examples/webgl_custom_attributes_points2.html

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		<title>three.js webgl - custom attributes [particles][billboards]</title>
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	<body>
		<div id="info"><a href="https://threejs.org" target="_blank" rel="noopener">three.js</a> - custom attributes example - particles - billboards</div>
		<div id="container"></div>

		<script type="x-shader/x-vertex" id="vertexshader">

			attribute float size;
			attribute vec3 ca;

			varying vec3 vColor;

			void main() {

				vColor = ca;

				vec4 mvPosition = modelViewMatrix * vec4( position, 1.0 );

				gl_PointSize = size * ( 300.0 / -mvPosition.z );

				gl_Position = projectionMatrix * mvPosition;

			}

		</script>

		<script type="x-shader/x-fragment" id="fragmentshader">

			uniform vec3 color;
			uniform sampler2D pointTexture;

			varying vec3 vColor;

			void main() {

				vec4 color = vec4( color * vColor, 1.0 ) * texture2D( pointTexture, gl_PointCoord );

				gl_FragColor = color;

			}

		</script>

		<script type="module">

			import * as THREE from '../build/three.module.js';

			import Stats from './jsm/libs/stats.module.js';

			var renderer, scene, camera, stats;
			var sphere, length1;

			var WIDTH = window.innerWidth;
			var HEIGHT = window.innerHeight;

			init();
			animate();

			function init() {

				camera = new THREE.PerspectiveCamera( 45, WIDTH / HEIGHT, 1, 10000 );
				camera.position.z = 300;

				scene = new THREE.Scene();

				var radius = 100, segments = 68, rings = 38;

				var vertices1 = new THREE.SphereGeometry( radius, segments, rings ).vertices;
				var vertices2 = new THREE.BoxGeometry( 0.8 * radius, 0.8 * radius, 0.8 * radius, 10, 10, 10 ).vertices;

				length1 = vertices1.length;

				var vertices = vertices1.concat( vertices2 );

				var positions = new Float32Array( vertices.length * 3 );
				var colors = new Float32Array( vertices.length * 3 );
				var sizes = new Float32Array( vertices.length );

				var vertex;
				var color = new THREE.Color();

				for ( var i = 0, l = vertices.length; i < l; i ++ ) {

					vertex = vertices[ i ];
					vertex.toArray( positions, i * 3 );

					if ( i < length1 ) {

						color.setHSL( 0.01 + 0.1 * ( i / length1 ), 0.99, ( vertex.y + radius ) / ( 4 * radius ) );

					} else {

						color.setHSL( 0.6, 0.75, 0.25 + vertex.y / ( 2 * radius ) );

					}

					color.toArray( colors, i * 3 );

					sizes[ i ] = i < length1 ? 10 : 40;

				}

				var geometry = new THREE.BufferGeometry();
				geometry.setAttribute( 'position', new THREE.BufferAttribute( positions, 3 ) );
				geometry.setAttribute( 'size', new THREE.BufferAttribute( sizes, 1 ) );
				geometry.setAttribute( 'ca', new THREE.BufferAttribute( colors, 3 ) );

				//

				var texture = new THREE.TextureLoader().load( "textures/sprites/disc.png" );
				texture.wrapS = THREE.RepeatWrapping;
				texture.wrapT = THREE.RepeatWrapping;

				var material = new THREE.ShaderMaterial( {

					uniforms: {
						color: { value: new THREE.Color( 0xffffff ) },
						pointTexture: { value: texture }
					},
					vertexShader: document.getElementById( 'vertexshader' ).textContent,
					fragmentShader: document.getElementById( 'fragmentshader' ).textContent,
					transparent: true

				} );

				//

				sphere = new THREE.Points( geometry, material );
				scene.add( sphere );

				//

				renderer = new THREE.WebGLRenderer();
				renderer.setPixelRatio( window.devicePixelRatio );
				renderer.setSize( WIDTH, HEIGHT );

				var container = document.getElementById( 'container' );
				container.appendChild( renderer.domElement );

				stats = new Stats();
				container.appendChild( stats.dom );

				//

				window.addEventListener( 'resize', onWindowResize, false );

			}

			function onWindowResize() {

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

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

			}

			function sortPoints() {

				var vector = new THREE.Vector3();

				// Model View Projection matrix

				var matrix = new THREE.Matrix4();
				matrix.multiplyMatrices( camera.projectionMatrix, camera.matrixWorldInverse );
				matrix.multiply( sphere.matrixWorld );

				//

				var geometry = sphere.geometry;

				var index = geometry.getIndex();
				var positions = geometry.getAttribute( 'position' ).array;
				var length = positions.length / 3;

				if ( index === null ) {

					var array = new Uint16Array( length );

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

						array[ i ] = i;

					}

					index = new THREE.BufferAttribute( array, 1 );

					geometry.setIndex( index );

				}

				var sortArray = [];

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

					vector.fromArray( positions, i * 3 );
					vector.applyMatrix4( matrix );

					sortArray.push( [ vector.z, i ] );

				}

				function numericalSort( a, b ) {

					return b[ 0 ] - a[ 0 ];

				}

				sortArray.sort( numericalSort );

				var indices = index.array;

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

					indices[ i ] = sortArray[ i ][ 1 ];

				}

				geometry.index.needsUpdate = true;

			}

			function animate() {

				requestAnimationFrame( animate );

				render();
				stats.update();

			}

			function render() {

				var time = Date.now() * 0.005;

				sphere.rotation.y = 0.02 * time;
				sphere.rotation.z = 0.02 * time;

				var geometry = sphere.geometry;
				var attributes = geometry.attributes;

				for ( var i = 0; i < attributes.size.array.length; i ++ ) {

					if ( i < length1 ) {

						attributes.size.array[ i ] = 16 + 12 * Math.sin( 0.1 * i + time );

					}

				}

				attributes.size.needsUpdate = true;

				sortPoints();

				renderer.render( scene, camera );

			}

		</script>

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