examples/webgpu_volume_cloud.html

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<html lang="en">
	<head>
		<title>three.js webgpu - volumetric cloud</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> webgpu - volumetric cloud
		</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 { float, vec3, vec4, If, Break, Fn, smoothstep, texture3D, uniform } from 'three/tsl';

			import { RaymarchingBox } from 'three/addons/tsl/utils/Raymarching.js';

			import { OrbitControls } from 'three/addons/controls/OrbitControls.js';
			import { ImprovedNoise } from 'three/addons/math/ImprovedNoise.js';

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

			let renderer, scene, camera;
			let mesh;

			init();

			function init() {

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

				scene = new THREE.Scene();

				camera = new THREE.PerspectiveCamera( 60, window.innerWidth / window.innerHeight, 0.1, 100 );
				camera.position.set( 0, 0, 1.5 );

				new OrbitControls( camera, renderer.domElement );

				// Sky

				const canvas = document.createElement( 'canvas' );
				canvas.width = 1;
				canvas.height = 32;

				const context = canvas.getContext( '2d' );
				const gradient = context.createLinearGradient( 0, 0, 0, 32 );
				gradient.addColorStop( 0.0, '#014a84' );
				gradient.addColorStop( 0.5, '#0561a0' );
				gradient.addColorStop( 1.0, '#437ab6' );
				context.fillStyle = gradient;
				context.fillRect( 0, 0, 1, 32 );

				const skyMap = new THREE.CanvasTexture( canvas );
				skyMap.colorSpace = THREE.SRGBColorSpace;

				const sky = new THREE.Mesh(
					new THREE.SphereGeometry( 10 ),
					new THREE.MeshBasicNodeMaterial( { map: skyMap, side: THREE.BackSide } )
				);
				scene.add( sky );

				// Texture

				const size = 128;
				const data = new Uint8Array( size * size * size );

				let i = 0;
				const scale = 0.05;
				const perlin = new ImprovedNoise();
				const vector = new THREE.Vector3();

				for ( let z = 0; z < size; z ++ ) {

					for ( let y = 0; y < size; y ++ ) {

						for ( let x = 0; x < size; x ++ ) {

							const d = 1.0 - vector.set( x, y, z ).subScalar( size / 2 ).divideScalar( size ).length();
							data[ i ] = ( 128 + 128 * perlin.noise( x * scale / 1.5, y * scale, z * scale / 1.5 ) ) * d * d;
							i ++;

						}

					}

				}

				const texture = new THREE.Data3DTexture( data, size, size, size );
				texture.format = THREE.RedFormat;
				texture.minFilter = THREE.LinearFilter;
				texture.magFilter = THREE.LinearFilter;
				texture.unpackAlignment = 1;
				texture.needsUpdate = true;

				// Shader

				const transparentRaymarchingTexture = Fn( ( {
					texture,
					range = float( 0.1 ),
					threshold = float( 0.25 ),
					opacity = float( 0.25 ),
					steps = float( 100 )
				} ) => {

					const finalColor = vec4( 0 ).toVar();

					RaymarchingBox( steps, ( { positionRay } ) => {

						const mapValue = float( texture.sample( positionRay.add( 0.5 ) ).r ).toVar();

						mapValue.assign( smoothstep( threshold.sub( range ), threshold.add( range ), mapValue ).mul( opacity ) );

						const shading = texture.sample( positionRay.add( vec3( - 0.01 ) ) ).r.sub( texture.sample( positionRay.add( vec3( 0.01 ) ) ).r );

						const col = shading.mul( 3.0 ).add( positionRay.x.add( positionRay.y ).mul( 0.25 ) ).add( 0.2 );

						finalColor.rgb.addAssign( finalColor.a.oneMinus().mul( mapValue ).mul( col ) );

						finalColor.a.addAssign( finalColor.a.oneMinus().mul( mapValue ) );

						If( finalColor.a.greaterThanEqual( 0.95 ), () => {

							Break();

						} );

					} );

					return finalColor;

				} );

				// Material

				const baseColor = uniform( new THREE.Color( 0x798aa0 ) );
				const range = uniform( 0.1 );
				const threshold = uniform( 0.25 );
				const opacity = uniform( 0.25 );
				const steps = uniform( 100 );

				const cloud3d = transparentRaymarchingTexture( {
					texture: texture3D( texture, null, 0 ),
					range,
					threshold,
					opacity,
					steps
				} );

				const finalCloud = cloud3d.setRGB( cloud3d.rgb.add( baseColor ) );

				const material = new THREE.NodeMaterial();
				material.colorNode = finalCloud;
				material.side = THREE.BackSide;
				material.transparent = true;

				mesh = new THREE.Mesh( new THREE.BoxGeometry( 1, 1, 1 ), material );
				scene.add( mesh );

				//

				const gui = new GUI();
				gui.add( threshold, 'value', 0, 1, 0.01 ).name( 'threshold' );
				gui.add( opacity, 'value', 0, 1, 0.01 ).name( 'opacity' );
				gui.add( range, 'value', 0, 1, 0.01 ).name( 'range' );
				gui.add( steps, 'value', 0, 200, 1 ).name( 'steps' );

				window.addEventListener( 'resize', onWindowResize );

			}

			function onWindowResize() {

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

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

			}

			function animate() {

				mesh.rotation.y = - performance.now() / 7500;

				renderer.render( scene, camera );

			}

		</script>

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