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<title>three.js webgl - nearest neighbour</title>
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<div id="info"><a href="http://threejs.org" target="_blank">three.js</a> webgl - typed arrays - nearest neighbour for 500,000 sprites</div>
<script src="../build/three.min.js"></script>
<script src="js/TypedArrayUtils.js"></script>
<script src="js/controls/FirstPersonControls.js"></script>
<script type="x-shader/x-vertex" id="vertexshader">
//uniform float zoom;
attribute float alpha;
varying float vAlpha;
void main() {
vAlpha = 1.0 - alpha;
vec4 mvPosition = modelViewMatrix * vec4( position, 1.0 );
gl_PointSize = 4.0 * ( 300.0 / length( mvPosition.xyz ) );
gl_Position = projectionMatrix * mvPosition;
}
</script>
<script type="x-shader/x-fragment" id="fragmentshader">
uniform sampler2D tex1;
varying float vAlpha;
void main() {
gl_FragColor = texture2D(tex1, gl_PointCoord);
gl_FragColor.r = (1.0 - gl_FragColor.r) * vAlpha + gl_FragColor.r;
}
</script>
<script>
var camera, scene, renderer;
var geometry, material, mesh;
var controls;
var objects = [];
var amountOfParticles = 500000, maxDistance = Math.pow(120, 2);
var positions, alphas, particles, _particleGeom
var clock = new THREE.Clock();
var blocker = document.getElementById( 'blocker' );
var instructions = document.getElementById( 'instructions' );
function init() {
camera = new THREE.PerspectiveCamera(75, window.innerWidth / window.innerHeight, 1, 1000000);
scene = new THREE.Scene();
controls = new THREE.FirstPersonControls( camera );
controls.movementSpeed = 100;
controls.lookSpeed = 0.1;
var materials = [
new THREE.MeshBasicMaterial( { map: THREE.ImageUtils.loadTexture( 'textures/cube/skybox/px.jpg' ) } ), // right
new THREE.MeshBasicMaterial( { map: THREE.ImageUtils.loadTexture( 'textures/cube/skybox/nx.jpg' ) } ), // left
new THREE.MeshBasicMaterial( { map: THREE.ImageUtils.loadTexture( 'textures/cube/skybox/py.jpg' ) } ), // top
new THREE.MeshBasicMaterial( { map: THREE.ImageUtils.loadTexture( 'textures/cube/skybox/ny.jpg' ) } ), // bottom
new THREE.MeshBasicMaterial( { map: THREE.ImageUtils.loadTexture( 'textures/cube/skybox/pz.jpg' ) } ), // back
new THREE.MeshBasicMaterial( { map: THREE.ImageUtils.loadTexture( 'textures/cube/skybox/nz.jpg' ) } ) // front
];
mesh = new THREE.Mesh( new THREE.BoxGeometry( 10000, 10000, 10000, 7, 7, 7 ), new THREE.MeshFaceMaterial( materials ) );
mesh.scale.x = - 1;
scene.add(mesh);
//
renderer = new THREE.WebGLRenderer(); // Detector.webgl? new THREE.WebGLRenderer(): new THREE.CanvasRenderer()
renderer.setPixelRatio( window.devicePixelRatio );
renderer.setSize( window.innerWidth, window.innerHeight );
document.body.appendChild( renderer.domElement );
// create the custom shader
var imagePreviewTexture = THREE.ImageUtils.loadTexture( 'textures/crate.gif');
imagePreviewTexture.minFilter = THREE.LinearMipMapLinearFilter;
imagePreviewTexture.magFilter = THREE.LinearFilter;
pointShaderMaterial = new THREE.ShaderMaterial( {
uniforms: {
tex1: { type: "t", value: imagePreviewTexture },
zoom: { type: 'f', value: 9.0 },
},
attributes: {
alpha: { type: 'f', value: null },
},
vertexShader: document.getElementById( 'vertexshader' ).textContent,
fragmentShader: document.getElementById( 'fragmentshader' ).textContent,
transparent: true
});
//create particles with buffer geometry
var distanceFunction = function(a, b){
return Math.pow(a[0] - b[0], 2) + Math.pow(a[1] - b[1], 2) + Math.pow(a[2] - b[2], 2);
};
positions = new Float32Array( amountOfParticles * 3 );
alphas = new Float32Array( amountOfParticles );
_particleGeom = new THREE.BufferGeometry();
_particleGeom.addAttribute( 'position', new THREE.BufferAttribute( positions, 3 ) );
_particleGeom.addAttribute( 'alpha', new THREE.BufferAttribute( alphas, 1 ) );
particles = new THREE.PointCloud( _particleGeom, pointShaderMaterial );
for (var x = 0; x < amountOfParticles; x++) {
positions[ x * 3 + 0 ] = Math.random() * 1000;
positions[ x * 3 + 1 ] = Math.random() * 1000;
positions[ x * 3 + 2 ] = Math.random() * 1000;
alphas[x] = 1.0;
}
var measureStart = new Date().getTime();
// creating the kdtree takes a lot of time to execute, in turn the nearest neighbour search will be much faster
kdtree = new THREE.TypedArrayUtils.Kdtree( positions, distanceFunction, 3 );
console.log('TIME building kdtree', new Date().getTime() - measureStart);
// display particles after the kd-tree was generated and the sorting of the positions-array is done
scene.add(particles);
window.addEventListener( 'resize', onWindowResize, false );
}
function onWindowResize() {
camera.aspect = window.innerWidth / window.innerHeight;
camera.updateProjectionMatrix();
renderer.setSize( window.innerWidth, window.innerHeight );
controls.handleResize();
}
function animate() {
requestAnimationFrame( animate );
//
displayNearest(camera.position);
controls.update( clock.getDelta() )
renderer.render( scene, camera );
}
function displayNearest(position) {
// take the nearest 200 around him. distance^2 'cause we use the manhattan distance and no square is applied in the distance function
var imagePositionsInRange = kdtree.nearest([position.x, position.y, position.z], 100, maxDistance);
// We combine the nearest neighbour with a view frustum. Doesn't make sense if we change the sprites not in our view... well maybe it does. Whatever you want.
var _frustum = new THREE.Frustum();
var _projScreenMatrix = new THREE.Matrix4();
camera.matrixWorldInverse.getInverse( camera.matrixWorld );
_projScreenMatrix.multiplyMatrices( camera.projectionMatrix, camera.matrixWorldInverse );
_frustum.setFromMatrix( _projScreenMatrix );
for ( i = 0, il = imagePositionsInRange.length; i < il; i ++ ) {
var object = imagePositionsInRange[i];
var objectPoint = new THREE.Vector3().fromArray( object[ 0 ].obj );
if (_frustum.containsPoint(objectPoint)){
var objectIndex = object[0].pos;
// set the alpha according to distance
alphas[ objectIndex ] = 1.0 / maxDistance * object[1];
// update the attribute
_particleGeom.attributes.alpha.needsUpdate = true;
}
}
}
init();
animate();
</script>
</body>
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