- **Advanced Biomes:** Multiple terrain/weather generators; distinct palettes per biome.
- **Lighting:** Model per-face/vertex lighting, dynamic sunlight; simple torch block type.
- **Inventory/Crafting:** Basic drag-and-drop inventory management UI.
- **Performance:** Asynchronous chunk streaming, frustum/LOD culling for vast worlds.
- **Mobile:** Touch controls, screen-size adaption.
- **Jump/Fly:** Add vertical navigation and gravity.

---

**End of Design Specification**

──────────────────────────────────────────────  
Web Voxel Engine – Complete Design & Roadmap  
──────────────────────────────────────────────  

The following document is intended as the sole hand-off between the specification writer and the eventual implementation team.  
No code is included.  Every required decision, data shape, algorithm, timeline, risk and test case is enumerated.

================================================================================
1.  Vision Card  
“Build a minimal browser FPS Voxel World.”  
Target Experience: A player spawns on a smooth hill.  They look around (mouse), walk (WASD), destroy blocks (left-click) and place blocks (right-click).  No crafting, no terrain streaming, no day-night cycle.

================================================================================
2.  Technology Pack  
2.1 Final Selections  
• Rendering engine … Three.js r155  
• UI framework ……… React 18  
  ‑ State container … Redux Toolkit  
• Build toolchain …… Vite  
• Persistence……….. IndexedDB via [Dexie]  
2.2 Rationale  
Three.js has the largest set of voxel examples.  
React+Vite gives HMR out of the box for ergonomic iteration.  
IndexedDB is asynchronous and zero-config for the user.

================================================================================
3.  Functional Requirements (ordered by priority)  
P0-USR-1  First-person navigation with discrete jump + gravity.  
P0-USR-2  Height-map terrain of at least 16 × 16 chunks (256 × 256 world).  
P0-USR-3  Minimum palette {Grass, Dirt, Stone, Log, Leaves}.  
P0-USR-4  Frustum-culled meshing of world.  
P0-USR-5  Left-click to break, right-click to place.  
P0-USR-6  Basic AABB collision – player may not phase into blocks.  
P1-USR-1  Icon bar for block selection (number keys 1-5).  
P1-USA-2  Persistent saves – every user has one world slot.  

================================================================================
4.  Non-functional Requirements  
NF-1  60 FPS desktop / 30 FPS phone (Moto G6).  
NF-2  First meaningful paint ≤ 3 s on 4G.  
NF-3  No blocking asset loads during gameplay.  
NF-4  Codebase must support later addition of biomes + multiplayer with < 10 % refactor.  

================================================================================
5.  Conceptual Architecture  

┌──────────────────────────┐  
│   Presentational Layer   │ React components (crosshair, block bar)  
└──────────┬───────────────┘  
           │ Flux actions  
┌──────────▼───────────────┐  
│    Redux Store Layer     │  {chunks, player, selections}  
└──────────┬───────────────┘  
           │ synchronous reads & batched writes  
┌──────────▼───────────────┐  
│   Simulation / Logic     │  chord.js           – world math  
│   voxelcast.js          – ray intersection   │  
│   collision.js          – AABB               │  
└──────────┬───────────────┘  
           │ mesh diff commands  
┌──────────▼───────────────┐  
│  Rendering Kernel        │ three.js scene  
│     • chunk meshes       │  
│     • texture atlas      │  
└──────────┬───────────────┘  
           │ binary glTF + 2048² atlas  
┌──────────▼───────────────┐  
│    Persistence Index     │ IndexedDB  
└──────────────────────────┘  

================================================================================
6.  Data Contract  

6.1 Chunks  
struct ChunkId = string “x_y_z” (decimal, origin at 0)  
struct Chunk = DenseUint16Array of length (WHC=16³)  
               0 = air, 1..N = material index  
compression: brotli byte buffer with pairing zeros → 1 kB avg  
storage key:  world_slot + chunk_id

6.2 Actor-Player  
interface PlayerState {  
   ‑ position: [x,y,z] ∈ ℝ³  
   ‑ rotation: [yaw,pitch] ∈ [-π,π] and [-½π,½π]  
   ‑ selectedSlot: 0..4  
}

6.3 Material Palette  
[
  { id: 1, name: "grass",  diffuseUvTop:[0,0], diffuseUvSide:[1,0], isSolid:true, breakTime:0.5 },
  { id: 2, name: "dirt",   diffuseUv:[0,1], … },
  ...
]

Texture atlas size: 16×16 tiles, 32 px each → single 512×512 png  
Matching glTF extension: KHR_texture_transform

================================================================================
7.  Key Algorithms in Isabelle-style prose  

7.1 Chunk Generation  
GenChunk(id c) =  
   Let base = id.c.xz as int  –  chunk top-left is o=(c.x*16, 0, c.z*16)  
   Let m[x][z] = round( 16 * Perlin(base.x + x/40, base.z + z/40) + 48 ) for x,z in 0..15  
   build buffer  
   for x,z,y  0..127  
     if y = m[x][z]   set voxel = grass  
     else if y < m[x][z]-3  set voxel = stone  
     else if y < m[x][z]    set voxel = dirt  
     else set 0

7.2 Mesh Generation (Greedy-Mesh w/ face culling)  
GreedyMesh(chunk) =  
   Direction = [+X,-X,+Y,-Y,+Z,-Z]  
   For each direction d  
      Start sweep-plane projection  
      Merge contiguous width×height regions  
      Emit one quad per merged rectangle  
   Total quad count ≤ 3 faces × exposed surface

7.3 Interaction Pipeline  
Ray origin = camera.worldPosition  
Ray direction = camera.getWorldDirection  
while step ≤ reach (5 voxels)  
   voxel = floor(origin + direction·step)  
   if worldLookup(voxel) ≠ 0 → return {voxel, face = sign(direction)}  
   else step += 0.1 voxels  

Placement = voxel + face.normal  
Blocked = worldLookup(placement) ≠ 0  
If !blocked   dispatch(placeAction)  
Break      dispatch(removeAction)

7.4 Collision  
Gravity dy = -0.02 m/tick  
For each axis in [x,z] – discrete, for Y continuous:  
   proposed = playerPosition + vel  
   candidateBlocks = floor(proposed) plus three auxiliary blocks  
   If AABB intersection with any solid block  
      undo move on that axis and set velocity axis to 0  

================================================================================
8.  Asset Plan  

Size          Format   Purpose  
512×512 png   atlas    diffuse  
16×8 png      ui       hotbar icons  
3 files       glTF     dummy cube meshes for potential future blocks  
www/sfx/      Ogg Vorbis 2 x short breaking / placing sound (optional, non-critical)  

================================================================================
9.  Dev-Tooling  

Enhance Vite plugin “vite-plugin-glsl” to compile small WGSL shaders for occlusion queries in a future sprint.  
Dev storybook for all block models, hot-reloaded.

================================================================================
10.  Two-Week Sprint Schedule  

Day 0   Kickoff, CI setup, branch policy (trunk-base).  
Sprint 1 – World Foundations  
  D1    Finalise palette & atlas.  Create compressed RGBA png.  
  D2    Shape Redux slice “chunks” and reducer contract.  
  D3    Implement ChunkArray class – indexed mapping from {x,y,z} to flat index.  
  D4    Inject Perlin noise simplex-fn.  Height-maps deterministically seeded.  
  D5    Bind IndexedDB driver with Dexie schema version 1.  
  D6    Create unit tests: chunk gen produces same bytes given same seed.  
  D7    Code review + merge.

Sprint 2 – Rendering & Interaction  
  D8    Texture loader (promise-queue for atlas).  
  D9    GreedyMesh implementation – assert max 4,000 triangles per chunk in stress test.  
  D10   Hook React root, mount Three scene, append single flat terrain (4×4 chunks)  
  D11   FPS camera controller – PointerLock + raw mouse deltas.  
  D12   Ray-cast interaction & action dispatch layer.  
  D13   AABB collision – unit tests in Jest with snapshots.  
  D14   Polish: shadow bias, fog, hotbar UI component, sound hooks.  
  D15   Non-functional performance profiling (Chrome FPS meter).  
  D16   Freeze “v0.1-release” and generate changelog.

================================================================================
11.  Test Strategy  

Unit Tests (Jest)  
• chunk generation invariant – random seed symmetry  
• mesher finds identical face count for mirrored voxel pair  
• reducer turns mutation strings into correct new chunk byte buffer  

Render Tests (Playwright)  
• FPS ≥ 30 during 64-chunk pan test on 1440×900.  
• Left-click ray-cast hits only visible front-face, not back-face.

Manual QA Checklist (release candidate)  
☐ Android Chrome hardware back navigates without crash.  
☐ iPhone 12 pointer-lock fallback graceful when denied.

================================================================================
12.  Deployment Guide  

Build & Publish:  
npm run build  
vite preview  (compression brotli, hashed assets)  
push-dir dist to GitHub Pages (no server needed).  
Game save still works, uses indexedDB at user agent domain path.  
Empty PR branch preview via Netlify with “deploy preview” checklists.

================================================================================
13.  Expandability Hooks – Non-breaking Future Work  

• P2-Net    WebRTC mesh w/ Yjs CRDT.  Chunk diff events already align.  
• P2-Light  Add sunlight flooding pass simply by tagging face quads with lightLevel.  
• P2-Biomes Chunk generator modulo key “floor((cx/4)^2 + (cz/4)^2) % 4” as biome index.  
• P2-Mod    Swap GreedyMesh for Transvoxel/voxel-lod without touching Redux slice.

================================================================================
14.  Roadmap Acceptance Definition of Done  

All P0 requirements functional, passing tests, landing page playable in Chrome and Safari without configuration.  
Add “/demo” shareable URL feed for social media launch.

================================================================================
End of Specification

Deliverable 1: Technical Specification

1. Purpose and scope
- Build a minimal, performant, web-based Minecraft-style voxel sandbox with terrain, first-person navigation, and real-time block placement/removal.
- Target devices: Modern desktop browsers (Chrome, Edge, Firefox, Safari) with optional mobile support.
- Focus on core loop: explore, place, destroy.

2. Technology choices and rationale
- Rendering: Three.js
  - Mature ecosystem, straightforward mesh management, widely adopted, ideal for custom meshing and texture atlases.
- UI framework: React
  - Predictable component model, broad ecosystem, pairs well with Redux, widely understood by web teams.
- State management: Redux Toolkit
  - Reliable, predictable app state management, middleware-friendly (e.g., for persistence and worker message handling).
- Build tool: Vite
  - Fast dev server, ES module support, good DX for Three.js projects, easy code splitting.
- Persistence (optional): IndexedDB via a minimal wrapper
  - Stores chunk diffs and player state without server dependencies. Can be replaced by Node.js + Express later for server persistence.

3. Core features
- Procedural terrain
  - Seeded 2D noise heightmap, deterministic per seed; chunked world representation; basic biome-like layering via simple thresholds.
- Voxel interaction
  - Left click to destroy blocks within reach; right click to place blocks of selected type on the targeted face.
- First-person controls
  - WASD movement; mouse look with pointer lock; no gravity in v1 (player rests on the ground and cannot pass through solid blocks).
- Collision detection
  - AABB for player; block-solid checks against nearby voxels; axis-separated resolution; step climbing disabled initially.
- Rendering
  - Chunk-based meshes with face culling; texture atlas for blocks; per-chunk mesh re-builds on edits; frustum culling using Three.js camera frustum.
- Minimal UI
  - Crosshair; block selection palette; selected block indicator; basic settings overlay (seed entry, render distance) as a non-blocking dialog.

4. Performance targets
- Desktop: 60 FPS at 5×5 chunks around the player (each chunk 16×16×16), on mid-range hardware.
- Initial load under 3 seconds on broadband, including asset fetch and first chunk generation.
- Memory ceiling: Under 500 MB in typical play session with default render distance (configurable).

5. Platform constraints and compatibility
- WebGL 1 baseline with progressive enhancement for WebGL 2 where available.
- Input: pointer lock for mouse; fallback touch scheme on mobile (virtual stick + look area) when enabled.
- Accessibility: rebindable keys planned; sensitivity sliders; color-blind friendly UI palette; UI readable at 125% zoom.

6. Block palette and behaviors (initial)
- Block IDs and properties:
  - 0: Air; transparent; non-solid; not rendered.
  - 1: Grass; top texture grass, side texture grass-side, bottom dirt; solid; opaque.
  - 2: Dirt; solid; opaque.
  - 3: Stone; solid; opaque.
  - 4: Sand; solid; opaque.
  - 5: Wood; solid; opaque; uniform texture.
  - 6: Water; semi-transparent; non-solid; rendered as simple translucent block; not simulated (no flow) in v1.
- Palette extensibility with unique ID, atlas coordinates, isSolid, isTransparent.

7. World model
- Coordinate system:
  - Right-handed, Y-up. World coordinates are floats in meters; voxel grid coordinates are integers in block units (1 meter per block).
- Chunk sizing:
  - 16×16×16 blocks (x, y, z). Indexed by chunk coords (cx, cy, cz), each an integer representing chunk position in chunk space.
- World extents:
  - Infinite conceptually; practically streamed around the player using a render radius measured in chunks (default 5 in xz, y limited to 2).

8. Persistence and determinism
- World seed determines terrain; noise function deterministic for given seed.
- Persistence saves only user modifications (overrides) per chunk in IndexedDB.
- Save scope: player position/rotation, selected block ID, modified chunk diffs keyed by chunk coordinate.

9. Multithreading (optional but recommended early)
- Web Worker(s) for chunk generation and meshing to avoid blocking the render thread.
- Communication via postMessage with structured payloads (generate chunk at coord, return block data, return mesh buffers).
- Main thread handles rendering and input; workers handle noise, voxel data filling, and mesh face building.


Deliverable 2: System Architecture Diagram (ASCII)

High-level architecture

┌─────────────────────────────────────────────────────────────────┐
│ React UI                                                        │
│ • HUD (crosshair, block picker, settings)                       │
│ • Debug overlays (FPS, chunk count)                             │
│ • Redux-connected components                                    │
└───────────────▲─────────────────────────────────────────────────┘
                │
        Redux Store (app state, player state, settings)
        • Reducers: player, ui, world-index, inventory
        • Actions: selectBlock, setSeed, setRenderRadius, etc.
                │
                ▼
┌─────────────────────────────────────────────────────────────────┐
│ Game Runtime                                                    │
│ • Scene/Renderer (Three.js)                                     │
│ • Camera and Input Controller                                   │
│ • Physics & Collision                                           │
│ • World Controller (chunk load/unload, mesh add/remove)         │
│ • Raycasting & Interaction                                      │
└───────────────▲─────────────────────────────────────────────────┘
                │                           ▲
                │                           │
                ▼                           │
     World Data Layer                        │
     • Chunk registry (in-memory)            │
     • Chunk cache (IndexedDB diffs)         │
     • Seeded terrain generator              │
     • Mesher (face culling, atlas UVs)      │
                │                            │
                ▼                            │
         Web Workers (optional)              │
         • Generate voxel data               │
         • Build mesh buffers                │
                │                            │
                ▼                            │
       Persistence (IndexedDB)               │
       • Save/load modified chunks,          │
       • Save player meta                    │
                                             │
                       Rendered Meshes (Three.js scene graph)
                       • One mesh per chunk
                       • Material uses texture atlas

Core data flow
- Input events → Player controller → Camera transform → Raycast/physics → World edits → Chunk re-mesh → Three.js scene update → Render
- Player movement triggers chunk management → Load/generate chunks in radius → Mesher produces geometry → Renderer attaches/detaches meshes.


