html5的canvas实现3d雪花飘舞效果

点评：使用HTML5 的canvas标签和 three.js 实现了 3D 的雪花飞舞效果。你可以拖动鼠标进行旋转，需要在支持CSS3属性的浏览器下浏览

var SCREEN_WIDTH = window.innerWidth;

var SCREEN_HEIGHT = window.innerHeight;</p><p> var container;</p><p> var particle;</p><p> var camera;

var scene;

var renderer;</p><p> var mouseX = 0;

var mouseY = 0;</p><p> var windowHalfX = window.innerWidth / 2;

var windowHalfY = window.innerHeight / 2;

var particles = [];

var particleImage = new Image();//THREE.ImageUtils.loadTexture( "img/ParticleSmoke.png" );

particleImage.src = 'images/ParticleSmoke.png'; </p><p>

function init() {</p><p> container = document.createElement('div');

document.body.appendChild(container);</p><p> camera = new THREE.PerspectiveCamera( 75, SCREEN_WIDTH / SCREEN_HEIGHT, 1, 10000 );

camera.position.z = 1000;</p><p> scene = new THREE.Scene();

scene.add(camera);

renderer = new THREE.CanvasRenderer();

renderer.setSize(SCREEN_WIDTH, SCREEN_HEIGHT);

var material = new THREE.ParticleBasicMaterial( { map: new THREE.Texture(particleImage) } );

for (var i = 0; i < 500; i++) {</p><p>particle = new Particle3D( material);

particle.position.x = Math.random() * 2000 - 1000;

particle.position.y = Math.random() * 2000 - 1000;

particle.position.z = Math.random() * 2000 - 1000;

particle.scale.x = particle.scale.y = 1;

scene.add( particle );

particles.push(particle);

}</p><p> container.appendChild( renderer.domElement );</p><p>

document.addEventListener( 'mousemove', onDocumentMouseMove, false );

document.addEventListener( 'touchstart', onDocumentTouchStart, false );

document.addEventListener( 'touchmove', onDocumentTouchMove, false );

setInterval( loop, 1000 / 60 );

}

function onDocumentMouseMove( event ) {</p><p> mouseX = event.clientX - windowHalfX;

mouseY = event.clientY - windowHalfY;

}</p><p> function onDocumentTouchStart( event ) {</p><p> if ( event.touches.length == 1 ) {</p><p>event.preventDefault();</p><p>mouseX = event.touches[ 0 ].pageX - windowHalfX;

mouseY = event.touches[ 0 ].pageY - windowHalfY;

}

}</p><p> function onDocumentTouchMove( event ) {</p><p> if ( event.touches.length == 1 ) {</p><p>event.preventDefault();</p><p>mouseX = event.touches[ 0 ].pageX - windowHalfX;

mouseY = event.touches[ 0 ].pageY - windowHalfY;

}

}</p><p> //</p><p> function loop() {</p><p> for(var i = 0; i<particles.length; i++)

{</p><p>var particle = particles[i];

particle.updatePhysics();

with(particle.position)

{

if(y<-1000) y+=2000;

if(x>1000) x-=2000;

else if(x<-1000) x+=2000;

if(z>1000) z-=2000;

else if(z<-1000) z+=2000;

}

}

camera.position.x += ( mouseX - camera.position.x ) * 0.05;

camera.position.y += ( - mouseY - camera.position.y ) * 0.05;

camera.lookAt(scene.position); </p><p> renderer.render( scene, camera );</p><p>

}