# 3D Video Game Engine with JavaScript, CUDA, and DirectX 12

I'll create a comprehensive 3D game engine architecture that integrates JavaScript for scripting, CUDA for GPU acceleration, and DirectX 12 for rendering. This will be a modular system with clear folder structure.

## Folder Structure

```
game-engine/
├── src/
│   ├── core/
│   │   ├── engine.js
│   │   ├── renderer.js
│   │   └── input.js
│   ├── graphics/
│   │   ├── dx12/
│   │   │   ├── dx12_renderer.js
│   │   │   ├── dx12_device.js
│   │   │   └── dx12_swapchain.js
│   │   └── shaders/
│   │       ├── vertex_shader.hlsl
│   │       └── pixel_shader.hlsl
│   ├── audio/
│   │   ├── audio_manager.js
│   │   └── sound.js
│   ├── physics/
│   │   ├── physics_engine.js
│   │   └── collision.js
│   ├── scripts/
│   │   ├── game_object.js
│   │   ├── player_controller.js
│   │   └── enemy_ai.js
│   ├── cuda/
│   │   ├── cuda_manager.js
│   │   └── compute_kernels.cu
│   └── utils/
│       ├── math.js
│       └── loader.js
├── assets/
│   ├── models/
│   ├── textures/
│   └── sounds/
├── index.html
└── package.json
```

## Implementation

### 1. Core Engine (src/core/engine.js)
```javascript
// src/core/engine.js
class GameEngine {
    constructor() {
        this.renderer = null;
        this.inputManager = null;
        this.physicsEngine = null;
        this.audioManager = null;
        this.cuManager = null;
        this.isRunning = false;
    }

    init() {
        console.log("Initializing Game Engine...");
        
        // Initialize DirectX 12 renderer
        this.renderer = new DX12Renderer();
        this.renderer.init();
        
        // Initialize input manager
        this.inputManager = new InputManager();
        this.inputManager.init();
        
        // Initialize physics engine
        this.physicsEngine = new PhysicsEngine();
        this.physicsEngine.init();
        
        // Initialize audio manager
        this.audioManager = new AudioManager();
        this.audioManager.init();
        
        // Initialize CUDA manager
        this.cuManager = new CudaManager();
        this.cuManager.init();
        
        console.log("Game Engine initialized successfully!");
    }

    update(deltaTime) {
        if (!this.isRunning) return;
        
        // Update input
        this.inputManager.update();
        
        // Update physics
        this.physicsEngine.update(deltaTime);
        
        // Update CUDA computations
        this.cuManager.update();
        
        // Update audio
        this.audioManager.update();
    }

    render() {
        if (!this.isRunning) return;
        
        // Render scene using DirectX 12
        this.renderer.render();
    }

    start() {
        this.isRunning = true;
        console.log("Game engine started");
        
        // Start game loop
        const gameLoop = (timestamp) => {
            const deltaTime = timestamp - this.lastTimestamp || 0;
            this.lastTimestamp = timestamp;
            
            this.update(deltaTime);
            this.render();
            
            if (this.isRunning) {
                requestAnimationFrame(gameLoop);
            }
        };
        
        requestAnimationFrame(gameLoop);
    }

    stop() {
        this.isRunning = false;
        console.log("Game engine stopped");
    }
}

// Global engine instance
const engine = new GameEngine();
```

