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<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0, user-scalable=yes">
<title>Three.js - Picking - RayCaster w/Transparency</title>
<style>
html, body {
height: 100%;
margin: 0;
}
#c {
width: 100%;
height: 100%;
display: block;
}
</style>
</head>
<body>
<canvas id="c"></canvas>
</body>
<!-- Import maps polyfill -->
<!-- Remove this when import maps will be widely supported -->
<script async src="https://unpkg.com/es-module-shims@1.8.0/dist/es-module-shims.js"></script>
<script type="importmap">
{
"imports": {
"three": "../../build/three.module.js"
}
}
</script>
<script type="module">
import * as THREE from 'three';
function main() {
const canvas = document.querySelector( '#c' );
const renderer = new THREE.WebGLRenderer( { antialias: true, canvas } );
const fov = 60;
const aspect = 2; // the canvas default
const near = 0.1;
const far = 200;
const camera = new THREE.PerspectiveCamera( fov, aspect, near, far );
camera.position.z = 30;
const scene = new THREE.Scene();
scene.background = new THREE.Color( 'white' );
// put the camera on a pole (parent it to an object)
// so we can spin the pole to move the camera around the scene
const cameraPole = new THREE.Object3D();
scene.add( cameraPole );
cameraPole.add( camera );
{
const color = 0xFFFFFF;
const intensity = 3;
const light = new THREE.DirectionalLight( color, intensity );
light.position.set( - 1, 2, 4 );
camera.add( light );
}
const boxWidth = 1;
const boxHeight = 1;
const boxDepth = 1;
const geometry = new THREE.BoxGeometry( boxWidth, boxHeight, boxDepth );
function rand( min, max ) {
if ( max === undefined ) {
max = min;
min = 0;
}
return min + ( max - min ) * Math.random();
}
function randomColor() {
return `hsl(${rand( 360 ) | 0}, ${rand( 50, 100 ) | 0}%, 50%)`;
}
const loader = new THREE.TextureLoader();
const texture = loader.load( 'resources/images/frame.png' );
const numObjects = 100;
for ( let i = 0; i < numObjects; ++ i ) {
const material = new THREE.MeshPhongMaterial( {
color: randomColor(),
map: texture,
transparent: true,
side: THREE.DoubleSide,
alphaTest: 0.1,
} );
const cube = new THREE.Mesh( geometry, material );
scene.add( cube );
cube.position.set( rand( - 20, 20 ), rand( - 20, 20 ), rand( - 20, 20 ) );
cube.rotation.set( rand( Math.PI ), rand( Math.PI ), 0 );
cube.scale.set( rand( 3, 6 ), rand( 3, 6 ), rand( 3, 6 ) );
}
function resizeRendererToDisplaySize( renderer ) {
const canvas = renderer.domElement;
const width = canvas.clientWidth;
const height = canvas.clientHeight;
const needResize = canvas.width !== width || canvas.height !== height;
if ( needResize ) {
renderer.setSize( width, height, false );
}
return needResize;
}
class PickHelper {
constructor() {
this.raycaster = new THREE.Raycaster();
this.pickedObject = null;
this.pickedObjectSavedColor = 0;
}
pick( normalizedPosition, scene, camera, time ) {
// restore the color if there is a picked object
if ( this.pickedObject ) {
this.pickedObject.material.emissive.setHex( this.pickedObjectSavedColor );
this.pickedObject = undefined;
}
// cast a ray through the frustum
this.raycaster.setFromCamera( normalizedPosition, camera );
// get the list of objects the ray intersected
const intersectedObjects = this.raycaster.intersectObjects( scene.children );
if ( intersectedObjects.length ) {
// pick the first object. It's the closest one
this.pickedObject = intersectedObjects[ 0 ].object;
// save its color
this.pickedObjectSavedColor = this.pickedObject.material.emissive.getHex();
// set its emissive color to flashing red/yellow
this.pickedObject.material.emissive.setHex( ( time * 8 ) % 2 > 1 ? 0xFFFF00 : 0xFF0000 );
}
}
}
const pickPosition = { x: 0, y: 0 };
const pickHelper = new PickHelper();
clearPickPosition();
function render( time ) {
time *= 0.001; // convert to seconds;
if ( resizeRendererToDisplaySize( renderer ) ) {
const canvas = renderer.domElement;
camera.aspect = canvas.clientWidth / canvas.clientHeight;
camera.updateProjectionMatrix();
}
cameraPole.rotation.y = time * .1;
pickHelper.pick( pickPosition, scene, camera, time );
renderer.render( scene, camera );
requestAnimationFrame( render );
}
requestAnimationFrame( render );
function getCanvasRelativePosition( event ) {
const rect = canvas.getBoundingClientRect();
return {
x: ( event.clientX - rect.left ) * canvas.width / rect.width,
y: ( event.clientY - rect.top ) * canvas.height / rect.height,
};
}
function setPickPosition( event ) {
const pos = getCanvasRelativePosition( event );
pickPosition.x = ( pos.x / canvas.width ) * 2 - 1;
pickPosition.y = ( pos.y / canvas.height ) * - 2 + 1; // note we flip Y
}
function clearPickPosition() {
// unlike the mouse which always has a position
// if the user stops touching the screen we want
// to stop picking. For now we just pick a value
// unlikely to pick something
pickPosition.x = - 100000;
pickPosition.y = - 100000;
}
window.addEventListener( 'mousemove', setPickPosition );
window.addEventListener( 'mouseout', clearPickPosition );
window.addEventListener( 'mouseleave', clearPickPosition );
window.addEventListener( 'touchstart', ( event ) => {
// prevent the window from scrolling
event.preventDefault();
setPickPosition( event.touches[ 0 ] );
}, { passive: false } );
window.addEventListener( 'touchmove', ( event ) => {
setPickPosition( event.touches[ 0 ] );
} );
window.addEventListener( 'touchend', clearPickPosition );
}
main();
</script>
</html>