Class/component diagram (conceptual)

- WorldController
  - Responsibilities: Chunk lifecycle, worker coordination, scene attachment, frustum culling.
  - Knows: ChunkRegistry, Mesher, TerrainGenerator, Persistence.

- ChunkRegistry
  - Responsibilities: Store chunks by coordinate; track dirty/modified flags; expose queries for block get/set.
  - Contains: Chunk objects.

- Chunk
  - Data: 3D block ID array, dirty flags, version.
  - Methods: getBlock, setBlock, serializeDiff.

- TerrainGenerator
  - Responsibilities: Heightmap noise, biome thresholds, initial block layering rules.

- Mesher
  - Responsibilities: Build visible faces; compute UVs from atlas; build normals; optional greedy meshing later.

- PlayerController
  - Responsibilities: Input mapping, movement vectors, collision checks, raycast origin/direction.

- Physics
  - Responsibilities: AABB vs voxel collision checks; axis-separated resolution; ground detection.

- InteractionSystem
  - Responsibilities: Raycast voxel traversal (DDA), block hit detection, placement/destroy actions.

- UI (React + Redux)
  - Components: HUD, BlockPicker, SettingsPanel, Debug.
  - State: Selected block, sensitivity, render distance, seed.

- Persistence
  - Responsibilities: Load/save player meta and chunk diffs; background save on changes.


Player state diagram

[Idle] → (W/A/S/D input) → [Walking]
[Walking] → (no input) → [Idle]
[Any] → (left click target in reach) → [Destroying] → (action complete) → [prior state]
[Any] → (right click target face) → [Placing] → (action complete) → [prior state]
[Any] → (menu open) → [UI-Focused] → (menu closed) → [prior state]


Deliverable 3: Detailed Implementation Plan With Timelines (2 weeks)

Assumptions
- 1–2 developers, 10 working days, ~6–7 focused hours per day.
- Workers and mobile are scoped as optional unless time allows.

Day 1: Project setup
- Initialize Vite + React + TypeScript (types improve safety even without code in this spec).
- Add Three.js, Redux Toolkit, and basic app scaffolding.
- Set build targets and lint/format tools; define directory structure:
  - src/engine (rendering, world, physics)
  - src/ui (React components)
  - src/state (Redux slices)
  - src/workers (optional)
  - assets/textures (atlas source tiles)
- Acceptance: App loads blank Three.js scene with camera and render loop; Redux store hooked to React.

Day 2: Camera, input, and pointer lock
- Implement FPS camera controller with WASD and mouse look.
- Add crosshair and simple HUD.
- Acceptance: Smooth camera movement and look; pointer lock works; FPS counter displayed.

Day 3: Data model for chunks and palette
- Define Chunk data structure and registry; implement palette definitions and atlas plan.
- Implement coordinate conversion functions (world ↔ chunk ↔ voxel).
- Acceptance: Can create empty chunks and query/set blocks in memory.

Day 4: Terrain generator (noise-based)
- Implement seeded 2D noise heightmap; map to simple stratification (stone below, dirt, grass top).
- Generate initial set of chunks in a small radius around player.
- Acceptance: Console-inspectable chunk contents; reproducible with same seed.

Day 5: Mesher (face culling) and texture atlas integration
- Implement per-chunk mesh generation:
  - Iterate voxels; add faces only where neighbor is empty or transparent.
  - Assign UVs from atlas coordinates; build Three.js mesh data.
- Attach meshes to scene; add basic directional light and ambient light.
- Acceptance: Terrain visible with expected textures; no faces between solid neighbors.

Day 6: Chunk management and frustum/render radius
- Manage active chunks based on player position; load/generate within radius; unload outside radius.
- Add frustum culling using camera frustum for further optimization.
- Acceptance: Moving through the world creates/destroys chunk meshes smoothly; FPS stable at default radius.

Day 7: Raycasting and block interaction
- Implement voxel DDA ray traversal from camera.
- Detect first solid block hit within reach; compute face normal and target position for placement.
- Wire up left click (destroy) and right click (place); update chunk data and trigger re-mesh on affected chunks (including neighbor if border touched).
- Acceptance: Can reliably place and destroy blocks within 3 units; visuals update instantly.

Day 8: Collision and basic physics
- Implement player AABB; check collisions against solid voxels in player’s vicinity.
- Axis-separated resolution; keep player above ground; disable gravity in v1 (grounding by collision).
- Acceptance: Cannot walk through blocks; can slide along surfaces; stable positioning at terrain surface.

Day 9: UI polish and block palette picker
- Implement block picker (bottom bar with selectable entries).
- Display selected block in HUD; add options overlay for seed and render distance.
- Acceptance: Selecting a block changes placement type; UI responsive on typical laptop resolutions.

Day 10: Persistence (optional) and optimization pass
- IndexedDB storage of modified chunk diffs and player meta; auto-save on changes and at intervals.
- Micro-optimizations: object pooling for meshing arrays, reduce allocations, ensure texture atlas is power-of-two and mipmapped.
- Acceptance: Reloading page restores player position and edits; performance at targets on desktop.

Stretch goals (if time allows)
- Web Workers for generation and meshing.
- Simple mobile control scheme toggle with virtual joystick and look region.
- Greedy meshing to reduce face count by merging coplanar faces within chunks.
- Water rendering as simple translucent quads with depth write disabled.

Risks and mitigations
- Mesh rebuild stutter: Move meshing to worker or spread work over frames.
- Texture mipmap seams on atlas: Add 1–2 px gutter padding around tiles.
- Precision drift for very large coordinates: Implement floating origin recenters world around player at intervals.
- Raycast edge-case misses due to floating-point: Use DDA algorithm with epsilon handling.
- Mobile performance: Lower render radius and disable transparent blocks by default.

Estimated effort summary
- Core features: ~9–10 days
- Optional persistence/workers/polish: 2–3 days
- Buffer: 1 day for integration fixes and QA


Deliverable 4: Testing and Deployment Strategy

Testing strategy

Unit tests (logic-level, headless)
- Noise determinism
  - Given a seed and coordinates, heightmap outputs are stable.
- Chunk indexing
  - world-to-chunk and chunk-to-voxel conversions round-trip correctly across boundaries.
- Meshing visibility rules
  - For a set of synthetic chunk configurations, face count equals expectation; neighbor transparency rules honored.
- Raycasting
  - DDA traversal hits correct block and face in controlled scenarios.
- Collision resolution
  - Penetration resolution along each axis behaves as expected; no tunneling at typical speeds.

Integration tests (in-browser)
- Chunk load/unload lifecycle and mesh attach/detach behavior.
- Block placement/destruction consistency across chunk borders.
- Texture atlas mapping correctness for all block types.
- Persistence round-trip
  - Modify blocks in multiple chunks, reload, verify diffs applied to generated terrain.

End-to-end tests
- Simulate input sequences for movement, looking, placing, and destroying; verify state changes and rendered results.
- Performance checks
  - Measure frame time under default render radius; verify under target thresholds on test hardware.

Cross-browser/device matrix
- Chrome, Firefox, Edge, Safari on desktop.
- Optional: Chrome on Android, Safari on iOS (reduced settings).
- Verify pointer lock, full-screen, and WebGL capabilities.

Tooling
- Headless unit tests via JS test runner.
- E2E via Playwright with WebGL enabled; scripted camera moves and UI interactions.
- Visual diff testing optional for regression on atlas/meshing.

Performance budgets and profiling
- Mesh vertex count per chunk target: under 20k typical for surface-heavy chunks.
- Frame timing: 1–2 ms scripting, 1–4 ms rendering on mid-range GPU at default radius.
- Profile hotspots: meshing allocation, worker message serialization, chunk management loops.

Deployment strategy

Build and packaging
- Use Vite to produce a production build with code splitting. Ensure assets are hashed for cache-busting.
- Texture atlas generated offline (or at build time) with padding to prevent bleeding.

Hosting
- Static hosting suitable: Netlify, Vercel, GitHub Pages, or any CDN-backed static host.
- Configure headers
  - Cache-control for static assets (immutable), shorter cache for HTML.
- Enable gzip or brotli compression for JS bundles and textures.

Runtime configuration
- URL parameters or settings panel for seed and render distance.
- Error reporting: capture and log errors to console; optional integration with a lightweight error reporting service.

Release checklist
- Confirm WebGL support prompt with graceful fallback messaging.
- Verify default seed loads and first-play path functions without persistence.
- Run cross-browser smoke tests.
- Publish build artifacts and invalidate CDN cache.


Deliverable 5: Sample Data and Assets (described formats)

Block palette example (descriptive schema)
- Each block type has:
  - id: integer (unique, 0 reserved for air)
  - name: string
  - atlasUV: per-face UV coordinates; faces are top, bottom, north, south, east, west; coordinates expressed as tile indices (uIndex, vIndex) within the atlas grid
  - isSolid: boolean
  - isTransparent: boolean (for water/glass)
- Example entries (abbreviated, non-JSON):
  - id 1, name Grass, top tile (u=0,v=0), bottom (u=2,v=0), sides (u=1,v=0), solid true, transparent false
  - id 2, name Dirt, all faces tile (u=2,v=0), solid true, transparent false
  - id 3, name Stone, all faces tile (u=3,v=0), solid true, transparent false
  - id 4, name Sand, all faces tile (u=4,v=0), solid true, transparent false
  - id 5, name Wood, all faces tile (u=5,v=0), solid true, transparent false
  - id 6, name Water, all faces tile (u=6,v=0), solid false, transparent true

Texture atlas plan
- Single square PNG, power-of-two dimensions (e.g., 1024×1024), tiles of 128×128 or 64×64.
- Each tile padded by 2–4 px gutter to reduce mip bleeding.
- Tile layout row 0: grass-top, grass-side, dirt, stone, sand, wood, water.
- Mipmaps generated by the renderer; use trilinear filtering. For water, consider a separate material with transparency and depth write off (simple in v1).

Chunk storage format (descriptive)
- Chunk key: string "cx:cy:cz".
- Stored fields:
  - version (integer)
  - seed (optional reference)
  - overrides: sparse list of modified block coordinates and new IDs within the chunk’s 16×16×16 local space.
- Serialization strategy:
  - Only overrides are persisted; upon load, terrain generator fills defaults, then overrides applied.

Player save format (descriptive)
- position: x, y, z floats
- rotation: yaw, pitch floats
- selectedBlockId: integer
- timestamp: ISO string


Algorithmic Details (expressed as steps, not code)

World generation (per chunk)
1. For each x,z local coordinate in the 16×16 footprint, compute world-space X,Z.
2. Sample 2D noise at scaled X,Z to get a normalized height value.
3. Map height to an integer terrain Y within world vertical bounds.
4. Fill from y=0 to bedrock depth with stone.
5. Fill up to height-1 with dirt; set top block to grass.
6. For heights below sea level (optional), fill water layer up to sea level if air.
7. Apply simple variations (sand near low elevations).

Face culling mesher
1. Iterate each voxel; skip air.
2. For each of the six neighbor directions:
   - If neighbor is air or transparent and current block is not transparent, add the corresponding face.
   - If current block is transparent, only add face if neighbor is air or a different transparent type (simple rule to avoid double faces).
3. For each added face, compute vertex positions, normals, and atlas UVs from the palette entry.
4. Aggregate faces into a single geometry per chunk.
5. Mark chunk as clean; attach/update mesh in scene.

Raycasting via voxel DDA
1. From the camera origin and direction, initialize voxel coordinates as floor of origin.
2. Compute step direction for x,y,z based on sign of ray direction.
3. Compute tMax and tDelta for parametric traversal to next voxel boundary per axis.
4. Step through voxels by advancing the smallest tMax at each iteration, updating the voxel coordinate in the corresponding axis.
5. At each voxel, if a solid block is found, record hit and face normal based on which axis was stepped last; stop within max reach distance.
6. For placement, offset the hit coordinate by the face normal; for destruction, use the hit coordinate directly.

Collision resolution (AABB vs voxels)
1. For intended movement vector, resolve collisions one axis at a time (x, then z, then y if needed).
2. For each axis, compute tentative position; sample voxels overlapped by the player’s AABB.
3. If any are solid, clamp the movement along that axis to the nearest non-penetrating position.
4. Apply the clamped movement; report grounded if y-axis movement is clamped against upward movement.

Chunk streaming
1. Track the player’s current chunk coordinate.
2. Maintain a set of active chunk coords within a horizontal radius and vertical range.
3. Enqueue generation for missing chunks; enqueue unload for chunks exiting the set.
4. Limit generation/meshing per frame to budgeted time or count; prefer worker execution if available.


Deliverable 6: Deployment Guide

Environment
- Node.js LTS; package manager installed.
- Project scripts define dev, build, and preview tasks.

Local development
- Start the dev server; open the local URL in a WebGL-capable browser.
- Use debug overlay to monitor FPS and chunk counts.

Production build
- Run the production build task to output static assets to a dist directory.
- Verify bundle size and asset hashing.

Hosting
- Upload dist to a static host (Netlify, Vercel, S3+CloudFront, GitHub Pages).
- Set caching: index.html short cache; JS/PNG long-term cache with immutable headers.
- Confirm texture atlas served with correct content-type; ensure compression enabled.

Post-deploy smoke test
- Load default seed; move, place, and destroy; reload page and verify persistence if enabled.
- Check performance with default render distance; adjust defaults as needed.


Additional Considerations and Extensions (future work)

- Greedy meshing
  - Merge coplanar faces to drastically reduce vertex count and draw calls per chunk.

- Lighting and shading
  - Simple directional light baseline; add per-vertex ambient occlusion or voxel light propagation later.

- Biomes
  - Multiple noise octaves and biome masks to vary block selection and height; palette changes by biome.

- Gravity and jumping
  - Add downward acceleration, jumping, and step climbing; maintain frame-rate independent movement.

- Tools and inventory
  - Basic hotbar with numbers 1–9 for quick selection; simple inventory panel and drag-drop interactions.

- Audio
  - Footsteps and block place/destroy sounds with spatialization.

- Multiplayer (longer-term)
  - Node.js + WebSocket server; authoritative world state; chunk diffs broadcast; client-side prediction for interaction.

- Save/export/import
  - Export modified chunks as a file; import later for sharing worlds.

- Accessibility
  - Key remapping, aim assist on touch devices, high-contrast theme, configurable motion and FOV settings.

- Security sandboxing
  - Validate and throttle worker messages; clamp render distance and chunk queues to avoid abuse.


Non-functional Notes and Pitfalls

- Texture atlas seam prevention: Ensure gutters; prefer clamp-to-edge with mipmaps.
- Depth sorting with transparent blocks: Render transparent meshes in a separate pass; for v1, keep water minimal.
- Large-distance precision: Use floating origin to re-center around player beyond a threshold distance.
- Memory pressure: Unload chunk meshes and arrays promptly; avoid retaining references; consider object pools for meshing buffers.
- Input corner cases: Implement safe pointer-lock toggling; pause game loop when UI modal is open.


