9th.js/examples/tutorials/03-scene-camera-renderer.html at master · syedrazaalino/9th.js · GitHub

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<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>03 - Scene, Camera, Renderer Deep Dive</title>
    <style>
        body {
            margin: 0;
            overflow: hidden;
            font-family: 'Courier New', monospace;
            background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
        }

        #canvas-container {
            width: 100vw;
            height: 100vh;
        }

        #info {
            position: absolute;
            top: 20px;
            left: 20px;
            color: white;
            background: rgba(0, 0, 0, 0.85);
            padding: 20px;
            border-radius: 10px;
            max-width: 350px;
            line-height: 1.5;
            font-size: 13px;
        }

        h1 {
            margin: 0 0 15px 0;
            font-size: 20px;
            color: #e1bee7;
        }

        .step {
            margin: 10px 0;
            padding: 8px;
            background: rgba(255, 255, 255, 0.1);
            border-radius: 5px;
            border-left: 3px solid #e1bee7;
        }

        .demo-section {
            margin: 10px 0;
            padding: 10px;
            background: rgba(255, 255, 255, 0.1);
            border-radius: 5px;
        }

        code {
            background: rgba(0, 0, 0, 0.5);
            padding: 2px 6px;
            border-radius: 3px;
            color: #81c784;
            font-size: 12px;
        }

        .highlight {
            color: #ffeb3b;
            font-weight: bold;
        }

        .controls {
            margin-top: 10px;
            padding: 8px;
            background: rgba(255, 255, 255, 0.1);
            border-radius: 5px;
            font-size: 12px;
        }

        .controls button {
            margin: 2px;
            padding: 5px 10px;
            background: rgba(255, 255, 255, 0.2);
            border: 1px solid rgba(255, 255, 255, 0.3);
            border-radius: 3px;
            color: white;
            cursor: pointer;
            font-family: inherit;
            font-size: 11px;
        }

        .controls button:hover {
            background: rgba(255, 255, 255, 0.3);
        }

        .controls button.active {
            background: #4caf50;
            border-color: #4caf50;
        }

        #camera-info {
            position: absolute;
            bottom: 20px;
            right: 20px;
            color: white;
            background: rgba(0, 0, 0, 0.7);
            padding: 15px;
            border-radius: 8px;
            font-size: 12px;
            line-height: 1.4;
        }
    </style>
</head>
<body>
    <div id="info">
        <h1>📹 Tutorial 03: Camera & Scene Setup</h1>
        <div class="step">
            <strong>Goal:</strong> Master camera and scene configuration
        </div>
        <div class="demo-section">
            <strong>🎬 Camera Types:</strong><br>
            <button id="perspective-btn" class="active">Perspective Camera</button><br>
            <button id="orthographic-btn">Orthographic Camera</button>
        </div>
        <div class="step">
            <strong>Scene Setup Concepts:</strong>
            <ul style="margin: 5px 0; padding-left: 15px; font-size: 12px;">
                <li>Scene as a 3D container</li>
                <li>Camera positioning and FOV</li>
                <li>Renderer configuration</li>
                <li>Coordinate systems</li>
                <li>View frustum and culling</li>
            </ul>
        </div>
        <div class="controls">
            <strong>🎮 Try These:</strong><br>
            <button id="toggle-grid">Toggle Grid</button>
            <button id="toggle-axes">Toggle Axes</button>
            <button id="change-fov">Change FOV</button>
            <button id="reset-camera">Reset Camera</button>
        </div>
        <div class="step">
            <span class="highlight">👁️ Watch how camera type affects perspective!</span>
        </div>
    </div>

    <div id="camera-info">
        <strong>Camera Settings:</strong><br>
        Type: <span id="camera-type">Perspective</span><br>
        FOV: <span id="fov-value">75°</span><br>
        Position: <span id="camera-pos">0, 5, 15</span>
    </div>

    <div id="canvas-container"></div>

    <script src="https://cdnjs.cloudflare.com/ajax/libs/three.js/r128/three.min.js"></script>

    <script>
        /**
         * ==========================================
         * TUTORIAL 03: SCENE, CAMERA, RENDERER DEEP DIVE
         * ==========================================
         *
         * This tutorial explores the three pillars of 3D rendering:
         *
         * 1. SCENE: The 3D world container
         *    - Holds all objects, lights, and cameras
         *    - Defines the coordinate system
         *    - Can have background colors, fog, etc.
         *
         * 2. CAMERA: Your "eye" in 3D space
         *    - Two main types: Perspective and Orthographic
         *    - Defines the viewpoint and what gets rendered
         *    - Has position, rotation, and viewing parameters
         *
         * 3. RENDERER: The drawing engine
         *    - Takes scene + camera → 2D image
         *    - Handles WebGL, color management, etc.
         *    - Manages the canvas and drawing buffer
         */

        // ==========================================
        // GLOBAL VARIABLES
        // ==========================================
        let scene, camera, renderer;
        let currentCameraType = 'perspective';
        let gridHelper, axesHelper;
        let animationId;

        // ==========================================
        // SCENE SETUP
        // ==========================================
        function createScene() {
            // Create the scene - our 3D world container
            scene = new THREE.Scene();

