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webgl_buffergeometry_selective_draw.html
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webgl_buffergeometry_selective_draw.html
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<!DOCTYPE html>
<html lang="en">
<head>
<title>three.js - BufferGeometry selectively drawn using attributes and a shader</title>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, user-scalable=no, minimum-scale=1.0, maximum-scale=1.0">
<style>
body {
background-color: #000;
font-family: Monospace;
margin: 0;
color: #000;
overflow: hidden;
}
a {
color:#ff0;
}
#title {
position: absolute;
width: 100%;
top: 0;
height: 20px;
padding: 0;
text-align: center;
font-size: 1.1em;
background-color: rgba(64,96,64,0.7);
color: #fff;
}
#ui {
position:absolute;
left:0;
top: 20px;
padding: 0;
text-align: center;
width:100%;
height:20px;
color: #fff;
background-color: rgba(64,96,64,0.6);
}
</style>
<script type="text/javascript" src="../build/three.js"></script>
<script type="text/javascript" src="js/Detector.js"></script>
<script type="text/javascript" src="js/libs/stats.min.js"></script>
<script type="x-shader/x-vertex" id="vertexshader">
attribute float visible;
varying float vVisible;
attribute vec3 vertColor;
varying vec3 vColor;
void main() {
vColor = vertColor;
vVisible = visible;
gl_Position = projectionMatrix * modelViewMatrix * vec4(position,1.0);
}
</script>
<script type="x-shader/x-fragment" id="fragmentshader">
varying float vVisible;
varying vec3 vColor;
void main() {
if ( vVisible > 0.0 ) {
gl_FragColor = vec4( vColor, 1.0 );
} else {
discard;
}
}
</script>
</head>
<body onload="app()">
<div id="title"></div>
<div id="ui"><a href="#" onclick="hideLines();">CULL SOME LINES</a> - <a href="#" onclick="showAllLines();">SHOW ALL LINES</a></div>
<script>
var camera, scene, renderer, stats;
var geometry, mesh;
var numLat = 100;
var numLng = 200;
var numLinesCulled = 0;
function app() {
if ( ! Detector.webgl ) {
Detector.addGetWebGLMessage();
}
init();
animate();
}
function init() {
renderer = new THREE.WebGLRenderer( {
antialias: true
} );
renderer.setClearColor( 0x000000, 0.0 );
renderer.setPixelRatio( window.devicePixelRatio );
renderer.setSize( window.innerWidth, window.innerHeight );
document.body.appendChild( renderer.domElement );
scene = new THREE.Scene();
camera = new THREE.PerspectiveCamera( 45, window.innerWidth / window.innerHeight, 0.01, 10 );
camera.position.z = 3.5;
scene.add( new THREE.AmbientLight( 0x444444 ) );
stats = new Stats();
document.body.appendChild( stats.dom );
window.addEventListener( 'resize', onWindowResize, false );
addLines( 1.0 );
}
function addLines( radius ) {
geometry = new THREE.BufferGeometry();
var linePositions = new Float32Array( numLat * numLng * 3 * 2 );
var lineColors = new Float32Array( numLat * numLng * 3 * 2 );
var visible = new Float32Array( numLat * numLng * 2 );
for ( var i = 0; i < numLat; ++ i ) {
for ( var j = 0; j < numLng; ++ j ) {
var lat = ( Math.random() * Math.PI ) / 50.0 + i / numLat * Math.PI;
var lng = ( Math.random() * Math.PI ) / 50.0 + j / numLng * 2 * Math.PI;
var index = i * numLng + j;
linePositions[ index * 6 + 0 ] = 0;
linePositions[ index * 6 + 1 ] = 0;
linePositions[ index * 6 + 2 ] = 0;
linePositions[ index * 6 + 3 ] = radius * Math.sin( lat ) * Math.cos( lng );
linePositions[ index * 6 + 4 ] = radius * Math.cos( lat );
linePositions[ index * 6 + 5 ] = radius * Math.sin( lat ) * Math.sin( lng );
var color = new THREE.Color( 0xffffff );
color.setHSL( lat / Math.PI, 1.0, 0.2 );
lineColors[ index * 6 + 0 ] = color.r;
lineColors[ index * 6 + 1 ] = color.g;
lineColors[ index * 6 + 2 ] = color.b;
color.setHSL( lat / Math.PI, 1.0, 0.7 );
lineColors[ index * 6 + 3 ] = color.r;
lineColors[ index * 6 + 4 ] = color.g;
lineColors[ index * 6 + 5 ] = color.b;
// non-0 is visible
visible[ index * 2 + 0 ] = 1.0;
visible[ index * 2 + 1 ] = 1.0;
}
}
geometry.addAttribute( 'position', new THREE.BufferAttribute( linePositions, 3 ) );
geometry.addAttribute( 'vertColor', new THREE.BufferAttribute( lineColors, 3 ) );
geometry.addAttribute( 'visible', new THREE.BufferAttribute( visible, 1 ) );
geometry.computeBoundingSphere();
var shaderMaterial = new THREE.ShaderMaterial( {
vertexShader: document.getElementById( 'vertexshader' ).textContent,
fragmentShader: document.getElementById( 'fragmentshader' ).textContent
} );
mesh = new THREE.LineSegments( geometry, shaderMaterial );
scene.add( mesh );
updateCount();
}
function updateCount() {
var str = 'BufferGeometry selective drawing: 1 draw call, ' + numLat * numLng + ' lines, ' + numLinesCulled + ' culled (<a target="_blank" href="http://callum.com">author</a>)';
document.getElementById( 'title' ).innerHTML = str.replace( /\B(?=(\d{3})+(?!\d))/g, "," );
}
function hideLines() {
for ( var i = 0; i < geometry.attributes.visible.array.length; i += 2 ) {
if ( Math.random() > 0.75 ) {
if ( geometry.attributes.visible.array[ i + 0 ] ) {
++ numLinesCulled;
}
geometry.attributes.visible.array[ i + 0 ] = 0;
geometry.attributes.visible.array[ i + 1 ] = 0;
}
}
geometry.attributes.visible.needsUpdate = true;
updateCount();
}
function showAllLines() {
numLinesCulled = 0;
for ( var i = 0; i < geometry.attributes.visible.array.length; i += 2 ) {
geometry.attributes.visible.array[ i + 0 ] = 1;
geometry.attributes.visible.array[ i + 1 ] = 1;
}
geometry.attributes.visible.needsUpdate = true;
updateCount();
}
function onWindowResize() {
camera.aspect = window.innerWidth / window.innerHeight;
camera.updateProjectionMatrix();
renderer.setSize( window.innerWidth, window.innerHeight );
}
function animate( time ) {
requestAnimationFrame( animate );
var time = Date.now() * 0.001;
mesh.rotation.x = time * 0.25;
mesh.rotation.y = time * 0.5;
stats.update();
renderer.render( scene, camera );
}
</script>
</body>
</html>