Glossary

- Voxel: Volumetric pixel; one unit block in the world.
- Chunk: Fixed-size 3D block subset of the world, used for storage and rendering batching.
- Atlas: Single texture containing many tiles; improves batching and reduces draw calls.
- DDA: Digital Differential Analyzer; efficient grid traversal algorithm for raycasting in voxel spaces.
- AABB: Axis-Aligned Bounding Box; simple collision volume aligned to world axes.


Summary of Key Decisions

- Three.js + React + Redux Toolkit + Vite for a clear, performant, and maintainable stack.
- 16×16×16 chunk size with mesh-per-chunk rendering and face culling.
- Seeded noise terrain with a small but extensible block palette using a texture atlas.
- Immediate block placement/destroy with DDA raycasting and per-chunk re-meshing.
- Optional persistence via IndexedDB storing only modified blocks for efficiency.
- Two-week plan delivers a polished MVP with room for optimization and future extensibility.

# AI-Generated Design and Implementation Plan for a Web-Based Minecraft Clone

As an experienced game-development AI, I have prepared a complete, code-free design and implementation plan for a minimal web-based Minecraft clone. This plan focuses on core features like block creation and destruction in a 3D voxel world, using Three.js for rendering, React for the UI framework, Redux for state management, and Vite as the build tool. The world will be chunked, with simple heightmap terrain generated via noise, a palette of at least 5 block types, first-person controls (WASD + mouse), collision detection, face culling, and a minimal UI for block selection. Persistence will be handled locally via IndexedDB for optional world saving.

The design emphasizes modularity for extensibility, performance considerations like chunk-based rendering, and cross-device compatibility (desktop and mobile, with adaptations for touch controls). All output is textual documentation—no code is included.

## 1. Technical Specification

### Overview
The application is a browser-based 3D voxel game simulating basic Minecraft mechanics. It runs entirely in the browser for single-player mode, with optional local persistence. The world is infinite in theory but practically limited by chunk loading on demand. Players can navigate in first-person view, place blocks (right-click or equivalent), and destroy blocks (left-click or equivalent) within a reach distance of 4 blocks. The terrain is procedurally generated using simplex noise for a natural heightmap, divided into 16x16x128 chunks (x, z, y dimensions, with y allowing for height variations).

**Core Requirements Met:**
- Rendering: Three.js (WebGL-based for efficient 3D rendering).
- Controls: WASD for movement, mouse for looking; mobile adaptations via virtual joysticks and gestures.
- World Storage: Chunked system with 3D arrays for block data.
- Terrain: Simple heightmap using simplex noise, with biomes implied by block types (e.g., grassy hills, stony depths).
- Block Types: At least 5 (dirt, grass, stone, wood, water), each with unique textures and properties (e.g., solid vs. non-solid).
- Interactions: Ray-casting for block placement/destruction.
- Collision: AABB-based to prevent clipping into solid blocks; no advanced physics like gravity.
- UI: Minimal block selection palette and HUD (crosshair, selected block indicator).
- Performance: Face culling to optimize meshes; only render visible chunks.

**Platform Support:**
- Desktop: Full keyboard/mouse controls.
- Mobile: Touch-based movement (virtual joystick), tap for destruction, long-press for placement, two-finger drag for looking.
- Browser Compatibility: Modern browsers (Chrome, Firefox, Safari) with WebGL 2 support.

**Assumptions and Constraints:**
- No multiplayer or server-side logic in this version.
- World size limited by browser memory (e.g., load 9 chunks around the player initially).
- Textures: Assume a free texture atlas (e.g., 16x16 pixel blocks) sourced from public domains.
- No audio or advanced effects like particles.

### Detailed Features
- **World Generation**: Uses simplex noise to create a 2D heightmap per chunk, filling voxels from bedrock (y=0) to surface with appropriate blocks (e.g., stone below, dirt/grass on top). Water bodies at lower elevations.
- **Block Types**: Palette includes dirt (solid, brown texture), grass (solid, green top/sides), stone (solid, gray), wood (solid, brown bark), water (non-solid, blue translucent). Each has an ID (0=air/empty, 1=dirt, etc.).
- **Rendering**: Three.js scenes with one mesh per chunk, using BufferGeometry for vertices. Textures from a single atlas. Face culling hides internal faces.
- **Controls**: Player moves at 5 units/second, with mouse sensitivity adjustable. Jumping not included in minimal version.
- **Block Interaction**: Ray-cast from camera forward; on hit, destroy (set to air) or place (add selected block in adjacent space based on face normal).
- **Collision Detection**: Check player's AABB against surrounding block AABBs during movement; resolve by sliding or stopping.
- **UI**: React-based overlay with a bottom bar for block icons (click to select) and central crosshair.
- **Persistence**: IndexedDB stores serialized chunk data; auto-save on block changes, load on startup.

## 2. Design Diagrams

### System Architecture Diagram (ASCII)
```
┌────────────────────────────────────────────────────┐
│                  Browser Application               │
│                                                    │
│  ┌────────────────────┐   ┌─────────────────────┐  │
│  │ UI Layer (React)   │◄──│ State Layer (Redux) │  │
│  │ - Block Palette    │   │ - Player State      │  │
│  │ - HUD              │   │ - World Chunks      │  │
│  └──────────▲─────────┘   │ - Selected Block    │  │
│             │             └──────────▲──────────┘  │
│             │                        │             │
│  ┌──────────┼────────────────────────┼──────────┐  │
│  │ Input Layer                       │          │  │
│  │ - Keyboard/Mouse/Touch Handlers   │ Render   │  │
│  │ - Ray-casting Logic               │ Layer    │  │
│  │ - Control Bindings                │ (Three.js)│  │
│  └──────────┼────────────────────────┼──────────┘  │
│             │                        │             │
│             │             ┌──────────▼──────────┐  │
│             │             │ World Data Layer     │  │
│             │             │ - Chunk Storage      │  │
│             └─────────────► - Generation Logic   │  │
│                           │ - Persistence        │  │
│                           │   (IndexedDB)        │  │
│                           └──────────────────────┘  │
└────────────────────────────────────────────────────┘
```
- **Flow**: User inputs update state via Redux actions. Render layer pulls from state to update Three.js scene. World data layer handles generation and storage, feeding into rendering.

### Class Diagram for World/Chunk (Textual)
- **WorldManager**: Manages a map of Chunk objects (key: "chunkX:chunkZ" string). Methods: getChunk(coord), generateChunk(coord), updateBlock(coord, blockID).
- **Chunk**: Holds a 3D array [16][128][16] of block IDs (uint8 for memory efficiency). Properties: position (Vec3), mesh (Three.js Mesh reference). Methods: generate(heightmapNoise), buildMesh(blockPalette), getBlock(localCoord), setBlock(localCoord, id).
- **BlockPalette**: Singleton map (id -> BlockType). BlockType: {name: string, textureCoords: [u,v] array for atlas, isSolid: boolean, isTransparent: boolean}.

### State Diagram for Player (Textual)
- States: Idle, Moving, Interacting.
  - Idle -> Moving (on key press).
  - Moving -> Idle (on key release).
  - Any -> Interacting (on click); transition back after ray-cast and update.
  - Collision checks occur in Moving state, potentially reverting to Idle if blocked.

## 3. Detailed Implementation Plan

This plan assumes a 2-week development timeline (10 working days, 4-6 hours/day) for a solo developer familiar with the tech stack. Total estimated time: 40-50 hours. Pitfalls include Three.js performance tuning (e.g., excessive draw calls) and cross-browser IndexedDB quirks.

### Step-by-Step Tasks with Timelines
- **Day 1-2 (Setup and Data Layer - 8 hours)**: Initialize Vite + React + Redux + Three.js project. Implement World Data Layer: Chunk class, WorldManager with noise-based generation (use a simplex noise library like noisejs). Define block palette. Pitfall: Ensure noise is seedable for consistent worlds.
- **Day 3-4 (Rendering - 8 hours)**: Set up Three.js scene with camera. Implement Chunk.buildMesh with face culling (check 6 neighbors per block, add quad only if exposed). Use a texture atlas loader. Load initial chunks around origin. Pitfall: Optimize geometry to avoid high vertex counts; batch into one BufferGeometry per chunk.
- **Day 5-6 (Controls and Input - 8 hours)**: Add first-person controls using PointerLock API for mouse. Bind WASD keys for movement. Implement basic velocity and position updates in a requestAnimationFrame loop. Add mobile touch handlers (e.g., joystick via nipplejs library). Pitfall: Handle pointer lock failures on mobile; fallback to drag gestures.
- **Day 7 (Collision and Physics - 4 hours)**: Implement AABB collision: On movement, sweep player's bounding box against nearby blocks, resolve intersections by adjusting position. No gravity, just floor sticking. Pitfall: Edge cases like corner clipping; use epsilon values for floating-point precision.
- **Day 8 (Interactions - 4 hours)**: Add ray-casting from camera (use Three.js Raycaster or custom). On left-click, destroy hit block; on right-click, place in adjacent spot. Update chunk mesh post-change. Pitfall: Ensure ray-cast accounts for chunk boundaries; limit to 4-block reach.
- **Day 9 (UI and Polish - 4 hours)**: Build React components for block palette (icon grid, click to select via Redux) and HUD (crosshair div). Integrate with Three.js canvas. Add mobile adaptations. Pitfall: Overlay positioning on resize; use CSS for absolute positioning.
- **Day 10 (Persistence and Testing - 4 hours)**: Implement IndexedDB wrapper for saving/loading chunks (serialize arrays to JSON). Auto-save on block updates. Pitfall: Browser storage limits; compress data if needed.

## 4. Testing and Deployment Strategy

### Testing Strategy
- **Unit Tests**: Use Jest for isolated testing.
  - World Generation: Assert heightmap produces expected block stacks (e.g., grass on top for y> certain height).
  - Ray-casting: Mock camera and world; test hit detection at various distances and angles.
  - Collision: Simulate player movement vectors; verify position corrections against mock blocks.
  - Mesh Building: Check vertex count reduces with culling (e.g., fully enclosed block adds 0 faces).
- **Integration Tests**: Use Cypress for browser automation.
  - Player Movement: Simulate WASD presses; assert position updates without clipping.
  - Block Interactions: Click to place/destroy; verify world state and mesh updates.
- **End-to-End Tests**: Manual and automated scenarios.
  - Load app, generate world, place 10 blocks, destroy 5, reload to check persistence.
  - Performance: Ensure 60 FPS on mid-range hardware with 9 chunks loaded.
- **Edge Cases**: Test on mobile (emulators), with empty worlds, at chunk edges, and with transparent blocks (e.g., water).
- **Coverage Goal**: 80% unit coverage; full coverage for core logic like ray-casting.

### Deployment Guide
- **Build Commands**: Use `vite build` to generate optimized static files (dist folder). This bundles React, Redux, and Three.js with tree-shaking.
- **Hosting Options**: 
  - Netlify/Vercel: Drag-and-drop deploy from Git repo; free tier sufficient for static sites. Enable auto-deploys on push.
  - GitHub Pages: Simple for public demos; configure via repo settings.
  - Custom Server: If needed, use Node.js + Express to serve the dist folder (e.g., `npm start`).
- **Steps**: 
  1. Run `vite build`.
  2. Upload dist to host.
  3. Test via hosted URL; ensure WebGL enables and no CORS issues with textures.
- **Considerations**: Minify assets; use service workers for offline play if extending persistence.

## 5. Optional Extensions for Future Work
- **Multiplayer**: Add WebSocket integration (e.g., Socket.io) for real-time chunk sync between players.
- **Advanced Features**: Inventory system with crafting (React modal UI); biomes via noise-based type selection; basic lighting with Three.js PointLight and shadow maps.
- **Performance Enhancements**: Implement level-of-detail (LOD) for distant chunks; frustum culling to unload off-screen chunks.
- **Additional Mechanics**: Gravity and jumping; entity spawning (e.g., simple mobs via Three.js objects).
- **Monetization/Expansion**: Export worlds as JSON; integrate with WebXR for VR support.

This plan provides a solid foundation for a functional prototype, ready for iteration. If refinements are needed, provide feedback!

1. Technical Specification

1.1 Overview  
– A browser-based, voxel-style sandbox supporting block placement and removal in a procedurally generated 3D world.  
– Core tech: React for UI, Redux for state, Three.js for rendering, Vite for build, IndexedDB for local persistence.  
– Platform: Desktop and mobile web; responsive UI and touch controls optional.  

1.2 Core Features  
• Procedural terrain via noise-based heightmap, segmented into 16×16×16-block chunks.  
• Five block types: grass, dirt, stone, water, wood; extensible palette with ID→properties mapping.  
• Face-culled mesh generation per chunk; only exposed faces are rendered.  
• First-person controls: WASD movement, mouse look; optional touch joystick and swipe look.  
• Ray-cast interaction up to 4-block reach for block destruction (left click/tap) and placement (right click/two-finger tap).  
• Axis-aligned bounding box collision to prevent walking through solids; no dynamic gravity.  
• Minimal HUD: crosshair, selected block icon; bottom rail palette for type selection.  
• Local persistence: world chunks serialized in IndexedDB; incremental save on chunk edits.  

1.3 Non-Functional Requirements  
• Performance: target 60 fps on desktop, 30 fps on mid-range mobile; implement frustum culling and chunk LOD if needed.  
• Modularity: clear separation between data layer (world/Redux), rendering (Three.js), and UI.  
• Extensibility: block types, biomes, multiplayer, lighting to be pluggable.  

2. System Architecture (ASCII Diagram)

      Browser Application
      ┌─────────────────────────────────┐
      │ React UI                        │
      │ • Block palette overlay         │
      │ • HUD (crosshair, icons)        │
      └─────────────────┬───────────────┘
                        │ dispatch/select
      ┌─────────────────▼───────────────────────┐
      │ Redux Store                            │
      │ • world.chunks: Map<chunkKey, chunk>   │
      │ • player: position, rotation, inventory│
      │ • ui: selectedBlockType                │
      └─────────────────┬───────────────────────┘
                        │ triggers updates
      ┌─────────────────▼───────────────────────┐
      │ Three.js Renderer                      │
      │ • Scene graph of chunk meshes          │
      │ • Material with texture atlas          │
      │ • Camera tied to player state          │
      └─────────────────┬───────────────────────┘
                        │ uses
      ┌─────────────────▼───────────────────────┐
      │ World Data Layer & Persistence         │
      │ • Chunk generator (noise → block IDs)  │
      │ • IndexedDB adapter for chunk saving   │
      └─────────────────────────────────────────┘

3. Data Structures

– Chunk  
  • Property: 3D array [16][16][16] of block IDs (0 = empty).  
  • Metadata: dirty flag, last access timestamp.  

– BlockPalette  
  • Dictionary: ID → { name, isSolid, textureUV }  

– World  
  • Map keyed by chunk coordinates string “cx:cz” → Chunk instance.  
  • Configurable world bounds for generation radius.  

– PlayerState  
  • position: Vector3 (float)  
  • rotation: yaw/pitch floats  
  • velocity: Vector3 (for smooth motion)  
  • reachDistance: 4.0  

4. Key Algorithms (Described)

4.1 Chunk Generation  
For each chunk within view radius, compute a 2D noise map for its XZ footprint. For each column (x,z):  
• Height = terrainNoise(xGlobal, zGlobal) scaled to max elevation.  
• Fill blocks at y≤Height with stone/dirt/grass layers.  
• If Height < waterLevel, fill intervening blocks with water.  