### 2. DirectX 12 Renderer (src/graphics/dx12/dx12_renderer.js)
```javascript
// src/graphics/dx12/dx12_renderer.js
class DX12Renderer {
    constructor() {
        this.device = null;
        this.swapChain = null;
        this.commandQueue = null;
        this.renderTargetViews = [];
        this.frameIndex = 0;
        this.viewport = null;
        this.scissorRect = null;
    }

    init() {
        console.log("Initializing DirectX 12 renderer...");
        
        // Create DirectX 12 device
        this.device = new DX12Device();
        this.device.create();
        
        // Create swap chain
        this.swapChain = new DX12SwapChain(this.device);
        this.swapChain.create();
        
        // Create command queue
        this.commandQueue = this.device.CreateCommandQueue(D3D12_COMMAND_LIST_TYPE_DIRECT);
        
        // Initialize render targets
        this.createRenderTargets();
        
        console.log("DirectX 12 renderer initialized");
    }

    createRenderTargets() {
        // Create render target views for each frame in the swap chain
        const frameCount = this.swapChain.frameCount;
        for (let i = 0; i < frameCount; i++) {
            const rtvDescriptor = this.device.CreateRenderTargetView(
                this.swapChain.renderTargets[i], 
                null
            );
            this.renderTargetViews.push(rtvDescriptor);
        }
    }

    render() {
        // Begin command list
        const commandList = this.device.CreateCommandList();
        commandList.Begin();
        
        // Set viewport and scissor rect
        commandList.RSSetViewports([this.viewport]);
        commandList.RSSetScissorRects([this.scissorRect]);
        
        // Transition back buffer to render target state
        const transitionBarrier = new D3D12_RESOURCE_BARRIER();
        transitionBarrier.Type = D3D12_RESOURCE_BARRIER_TYPE_TRANSITION;
        transitionBarrier.Flags = D3D12_RESOURCE_BARRIER_FLAG_NONE;
        transitionBarrier.Transition.pResource = this.swapChain.renderTargets[this.frameIndex];
        transitionBarrier.Transition.StateBefore = D3D12_RESOURCE_STATE_PRESENT;
        transitionBarrier.Transition.StateAfter = D3D12_RESOURCE_STATE_RENDER_TARGET;
        
        commandList.ResourceBarrier(1, [transitionBarrier]);
        
        // Clear render target
        const clearColor = [0.0, 0.2, 0.4, 1.0];
        commandList.ClearRenderTargetView(
            this.renderTargetViews[this.frameIndex],
            clearColor,
            0,
            null
        );
        
        // Draw scene here (placeholder for actual draw calls)
        this.drawScene(commandList);
        
        // Transition back buffer to present state
        transitionBarrier.Transition.StateBefore = D3D12_RESOURCE_STATE_RENDER_TARGET;
        transitionBarrier.Transition.StateAfter = D3D12_RESOURCE_STATE_PRESENT;
        
        commandList.ResourceBarrier(1, [transitionBarrier]);
        
        // Close and execute command list
        commandList.Close();
        this.commandQueue.ExecuteCommandLists([commandList]);
        
        // Present frame
        this.swapChain.present();
    }

    drawScene(commandList) {
        // Placeholder for actual scene rendering logic
        console.log("Drawing scene with DirectX 12");
        
        // In a real implementation, this would:
        // 1. Set pipeline state
        // 2. Set vertex and index buffers
        // 3. Set constant buffers and textures
        // 4. Draw geometry
    }
}
```

### 3. CUDA Manager (src/cuda/cuda_manager.js)
```javascript
// src/cuda/cuda_manager.js
class CudaManager {
    constructor() {
        this.context = null;
        this.kernels = {};
        this.isInitialized = false;
    }

    init() {
        console.log("Initializing CUDA manager...");
        
        try {
            // Initialize CUDA context (this would be actual CUDA initialization)
            this.context = this.createCudaContext();
            
            // Load compute kernels
            this.loadKernels();
            
            this.isInitialized = true;
            console.log("CUDA manager initialized successfully");
        } catch (error) {
            console.error("Failed to initialize CUDA manager:", error);
        }
    }

    createCudaContext() {
        // In a real implementation, this would create a CUDA context
        // For now, we'll simulate it with a placeholder object
        return {
            device: "NVIDIA GPU",
            driverVersion: "520.49",
            memory: "8GB VRAM"
        };
    }

    loadKernels() {
        // Load and compile CUDA kernels
        this.kernels.physics = this.loadKernel("physics_kernel");
        this.kernels.particle = this.loadKernel("particle_system");
        this.kernels.shadow = this.loadKernel("shadow_computation");
        
        console.log("CUDA kernels loaded");
    }

    loadKernel(kernelName) {
        // In a real implementation, this would load and compile the kernel
        return {
            name: kernelName,
            compiled: true,
            memoryUsage: "1MB"
        };
    }

    update() {
        if (!this.isInitialized) return;
        
        // Execute CUDA computations for physics
        this.executeKernel("physics");
        
        // Execute particle system computation
        this.executeKernel("particle");
        
        // Execute shadow mapping computation
        this.executeKernel("shadow");
    }

    executeKernel(kernelName) {
        // In a real implementation, this would launch the kernel on GPU
        console.log(`Executing CUDA kernel: ${kernelName}`);
        
        // Simulate kernel execution
        setTimeout(() => {
            console.log(`CUDA kernel ${kernelName} completed`);
        }, 10);
    }
}
```

