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<!DOCTYPE html>
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<head>
<title>three.js webgl - simple global illumination</title>
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<a href="https://threejs.org" target="_blank" rel="noopener">three.js</a> - simple global illumination (<a href="http://www.iquilezles.org/www/articles/simplegi/simplegi.htm">article</a>)
</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 { OrbitControls } from 'three/addons/controls/OrbitControls.js';
class GIMesh extends THREE.Mesh {
copy( source ) {
super.copy( source );
this.geometry = source.geometry.clone();
return this;
}
}
//
const SimpleGI = function ( renderer, scene ) {
const SIZE = 32, SIZE2 = SIZE * SIZE;
const camera = new THREE.PerspectiveCamera( 90, 1, 0.01, 100 );
scene.updateMatrixWorld( true );
let clone = scene.clone();
clone.autoUpdate = false;
const rt = new THREE.WebGLRenderTarget( SIZE, SIZE );
const normalMatrix = new THREE.Matrix3();
const position = new THREE.Vector3();
const normal = new THREE.Vector3();
let bounces = 0;
let currentVertex = 0;
const color = new Float32Array( 3 );
const buffer = new Uint8Array( SIZE2 * 4 );
function compute() {
if ( bounces === 3 ) return;
const object = scene.children[ 0 ]; // torusKnot
const geometry = object.geometry;
const attributes = geometry.attributes;
const positions = attributes.position.array;
const normals = attributes.normal.array;
if ( attributes.color === undefined ) {
const colors = new Float32Array( positions.length );
geometry.setAttribute( 'color', new THREE.BufferAttribute( colors, 3 ).setUsage( THREE.DynamicDrawUsage ) );
}
const colors = attributes.color.array;
const startVertex = currentVertex;
const totalVertex = positions.length / 3;
for ( let i = 0; i < 32; i ++ ) {
if ( currentVertex >= totalVertex ) break;
position.fromArray( positions, currentVertex * 3 );
position.applyMatrix4( object.matrixWorld );
normal.fromArray( normals, currentVertex * 3 );
normal.applyMatrix3( normalMatrix.getNormalMatrix( object.matrixWorld ) ).normalize();
camera.position.copy( position );
camera.lookAt( position.add( normal ) );
renderer.setRenderTarget( rt );
renderer.render( clone, camera );
renderer.readRenderTargetPixels( rt, 0, 0, SIZE, SIZE, buffer );
color[ 0 ] = 0;
color[ 1 ] = 0;
color[ 2 ] = 0;
for ( let k = 0, kl = buffer.length; k < kl; k += 4 ) {
color[ 0 ] += buffer[ k + 0 ];
color[ 1 ] += buffer[ k + 1 ];
color[ 2 ] += buffer[ k + 2 ];
}
colors[ currentVertex * 3 + 0 ] = color[ 0 ] / ( SIZE2 * 255 );
colors[ currentVertex * 3 + 1 ] = color[ 1 ] / ( SIZE2 * 255 );
colors[ currentVertex * 3 + 2 ] = color[ 2 ] / ( SIZE2 * 255 );
currentVertex ++;
}
attributes.color.updateRange.offset = startVertex * 3;
attributes.color.updateRange.count = ( currentVertex - startVertex ) * 3;
attributes.color.needsUpdate = true;
if ( currentVertex >= totalVertex ) {
clone = scene.clone();
clone.autoUpdate = false;
bounces ++;
currentVertex = 0;
}
requestAnimationFrame( compute );
}
requestAnimationFrame( compute );
};
//
let camera, scene, renderer;
init();
animate();
function init() {
camera = new THREE.PerspectiveCamera( 70, window.innerWidth / window.innerHeight, 0.1, 100 );
camera.position.z = 4;
scene = new THREE.Scene();
// torus knot
const torusGeometry = new THREE.TorusKnotGeometry( 0.75, 0.3, 128, 32, 1 );
const material = new THREE.MeshBasicMaterial( { vertexColors: true } );
const torusKnot = new GIMesh( torusGeometry, material );
scene.add( torusKnot );
// room
const materials = [];
for ( let i = 0; i < 8; i ++ ) {
materials.push( new THREE.MeshBasicMaterial( { color: Math.random() * 0xffffff, side: THREE.BackSide } ) );
}
const boxGeometry = new THREE.BoxGeometry( 3, 3, 3 );
const box = new THREE.Mesh( boxGeometry, materials );
scene.add( box );
//
renderer = new THREE.WebGLRenderer();
renderer.setPixelRatio( window.devicePixelRatio );
renderer.setSize( window.innerWidth, window.innerHeight );
document.body.appendChild( renderer.domElement );
new SimpleGI( renderer, scene );
const controls = new OrbitControls( camera, renderer.domElement );
controls.minDistance = 1;
controls.maxDistance = 10;
window.addEventListener( 'resize', onWindowResize );
}
function onWindowResize() {
camera.aspect = window.innerWidth / window.innerHeight;
camera.updateProjectionMatrix();
renderer.setSize( window.innerWidth, window.innerHeight );
}
function animate() {
requestAnimationFrame( animate );
renderer.setRenderTarget( null );
renderer.render( scene, camera );
}
</script>
</body>
</html>