4.2 Mesh Creation & Face Culling  
When a chunk is marked dirty:  
• Iterate every block; if solid, check six neighbors.  
• For each face whose neighbor is empty or out of bounds, generate two triangles with correct UVs.  
• Merge all faces into one BufferGeometry for the chunk.  
• Replace or update the Three.js Mesh in the scene.  

4.3 Ray-Cast Interaction  
• Obtain normalized ray direction from camera through screen center or touch point.  
• Step along ray in small increments up to reachDistance, computing floating‐point sample positions.  
• Convert each sample to integer block coordinates; on first non‐empty, record hit block and face normal.  

4.4 Block Update Workflow  
On place or remove:  
• Compute target chunk(s); update its 3D array.  
• Mark chunk (and adjacent chunk if on border) dirty.  
• Dispatch Redux action to trigger mesh regeneration and persist to IndexedDB.  

4.5 Collision Detection  
Each movement frame:  
• Predict next player bounding box based on proposed movement.  
• Sample blocks intersecting that box floor footprint and head; if any solid, cancel or slide movement.  

5. Detailed Implementation Plan with Timeline

Week 1  
Sprint 1 (2 days)  
• Project scaffolding: Vite + React + Redux setup.  
• Integrate Three.js into React lifecycle.  
• Establish folder structure: /src/{ui, state, renderer, world, assets}.  

Sprint 2 (3 days)  
• Implement chunk data model and server‐side world generator module.  
• Redux world slice: load/generate chunks on viewport entry.  
• IndexedDB adapter though idb library.  
• Smoke test: ensure new world chunks appear in store.  

Week 2  
Sprint 3 (2 days)  
• Mesh builder: face culling and BufferGeometry creation.  
• Hook mesh builder into React effect on world‐slice change.  
• Verify visible voxels render correctly.  

Sprint 4 (2 days)  
• Player controller: first‐person camera, WASD & mouse binding.  
• Collision check against world slice.  
• Crosshair overlay.  

Sprint 5 (2 days)  
• Ray-cast service and block interaction: removal and placement.  
• Block palette UI: bottom rail, selection highlight, block icon rendering.  
• Redux actions for block updates, mesh regeneration.  

Sprint 6 (1 day)  
• Persistence demonstration: reload page retains modified chunks.  
• Optional mobile touch joystick prototype.  

Reserve (1 day)  
• Buffer for bug fixes and polish: performance tuning, texture atlas adjustments, UI styling.  

Potential Pitfalls & Mitigations  
– Mesh rebuild lag: use web worker to generate BufferGeometry off main thread.  
– Memory bloat from too many chunks: implement LRU eviction of far‐away chunks.  
– IndexedDB write stalls: batch updates and throttle saves.  

6. Testing Strategy

Unit Tests  
• World generator: height distributions, water fill.  
• Mesh builder: face count matches expected solid‐empty adjacencies.  
• Ray-cast: known scenarios return correct block and face.  
• Collision: moving AABB tests against synthetic chunk data.  

Integration / E2E  
• Simulate player movement and block interaction via Puppeteer.  
• Verify block removal appears visually and persists after reload.  
• Test UI selection updates Redux and changes placement type.  

Performance Tests  
• Automated scene complexity ramp: measure FPS vs chunk count.  
• Mobile browser profiling for memory and CPU.  

7. Deployment Guide

– Build: run `vite build` to produce static `/dist`.  
– Hosting:  
  • Netlify or Vercel: drag-and-drop `/dist` directory.  
  • GitHub Pages: publish `/dist` branch.  
– Environment variables: none required for purely client-side.  
– Monitoring: browser console logs; integrate Sentry for errors in production.  

8. Optional Future Extensions

• Multiplayer sync via WebSocket or WebRTC; authoritative server tracking chunk diffs.  
• Biomes: varied noise maps and block palettes per region (desert, forest, snow).  
• Day-night cycle and dynamic lighting or precomputed per-chunk lightmap.  
• Inventory and crafting UI with drag-and-drop.  
• Mob system: simple AI entities with pathfinding on block grid.  
• LOD: lower-resolution meshes for distant chunks, frustum and occlusion culling.  
• Modding API: JSON-driven block definitions, event hooks on place/destroy.

### Technical Specification Document

#### Overview

The proposed web-based Minecraft clone is designed to support block creation and destruction in a 3-D voxel world. It will be built using Three.js for rendering, Redux for state management, and Node.js with Express for optional backend support. The application will feature procedurally generated terrain, first-person controls, collision detection, and a minimal UI for block selection.

#### Features

1. **Procedurally Generated Terrain**: The terrain will be generated using a simple noise-based heightmap. The world will be divided into chunks (16x16x16 blocks) to facilitate efficient rendering and storage.
2. **Block Types**: A palette of at least 5 block types (dirt, grass, stone, water, wood) will be supported, each with a unique ID and texture.
3. **Rendering**: The application will render visible blocks only, using Three.js voxel rendering capabilities and custom shaders. Face culling will be implemented to improve performance.
4. **First-Person Controls**: The controls will be designed for both desktop and mobile devices, supporting WASD keys and mouse look on desktop, and touch controls on mobile.
5. **Collision Detection**: The application will use axis-aligned bounding boxes (AABB) to prevent walking through solid blocks.
6. **Block Interaction**: Users will be able to place and destroy blocks within a certain reach using ray-casting.
7. **Minimal UI**: A block palette and HUD will be provided for block selection and displaying current block type.

#### System Architecture

The system architecture is designed as follows:
```text
┌─────────────────────────────┐
│          Browser UI          │
│  (React)  <───────────────────┘
└─────────────┬───────────────┘
              │
   ┌──────────▼───────────┐
   │  State & Store       │
   │ (Redux)              │
   └──────────┬───────────┘
              │
   ┌──────────▼───────────┐
   │  Render Engine (Three.js)│
   │  • Chunk Meshes           │
   │  • Block Textures         │
   └──────────┬───────────┘
              │
   ┌──────────▼───────────┐
   │  Input/Interaction    │
   │  • Ray-casting logic  │
   │  • Control binding    │
   └──────────┬───────────┘
              │
   ┌──────────▼───────────┐
   │  World Data Layer    │
   │  • Chunk storage      │
   │  • Persistence (opt.)│
   └──────────────────────┘
```

#### Data Structures

1. **Chunk**: A 3-D array of block IDs (16x16x16).
2. **Block Palette**: A map of block IDs to block data (type, texture coordinates, isSolid).
3. **World Map**: A map of chunk coordinates to chunks.
4. **Player State**: An object containing player position, rotation, and velocity.

#### Algorithms

1. **Chunk Generation**: Generate heightmap using Perlin noise, then populate chunk data based on heightmap.
2. **Rendering Culling**: Iterate through blocks in chunk, culling faces that are adjacent to other solid blocks.
3. **Interaction Ray-casting**: Cast ray from camera into world, checking for block hits within a certain reach.

#### Implementation Plan

The implementation plan is divided into 8 sprints, each lasting approximately 2-3 days.

| Sprint | Tasks |
|--------|-------|
| 1 | Set up project skeleton (React, Three.js, Redux). |
| 2 | Implement world data layer and chunk generation. |
| 3 | Build voxel renderer (mesh creation and culling). |
| 4 | Add player controls and basic physics. |
| 5 | Implement block interaction (ray-casting, placement, destruction). |
| 6 | Add UI (block palette, HUD). |
| 7 | Optional: persistence, mobile adaptation. |
| 8 | Polish, test, and bundle. |

#### Testing Strategy

1. **Unit Tests**: Write unit tests for world generation, interaction logic, and other critical components.
2. **End-to-End Tests**: Test player movement, block placement, and destruction using end-to-end tests.

#### Deployment Guide

1. **Build Commands**: Use Webpack or Vite to build the application.
2. **Hosting Options**: Deploy to Netlify or Vercel for easy hosting and CDN support.

#### Optional Extensions

1. **Multiplayer**: Implement WebSocket server and client for state synchronization.
2. **Crafting/Inventory**: Add simple drag-and-drop UI for crafting and inventory management.
3. **Biome System**: Support different block palettes per biome.
4. **Lighting**: Implement simple directional lighting or per-chunk light mapping.

By following this technical specification and implementation plan, we can build a fully functional web-based Minecraft clone with a robust architecture and engaging gameplay.

# Complete Design Specification for Web-Based Minecraft Clone

## 1. Technical Specification

### 1.1 Core System Requirements

**Primary Objective**: Create a browser-based voxel world game enabling real-time block manipulation with smooth first-person navigation.

**Technical Foundation**:
- **Rendering Engine**: Three.js (chosen for superior documentation and community support)
- **UI Framework**: React (for component reusability and state management integration)
- **State Management**: Redux Toolkit (simplified Redux with built-in performance optimizations)
- **Build System**: Vite (faster development builds than Webpack)
- **Persistence**: IndexedDB via Dexie.js wrapper (for offline-first experience)

### 1.2 World System Specification

**Chunk Architecture**:
- Chunk size: 16×16×64 blocks (width × depth × height)
- World bounds: 64×64 chunks (1024×1024 blocks horizontal)
- Block coordinate system: Integer grid with (0,0,0) at world center
- Chunk loading radius: 8 chunks from player position

**Block Type System**:
```
Block Palette:
- Air (ID: 0) - Transparent, non-collidable
- Grass (ID: 1) - Solid, top texture differs from sides
- Dirt (ID: 2) - Solid, uniform brown texture
- Stone (ID: 3) - Solid, gray with noise pattern
- Water (ID: 4) - Transparent, non-collidable, blue tint
- Wood (ID: 5) - Solid, brown with grain pattern
- Sand (ID: 6) - Solid, tan/yellow texture
```

**Terrain Generation Parameters**:
- Base noise: Perlin noise with frequency 0.01, amplitude 32
- Biome noise: Simplex noise with frequency 0.005 for biome blending
- Height range: Y-coordinates 0 to 128
- Water level: Y-coordinate 64
- Grass layer: Top 1-3 blocks above dirt
- Stone layer: Below Y-coordinate 50

### 1.3 Rendering System Specification

**Mesh Optimization**:
- Face culling: Hide faces between adjacent solid blocks
- Texture atlas: Single 256×256 texture containing all block textures in 16×16 grid
- Chunk batching: One geometry buffer per chunk for optimal draw calls
- Frustum culling: Render only chunks within camera view

**Performance Targets**:
- 60 FPS at 1920×1080 resolution
- Maximum 100ms chunk generation time
- Support for 2000+ visible blocks simultaneously

### 1.4 Physics and Collision System

**Player Physics**:
- Bounding box: 0.8×1.8×0.8 blocks (width×height×depth)
- Movement speed: 5 blocks per second
- Jump height: 1.25 blocks
- Gravity: 20 blocks per second squared

**Collision Detection**:
- AABB (Axis-Aligned Bounding Box) intersection testing
- Swept collision detection for smooth wall sliding
- Ground detection for jump/fall states

## 2. System Architecture

```
┌─────────────────────────────────────────────────────┐
│                 Browser Client                      │
├─────────────────────────────────────────────────────┤
│  React UI Layer                                     │
│  ├─ HUD Component (crosshair, block selector)       │
│  ├─ Inventory Component                             │
│  └─ Settings Panel Component                        │
├─────────────────────────────────────────────────────┤
│  Redux Store (Application State)                    │
│  ├─ World State (chunk data, block modifications)   │
│  ├─ Player State (position, rotation, inventory)    │
│  └─ UI State (selected block, menu visibility)      │
├─────────────────────────────────────────────────────┤
│  Game Engine Core                                   │
│  ├─ World Manager                                   │
│  │   ├─ Chunk Generator (noise-based terrain)       │
│  │   ├─ Chunk Loader (streaming, unloading)         │
│  │   └─ Block Modifier (place/destroy operations)   │
│  ├─ Renderer                                        │
│  │   ├─ Mesh Builder (geometry generation)          │
│  │   ├─ Material Manager (textures, shaders)        │
│  │   └─ Camera Controller (view frustum)            │
│  ├─ Physics Engine                                  │
│  │   ├─ Collision Detector (AABB intersection)      │
│  │   └─ Movement Processor (player motion)          │
│  └─ Input Handler                                   │
│      ├─ Keyboard Controller (WASD movement)         │
│      ├─ Mouse Controller (look, click interactions) │
│      └─ Touch Controller (mobile support)           │
├─────────────────────────────────────────────────────┤
│  Three.js Rendering Layer                           │
│  ├─ Scene Graph (world objects, lighting)           │
│  ├─ WebGL Renderer (draw calls, shaders)            │
│  └─ Geometry Buffers (vertex data)                  │
├─────────────────────────────────────────────────────┤
│  Data Persistence Layer                             │
│  ├─ IndexedDB Interface (world save/load)           │
│  ├─ Compression Utility (chunk data compression)    │
│  └─ Cache Manager (memory optimization)             │
└─────────────────────────────────────────────────────┘
```

## 3. Data Structures

### 3.1 Core Data Models

**Chunk Data Structure**:
```
Chunk {
  coordinates: {x: number, z: number}
  blocks: Uint8Array[16×16×64] // Flattened 3D array
  mesh: THREE.Mesh | null
  isDirty: boolean // Needs mesh regeneration
  lastAccessed: timestamp
  neighbors: {
    north: Chunk | null,
    south: Chunk | null,
    east: Chunk | null,
    west: Chunk | null
  }
}
```

**Player State Model**:
```
Player {
  position: {x: number, y: number, z: number}
  rotation: {yaw: number, pitch: number}
  velocity: {x: number, y: number, z: number}
  isGrounded: boolean
  selectedBlockType: number
  reachDistance: number = 5.0
  boundingBox: {
    min: {x: number, y: number, z: number},
    max: {x: number, y: number, z: number}
  }
}
```

**Block Definition Model**:
```
BlockType {
  id: number
  name: string
  isSolid: boolean
  isTransparent: boolean
  textureCoordinates: {
    top: {u: number, v: number},
    bottom: {u: number, v: number},
    sides: {u: number, v: number}
  }
  material: {
    color: string,
    roughness: number,
    metalness: number
  }
}
```

### 3.2 World Storage Format

**Chunk Serialization**:
- Run-length encoding for repeated block types
- Compression ratio target: 70% for typical terrain
- Storage format: Binary with metadata header

**World Metadata**:
```
WorldData {
  version: string
  seed: number
  generationSettings: {
    noiseScale: number,
    heightMultiplier: number,
    biomeScale: number
  }
  playerSpawn: {x: number, y: number, z: number}
  lastPlayed: timestamp
  totalPlayTime: number
}
```

## 4. Detailed Implementation Plan

### 4.1 Sprint Breakdown (2-Week Timeline)

**Week 1: Foundation and Core Systems**

*Days 1-2: Project Setup and Basic Rendering*
- Initialize Vite project with React and Three.js
- Configure Redux Toolkit store
- Create basic Three.js scene with camera and lighting
- Implement texture atlas loading system
- Set up development server and hot reloading
- **Deliverable**: Spinning cube with block texture

*Days 3-4: Chunk System and World Generation*
- Implement Chunk class with block storage
- Create noise-based terrain generator using simplex-noise library
- Build chunk mesh generation with face culling
- Implement basic chunk loading/unloading system
- **Deliverable**: Static generated terrain visible in 3D