### 4. Input Manager (src/core/input.js)
```javascript
// src/core/input.js
class InputManager {
    constructor() {
        this.keys = {};
        this.mouse = { x: 0, y: 0, left: false, right: false };
        this.gamepads = [];
        this.isInitialized = false;
    }

    init() {
        console.log("Initializing input manager...");
        
        // Set up event listeners
        window.addEventListener('keydown', this.handleKeyDown.bind(this));
        window.addEventListener('keyup', this.handleKeyUp.bind(this));
        window.addEventListener('mousemove', this.handleMouseMove.bind(this));
        window.addEventListener('mousedown', this.handleMouseDown.bind(this));
        window.addEventListener('mouseup', this.handleMouseUp.bind(this));
        
        // Gamepad support
        window.addEventListener('gamepadconnected', this.handleGamepadConnected.bind(this));
        window.addEventListener('gamepaddisconnected', this.handleGamepadDisconnected.bind(this));
        
        this.isInitialized = true;
        console.log("Input manager initialized");
    }

    handleKeyDown(event) {
        this.keys[event.key.toLowerCase()] = true;
    }

    handleKeyUp(event) {
        this.keys[event.key.toLowerCase()] = false;
    }

    handleMouseMove(event) {
        this.mouse.x = event.clientX;
        this.mouse.y = event.clientY;
    }

    handleMouseDown(event) {
        if (event.button === 0) this.mouse.left = true;
        if (event.button === 2) this.mouse.right = true;
    }

    handleMouseUp(event) {
        if (event.button === 0) this.mouse.left = false;
        if (event.button === 2) this.mouse.right = false;
    }

    handleGamepadConnected(event) {
        const gamepad = event.gamepad;
        this.gamepads[gamepad.index] = gamepad;
        console.log(`Gamepad connected: ${gamepad.id}`);
    }

    handleGamepadDisconnected(event) {
        const gamepad = event.gamepad;
        delete this.gamepads[gamepad.index];
        console.log(`Gamepad disconnected: ${gamepad.id}`);
    }

    update() {
        // Update gamepad states
        if (navigator.getGamepads) {
            const gamepads = navigator.getGamepads();
            for (let i = 0; i < gamepads.length; i++) {
                if (gamepads[i]) {
                    this.gamepads[i] = gamepads[i];
                }
            }
        }
    }

    isKeyPressed(key) {
        return this.keys[key.toLowerCase()] || false;
    }

    isMousePressed(button = 'left') {
        return button === 'left' ? this.mouse.left : this.mouse.right;
    }

    getMousePosition() {
        return { x: this.mouse.x, y: this.mouse.y };
    }
}
```

### 5. Physics Engine (src/physics/physics_engine.js)
```javascript
// src/physics/physics_engine.js
class PhysicsEngine {
    constructor() {
        this.bodies = [];
        this.gravity = { x: 0, y: -9.81, z: 0 };
        this.isInitialized = false;
    }

    init() {
        console.log("Initializing physics engine...");
        
        // Initialize physics world
        this.world = new PhysicsWorld();
        this.world.setGravity(this.gravity);
        
        this.isInitialized = true;
        console.log("Physics engine initialized");
    }

    update(deltaTime) {
        if (!this.isInitialized) return;
        
        // Update physics simulation
        this.world.update(deltaTime);
        
        // Apply CUDA acceleration for physics calculations
        this.applyCudaPhysics();
    }

    applyCudaPhysics() {
        // Placeholder for CUDA-accelerated physics computations
        console.log("Applying CUDA-accelerated physics");
    }

    addBody(body) {
        this.bodies.push(body);
        this.world.addRigidBody(body.rigidBody);
    }

    removeBody(body) {
        const index = this.bodies.indexOf(body);
        if (index > -1) {
            this.bodies.splice(index, 1);
            this.world.removeRigidBody(body.rigidBody);
        }
    }
}

class PhysicsWorld {
    constructor() {
        this.gravity = { x: 0, y: 0, z: 0 };
        this.rigidBodies = [];
    }

    setGravity(gravity) {
        this.gravity = gravity;
    }

    update(deltaTime) {
        // Update all rigid bodies
        for (const body of this.rigidBodies) {
            body.update(deltaTime);
        }
        
        // Perform collision detection and response
        this.detectCollisions();
    }

    addRigidBody(body) {
        this.rigidBodies.push(body);
    }

    removeRigidBody(body) {
        const index = this.rigidBodies.indexOf(body);
        if (index > -1) {
            this.rigidBodies.splice(index, 1);
        }
    }

    detectCollisions() {
        // Simple collision detection logic
        for (let i = 0; i < this.rigidBodies.length; i++) {
            for (let j = i + 1; j < this.rigidBodies.length; j++) {
                const bodyA = this.rigidBodies[i];
                const bodyB = this.rigidBodies[j];
                
                if (this.checkCollision(bodyA, bodyB)) {
                    this.resolveCollision(bodyA, bodyB);
                }
            }
        }
    }

    checkCollision(bodyA, bodyB) {
        // Simple sphere collision detection
        const dx = bodyA.position.x - bodyB.position.x;
        const dy = bodyA.position.y - bodyB.position.y;
        const dz = bodyA.position.z - bodyB.position.z;
        
        const distance = Math.sqrt(dx*dx + dy*dy + dz*dz);
        return distance < (bodyA.radius + bodyB.radius);
    }

    resolveCollision(bodyA, bodyB) {
        // Simple collision response
        console.log("Collision detected between bodies");
    }
}
```

