<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Three.js Sphere in Modal</title>
    <style>
        /* Basic styles */
        body {
            margin: 0;
            font-family: Arial, sans-serif;
            background-color: #222;
            color: white;
        }

/* Modal styles */
        .modal {
            position: fixed;
            top: 10%;
            left: 10%;
            width: 80%;
            height: 80%;
            background-color: rgba(0, 0, 0, 0.9);
            border-radius: 10px;
            display: flex;
            justify-content: center;
            align-items: center;
            overflow: hidden;
        }

#threeCanvas {
            width: 100%;
            height: 100%;
        }
    </style>
</head>
<body>
    
    <div class="modal">
        
        <div id="threeCanvas"></div>
    </div>

<script src="https://cdnjs.cloudflare.com/ajax/libs/three.js/r128/three.min.js"></script>
    <script>
        // Initialize Three.js in the modal container
        const canvasContainer = document.getElementById('threeCanvas');

// Create scene, camera, and renderer
        const scene = new THREE.Scene();
        const camera = new THREE.PerspectiveCamera(
            75, 
            canvasContainer.offsetWidth / canvasContainer.offsetHeight, 
            0.1, 
            1000
        );
        const renderer = new THREE.WebGLRenderer();
        renderer.setSize(canvasContainer.offsetWidth, canvasContainer.offsetHeight);
        canvasContainer.appendChild(renderer.domElement);

// Add ambient light
        const ambientLight = new THREE.AmbientLight(0xffffff, 0.5);
        scene.add(ambientLight);

// Add point light
        const pointLight = new THREE.PointLight(0xffffff, 1);
        pointLight.position.set(5, 5, 5);
        scene.add(pointLight);

// Create a sphere
        const geometry = new THREE.SphereGeometry(1, 64, 64);
        const material = new THREE.MeshStandardMaterial({
            color: 0xadd8e6, // Light blue
            wireframe: true, // Wireframe for clear visualization
        });
        const sphere = new THREE.Mesh(geometry, material);
        scene.add(sphere);

// Position the camera
        camera.position.z = 5;

// Animation loop
        function animate() {
            requestAnimationFrame(animate);

// Rotate the sphere for better visibility
            sphere.rotation.x += 0.02;
            sphere.rotation.y += 0.01;

// Render the scene
            renderer.render(scene, camera);
        }

animate();

// Ensure the renderer resizes properly with the modal
        window.addEventListener('resize', () => {
            const width = canvasContainer.offsetWidth;
            const height = canvasContainer.offsetHeight;
            renderer.setSize(width, height);
            camera.aspect = width / height;
            camera.updateProjectionMatrix();
        });
    </script>
</body>
</html>

About THIS CODE (CANVASOR.NET):