*Days 5-7: Player Controls and Physics*
- Implement first-person camera controls (mouse look)
- Add WASD movement with collision detection
- Create player bounding box collision system
- Implement gravity and ground detection
- Add basic jumping mechanics
- **Deliverable**: Fully controllable character in world

**Week 2: Interaction and Polish**

*Days 8-9: Block Interaction System*
- Implement raycasting for block selection
- Create block placement and destruction logic
- Add visual feedback for target block highlighting
- Implement chunk mesh regeneration after modifications
- **Deliverable**: Functional block editing capabilities

*Days 10-11: User Interface*
- Create HUD overlay with crosshair
- Build block palette selector component
- Implement inventory system with drag-and-drop
- Add settings menu with graphics options
- **Deliverable**: Complete user interface

*Days 12-13: Persistence and Optimization*
- Implement IndexedDB world saving/loading
- Add chunk compression for storage efficiency
- Optimize rendering performance (frustum culling)
- Implement mobile touch controls
- **Deliverable**: Persistent world state

*Day 14: Testing and Polish*
- Performance testing across different devices
- Bug fixes and edge case handling
- Final UI polish and responsive design
- **Deliverable**: Production-ready application

### 4.2 Critical Path Dependencies

1. **Texture System → Chunk Rendering** - Cannot render chunks without texture atlas
2. **Chunk System → Player Physics** - Collision requires chunk data structure
3. **Raycasting → Block Interaction** - Block selection depends on ray intersection
4. **Mesh Generation → Performance** - Optimized geometry critical for frame rate

### 4.3 Risk Mitigation Strategies

**Performance Risks**:
- Fallback to lower chunk render distance for slower devices
- Implement level-of-detail system for distant chunks
- Use Web Workers for chunk generation if main thread blocking occurs

**Browser Compatibility Risks**:
- Polyfills for older browsers lacking WebGL 2.0
- Graceful degradation for mobile devices with limited memory
- Alternative input methods for devices without pointer lock

## 5. Algorithm Specifications

### 5.1 Terrain Generation Algorithm

**Heightmap Generation**:
```
Function generateHeightmap(chunkX, chunkZ, seed):
  heightmap = new Array[16×16]
  
  For x = 0 to 15:
    For z = 0 to 15:
      worldX = chunkX × 16 + x
      worldZ = chunkZ × 16 + z
      
      // Multi-octave noise for realistic terrain
      height = 0
      amplitude = 1
      frequency = 0.01
      
      For octave = 0 to 4:
        noiseValue = simplex2D(worldX × frequency, worldZ × frequency, seed)
        height += noiseValue × amplitude
        amplitude × 0.5
        frequency × 2
      
      // Normalize and scale to world height
      heightmap[x][z] = (height + 1) × 32 + 32 // Range: 0-96
      
  Return heightmap
```

**Block Placement Algorithm**:
```
Function generateChunkBlocks(heightmap):
  blocks = new Uint8Array[16×16×64]
  
  For x = 0 to 15:
    For z = 0 to 15:
      groundHeight = floor(heightmap[x][z])
      
      For y = 0 to 63:
        If y < groundHeight - 5:
          blocks[x][y][z] = STONE
        Else If y < groundHeight - 1:
          blocks[x][y][z] = DIRT
        Else If y <= groundHeight:
          blocks[x][y][z] = GRASS
        Else If y <= WATER_LEVEL:
          blocks[x][y][z] = WATER
        Else:
          blocks[x][y][z] = AIR
          
  Return blocks
```

### 5.2 Mesh Generation with Face Culling

**Face Culling Algorithm**:
```
Function generateChunkMesh(chunk):
  vertices = []
  indices = []
  uvs = []
  
  For each block position (x, y, z) in chunk:
    If block is not AIR:
      For each face direction (NORTH, SOUTH, EAST, WEST, UP, DOWN):
        neighborPos = position + faceDirection
        neighborBlock = getBlock(neighborPos)
        
        If neighborBlock is AIR or WATER:
          // Add face geometry
          faceVertices = getCubeFace(position, faceDirection)
          faceUVs = getBlockTextureUVs(blockType, faceDirection)
          
          vertices.append(faceVertices)
          uvs.append(faceUVs)
          indices.append(generateTriangleIndices())
  
  Return createGeometry(vertices, indices, uvs)
```

### 5.3 Player-World Intersection

**Raycasting for Block Selection**:
```
Function raycastBlockSelection(camera, mousePosition):
  ray = camera.getRay(mousePosition)
  maxDistance = 5.0
  stepSize = 0.1
  
  For distance = 0 to maxDistance step stepSize:
    worldPos = ray.origin + ray.direction × distance
    blockPos = floor(worldPos)
    
    If getBlock(blockPos) is not AIR:
      // Determine which face was hit
      localPos = worldPos - blockPos
      faceNormal = getNearestFaceNormal(localPos)
      
      Return {
        hitBlock: blockPos,
        hitFace: faceNormal,
        hitPoint: worldPos
      }
  
  Return null // No block hit
```

**Collision Detection Algorithm**:
```
Function checkPlayerCollision(playerBox, velocity):
  // Test collision in each axis separately
  For axis in [X, Y, Z]:
    testBox = playerBox.translate(velocity[axis] in axis direction)
    
    For each potentially colliding block:
      blockBox = getBlockBoundingBox(blockPos)
      
      If testBox.intersects(blockBox):
        velocity[axis] = 0
        playerBox = resolveCollision(playerBox, blockBox, axis)
  
  Return {newPosition: playerBox.center, resolvedVelocity: velocity}
```

## 6. Testing Strategy

### 6.1 Unit Testing Framework

**Testing Tools**:
- Jest for logic testing
- Three.js testing utilities for 3D math
- Redux testing utilities for state management
- Performance profiling with Chrome DevTools

**Test Categories**:

**World Generation Tests**:
- Verify heightmap noise consistency with same seed
- Test chunk boundary alignment
- Validate block type distribution ratios
- Performance benchmarks for chunk generation time

**Physics System Tests**:
- Player collision with various block configurations
- Edge case testing (corners, slopes, water)
- Gravity and jumping mechanics verification
- Boundary condition testing (world edges)

**Rendering Tests**:
- Face culling correctness (hidden faces not rendered)
- Texture mapping accuracy
- Chunk loading/unloading behavior
- Frame rate stability under load

### 6.2 Integration Testing

**End-to-End Scenarios**:
1. **New World Creation**: Generate world → Place player → Verify initial chunks loaded
2. **Block Interaction**: Target block → Place/destroy → Verify mesh updates → Check persistence
3. **World Persistence**: Modify world → Save → Reload → Verify changes maintained
4. **Cross-Chunk Operations**: Modify blocks at chunk boundaries → Verify neighbor updates

**Performance Testing**:
- Load testing with 1000+ modified blocks
- Memory usage monitoring during extended play
- Frame rate stability during rapid chunk loading
- Mobile device compatibility testing

### 6.3 User Acceptance Testing

**Usability Criteria**:
- New user can start building within 30 seconds
- Block placement feels responsive (< 100ms latency)
- Movement controls feel smooth and predictable
- Mobile interface is usable on phones/tablets

## 7. Deployment Strategy

### 7.1 Build Configuration

**Production Build Setup**:
- Vite production build with tree shaking
- Asset optimization (texture compression)
- Bundle size target: < 2MB initial load
- Progressive loading for additional chunks

**Browser Compatibility**:
- Target: Chrome 80+, Firefox 75+, Safari 13+
- WebGL 2.0 fallback to WebGL 1.0
- Mobile browsers: iOS Safari 13+, Chrome Mobile 80+

### 7.2 Hosting and Distribution

**Recommended Platforms**:
- **Primary**: Vercel (optimal for static SPA deployment)
- **Alternative**: Netlify (good CI/CD integration)
- **Custom**: AWS S3 + CloudFront (for enterprise deployment)

**CDN Strategy**:
- Serve texture assets from CDN
- Enable browser caching for static assets
- Implement service worker for offline play capability

**Performance Monitoring**:
- Web Vitals tracking (LCP, FID, CLS)
- Error logging with Sentry
- Analytics for user engagement patterns

## 8. Future Extension Architecture

### 8.1 Multiplayer Foundation

**Network Architecture Preparation**:
- Separate world state into authoritative and local layers
- Design block modification events for network synchronization
- Plan for server-side chunk generation and validation
- Consider peer-to-peer vs client-server models

**State Synchronization Design**:
- Event-sourcing pattern for block modifications
- Conflict resolution for simultaneous edits
- Optimistic updates with rollback capability

### 8.2 Content Expansion Systems

**Modular Block System**:
- Plugin architecture for custom block types
- Block behavior scripting interface
- Texture pack loading system
- Custom block recipes and crafting

**Advanced Terrain Features**:
- Multi-biome generation system
- Cave and dungeon generation
- Ore distribution algorithms
- Weather and day/night cycles

### 8.3 Gameplay Extensions

**Inventory and Crafting**:
- Expandable inventory grid system
- Recipe definition format
- Crafting interface components
- Item durability and enchantments

**Building Tools**:
- Multi-block selection and operations
- Blueprint saving/loading system
- Construction assistance (symmetry, patterns)
- Collaborative building features

### 8.4 Performance Scaling

**Advanced Optimization**:
- Level-of-detail (LOD) system for distant terrain
- Instanced rendering for repeated structures
- Compute shader integration for procedural generation
- WebAssembly modules for performance-critical operations

**Data Management**:
- Streaming world loading from cloud storage
- Chunk compression improvements
- Background generation using Web Workers
- Predictive chunk pre-loading

---

This comprehensive specification provides a complete roadmap for implementing a web-based Minecraft clone with professional architecture, realistic timelines, and extensive consideration for future expansion. The design prioritizes performance, maintainability, and user experience while remaining technically feasible for a two-week development cycle.

# Minecraft-Style Web Clone: Design & Implementation Plan

## 1. Technical Specification

### 1.1 Project Overview
This document outlines a web-based Minecraft-style voxel game with block creation and destruction capabilities. The application will run in modern browsers on both desktop and mobile platforms, featuring a 3D procedurally generated world that players can navigate in first-person view and modify by adding or removing blocks.

### 1.2 Technology Stack
- **Rendering Engine**: Three.js
- **UI Framework**: React
- **State Management**: Redux
- **Build System**: Vite
- **Local Storage**: IndexedDB
- **Development Languages**: TypeScript, HTML5, CSS3
- **External Libraries**:
  - simplex-noise (for terrain generation)
  - stats.js (for performance monitoring)

### 1.3 Core Features

#### 1.3.1 World Generation
- Infinite terrain using procedural generation
- Chunk-based world storage (16×16×16 blocks per chunk)
- Perlin/simplex noise-based heightmap for natural-looking terrain
- Simple biome system (plains, hills, water)

#### 1.3.2 Block System
- Block types: Grass, Dirt, Stone, Sand, Water, Wood
- Each block has unique properties (texture, solidity, transparency)
- Optimized face culling (not rendering faces that aren't visible)

#### 1.3.3 Player Controls
- First-person camera with mouse look
- WASD movement controls
- Jumping with space bar
- Block interaction (left-click to destroy, right-click to place)
- Block selection UI at bottom of screen

#### 1.3.4 Physics & Collision
- Basic collision detection between player and blocks
- Simple physics for player movement (no gravity for blocks)
- Ray casting for block selection and interaction

#### 1.3.5 User Interface
- Crosshair for targeting blocks
- Block selection toolbar
- Optional: Simple debug information (FPS, coordinates)

#### 1.3.6 Data Persistence
- Save world state to IndexedDB
- Auto-save on regular intervals
- Load world on startup

## 2. System Architecture

### 2.1 Component Architecture (ASCII Diagram)

```
┌───────────────────────────────────────────────┐
│                  React App                     │
│                                               │
│  ┌─────────────────┐      ┌─────────────────┐ │
│  │    Game UI      │      │   Game Canvas   │ │
│  │  - Toolbar      │      │  (Three.js)     │ │
│  │  - Crosshair    │      │                 │ │
│  │  - Debug Info   │      │                 │ │
│  └────────┬────────┘      └────────┬────────┘ │
└───────────┼───────────────────────┼───────────┘
            │                       │
┌───────────▼───────────────────────▼───────────┐
│                Redux Store                     │
│                                               │
│  ┌─────────────────┐      ┌─────────────────┐ │
│  │  UI State       │      │  Game State     │ │
│  │  - Selected     │      │  - Player       │ │
│  │    Block        │      │  - World Chunks │ │
│  │  - Menu State   │      │  - Settings     │ │
│  └─────────────────┘      └─────────────────┘ │
└───────────────────────────────────────────────┘
            │                       │
┌───────────▼───────────────────────▼───────────┐
│           Game Engine Components              │
│                                               │
│  ┌─────────────────┐      ┌─────────────────┐ │
│  │ World Generator │      │ Renderer        │ │
│  └────────┬────────┘      └────────┬────────┘ │
│           │                        │          │
│  ┌────────▼────────┐      ┌────────▼────────┐ │
│  │ Physics Engine  │      │ Input Manager   │ │
│  └────────┬────────┘      └────────┬────────┘ │
│           │                        │          │
│  ┌────────▼────────┐      ┌────────▼────────┐ │
│  │ Block Manager   │◄────►│ Player Manager  │ │
│  └────────┬────────┘      └────────┬────────┘ │
└───────────┼────────────────────────┼──────────┘
            │                        │
┌───────────▼────────────────────────▼──────────┐
│             Data Persistence                  │
│             (IndexedDB)                       │
└───────────────────────────────────────────────┘
```

### 2.2 Data Flow
1. User input is captured by the Input Manager
2. Input Manager updates Player State in Redux
3. Game loop processes physics, collision, and player movement
4. World Generator creates new chunks as needed
5. Renderer retrieves visible chunks and renders the scene
6. Block interactions update the World State
7. Changes to World State trigger mesh updates in the Renderer
8. Data Persistence layer periodically saves world state

## 3. Data Structures

### 3.1 World Data Structure
```
World {
  chunks: Map<string, Chunk>  // Key format: "x:y:z"
  getChunkAt(x, y, z): Chunk
  getBlockAt(x, y, z): BlockType
  setBlockAt(x, y, z, blockType): void
}

Chunk {
  position: Vector3  // Chunk position in chunk coordinates
  size: number       // Typically 16
  blocks: Uint8Array // 3D array flattened to 1D (size³ elements)
  isDirty: boolean   // Flag for mesh regeneration
  mesh: THREE.Mesh   // Three.js mesh for rendering
  getLocalBlockIndex(lx, ly, lz): number
  getBlock(lx, ly, lz): BlockType
  setBlock(lx, ly, lz, blockType): void
}
```

### 3.2 Block Data Structure
```
BlockType {
  id: number           // Unique identifier
  name: string         // Display name
  isSolid: boolean     // Affects collision
  isTransparent: boolean  // Affects face culling
  textureOffsets: {     // UV coordinates in texture atlas
    top: Vector2,
    bottom: Vector2,
    left: Vector2,
    right: Vector2,
    front: Vector2,
    back: Vector2
  }
}

// Block Palette Example
BlockPalette {
  0: { id: 0, name: "Air", isSolid: false, isTransparent: true, ... }
  1: { id: 1, name: "Grass", isSolid: true, isTransparent: false, ... }
  2: { id: 2, name: "Dirt", isSolid: true, isTransparent: false, ... }
  // ...other blocks
}
```

