examples/webgl_interactive_buffergeometry.html

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	<head>
		<title>three.js webgl - interactive - buffergeometry</title>
		<meta charset="utf-8">
		<meta name="viewport" content="width=device-width, user-scalable=no, minimum-scale=1.0, maximum-scale=1.0">
		<link type="text/css" rel="stylesheet" href="main.css">
	</head>
	<body>

		<div id="container"></div>
		<div id="info"><a href="https://threejs.org" target="_blank" rel="noopener">three.js</a> webgl - interactive - buffergeometry</div>

		<script type="importmap">
			{
				"imports": {
					"three": "../build/three.module.js",
					"three/addons/": "./jsm/"
				}
			}
		</script>

		<script type="module">

			import * as THREE from 'three';

			import Stats from 'three/addons/libs/stats.module.js';

			let container, stats;

			let camera, scene, renderer;

			let raycaster, pointer;

			let mesh, line;

			init();

			function init() {

				container = document.getElementById( 'container' );

				//

				camera = new THREE.PerspectiveCamera( 27, window.innerWidth / window.innerHeight, 1, 3500 );
				camera.position.z = 2750;

				scene = new THREE.Scene();
				scene.background = new THREE.Color( 0x050505 );
				scene.fog = new THREE.Fog( 0x050505, 2000, 3500 );

				//

				scene.add( new THREE.AmbientLight( 0x444444, 3 ) );

				const light1 = new THREE.DirectionalLight( 0xffffff, 1.5 );
				light1.position.set( 1, 1, 1 );
				scene.add( light1 );

				const light2 = new THREE.DirectionalLight( 0xffffff, 4.5 );
				light2.position.set( 0, - 1, 0 );
				scene.add( light2 );

				//

				const triangles = 5000;

				let geometry = new THREE.BufferGeometry();

				const positions = new Float32Array( triangles * 3 * 3 );
				const normals = new Float32Array( triangles * 3 * 3 );
				const colors = new Float32Array( triangles * 3 * 3 );

				const color = new THREE.Color();

				const n = 800, n2 = n / 2;	// triangles spread in the cube
				const d = 120, d2 = d / 2;	// individual triangle size

				const pA = new THREE.Vector3();
				const pB = new THREE.Vector3();
				const pC = new THREE.Vector3();

				const cb = new THREE.Vector3();
				const ab = new THREE.Vector3();

				for ( let i = 0; i < positions.length; i += 9 ) {

					// positions

					const x = Math.random() * n - n2;
					const y = Math.random() * n - n2;
					const z = Math.random() * n - n2;

					const ax = x + Math.random() * d - d2;
					const ay = y + Math.random() * d - d2;
					const az = z + Math.random() * d - d2;

					const bx = x + Math.random() * d - d2;
					const by = y + Math.random() * d - d2;
					const bz = z + Math.random() * d - d2;

					const cx = x + Math.random() * d - d2;
					const cy = y + Math.random() * d - d2;
					const cz = z + Math.random() * d - d2;

					positions[ i ] = ax;
					positions[ i + 1 ] = ay;
					positions[ i + 2 ] = az;

					positions[ i + 3 ] = bx;
					positions[ i + 4 ] = by;
					positions[ i + 5 ] = bz;

					positions[ i + 6 ] = cx;
					positions[ i + 7 ] = cy;
					positions[ i + 8 ] = cz;

					// flat face normals

					pA.set( ax, ay, az );
					pB.set( bx, by, bz );
					pC.set( cx, cy, cz );

					cb.subVectors( pC, pB );
					ab.subVectors( pA, pB );
					cb.cross( ab );

					cb.normalize();

					const nx = cb.x;
					const ny = cb.y;
					const nz = cb.z;

					normals[ i ] = nx;
					normals[ i + 1 ] = ny;
					normals[ i + 2 ] = nz;

					normals[ i + 3 ] = nx;
					normals[ i + 4 ] = ny;
					normals[ i + 5 ] = nz;

					normals[ i + 6 ] = nx;
					normals[ i + 7 ] = ny;
					normals[ i + 8 ] = nz;

					// colors

					const vx = ( x / n ) + 0.5;
					const vy = ( y / n ) + 0.5;
					const vz = ( z / n ) + 0.5;

					color.setRGB( vx, vy, vz );

					colors[ i ] = color.r;
					colors[ i + 1 ] = color.g;
					colors[ i + 2 ] = color.b;

					colors[ i + 3 ] = color.r;
					colors[ i + 4 ] = color.g;
					colors[ i + 5 ] = color.b;

					colors[ i + 6 ] = color.r;
					colors[ i + 7 ] = color.g;
					colors[ i + 8 ] = color.b;

				}

				geometry.setAttribute( 'position', new THREE.BufferAttribute( positions, 3 ) );
				geometry.setAttribute( 'normal', new THREE.BufferAttribute( normals, 3 ) );
				geometry.setAttribute( 'color', new THREE.BufferAttribute( colors, 3 ) );

				geometry.computeBoundingSphere();

				let material = new THREE.MeshPhongMaterial( {
					color: 0xaaaaaa, specular: 0xffffff, shininess: 250,
					side: THREE.DoubleSide, vertexColors: true
				} );

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

				//

				raycaster = new THREE.Raycaster();

				pointer = new THREE.Vector2();

				geometry = new THREE.BufferGeometry();
				geometry.setAttribute( 'position', new THREE.BufferAttribute( new Float32Array( 4 * 3 ), 3 ) );

				material = new THREE.LineBasicMaterial( { color: 0xffffff, transparent: true } );

				line = new THREE.Line( geometry, material );
				scene.add( line );

				//

				renderer = new THREE.WebGLRenderer( { antialias: true } );
				renderer.setPixelRatio( window.devicePixelRatio );
				renderer.setSize( window.innerWidth, window.innerHeight );
				renderer.setAnimationLoop( animate );
				container.appendChild( renderer.domElement );

				//

				stats = new Stats();
				container.appendChild( stats.dom );

				//

				window.addEventListener( 'resize', onWindowResize );
				document.addEventListener( 'pointermove', onPointerMove );

			}

			function onWindowResize() {

				camera.aspect = window.innerWidth / window.innerHeight;
				camera.updateProjectionMatrix();

				renderer.setSize( window.innerWidth, window.innerHeight );

			}

			function onPointerMove( event ) {

				pointer.x = ( event.clientX / window.innerWidth ) * 2 - 1;
				pointer.y = - ( event.clientY / window.innerHeight ) * 2 + 1;

			}

			//

			function animate() {

				render();
				stats.update();

			}

			function render() {

				const time = Date.now() * 0.001;

				mesh.rotation.x = time * 0.15;
				mesh.rotation.y = time * 0.25;

				raycaster.setFromCamera( pointer, camera );

				const intersects = raycaster.intersectObject( mesh );

				if ( intersects.length > 0 ) {

					const intersect = intersects[ 0 ];
					const face = intersect.face;

					const linePosition = line.geometry.attributes.position;
					const meshPosition = mesh.geometry.attributes.position;

					linePosition.copyAt( 0, meshPosition, face.a );
					linePosition.copyAt( 1, meshPosition, face.b );
					linePosition.copyAt( 2, meshPosition, face.c );
					linePosition.copyAt( 3, meshPosition, face.a );

					mesh.updateMatrix();

					line.geometry.applyMatrix4( mesh.matrix );

					line.visible = true;

				} else {

					line.visible = false;

				}

				renderer.render( scene, camera );

			}

		</script>

	</body>
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