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<title>three.js webgl - interactive cubes (gpu)</title>
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<a href="https://threejs.org" target="_blank" rel="noopener">three.js</a> webgl - gpu picking
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<div id="container"></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';
import { TrackballControls } from 'three/addons/controls/TrackballControls.js';
import * as BufferGeometryUtils from 'three/addons/utils/BufferGeometryUtils.js';
let container, stats;
let camera, controls, scene, renderer;
let pickingTexture, pickingScene;
let highlightBox;
const pickingData = [];
const pointer = new THREE.Vector2();
const offset = new THREE.Vector3( 10, 10, 10 );
init();
animate();
function init() {
container = document.getElementById( 'container' );
camera = new THREE.PerspectiveCamera( 70, window.innerWidth / window.innerHeight, 1, 10000 );
camera.position.z = 1000;
scene = new THREE.Scene();
scene.background = new THREE.Color( 0xffffff );
pickingScene = new THREE.Scene();
pickingTexture = new THREE.WebGLRenderTarget( 1, 1 );
scene.add( new THREE.AmbientLight( 0x555555 ) );
const light = new THREE.SpotLight( 0xffffff, 1.5 );
light.position.set( 0, 500, 2000 );
scene.add( light );
const pickingMaterial = new THREE.MeshBasicMaterial( { vertexColors: true } );
const defaultMaterial = new THREE.MeshPhongMaterial( { color: 0xffffff, flatShading: true, vertexColors: true, shininess: 0 } );
function applyVertexColors( geometry, color ) {
const position = geometry.attributes.position;
const colors = [];
for ( let i = 0; i < position.count; i ++ ) {
colors.push( color.r, color.g, color.b );
}
geometry.setAttribute( 'color', new THREE.Float32BufferAttribute( colors, 3 ) );
}
const geometriesDrawn = [];
const geometriesPicking = [];
const matrix = new THREE.Matrix4();
const quaternion = new THREE.Quaternion();
const color = new THREE.Color();
for ( let i = 0; i < 5000; i ++ ) {
let geometry = new THREE.BoxGeometry();
const position = new THREE.Vector3();
position.x = Math.random() * 10000 - 5000;
position.y = Math.random() * 6000 - 3000;
position.z = Math.random() * 8000 - 4000;
const rotation = new THREE.Euler();
rotation.x = Math.random() * 2 * Math.PI;
rotation.y = Math.random() * 2 * Math.PI;
rotation.z = Math.random() * 2 * Math.PI;
const scale = new THREE.Vector3();
scale.x = Math.random() * 200 + 100;
scale.y = Math.random() * 200 + 100;
scale.z = Math.random() * 200 + 100;
quaternion.setFromEuler( rotation );
matrix.compose( position, quaternion, scale );
geometry.applyMatrix4( matrix );
// give the geometry's vertices a random color, to be displayed
applyVertexColors( geometry, color.setHex( Math.random() * 0xffffff ) );
geometriesDrawn.push( geometry );
geometry = geometry.clone();
// give the geometry's vertices a color corresponding to the "id"
applyVertexColors( geometry, color.setHex( i ) );
geometriesPicking.push( geometry );
pickingData[ i ] = {
position: position,
rotation: rotation,
scale: scale
};
}
const objects = new THREE.Mesh( BufferGeometryUtils.mergeBufferGeometries( geometriesDrawn ), defaultMaterial );
scene.add( objects );
pickingScene.add( new THREE.Mesh( BufferGeometryUtils.mergeBufferGeometries( geometriesPicking ), pickingMaterial ) );
highlightBox = new THREE.Mesh(
new THREE.BoxGeometry(),
new THREE.MeshLambertMaterial( { color: 0xffff00 }
) );
scene.add( highlightBox );
renderer = new THREE.WebGLRenderer( { antialias: true } );
renderer.setPixelRatio( window.devicePixelRatio );
renderer.setSize( window.innerWidth, window.innerHeight );
container.appendChild( renderer.domElement );
controls = new TrackballControls( camera, renderer.domElement );
controls.rotateSpeed = 1.0;
controls.zoomSpeed = 1.2;
controls.panSpeed = 0.8;
controls.noZoom = false;
controls.noPan = false;
controls.staticMoving = true;
controls.dynamicDampingFactor = 0.3;
stats = new Stats();
container.appendChild( stats.dom );
renderer.domElement.addEventListener( 'pointermove', onPointerMove );
}
//
function onPointerMove( e ) {
pointer.x = e.clientX;
pointer.y = e.clientY;
}
function animate() {
requestAnimationFrame( animate );
render();
stats.update();
}
function pick() {
//render the picking scene off-screen
// set the view offset to represent just a single pixel under the mouse
camera.setViewOffset( renderer.domElement.width, renderer.domElement.height, pointer.x * window.devicePixelRatio | 0, pointer.y * window.devicePixelRatio | 0, 1, 1 );
// render the scene
renderer.setRenderTarget( pickingTexture );
renderer.render( pickingScene, camera );
// clear the view offset so rendering returns to normal
camera.clearViewOffset();
//create buffer for reading single pixel
const pixelBuffer = new Uint8Array( 4 );
//read the pixel
renderer.readRenderTargetPixels( pickingTexture, 0, 0, 1, 1, pixelBuffer );
//interpret the pixel as an ID
const id = ( pixelBuffer[ 0 ] << 16 ) | ( pixelBuffer[ 1 ] << 8 ) | ( pixelBuffer[ 2 ] );
const data = pickingData[ id ];
if ( data ) {
//move our highlightBox so that it surrounds the picked object
if ( data.position && data.rotation && data.scale ) {
highlightBox.position.copy( data.position );
highlightBox.rotation.copy( data.rotation );
highlightBox.scale.copy( data.scale ).add( offset );
highlightBox.visible = true;
}
} else {
highlightBox.visible = false;
}
}
function render() {
controls.update();
pick();
renderer.setRenderTarget( null );
renderer.render( scene, camera );
}
</script>
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