            // Set a gradient background
            const bgColor = new THREE.Color(0x1a1a2e);
            scene.background = bgColor;

            // Add fog for depth perception (optional)
            // scene.fog = new THREE.Fog(0x1a1a2e, 10, 50);

            console.log('✅ Scene created with gradient background');
            return scene;
        }

        // ==========================================
        // CAMERA SETUP - TWO TYPES
        // ==========================================

        // 1. PERSPECTIVE CAMERA (Most common)
        // Mimics how human eyes see - objects get smaller with distance
        function createPerspectiveCamera() {
            const fov = 75;  // Field of View in degrees
            const aspect = window.innerWidth / window.innerHeight;
            const near = 0.1;  // Near clipping plane
            const far = 1000;   // Far clipping plane

            camera = new THREE.PerspectiveCamera(fov, aspect, near, far);

            // Position the camera
            camera.position.set(0, 5, 15);
            camera.lookAt(0, 0, 0);  // Look at the center of the scene

            console.log(`✅ Perspective camera created (FOV: ${fov}°)`);
            updateCameraInfo();
            return camera;
        }

        // 2. ORTHOGRAPHIC CAMERA
        // No perspective distortion - objects stay same size regardless of distance
        // Good for 2D games, architectural drawings, UI elements
        function createOrthographicCamera() {
            const frustumSize = 20;  // How much of the scene is visible
            const aspect = window.innerWidth / window.innerHeight;

            camera = new THREE.OrthographicCamera(
                -frustumSize * aspect / 2,  // left
                frustumSize * aspect / 2,   // right
                frustumSize / 2,            // top
                -frustumSize / 2,           // bottom
                0.1,                        // near
                1000                        // far
            );

            camera.position.set(0, 0, 10);
            camera.lookAt(0, 0, 0);

            console.log('✅ Orthographic camera created');
            updateCameraInfo();
            return camera;
        }

        // ==========================================
        // RENDERER SETUP
        // ==========================================
        function createRenderer() {
            renderer = new THREE.WebGLRenderer({
                antialias: true,
                alpha: false
            });

            // Set the size
            renderer.setSize(window.innerWidth, window.innerHeight);

            // Handle high-DPI displays
            renderer.setPixelRatio(window.devicePixelRatio);

            // Optional: Enable shadow mapping
            renderer.shadowMap.enabled = true;
            renderer.shadowMap.type = THREE.PCFSoftShadowMap;

            // Color management (for better color reproduction)
            renderer.outputEncoding = THREE.sRGBEncoding;

            document.getElementById('canvas-container').appendChild(renderer.domElement);

            console.log('✅ Renderer configured with shadows and color management');
            return renderer;
        }

        // ==========================================
        // SCENE CONTENT - HELPFUL VISUAL AIDS
        // ==========================================
        function createSceneContent() {
            // Grid Helper - shows the ground plane
            gridHelper = new THREE.GridHelper(30, 30, 0x888888, 0x444444);
            scene.add(gridHelper);

            // Axes Helper - shows X (red), Y (green), Z (blue) axes
            axesHelper = new THREE.AxesHelper(5);
            scene.add(axesHelper);

            // Create a few objects at different distances
            const objectCount = 8;
            const objects = [];

            for (let i = 0; i < objectCount; i++) {
                const geometry = new THREE.BoxGeometry(1, 1, 1);
                const material = new THREE.MeshStandardMaterial({
                    color: new THREE.Color().setHSL(i / objectCount, 0.7, 0.5),
                    roughness: 0.3,
                    metalness: 0.1
                });

                const mesh = new THREE.Mesh(geometry, material);

                // Position objects in a circle and at different heights
                const angle = (i / objectCount) * Math.PI * 2;
                const radius = 8;
                mesh.position.x = Math.cos(angle) * radius;
                mesh.position.z = Math.sin(angle) * radius;
                mesh.position.y = Math.sin(angle * 2) * 3;

                // Enable shadows
                mesh.castShadow = true;
                mesh.receiveShadow = true;

                scene.add(mesh);
                objects.push(mesh);
            }

            // Add a large ground plane
            const groundGeometry = new THREE.PlaneGeometry(40, 40);
            const groundMaterial = new THREE.MeshStandardMaterial({
                color: 0x333333,
                roughness: 0.8,
                metalness: 0.2
            });
            const ground = new THREE.Mesh(groundGeometry, groundMaterial);
            ground.rotation.x = -Math.PI / 2;
            ground.position.y = -5;
            ground.receiveShadow = true;
            scene.add(ground);

            // Add lights
            const ambientLight = new THREE.AmbientLight(0x404040, 0.4);
            scene.add(ambientLight);

            const directionalLight = new THREE.DirectionalLight(0xffffff, 0.8);
            directionalLight.position.set(10, 10, 5);
            directionalLight.castShadow = true;
            directionalLight.shadow.mapSize.width = 2048;
            directionalLight.shadow.mapSize.height = 2048;
            scene.add(directionalLight);

            console.log(`✅ Scene content created with ${objectCount} objects, grid, axes, and lights`);
            return objects;
        }

