examples/webgpu_postprocessing_afterimage.html

<!DOCTYPE html>
<html lang="en">
	<head>
		<title>three.js webgpu - postprocessing afterimage</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="info">
			<a href="https://threejs.org" target="_blank" rel="noopener">three.js</a> - postprocessing - after image<br />
			Based on <a href="https://web.archive.org/web/20220629101314/http://oos.moxiecode.com/js_webgl/spiral/" target="_blank" rel="noopener">Particle Spiral</a>
			by <a href="https://github.com/oosmoxiecode" target="_blank" rel="noopener">oosmoxiecode</a>
		</div>

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

		<script type="module">

			import * as THREE from 'three';
			import { instancedBufferAttribute, mod, pass, texture, float, time, vec2, vec3, vec4, sin, cos } from 'three/tsl';
			import { afterImage } from 'three/addons/tsl/display/AfterImageNode.js';

			import { GUI } from 'three/addons/libs/lil-gui.module.min.js';
			import Stats from 'three/addons/libs/stats.module.js';

			let camera, scene, renderer, particles, stats;
			let postProcessing, afterImagePass, scenePass;

			const params = {

				damp: 0.8,
				enabled: true

			};

			init();

			function init() {

				renderer = new THREE.WebGPURenderer();
				renderer.setPixelRatio( window.devicePixelRatio );
				renderer.setSize( window.innerWidth, window.innerHeight );
				renderer.setAnimationLoop( animate );
				document.body.appendChild( renderer.domElement );

				camera = new THREE.PerspectiveCamera( 60, window.innerWidth / window.innerHeight, 1, 10000 );
				camera.position.z = 1000;

				scene = new THREE.Scene();

				const sprite = new THREE.TextureLoader().load( 'textures/sprites/circle.png' );

				// geometry

				const radius = 600;
				const count = 50000;

				const vertex = new THREE.Vector3();
				const color = new THREE.Color();

				const colors = [];
				const vertices = [];
				const timeOffsets = [];

				for ( var i = 0; i < count; i ++ ) {

					getRandomPointOnSphere( radius, vertex );
					vertices.push( vertex.x, vertex.y, vertex.z );

					color.setHSL( i / count, 0.7, 0.7, THREE.SRGBColorSpace );
					colors.push( color.r, color.g, color.b );

					timeOffsets.push( i / count );
			
				}

				const positionAttribute = new THREE.InstancedBufferAttribute( new Float32Array( vertices ), 3 );
				const colorAttribute = new THREE.InstancedBufferAttribute( new Float32Array( colors ), 3 );
				const timeAttribute = new THREE.InstancedBufferAttribute( new Float32Array( timeOffsets ), 1 );

				// material and TSL

				const material = new THREE.SpriteNodeMaterial( { blending: THREE.AdditiveBlending, depthWrite: false } );

				const localTime = instancedBufferAttribute( timeAttribute ).add( time.mul( 0.1 ) );
				const modTime = mod( localTime, 1.0 );
				const accTime = modTime.mul( modTime );

				const angle = accTime.mul( 40.0 );
				const pulse = vec2( sin( angle ).mul( 20.0 ), cos( angle ).mul( 20.0 ) );
				const pos = instancedBufferAttribute( positionAttribute );

				const animated = vec3( pos.x.mul( accTime ).add( pulse.x ), pos.y.mul( accTime ).add( pulse.y ), pos.z.mul( accTime ).mul( 1.75 ) );
				const fAlpha = modTime.oneMinus().mul( 2.0 );

				material.colorNode = texture( sprite ).mul( vec4( instancedBufferAttribute( colorAttribute ), fAlpha ) );
				material.positionNode = animated;
				material.scaleNode = float( 2 );

				particles = new THREE.Sprite( material );
				particles.count = count;
				scene.add( particles );

				// postprocessing

				postProcessing = new THREE.PostProcessing( renderer );

				scenePass = pass( scene, camera );

				afterImagePass = afterImage( scenePass, params.damp );

				postProcessing.outputNode = afterImagePass;

				//

				const gui = new GUI( { title: 'Damp setting' } );
				gui.add( afterImagePass.damp, 'value', 0.25, 1 );
				gui.add( params, 'enabled' ).onChange( updatePassChain );

				//

				stats = new Stats();
				document.body.appendChild( stats.dom );

				window.addEventListener( 'resize', onWindowResize );

			}

			function updatePassChain() {

				if ( params.enabled === true ) {

					postProcessing.outputNode = afterImagePass;

				} else {

					postProcessing.outputNode = scenePass;

				}

				postProcessing.needsUpdate = true;


			}


			function getRandomPointOnSphere( r, v ) {

				const angle = Math.random() * Math.PI * 2;
				const u = Math.random() * 2 - 1;
			
				v.set(
					Math.cos( angle ) * Math.sqrt( 1 - Math.pow( u, 2 ) ) * r,
					Math.sin( angle ) * Math.sqrt( 1 - Math.pow( u, 2 ) ) * r,
					u * r
				);
			
				return v;

			}

			function onWindowResize() {

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

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

			}

			function animate( time ) {

				particles.rotation.z = time * 0.001;

				postProcessing.render();

				stats.update();

			}

		</script>
	</body>
</html>