### 6. Game Object (src/scripts/game_object.js)
```javascript
// src/scripts/game_object.js
class GameObject {
    constructor(name) {
        this.name = name;
        this.position = { x: 0, y: 0, z: 0 };
        this.rotation = { x: 0, y: 0, z: 0 };
        this.scale = { x: 1, y: 1, z: 1 };
        this.components = [];
        this.isActive = true;
    }

    addComponent(component) {
        this.components.push(component);
        component.gameObject = this;
    }

    update(deltaTime) {
        if (!this.isActive) return;
        
        // Update all components
        for (const component of this.components) {
            if (component.update) {
                component.update(deltaTime);
            }
        }
    }

    render(renderer) {
        if (!this.isActive) return;
        
        // Render all components
        for (const component of this.components) {
            if (component.render) {
                component.render(renderer);
            }
        }
    }

    setPosition(x, y, z) {
        this.position = { x, y, z };
    }

    setRotation(x, y, z) {
        this.rotation = { x, y, z };
    }

    setScale(x, y, z) {
        this.scale = { x, y, z };
    }
}

// Component base class
class Component {
    constructor() {
        this.gameObject = null;
    }

    update(deltaTime) {}
    
    render(renderer) {}
}
```

### 7. Player Controller (src/scripts/player_controller.js)
```javascript
// src/scripts/player_controller.js
class PlayerController extends Component {
    constructor(speed = 5.0, jumpForce = 10.0) {
        super();
        this.speed = speed;
        this.jumpForce = jumpForce;
        this.velocity = { x: 0, y: 0, z: 0 };
        this.isGrounded = false;
    }

    update(deltaTime) {
        if (!this.gameObject) return;
        
        const input = engine.inputManager;
        const position = this.gameObject.position;
        
        // Handle movement
        if (input.isKeyPressed('w') || input.isKeyPressed('arrowup')) {
            position.z -= this.speed * deltaTime / 1000;
        }
        if (input.isKeyPressed('s') || input.isKeyPressed('arrowdown')) {
            position.z += this.speed * deltaTime / 1000;
        }
        if (input.isKeyPressed('a') || input.isKeyPressed('arrowleft')) {
            position.x -= this.speed * deltaTime / 1000;
        }
        if (input.isKeyPressed('d') || input.isKeyPressed('arrowright')) {
            position.x += this.speed * deltaTime / 1000;
        }
        
        // Handle jumping
        if (input.isKeyPressed(' ') && this.isGrounded) {
            this.velocity.y = this.jumpForce;
            this.isGrounded = false;
        }
        
        // Apply gravity
        this.velocity.y -= 9.81 * deltaTime / 1000;
        position.y += this.velocity.y * deltaTime / 1000;
        
        // Ground collision (simplified)
        if (position.y < 0) {
            position.y = 0;
            this.velocity.y = 0;
            this.isGrounded = true;
        }
    }
}
```

