<!--效果html开始-->
<div id="container"></div>
<script type="text/javascript">
var Sketch=function(){function e(e){e=n(e||{},l);var t="sketch-"+r++,o=e.hasOwnProperty("canvas"),u=o?e.canvas:document.createElement("canvas");switch(e.type){case m:try{s=u.getContext("webgl",e)}catch(d){}try{s=s||u.getContext("experimental-webgl",e)}catch(d){}if(!s)throw"WebGL not supported";break;case c:try{s=u.getContext("2d",e)}catch(d){}if(!s)throw"Canvas not supported";break;default:u=s=document.createElement("div")}return s.canvas=u,u.className="sketch",o?e.autoresize=!1:(e.container.appendChild(u),e.hasOwnProperty("autoresize")||(e.autoresize=l.autoresize),u.id=t),n(self,g),n(s,e),n(s,p),a(),e.autoresize&&i(),w.push(s),s.autostart&&setTimeout(s.start,0),s}function n(e,n){for(var t in n)e.hasOwnProperty(t)||(e[t]=n[t]);return e}function t(e){function n(e,n){return function(){e.call(n,arguments)}}var t={};for(var o in e)t[o]="function"==typeof e[o]?n(e[o],e):e[o];return t}function o(e,n){e.length=0;for(var t=0,o=n.length;o>t;t++)e[t]=n[t];return e}function a(){function 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<script type="text/javascript" >
function Particle( x, y, radius ) {
this.init( x, y, radius );
}
Particle.prototype = {
init: function( x, y, radius ) {
this.alive = true;
this.radius = radius || 10;
this.wander = 0.15;
this.theta = random( TWO_PI );
this.drag = 0.92;
this.color = '#fff';
this.x = x || 0.0;
this.y = y || 0.0;
this.vx = 0.0;
this.vy = 0.0;
},
move: function() {
this.x += this.vx;
this.y += this.vy;
this.vx *= this.drag;
this.vy *= this.drag;
this.theta += random( -0.5, 0.5 ) * this.wander;
this.vx += sin( this.theta ) * 0.1;
this.vy += cos( this.theta ) * 0.1;
this.radius *= 0.96;
this.alive = this.radius > 0.5;
},
draw: function( ctx ) {
ctx.beginPath();
ctx.arc( this.x, this.y, this.radius, 0, TWO_PI );
ctx.fillStyle = this.color;
ctx.fill();
}
};
// ----------------------------------------
// Example
// ----------------------------------------
var MAX_PARTICLES = 280;
var COLOURS = [ '#69D2E7', '#A7DBD8', '#E0E4CC', '#F38630', '#FA6900', '#FF4E50', '#F9D423' ];
var particles = [];
var pool = [];
var demo = Sketch.create({
container: document.getElementById( 'container' )
});
demo.setup = function() {
// Set off some initial particles.
var i, x, y;
for ( i = 0; i < 20; i++ ) {
x = ( demo.width * 0.5 ) + random( -100, 100 );
y = ( demo.height * 0.5 ) + random( -100, 100 );
demo.spawn( x, y );
}
};
demo.spawn = function( x, y ) {
if ( particles.length >= MAX_PARTICLES )
pool.push( particles.shift() );
particle = pool.length ? pool.pop() : new Particle();
particle.init( x, y, random( 5, 20 ) );
particle.wander = random( 0.5, 2.0 );
particle.color = random( COLOURS );
particle.drag = random( 0.7, 0.99 );//0.9 0.99
theta = random( TWO_PI );
force = random( 2, 8 );
particle.vx = sin( theta ) * force;
particle.vy = cos( theta ) * force;
particles.push( particle );
}
demo.update = function() {
var i, particle;
for ( i = particles.length - 1; i >= 0; i-- ) {
particle = particles[i];
if ( particle.alive ) particle.move();
else pool.push( particles.splice( i, 1 )[0] );
}
};
demo.draw = function() {
demo.globalCompositeOperation = 'lighter';
for ( var i = particles.length - 1; i >= 0; i-- ) {
particles[i].draw( demo );
}
};
demo.mousemove = function() {
var particle, theta, force, touch, max, i, j, n;
for ( i = 0, n = demo.touches.length; i < n; i++ ) {
touch = demo.touches[i], max = random( 1, 4 );
for ( j = 0; j < max; j++ ) demo.spawn( touch.x, touch.y );
}
};
</script>
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</div>