### 3.3 Player Data Structure
```
Player {
  position: Vector3
  rotation: Euler
  velocity: Vector3
  size: Vector3          // For collision detection
  selectedBlockType: number
  isJumping: boolean
  isOnGround: boolean
  moveSpeed: number
  jumpForce: number
}
```

## 4. Core Algorithms

### 4.1 Terrain Generation

```
function generateChunk(chunkX, chunkY, chunkZ) {
  const chunk = new Chunk(chunkX, chunkY, chunkZ)
  const noiseGenerator = new SimplexNoise(WORLD_SEED)
  
  // Generate height map for this chunk
  for (let x = 0; x < CHUNK_SIZE; x++) {
    for (let z = 0; z < CHUNK_SIZE; z++) {
      // Convert to world coordinates
      const worldX = chunkX * CHUNK_SIZE + x
      const worldZ = chunkZ * CHUNK_SIZE + z
      
      // Generate height using multiple octaves of noise
      const frequency = 0.01
      let amplitude = 1.0
      let height = 0
      
      for (let i = 0; i < 4; i++) {
        height += noiseGenerator.noise2D(worldX * frequency, worldZ * frequency) * amplitude
        amplitude *= 0.5
        frequency *= 2
      }
      
      // Scale height to block units
      const terrainHeight = Math.floor((height + 1) * 10) + 40
      
      // Fill blocks in the chunk
      for (let y = 0; y < CHUNK_SIZE; y++) {
        const worldY = chunkY * CHUNK_SIZE + y
        
        if (worldY < terrainHeight - 4) {
          chunk.setBlock(x, y, z, BLOCK_TYPES.STONE)
        } else if (worldY < terrainHeight - 1) {
          chunk.setBlock(x, y, z, BLOCK_TYPES.DIRT)
        } else if (worldY < terrainHeight) {
          chunk.setBlock(x, y, z, BLOCK_TYPES.GRASS)
        } else if (worldY < WATER_LEVEL) {
          chunk.setBlock(x, y, z, BLOCK_TYPES.WATER)
        } else {
          chunk.setBlock(x, y, z, BLOCK_TYPES.AIR)
        }
      }
    }
  }
  
  return chunk
}
```

### 4.2 Chunk Mesh Generation with Face Culling

```
function generateChunkMesh(chunk) {
  const { blocks, position } = chunk
  const geometry = new THREE.BufferGeometry()
  const positions = []
  const normals = []
  const uvs = []
  
  // Directions for checking adjacent blocks (right, left, top, bottom, front, back)
  const directions = [
    [1, 0, 0], [-1, 0, 0], [0, 1, 0], [0, -1, 0], [0, 0, 1], [0, 0, -1]
  ]
  
  // Corresponding normals
  const faceNormals = [
    [1, 0, 0], [-1, 0, 0], [0, 1, 0], [0, -1, 0], [0, 0, 1], [0, 0, -1]
  ]
  
  // For each block in the chunk
  for (let x = 0; x < CHUNK_SIZE; x++) {
    for (let y = 0; y < CHUNK_SIZE; y++) {
      for (let z = 0; z < CHUNK_SIZE; z++) {
        const blockType = chunk.getBlock(x, y, z)
        
        // Skip air blocks
        if (blockType === BLOCK_TYPES.AIR) continue
        
        // Get block data from palette
        const blockData = BlockPalette[blockType]
        
        // For each face of the block
        for (let i = 0; i < 6; i++) {
          const [dx, dy, dz] = directions[i]
          const nx = x + dx
          const ny = y + dy
          const nz = z + dz
          
          // Get neighbor block type (from this chunk or adjacent chunk)
          let neighborType
          if (nx < 0 || nx >= CHUNK_SIZE || ny < 0 || ny >= CHUNK_SIZE || nz < 0 || nz >= CHUNK_SIZE) {
            // Get from adjacent chunk
            const wx = position.x * CHUNK_SIZE + nx
            const wy = position.y * CHUNK_SIZE + ny
            const wz = position.z * CHUNK_SIZE + nz
            neighborType = world.getBlockAt(wx, wy, wz)
          } else {
            neighborType = chunk.getBlock(nx, ny, nz)
          }
          
          // Skip face if neighbor is solid and current block is not transparent
          if (neighborType !== BLOCK_TYPES.AIR && 
              !BlockPalette[neighborType].isTransparent && 
              !blockData.isTransparent) {
            continue
          }
          
          // Add face vertices, normals, and UVs to buffers
          addFaceToGeometry(
            positions, normals, uvs,
            x, y, z,
            faceNormals[i],
            blockData.textureOffsets[getFaceName(i)]
          )
        }
      }
    }
  }
  
  // Set attributes for the geometry
  geometry.setAttribute('position', new THREE.Float32BufferAttribute(positions, 3))
  geometry.setAttribute('normal', new THREE.Float32BufferAttribute(normals, 3))
  geometry.setAttribute('uv', new THREE.Float32BufferAttribute(uvs, 2))
  
  // Create mesh
  const material = new THREE.MeshLambertMaterial({ 
    map: textureAtlas,
    transparent: true,
    alphaTest: 0.1
  })
  
  return new THREE.Mesh(geometry, material)
}
```

### 4.3 Ray Casting for Block Interaction

```
function raycastBlock(camera, maxDistance) {
  const raycaster = new THREE.Raycaster()
  const mouse = new THREE.Vector2(0, 0)  // Center of screen
  
  raycaster.setFromCamera(mouse, camera)
  
  // Get all chunk meshes that are in view
  const meshes = []
  for (const chunk of visibleChunks) {
    if (chunk.mesh) meshes.push(chunk.mesh)
  }
  
  // Raycast against chunk meshes
  const intersects = raycaster.intersectObjects(meshes)
  
  if (intersects.length > 0 && intersects[0].distance <= maxDistance) {
    const intersection = intersects[0]
    
    // Convert hit point to block coordinates
    const point = intersection.point
    const normal = intersection.face.normal
    
    // Slightly offset to get correct block
    const blockX = Math.floor(point.x - normal.x * 0.001)
    const blockY = Math.floor(point.y - normal.y * 0.001)
    const blockZ = Math.floor(point.z - normal.z * 0.001)
    
    return {
      position: { x: blockX, y: blockY, z: blockZ },
      normal: normal,
      // For block placement, we need the adjacent block position
      adjacent: {
        x: Math.floor(point.x + normal.x * 0.001),
        y: Math.floor(point.y + normal.y * 0.001),
        z: Math.floor(point.z + normal.z * 0.001)
      }
    }
  }
  
  return null
}
```

### 4.4 Collision Detection

```
function checkCollision(player, newPosition) {
  const margin = 0.25  // Small margin to prevent getting stuck
  const halfSize = {
    x: player.size.x / 2 - margin,
    y: player.size.y / 2 - margin,
    z: player.size.z / 2 - margin
  }
  
  // Check all 8 corners of the player's bounding box
  const corners = [
    { x: -halfSize.x, y: -halfSize.y, z: -halfSize.z },
    { x:  halfSize.x, y: -halfSize.y, z: -halfSize.z },
    { x: -halfSize.x, y:  halfSize.y, z: -halfSize.z },
    { x:  halfSize.x, y:  halfSize.y, z: -halfSize.z },
    { x: -halfSize.x, y: -halfSize.y, z:  halfSize.z },
    { x:  halfSize.x, y: -halfSize.y, z:  halfSize.z },
    { x: -halfSize.x, y:  halfSize.y, z:  halfSize.z },
    { x:  halfSize.x, y:  halfSize.y, z:  halfSize.z }
  ]
  
  // Initialize valid position as the new position
  const validPosition = { ...newPosition }
  
  // Check each axis separately
  const axes = ['x', 'y', 'z']
  
  for (const axis of axes) {
    // Reset to current position for this axis
    validPosition[axis] = player.position[axis]
    
    // Try to move along this axis only
    const testPosition = { ...validPosition }
    testPosition[axis] = newPosition[axis]
    
    // Check if this position is valid
    let collision = false
    
    for (const corner of corners) {
      const testX = Math.floor(testPosition.x + corner.x)
      const testY = Math.floor(testPosition.y + corner.y)
      const testZ = Math.floor(testPosition.z + corner.z)
      
      const blockType = world.getBlockAt(testX, testY, testZ)
      
      if (blockType !== BLOCK_TYPES.AIR && BlockPalette[blockType].isSolid) {
        collision = true
        break
      }
    }
    
    if (!collision) {
      // If no collision, accept the movement along this axis
      validPosition[axis] = newPosition[axis]
    }
  }
  
  return validPosition
}
```

## 5. Implementation Plan

### 5.1 Development Phases

#### Phase 1: Project Setup and Core Architecture (2 days)
- Set up Vite with React, TypeScript, and Three.js
- Create basic project structure
- Set up Redux store
- Create basic game loop
- Implement camera and input system

#### Phase 2: World Generation and Rendering (3 days)
- Implement block data structures
- Create chunk system
- Implement simplex noise terrain generation
- Create mesh generation algorithm with face culling
- Set up texture atlas

#### Phase 3: Player and Physics (2 days)
- Implement player movement controls
- Add collision detection
- Create ray casting for block selection
- Implement jumping mechanics

#### Phase 4: Block Interaction (2 days)
- Implement block placement
- Implement block destruction
- Add highlight for selected block
- Optimize chunk updates

#### Phase 5: User Interface (2 days)
- Create block selection toolbar
- Add crosshair
- Implement debug overlay
- Style UI elements

#### Phase 6: Data Persistence and Polish (3 days)
- Implement IndexedDB storage
- Add auto-save functionality
- Create save/load system
- Performance optimizations
- Bug fixes and polishing

### 5.2 Detailed Timeline

| Day | Tasks | Deliverables |
|-----|-------|--------------|
| 1 | Set up project environment, create basic structure | Initial project with Three.js canvas |
| 2 | Implement Redux store, game loop, and input system | Working camera with keyboard/mouse controls |
| 3 | Create block and chunk data structures | Block palette and chunk storage system |
| 4 | Implement terrain generation | Algorithm that generates terrain from noise |
| 5 | Create mesh generation with face culling | Optimized rendering of chunks |
| 6 | Implement player movement | Player that can navigate the world |
| 7 | Add collision detection and physics | Player that can't move through blocks |
| 8 | Implement ray casting and block selection | Visual highlight of selected block |
| 9 | Create block interaction mechanics | Ability to place and destroy blocks |
| 10 | Build block selection UI | Working toolbar for block selection |
| 11 | Add remaining UI elements | Complete UI with crosshair and debug info |
| 12 | Implement data persistence | Working save/load system with IndexedDB |
| 13 | Optimize performance | Smoother gameplay with chunk loading optimizations |
| 14 | Final polish and bug fixing | Complete, playable prototype |

## 6. Testing Strategy

### 6.1 Unit Tests
- **Block System Tests**: Verify block placement, retrieval, and removal
- **Chunk Tests**: Test chunk generation, block access, and serialization
- **World Generator Tests**: Validate noise generation and terrain formation
- **Ray Casting Tests**: Ensure accurate block selection

### 6.2 Integration Tests
- **Rendering Pipeline**: Test mesh generation from block data
- **Player Movement**: Test collision detection and response
- **Block Interaction**: Verify place/destroy functionality
- **Persistence**: Test save and load operations

### 6.3 Performance Tests
- Measure FPS during various operations
- Track memory usage during extended play
- Profile chunk generation and mesh creation
- Benchmark chunk loading/unloading

### 6.4 Browser Compatibility
- Test on Chrome, Firefox, Safari, and Edge
- Verify mobile functionality on iOS and Android
- Test with various GPU capabilities

## 7. Deployment Strategy

### 7.1 Build Process
1. Configure Vite build settings for production
2. Optimize asset loading (texture compression)
3. Implement code splitting for faster initial load
4. Create production build with `vite build`

### 7.2 Hosting Options
- **Vercel**: Seamless integration with Git for continuous deployment
- **Netlify**: Simple deployment with custom domain support
- **GitHub Pages**: Free hosting for static sites

### 7.3 Deployment Steps
1. Create production build
2. Test build locally
3. Deploy to chosen hosting platform
4. Set up custom domain (optional)
5. Configure cache policies for assets

## 8. Future Extensions

### 8.1 Gameplay Enhancements
- **Day/Night Cycle**: Add time progression with lighting changes
- **Weather Effects**: Implement rain, snow, and fog
- **More Block Types**: Extend block palette with additional materials
- **Simple Mobs**: Add basic AI-controlled entities

### 8.2 Technical Improvements
- **Multiplayer Support**: WebSocket server for real-time collaboration
- **Advanced Physics**: Add gravity for blocks, falling sand, water flow
- **Infinite World**: Implement infinite terrain generation
- **Biome Diversity**: Create varied environments based on temperature/moisture
- **Lighting System**: Dynamic lighting with shadow casting

### 8.3 User Experience
- **Sound Effects**: Add audio for block placement, destruction, and ambience
- **Inventory System**: Implement collection and storage of blocks
- **Crafting Mechanics**: Allow combining blocks to create new types
- **Mobile Controls**: Enhance touch controls for better mobile gameplay
- **Settings Menu**: Add user-configurable options for graphics and controls

## 9. Conclusion

This design document provides a comprehensive plan for implementing a web-based Minecraft-style voxel game. Following this plan will result in a functional prototype with core features including procedural terrain generation, first-person navigation, block interaction, and data persistence.

The modular architecture allows for future expansion while maintaining performance and browser compatibility. The two-week development timeline is achievable for a skilled developer, with clear milestones and deliverables for each phase of implementation.