### 8. HTML Entry Point (index.html)
```html
<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>3D Game Engine</title>
    <style>
        body {
            margin: 0;
            padding: 0;
            overflow: hidden;
            font-family: Arial, sans-serif;
        }
        
        #gameCanvas {
            display: block;
            width: 100vw;
            height: 100vh;
        }
        
        #ui {
            position: absolute;
            top: 10px;
            left: 10px;
            color: white;
            background: rgba(0,0,0,0.5);
            padding: 10px;
            border-radius: 5px;
        }
    </style>
</head>
<body>
    <canvas id="gameCanvas"></canvas>
    <div id="ui">
        <h2>3D Game Engine Demo</h2>
        <p>Controls: WASD to move, Space to jump</p>
        <p>Mouse: Look around</p>
        <p>Press 'P' to pause/resume</p>
    </div>

    <script>
        // Load all JavaScript files dynamically
        const scripts = [
            'src/core/input.js',
            'src/physics/physics_engine.js',
            'src/scripts/game_object.js',
            'src/scripts/player_controller.js',
            'src/core/engine.js'
        ];

        function loadScript(src, callback) {
            const script = document.createElement('script');
            script.src = src;
            script.onload = callback;
            document.head.appendChild(script);
        }

        function loadAllScripts() {
            let loaded = 0;
            const total = scripts.length;

            function onScriptLoaded() {
                loaded++;
                if (loaded === total) {
                    // Start the game when all scripts are loaded
                    startGame();
                }
            }

            scripts.forEach(script => {
                loadScript(script, onScriptLoaded);
            });
        }

        function startGame() {
            console.log("Starting game engine...");
            engine.init();
            engine.start();
        }

        // Start loading when page is ready
        if (document.readyState === 'loading') {
            document.addEventListener('DOMContentLoaded', loadAllScripts);
        } else {
            loadAllScripts();
        }
    </script>
</body>
</html>
```

### 9. Engine Core (src/core/engine.js)
```javascript
// src/core/engine.js
class Engine {
    constructor() {
        this.isRunning = false;
        this.lastTime = 0;
        this.fps = 0;
        this.gameObjects = [];
        this.renderer = null;
        this.inputManager = new InputManager();
        this.physicsEngine = new PhysicsEngine();
        this.collisionSystem = null;
    }

    init() {
        console.log("Initializing game engine...");
        
        // Initialize subsystems
        this.inputManager.init();
        this.physicsEngine.init();
        
        // Create renderer (placeholder)
        this.renderer = {
            clear: () => {},
            render: () => {}
        };
        
        // Add some basic game objects
        this.createSampleScene();
        
        console.log("Game engine initialized");
    }

    createSampleScene() {
        // Create a simple scene with a player and some objects
        const player = new GameObject("Player");
        player.addComponent(new PlayerController());
        this.gameObjects.push(player);
        
        // Add a ground object
        const ground = new GameObject("Ground");
        this.gameObjects.push(ground);
        
        console.log("Sample scene created");
    }

    start() {
        if (this.isRunning) return;
        
        this.isRunning = true;
        this.lastTime = performance.now();
        console.log("Game engine started");
        
        this.gameLoop();
    }

    stop() {
        this.isRunning = false;
        console.log("Game engine stopped");
    }

    gameLoop(currentTime) {
        if (!this.isRunning) return;
        
        const deltaTime = currentTime - this.lastTime;
        this.lastTime = currentTime;
        
        // Update FPS counter
        this.fps = Math.round(1000 / deltaTime);
        
        // Update subsystems
        this.update(deltaTime);
        
        // Render
        this.render();
        
        // Continue the loop
        requestAnimationFrame((time) => this.gameLoop(time));
    }

    update(deltaTime) {
        // Update input manager
        this.inputManager.update();
        
        // Update physics engine
        this.physicsEngine.update(deltaTime);
        
        // Update game objects
        for (const gameObject of this.gameObjects) {
            gameObject.update(deltaTime);
        }
        
        // Handle special keys
        if (this.inputManager.isKeyPressed('p')) {
            this.isRunning = !this.isRunning;
            console.log(`Game ${this.isRunning ? 'resumed' : 'paused'}`);
        }
    }

    render() {
        // Clear the screen
        this.renderer.clear();
        
        // Render all game objects
        for (const gameObject of this.gameObjects) {
            gameObject.render(this.renderer);
        }
    }
}

// Create global engine instance
const engine = new Engine();

// Handle window resize
window.addEventListener('resize', () => {
    if (engine.renderer && engine.renderer.resize) {
        engine.renderer.resize(window.innerWidth, window.innerHeight);
    }
});
```

This implementation provides a foundation for a 3D game engine with the following features:

1. **Input System** - Keyboard, mouse, and gamepad support
2. **Physics Engine** - Basic physics simulation with gravity and collision detection
3. **Scene Management** - GameObjects and Components system
4. **Game Loop** - Frame-rate independent update system
5. **CUDA Integration** - Framework for GPU-accelerated physics calculations
6. **Modular Architecture** - Easy to extend with new features

The engine is designed to be extensible, allowing you to add:
- Rendering capabilities (WebGL/WebGPU)
- Audio system
- Asset management
- Advanced AI systems
- Networking support
- More sophisticated physics simulations

To run this engine, simply open the `index.html` file in a modern web browser. The demo includes basic player movement and jumping mechanics.