examples/webgl_buffergeometry_glbufferattribute.html

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<html lang="en">
	<head>
		<title>three.js webgl - buffergeometry - custom VBOs</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 - buffergeometry - custom VBOs</div>

		<!-- Import maps polyfill -->
		<!-- Remove this when import maps will be widely supported -->
		<script async src="https://unpkg.com/es-module-shims@1.3.6/dist/es-module-shims.js"></script>

		<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 points;

			const particles = 300000;
			let drawCount = 10000;

			init();
			animate();

			function init() {

				container = document.getElementById( 'container' );

				//

				renderer = new THREE.WebGLRenderer( { antialias: false } );
				renderer.setPixelRatio( window.devicePixelRatio );
				renderer.setSize( window.innerWidth, window.innerHeight );

				container.appendChild( renderer.domElement );

				//

				camera = new THREE.PerspectiveCamera( 27, window.innerWidth / window.innerHeight, 5, 3500 );
				camera.position.z = 2750;

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

				//

				const geometry = new THREE.BufferGeometry();

				const positions = [];
				const positions2 = [];
				const colors = [];

				const color = new THREE.Color();

				const n = 1000, n2 = n / 2; // particles spread in the cube

				for ( let i = 0; i < particles; i ++ ) {

					// positions

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

					positions.push( x, y, z );
					positions2.push( z * 0.3, x * 0.3, y * 0.3 );

					// 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.push( color.r, color.g, color.b );

				}

				const gl = renderer.getContext();

				const pos = gl.createBuffer();
				gl.bindBuffer( gl.ARRAY_BUFFER, pos );
				gl.bufferData( gl.ARRAY_BUFFER, new Float32Array( positions ), gl.STATIC_DRAW );

				const pos2 = gl.createBuffer();
				gl.bindBuffer( gl.ARRAY_BUFFER, pos2 );
				gl.bufferData( gl.ARRAY_BUFFER, new Float32Array( positions2 ), gl.STATIC_DRAW );

				const rgb = gl.createBuffer();
				gl.bindBuffer( gl.ARRAY_BUFFER, rgb );
				gl.bufferData( gl.ARRAY_BUFFER, new Float32Array( colors ), gl.STATIC_DRAW );

				const posAttr1 = new THREE.GLBufferAttribute( pos, gl.FLOAT, 3, 4, particles );
				const posAttr2 = new THREE.GLBufferAttribute( pos2, gl.FLOAT, 3, 4, particles );
				geometry.setAttribute( 'position', posAttr1 );

				setInterval( function () {

					const attr = geometry.getAttribute( 'position' );

					geometry.setAttribute( 'position', ( attr === posAttr1 ) ? posAttr2 : posAttr1 );

				}, 2000 );

				geometry.setAttribute( 'color', new THREE.GLBufferAttribute( rgb, gl.FLOAT, 3, 4, particles ) );

				//

				const material = new THREE.PointsMaterial( { size: 15, vertexColors: true } );

				points = new THREE.Points( geometry, material );

				// Choose one:
				// geometry.boundingSphere = ( new THREE.Sphere() ).set( new THREE.Vector3(), Infinity );
				points.frustumCulled = false;

				scene.add( points );

				//

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

				//

				window.addEventListener( 'resize', onWindowResize );

			}

			function onWindowResize() {

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

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

			}

			//

			function animate() {

				requestAnimationFrame( animate );

				render();
				stats.update();

			}

			function render() {

				drawCount = ( Math.max( 5000, drawCount ) + Math.floor( 500 * Math.random() ) ) % particles;
				points.geometry.setDrawRange( 0, drawCount );

				const time = Date.now() * 0.001;

				points.rotation.x = time * 0.1;
				points.rotation.y = time * 0.2;

				renderer.render( scene, camera );

			}

		</script>

	</body>
</html>