        // ==========================================
        // CAMERA TYPE SWITCHING
        // ==========================================
        function switchCamera(type) {
            // Remove old camera from scene
            if (camera) {
                scene.remove(camera);
            }

            // Create new camera
            if (type === 'perspective') {
                createPerspectiveCamera();
            } else {
                createOrthographicCamera();
            }

            currentCameraType = type;
            updateCameraInfo();

            console.log(`Switched to ${type} camera`);
        }

        // ==========================================
        // CAMERA INFORMATION DISPLAY
        // ==========================================
        function updateCameraInfo() {
            document.getElementById('camera-type').textContent =
                currentCameraType.charAt(0).toUpperCase() + currentCameraType.slice(1);

            if (camera instanceof THREE.PerspectiveCamera) {
                document.getElementById('fov-value').textContent = `${camera.fov}°`;
            } else {
                document.getElementById('fov-value').textContent = 'N/A';
            }

            document.getElementById('camera-pos').textContent =
                `${camera.position.x.toFixed(1)}, ${camera.position.y.toFixed(1)}, ${camera.position.z.toFixed(1)}`;
        }

        // ==========================================
        // INTERACTIVE CONTROLS
        // ==========================================
        function setupControls() {
            // Camera type buttons
            document.getElementById('perspective-btn').addEventListener('click', () => {
                switchCamera('perspective');
                document.getElementById('perspective-btn').classList.add('active');
                document.getElementById('orthographic-btn').classList.remove('active');
            });

            document.getElementById('orthographic-btn').addEventListener('click', () => {
                switchCamera('orthographic');
                document.getElementById('orthographic-btn').classList.add('active');
                document.getElementById('perspective-btn').classList.remove('active');
            });

            // Grid toggle
            document.getElementById('toggle-grid').addEventListener('click', () => {
                gridHelper.visible = !gridHelper.visible;
            });

            // Axes toggle
            document.getElementById('toggle-axes').addEventListener('click', () => {
                axesHelper.visible = !axesHelper.visible;
            });

            // Change FOV
            document.getElementById('change-fov').addEventListener('click', () => {
                if (camera instanceof THREE.PerspectiveCamera) {
                    camera.fov = Math.random() * 100 + 30; // Random FOV between 30-130
                    camera.updateProjectionMatrix();
                    updateCameraInfo();
                }
            });

            // Reset camera
            document.getElementById('reset-camera').addEventListener('click', () => {
                camera.position.set(0, 5, 15);
                camera.lookAt(0, 0, 0);
                if (camera instanceof THREE.PerspectiveCamera) {
                    camera.fov = 75;
                    camera.updateProjectionMatrix();
                }
                updateCameraInfo();
            });
        }

        // ==========================================
        // ANIMATION LOOP
        // ==========================================
        function animate() {
            animationId = requestAnimationFrame(animate);

            // Rotate all the colored cubes
            scene.traverse((child) => {
                if (child instanceof THREE.Mesh && child.geometry instanceof THREE.BoxGeometry) {
                    child.rotation.x += 0.01;
                    child.rotation.y += 0.02;
                }
            });

            // Gentle camera movement for visual interest
            if (camera instanceof THREE.PerspectiveCamera) {
                const time = Date.now() * 0.0005;
                camera.position.x = Math.sin(time) * 15;
                camera.position.z = Math.cos(time) * 15;
                camera.lookAt(0, 0, 0);
                updateCameraInfo();
            }

            renderer.render(scene, camera);
        }

        // ==========================================
        // RESIZE HANDLING
        // ==========================================
        function handleResize() {
            camera.aspect = window.innerWidth / window.innerHeight;
            camera.updateProjectionMatrix();
            renderer.setSize(window.innerWidth, window.innerHeight);

            // For orthographic camera, also update the frustum
            if (camera instanceof THREE.OrthographicCamera) {
                const frustumSize = 20;
                const aspect = window.innerWidth / window.innerHeight;
                camera.left = -frustumSize * aspect / 2;
                camera.right = frustumSize * aspect / 2;
                camera.top = frustumSize / 2;
                camera.bottom = -frustumSize / 2;
                camera.updateProjectionMatrix();
            }
        }

        // ==========================================
        // INITIALIZATION
        // ==========================================
        function init() {
            console.log('🎬 Starting Scene, Camera, Renderer Demo...');

            createScene();
            createPerspectiveCamera();  // Start with perspective
            createRenderer();
            createSceneContent();
            setupControls();

            window.addEventListener('resize', handleResize);

            animate();

            console.log('✅ Demo initialized successfully!');
            console.log('💡 Try switching between Perspective and Orthographic cameras to see the difference!');
        }

        // Start the application
        init();

        // ==========================================
        // EXPERIMENT IDEAS:
        // ==========================================
        // 1. Try different FOV values (30, 60, 120 degrees)
        // 2. Move the camera closer and further from objects
        // 3. Look at the scene from different angles
        // 4. Add fog to the scene to understand near/far planes
        // 5. Experiment with orthographic camera for UI elements
        // 6. Try placing the camera inside the object circle
        // 7. Add a second camera and render both to different parts of the screen
    </script>
</body>
</html>