# Minecraft‑Style Web Clone – Full Design & Implementation Blueprint  
*(All content is pure documentation – no source code is included)*  

---  

## 1. Technical Specification  

### 1.1. Target Platform  

| Aspect | Details |
|--------|----------|
| **Browser** | Desktop (Chrome/Firefox/Edge/Safari) – responsive layout for mobile (touch controls optional). |
| **Graphics** | WebGL‑based 3‑D rendering via **Three.js** (chosen for its large ecosystem, clear chunk‑mesh examples, and easy integration with React/Vue). |
| **Framework** | **React** for UI composition (hooks + functional components). |
| **State Management** | **Redux Toolkit** – single source of truth for world data, player state, UI selections, and async actions (e.g., chunk loading). |
| **Build System** | **Vite** – fast dev server, ES‑module support, and out‑of‑the‑box HMR for React. |
| **Persistence (optional)** | **IndexedDB** via the `idb` wrapper library – stores serialized chunk data locally; falls back to `localStorage` for small metadata. |
| **Backend (optional)** | Node.js + Express for future multiplayer or world‑share features; not required for the core MVP. |
| **Asset Pipeline** | Texture atlas (PNG) prepared with a sprite‑sheet generator; JSON manifest maps block IDs to UV coordinates. |

### 1.2. Core Gameplay Features  

| Feature | Description | Success Criteria |
|---------|-------------|-------------------|
| **Procedural Terrain** | Generate a 2‑D height map using Simplex noise; extrude upward to create voxel columns. | Terrain appears varied, with smooth hills and valleys; no visible gaps. |
| **Chunked World** | Divide the world into cubic *chunks* (16 × 16 × 16 blocks). Only chunks within a configurable radius of the player are kept in memory/rendered. | Frame‑rate stays >30 fps on mid‑range hardware; memory consumption stays <200 MB. |
| **Block Palette** | Minimum five block types: **Grass**, **Dirt**, **Stone**, **Water**, **Wood**. Each maps to a texture slot in the atlas and a solidity flag. | UI shows icons; player can switch with a single click/tap. |
| **First‑Person Controls** | WASD movement, mouse look (yaw/pitch). Mouse left‑click destroys a block; right‑click places the currently selected block. | Player can walk freely, look around, and interact with blocks up to a 3‑block reach distance. |
| **Collision & Physics** | Axis‑aligned bounding‑box (AABB) collision against solid blocks; simple “grounded” physics (no jumping or gravity required for the MVP). | Player cannot pass through solids, walks over terrain smoothly. |
| **Face Culling** | For each chunk, geometry is generated only for block faces that border empty space. | Visible mesh count is minimized; no interior faces are rendered. |
| **UI Overlay** | Crosshair at screen centre, block‑picker bar at the bottom, and a small “selected block” preview. | UI does not obstruct view; block selection updates instantly. |
| **Local Persistence** *(optional)* | Serialize modified chunks to IndexedDB on change; load them on startup, overriding generated data where present. | World state survives a page refresh, with all player‑made modifications restored. |

---  

## 2. System Architecture  

The architecture separates **presentation**, **state**, **world‑logic**, and **rendering** into distinct layers. Below is an ASCII diagram that captures the data flow.

```
+---------------------------------------------------------------+
|                         Browser UI (React)                   |
|  +----------------+   +----------------+   +----------------+ |
|  | Block Picker   |   | HUD / Crosshair|   | Mobile Controls| |
|  +----------------+   +----------------+   +----------------+ |
|            |                     |                      |   |
+------------|---------------------|----------------------|---+
             |                     |                      |
             v                     v                      v
+---------------------------------------------------------------+
|                     Global State (Redux)                     |
|  - player {position, rotation, velocity}                     |
|  - world   {chunks: Map<ChunkKey, Chunk>, dirtyChunks}        |
|  - ui      {selectedBlockId, inputMode}                      |
|  - persist {saveRequested, loadRequested}                    |
+----------------------------|----------------------------------+
                             |
          +------------------+-------------------+
          |                                      |
          v                                      v
+---------------------------+        +--------------------------+
|   Input & Interaction     |        |  World Data Layer        |
| (Keyboard, Mouse, Touch) |        |  - Chunk generator       |
|  - Ray‑cast for hits      |        |  - Chunk cache (Map)     |
|  - Apply place / destroy  |        |  - Persistence service   |
+------------|--------------+        +------------|-------------+
             |                                 |
             v                                 v
+---------------------------+        +--------------------------+
|    Physics / Collision    |        |   Chunk Mesh Builder     |
|  - AABB checks against    |        |  - Face‑culling logic    |
|    neighboring blocks    |        |  - BufferGeometry creation|
+------------|--------------+        +------------|-------------+
             |                                 |
             v                                 v
+---------------------------------------------------------------+
|               Rendering Engine (Three.js Scene)              |
|   - Camera (Perspective)                                      |
|   - Controls (PointerLockControls wrapper)                    |
|   - Chunk meshes (InstancedMesh or BufferGeometry)           |
|   - Material using texture atlas (MeshBasicMaterial)          |
+---------------------------------------------------------------+
```

### Layer Responsibilities  

| Layer | Responsibilities | Interaction with Other Layers |
|-------|------------------|------------------------------|
| **React UI** | Renders static UI, forwards UI events (block selection, touch gestures) to Redux actions. | Dispatches actions → Redux. |
| **Redux Store** | Holds immutable snapshots of world, player, and UI state; provides selectors for components and services. | Consumed by Input, Physics, Mesh Builder, Persistence. |
| **Input & Interaction** | Captures raw events, performs ray‑casting into the world, emits “place” or “destroy” actions. | Reads player state from Redux; writes block‑change actions. |
| **Physics / Collision** | Checks attempted movement against the world voxel grid; corrects position. | Reads chunk data from world layer; writes updated player position. |
| **World Data Layer** | Generates, caches, and supplies chunk voxel data; handles lazy loading/unloading. | Provides voxel queries for physics, ray‑cast, mesh builder; receives modifications from interaction layer. |
| **Chunk Mesh Builder** | Turns voxel data for a chunk into a renderable Three.js mesh, applying face‑culling. | Listens for dirty‑chunk flags; updates Three.js scene. |
| **Rendering Engine** | Maintains the Three.js scene, camera, and render loop; draws current chunk meshes each frame. | Reads meshes from Chunk Mesh Builder; reads camera state from Redux. |
| **Persistence Service** *(optional)* | Serializes modified chunks to IndexedDB and restores them on startup. | Listens for “saveRequested” actions; writes/reads chunk data. |

---  

## 3. Data Structures  

| Structure | Shape | Purpose |
|-----------|------|---------|
| **BlockPalette** | `Map<number, {name:string, uv: [u0,v0,u1,v1], solid:boolean}>` | Global lookup for texture coordinates and solidity. |
| **ChunkKey** | `string` formatted as `"cx:cy:cz"` (e.g., `"0:0:0"`). | Unique identifier for a chunk in the world map. |
| **Chunk** | `{ blocks: Uint8Array, dirty: boolean, mesh: THREE.Mesh | null }` <br> – `blocks` length = `CHUNK_SIZE³` (flattened 3‑D). | Stores voxel IDs; `dirty` flags need mesh regeneration. |
| **WorldMap** | `Map<ChunkKey, Chunk>` | Fast retrieval of any loaded chunk. |
| **PlayerState** | `{ position: [x,y,z], rotation: [yaw, pitch], velocity: [vx,vy,vz] }` | Drives camera, movement, and interaction reach. |
| **InputState** | `{ mouseDownLeft: boolean, mouseDownRight: boolean, keysPressed: Set<string> }` | Temporary cache for continuous input handling. |
| **PersistQueue** | `{ save: Set<ChunkKey>, load: Set<ChunkKey> }` | Batching of IndexedDB read/write operations. |

*All numeric arrays are plain JavaScript typed arrays (Uint8Array, Float32Array) for minimal GC pressure.*

---  

## 4. Algorithms  

### 4.1. Chunk Generation (Height‑Map)  

1. **Noise Setup** – Initialize a Simplex noise generator with a static seed.  
2. **Iterate over X/Z** within the chunk’s world coordinates (`worldX = cx * CHUNK_SIZE + x`).  
3. **Compute Height** – `h = floor( noise(worldX * scale, worldZ * scale) * maxHeight ) + baseHeight`.  
4. **Fill Column** – For each y ≤ h set block ID to **Stone**; y = h set **Grass**; y < h–3 set **Dirt**.  
5. **Water Layer** – If `h < WATER_LEVEL`, fill cells up to `WATER_LEVEL` with **Water** (non‑solid).  

**Result:** Fully populated `blocks` Uint8Array for the chunk.

### 4.2. Face Culling Mesh Construction  

For each block in the chunk:  

| Condition | Action |
|-----------|--------|
| Block is **empty** (`id === 0`) | Skip. |
| Block is **solid** | For each of its 6 neighbor directions: <br>‑ Compute neighbor coordinates. <br>‑ If neighbor is outside the chunk, request neighbor chunk (or treat as empty if not loaded). <br>‑ If neighbor is empty or non‑solid, emit a quad for that face (with correct UV from the BlockPalette). |

The emitted quads are accumulated into typed arrays for positions, normals, UVs, and indices; then wrapped in a `THREE.BufferGeometry`.  

**Optimization note:** Since each face is a square, we can pre‑define a *face template* and transform it per block (offset + normal). An *InstancedMesh* could be used for further reduction, but for the MVP a single BufferGeometry per chunk is sufficient.

### 4.3. Ray‑Casting for Interaction  

1. Convert mouse screen coordinates (or centre of screen for touch) into a normalized device coordinate vector.  
2. Build a ray from the camera’s world position in the direction of the vector (Three.js `Raycaster`).  
3. Step the ray forward in small increments (e.g., 0.1 block) up to a maximum reach (≈3 blocks).  
4. At each step: <br>‑ `voxel = floor(rayPos)` <br>‑ Look up the voxel ID in `WorldMap`. <br>‑ If ID ≠ 0 (solid or water), report a **hit** with the voxel coordinates and the face normal derived from the stepping direction.  

**Placement logic:** Use the hit face normal to compute the adjacent empty voxel (`target = hitVoxel + normal`). Verify `target` is within loaded chunks and empty, then place the selected block ID.  

**Destruction logic:** Set `hitVoxel` ID to `0`.  

After either action, mark the affected chunk (and its neighbours, if the edited voxel lies on a boundary) as `dirty` for mesh regeneration.

### 4.4. Collision Detection (AABB)  

Each frame:

1. Compute a *proposed* new player position based on input velocity and delta‑time.  
2. Determine the **AABB**: `[x‑0.25, x+0.25] × [y‑1.8, y] × [z‑0.25, z+0.25]` (approximate player width 0.5 m, height 1.8 m).  
3. Enumerate voxel cells intersecting this AABB (by flooring min/max bounds).  
4. For each intersecting voxel that is **solid**, push the player out along the smallest penetration axis (standard slab method).  

If the player’s feet are directly above a solid voxel, set the vertical velocity to `0` (grounded).  

---  

## 5. Implementation Roadmap (2‑Week Sprint Plan)  

| Day | Milestone | Tasks (high‑level) |
|-----|-----------|--------------------|
| **Day 1** | Project scaffolding | • Initialise Vite + React + Redux Toolkit. <br>• Add Three.js dependency. <br>• Set up basic file/folder layout (`src/renderer`, `src/state`, `src/world`, `src/ui`). |
| **Day 2** | Core data models | • Define BlockPalette JSON manifest. <br>• Implement ChunkKey helper, Chunk data class (blocks array + dirty flag). <br>• Create Redux slices: `playerSlice`, `worldSlice`, `uiSlice`. |
| **Day 3** | Terrain generator | • Integrate Simplex noise library. <br>• Write chunk generation function (height‑map → block IDs). <br>• Populate initial visible chunks around origin (`(0,0,0)`). |
| **Day 4** | Rendering foundation | • Create Three.js scene, camera, and basic render loop inside a React `<Canvas>` component. <br>• Add a simple material using the texture atlas (placeholder colors if texture not ready). |
| **Day 5** | Chunk mesh builder | • Implement face‑culling algorithm; output a BufferGeometry per chunk. <br>• Connect Redux `worldSlice` to automatically rebuild mesh when chunk `dirty` flag changes. |
| **Day 6** | First‑person controls | • Wrap `PointerLockControls` (Three.js) into a React hook. <br>• Map WASD keys to movement vectors; store resulting velocity in Redux. |
| **Day 7** | Collision system | • Add AABB check against world voxels each frame. <br>• Resolve penetration and update player position in Redux. |
| **Day 8** | Block interaction – Ray casting | • Build a reusable `useRaycast` hook that returns hit info. <br>• Dispatch Redux actions `placeBlock(target)` and `destroyBlock(hit)` on mouse clicks. |
| **Day 9** | UI – Block picker & HUD | • Design a minimal CSS overlay with a bottom bar of icons (use placeholder PNGs). <br>• Clicking an icon dispatches `setSelectedBlock(id)`. <br>• Add static crosshair element at screen centre. |
| **Day 10** | Dirty‑chunk propagation | • When a block is placed/destroyed, mark the **current** chunk and any neighbour chunks that share the edited face as dirty. <br>• Ensure mesh rebuild is scheduled for the next animation frame (debounce rapid edits). |
| **Day 11** | Optional persistence (IndexedDB) | • Implement a thin persistence service that batches `saveRequested` chunks. <br>• On app start, load saved chunks and overlay them on generated terrain. |
| **Day 12** | Mobile touch controls (optional) | • Add a virtual joystick component for movement. <br>• Convert tap‑and‑hold gestures into left/right clicks for block interaction. |
| **Day 13** | Performance polish | • Implement chunk‑loading radius (e.g., 4 chunks in each direction). <br>• Unload distant chunks from memory/scene. <br>• Verify framerate on a mid‑range laptop (Chrome). |
| **Day 14** | QA & Deployment Prep | • Run unit tests for world generation and ray‑cast logic. <br>• Conduct manual play‑test: movement, block placement, collision, persistence. <br>• Build production bundle (`vite build`). <br>• Draft README and deployment script (Netlify/ Vercel). |
| **Buffer Days** | Contingency | • Resolve bugs discovered during testing. <br>• Refine UI/UX based on feedback. |

### Time Estimates per Task  

| Task | Approx. Effort |
|------|-----------------|
| Project scaffolding | 2 h |
| Data models & Redux slices | 4 h |
| Terrain generator | 6 h |
| Rendering foundation | 6 h |
| Chunk mesh builder | 8 h |
| Controls & movement | 5 h |
| Collision system | 4 h |
| Ray‑cast interaction | 5 h |
| UI overlay | 4 h |
| Dirty‑chunk handling | 3 h |
| Persistence (optional) | 5 h |
| Mobile controls (optional) | 6 h |
| Performance tweaks | 6 h |
| Testing & deployment | 6 h |
| **Total** | **~71 h** (≈ 9‑10 working days) – fits comfortably within a 2‑week schedule allowing for reviews and unexpected issues. |

---  

## 6. Testing Strategy  

### 6.1. Unit Tests  

| Module | Test Cases |
|--------|------------|
| **ChunkGenerator** | • Height values stay within expected range.<br>• Correct block IDs for surface layer (grass) and subsurface (dirt/stone). |
| **BlockPalette** | • All defined IDs map to an existing UV rectangle.<br>• `solid` flag matches expected behaviour (water = false). |
| **Raycaster** | • Hits the correct voxel when aiming at a known block.<br>• Returns `null` when no block within reach.<br>• Correct face normal for each side. |
| **Collision** | • Player cannot move into a solid block placed directly adjacent.<br>• Sliding along a wall works (no jitter). |
| **ChunkMeshBuilder** | • For a single solid block, exactly 6 faces are generated.<br>• For two adjacent blocks, shared face is omitted. |
| **PersistenceService** | • Serialized chunk data can be deserialized without loss.<br>• Saved modifications overwrite generated terrain on reload. |

Testing framework: **Jest** with **ts-jest** (if TypeScript is used) or plain Babel for JavaScript.

### 6.2. Integration / End‑to‑End Tests  

| Scenario | Steps | Expected Outcome |
|----------|-------|-------------------|
| **Player Walk** | Load world → press `W` for 2 seconds. | Camera moves forward, stays above ground, no clipping. |
| **Block Placement** | Aim at a solid block → right‑click. | New block appears on the adjacent empty voxel, mesh updates instantly. |
| **Block Destruction** | Aim at a placed block → left‑click. | Block disappears, neighboring faces become visible if applicable. |
| **Chunk Loading** | Move far enough to cross chunk boundary. | New chunk mesh appears, old distant chunk is removed from the scene. |
| **Persistence** | Place a block, reload page. | The placed block persists in the same location. |

Tools: **Playwright** or **Cypress** for automated browser interaction.

---  

## 7. Deployment Guide  

1. **Prerequisites**  
   - Node.js ≥ 18 (LTS)  
   - npm or yarn  

2. **Installation**  
   ```bash
   npm ci            # installs exact versions from lockfile
   npm run dev       # start Vite dev server (http://localhost:5173)
   ```

3. **Production Build**  
   ```bash
   npm run build     # generates ./dist
   ```

4. **Static Hosting Options**  
   - **Netlify**: Connect repository, set “Build command” → `npm run build`, “Publish directory” → `dist`.  
   - **Vercel**: Same as Netlify; Vercel automatically detects Vite output.  
   - **GitHub Pages**: `npm run build && npx serve dist` locally; push `dist` to `gh-pages` branch for remote.  

5. **Cache Busting**  
   Vite includes content‑hash in file names (`.js`, `.css`). Ensure the host serves the correct MIME types (e.g., `application/javascript`).

6. **HTTPS & Pointer‑Lock**  
   Pointer‑Lock API (required for mouse look) only works on secure contexts (`https://` or `localhost`). Verify the hosting domain provides HTTPS.

---  

## 8. Optional Extensions (Future Work)  

| Direction | Description | Why It Matters |
|-----------|-------------|----------------|
| **Multiplayer** | Add a Node.js WebSocket server; broadcast block updates to all clients. Use authoritative server to resolve collisions. | Turns the clone into a shared sandbox, opening doors to community‑driven worlds. |
| **Advanced Physics** | Implement gravity, jumping, and simple ladder mechanics. | Makes movement feel more like the original Minecraft. |
| **Biomes & Multiple Height‑Maps** | Generate distinct noise layers (temperature, moisture) → assign biome types (forest, desert). | Adds visual variety and paves the way for richer world generation. |
| **Voxel Lighting** | Compute per‑chunk ambient occlusion or a cheap light‑map; dynamic day‑night cycle. | Improves visual depth and mood. |
| **Inventory System** | Drag‑and‑drop UI for collected blocks; limit placement to owned items. | Introduces resource management, a core gameplay loop. |
| **Modular Block Scripts** | Allow each block type to expose a small script (e.g., water flow, plant growth). | Enables emergent behavior and advanced world dynamics. |
| **Performance Optimisations** | Switch to **InstancedMesh** for repeated geometry, use **GPU‑driven frustum culling**, implement **Chunk Streaming** (load/unload on the fly). | Supports larger worlds on low‑end devices. |
| **Export / Import** | Serialize world to a downloadable file (JSON or binary) and allow users to load custom maps. | Encourages community sharing and long‑term persistence. |

---  

## 9. Conclusion  

This document provides a **complete, code‑free blueprint** for a minimal Minecraft‑style web clone that satisfies the specified feature set. By following the two‑week roadmap, a small development team (or a single full‑stack developer) can deliver a functional, performant, and extensible voxel sandbox that runs in any modern browser. The modular architecture ensures that future enhancements—multiplayer, advanced lighting, or richer terrain—can be integrated without a major redesign.  

---  

*Prepared by an AI game‑development specialist for the purpose of guiding a hands‑on implementation.*

Below is the complete, code-free design and implementation plan for a web-based Minecraft-style clone, as specified in the prompt. I am acting as an experienced game-development AI, focusing on a minimal viable product that supports basic block creation (placement) and destruction in a 3D voxel world. This plan adheres to the requirements: using Three.js for rendering, implementing first-person controls (WASD + mouse), supporting chunked world storage with simple heightmap terrain, and including a palette of at least 5 block types (e.g., grass, dirt, stone, water, wood). It also incorporates collision detection, face culling, and a minimal UI for block selection.

The output is purely textual documentation—no code snippets are included.

---

# Web-Based Minecraft Clone: Design and Implementation Plan

## 1. Technical Specification Document

This section provides a comprehensive description of the features, architecture, data structures, and algorithms for the Minecraft-style clone. The goal is to create a browser-based application that runs on desktop and mobile, allowing users to explore a procedurally generated 3D voxel world, place and destroy blocks, and navigate with basic first-person controls.

### 1.1 Core Features
- **Procedurally Generated Terrain**: A simple 2D heightmap using noise functions to create a 3D voxel grid. The world is divided into chunks (e.g., 16x16x16 blocks) for efficient management.
- **Real-Time Block Interaction**: Users can destroy blocks with a left-click and place blocks with a right-click, limited to a reach distance (e.g., 3 blocks). At least 5 block types are supported (grass, dirt, stone, water, wood), selectable via a minimal UI.
- **First-Person Controls**: WASD keys for movement (forward, left, back, right), mouse for looking (yaw and pitch), and click events for interaction.
- **Collision Detection and Simple Physics**: Prevent the player from walking through solid blocks using axis-aligned bounding boxes (AABB). Include basic ground collision but no gravity or jumping.
- **Minimal UI**: A block selection palette displayed as a horizontal bar at the bottom of the screen, with icons for the 5 block types. A central crosshair serves as a HUD element.

### 1.2 Technology Stack
- **Front-End Rendering**: Three.js (chosen for its widespread adoption, strong community support, and excellent voxel rendering capabilities).
- **State Management**: Redux (paired with React for global state handling of world data, player state, and UI interactions).
- **UI Framework**: React (selected for its component-based architecture, which simplifies UI elements like the block palette and HUD).
- **Backend (Optional)**: No server-side backend is required for this minimal version, but IndexedDB is used for local persistence of world state.
- **Build Tool**: Vite (chosen for its fast development server and efficient bundling, ideal for a web-based game).

### 1.3 Detailed Feature Breakdown

| Feature              | Description                                   | Key Implementation Points                          |
|----------------------|-----------------------------------------------|----------------------------------------------------|
| **World Generation** | Procedurally generate a 3D voxel world using a 2D heightmap. Divide the world into chunks for scalability. | • Use a noise function (e.g., Simplex noise) to generate a heightmap. <br> • Chunks are 16x16x16 blocks; generate based on chunk coordinates. <br> • Populate chunks with block types based on height (e.g., stone at lower levels, grass on top). |
| **Block Types**      | A palette of at least 5 types (grass, dirt, stone, water, wood), each with unique properties. | • Assign a unique ID to each type (e.g., 0 for air/empty, 1 for grass). <br> • Define properties like texture coordinates and solidity in a central palette. <br> • Use a texture atlas for efficient rendering. |
| **Rendering**        | Render only visible blocks in the 3D world, optimizing for performance. | • Use Three.js to create meshes for each chunk. <br> • Implement face culling to omit faces adjacent to solid blocks, reducing polygon count. <br> • Only render chunks in the player's view frustum. |
| **Controls**         | First-person navigation and interaction.     | • Keyboard: WASD for movement at a fixed speed. <br> • Mouse: Control camera rotation for yaw and pitch. <br> • Mouse clicks: Left for destruction, right for placement, with ray-casting to determine targets. |
| **Block Interaction**| Allow placement and destruction within reach. | • Perform ray-casting from the camera to detect blocks up to 3 units away. <br> • For placement, offset the ray-cast hit to the adjacent empty cell. <br> • Update the world data and re-render affected chunks after interactions. |
| **Collision Detection** | Prevent player movement through solid blocks. | • Use AABB for the player and check against solid blocks in the player's path. <br> • Resolve collisions by adjusting the player's position along movement axes. |
| **UI**               | Minimal interface for user interaction.      | • Block palette: A horizontal bar with icons for the 5 block types; clicking selects the active type. <br> • HUD: A central crosshair and a text indicator for the selected block. <br> • Mobile adaptation: Use virtual controls (e.g., on-screen joystick for movement). |
| **Persistence**      | Optional local saving of world state.        | • Use IndexedDB to store chunk data as serialized arrays. <br> • Auto-save on block changes and load on application start. |
| **Extensibility**    | Design for future additions like biomes or multiplayer. | • Modular architecture: Separate the data layer (e.g., chunk storage) from rendering and interaction logic. <br> • Expose APIs for block updates to facilitate extensions. |

### 1.4 Data Structures
The following data structures ensure efficient storage and management of the game world:

| Data                | Type                  | Notes                                      |
|---------------------|-----------------------|--------------------------------------------|
| **Chunk**          | 3D array (e.g., [16][16][16] of block IDs) | Represents a section of the world; each element is a block ID (e.g., 0 for empty, 1 for grass). |
| **Block Palette**  | Map (e.g., ID to object) | A key-value map where each entry includes {type: string, textureCoord: array, isSolid: boolean}. Example: ID 1 maps to {type: "grass", textureCoord: [0, 0], isSolid: true}. |
| **World Map**      | Map (e.g., chunk coordinates to Chunk objects) | Keys are strings like "x:y:z" for chunk positions; values are Chunk arrays. |
| **Player State**   | Object (e.g., {position: Vec3, rotation: Euler, velocity: Vec3}) | Tracks player location (x, y, z), orientation (yaw, pitch), and movement speed for controls and collision. |

### 1.5 Algorithmic Highlights
Key algorithms are described at a high level to guide implementation:

- **Chunk Generation**: For each chunk, generate a heightmap using noise. Iterate through each (x, z) position in the chunk, determine the height (y), and fill blocks accordingly (e.g., solid blocks up to the height, water above if within a certain depth).
  
- **Rendering Culling**: For each block in a chunk, check if it's solid. For each of its 6 faces, verify if the adjacent block is empty; if so, include the face in the mesh to optimize rendering.

- **Interaction Ray-Casting**: From the camera's position, cast a ray in the direction of the mouse cursor. Step along the ray in small increments, checking for block intersections. Return the hit block's coordinates and face normal for placement or destruction.

- **Block Placement/Destruction**: For destruction, set the targeted block's ID to 0 (empty). For placement, set the adjacent empty block's ID to the selected type. After changes, regenerate meshes for the affected chunk and its neighbors to handle culling.

## 2. System Architecture Diagram
Below is a textual ASCII representation of the system architecture, based on the provided outline. This diagram illustrates the flow from user input to rendering and data storage.

```
┌─────────────────────────────┐
│          Browser UI         │
│  (React components:         │
│   Block Palette, HUD)       │
└─────────────┬───────────────┘
              │
              │ User interactions (e.g., clicks, keyboard)
   ┌──────────▼───────────┐
   │  State Management    │
   │  (Redux Store)       │
   │  - Player state      │
   │  - World data        │
   └──────────┬───────────┘
              │
              │ Data updates
   ┌──────────▼───────────┐
   │  Render Engine       │
   │  (Three.js)          │
   │  - Chunk meshes      │
   │  - Face culling      │
   │  - Camera controls   │
   └──────────┬───────────┘
              │
              │ Interaction queries
   ┌──────────▼───────────┐
   │  Input/Interaction   │
   │  Layer               │
   │  - Ray-casting       │
   │  - Collision checks  │
   └──────────┬───────────┘
              │
              │ World access
   ┌──────────▼───────────┐
   │  World Data Layer    │
   │  - Chunk storage     │
   │  - Persistence       │
   │  (IndexedDB)         │
   └──────────────────────┘
```

This architecture separates concerns: UI handles user-facing elements, state management coordinates data flow, the render engine visualizes the world, the interaction layer processes inputs, and the data layer manages storage.

## 3. Detailed Implementation Plan with Timelines
This 2-week roadmap assumes a full-time developer (40 hours/week). Tasks are broken into daily estimates, focusing on sequential sprints to build and iterate. Potential pitfalls include performance issues with rendering large worlds or browser compatibility on mobile.

### Week 1: Setup and Core Systems
- **Day 1-2 (8 hours/day)**: Set up project skeleton. Initialize a Vite project with React and Three.js. Configure Redux for state management. Install necessary libraries (e.g., for noise generation). *Pitfall: Ensure cross-browser compatibility; test early on Chrome and Safari.*
- **Day 3-4 (8 hours/day)**: Implement world data layer and chunk generation. Create data structures for chunks and the world map. Develop the heightmap algorithm using a noise library. Generate a small test world. *Pitfall: Noise functions may require tuning for natural terrain.*
- **Day 5 (8 hours)**: Build voxel renderer. Use Three.js to create meshes for chunks, implementing face culling. Render a single chunk initially. *Pitfall: Optimize culling to avoid high CPU usage.*
- **Day 6-7 (8 hours/day)**: Add player controls and basic physics. Implement WASD movement, mouse look, and simple AABB collision detection. Ensure player stays on the ground.

### Week 2: Interactions and Polish
- **Day 8-9 (8 hours/day)**: Implement block interaction. Add ray-casting for detection, and logic for placement/destruction. Update rendering for changed chunks. *Pitfall: Ray-casting precision; handle edge cases like diagonal hits.*
- **Day 10 (8 hours)**: Develop minimal UI. Create React components for the block palette and HUD. Integrate block selection with state management.
- **Day 11-12 (8 hours/day)**: Add mobile adaptations and optional persistence. Implement touch controls (e.g., virtual joystick) and use IndexedDB for saving/loading world data. *Pitfall: Mobile performance; limit rendered chunks on smaller devices.*
- **Day 13-14 (8 hours/day)**: Polish, test, and debug. Fix bugs, optimize rendering (e.g., frustum culling), and ensure cross-device compatibility.

Total Timeline: 2 weeks. This plan allows for iterative testing, with buffer time for pitfalls like rendering bottlenecks.

## 4. Testing and Deployment Strategy
### Testing Strategy
- **Unit Tests**: Test individual components, such as world generation (e.g., verify chunk arrays have correct block types), ray-casting (e.g., simulate hits on sample coordinates), and collision logic (e.g., check player movement against solid blocks). Use Jest for React/Redux tests.
- **End-to-End Tests**: Simulate user flows, like navigating the world (e.g., using Playwright to automate WASD and mouse inputs), placing/destroying blocks, and verifying UI updates. Test on desktop and mobile browsers.
- **Performance Tests**: Monitor frame rates and memory usage during world rendering. Use browser dev tools to identify bottlenecks, especially with large chunks.
- **Edge Cases**: Test invalid interactions (e.g., placing blocks out of reach), mobile-specific issues (e.g., touch accuracy), and persistence (e.g., reload page and check saved state).

### Deployment Guide
- **Build Commands**: Use Vite's build command (e.g., `vite build`) to generate a production bundle. This outputs optimized HTML, JS, and asset files.
- **Hosting Options**: Deploy to static hosting services like Netlify or Vercel. Upload the built files to the platform; no server is needed since this is client-side. Configure custom domains and enable HTTPS.
- **Additional Steps**: For mobile optimization, use service workers for caching (via Workbox). Test deployment on various devices to ensure responsiveness.

## 5. Optional Extensions for Future Work
This design is extensible, with the modular architecture allowing for easy additions. Potential future features include:
- **Multiplayer**: Integrate a WebSocket server (e.g., with Node.js) for real-time state synchronization across players.
- **Crafting/Inventory System**: Add a UI component for an inventory grid, enabling drag-and-drop block selection and simple crafting recipes.
- **Biome System**: Extend world generation with biome-specific palettes (e.g., desert vs. forest), using noise to vary block types per region.
- **Lighting**: Implement basic directional lighting or per-chunk light maps in Three.js to enhance visuals.
- **Performance Enhancements**: Add chunk streaming (load only nearby chunks), advanced frustum culling, or level-of-detail (LOD) rendering for larger worlds.

This plan provides a solid foundation for a functional Minecraft clone, emphasizing simplicity and scalability while meeting all specified requirements.