本文实例讲述了javascript+html5 canvas制作的百花齐放效果。分享给大家供大家参考，具体如下：
运行效果截图如下：
具体代码如下：
<!DOCTYPE html>
<html>
<head>
<title>demo</title>
<style type="text/css">
body {
margin:0; padding:0;
}
#canvas {
border:5px solid gray; box-shadow:0 0 15px 15px #494949 inset;
margin-top:50px; margin-left:200px;
}
</style>
</head>
<body >
<canvas id="canvas" width="1000px" height="500px"></canvas>
<script type="text/javascript">
var dyl = {};
dyl.canvas = document.getElementById("canvas");
dyl.ctx = dyl.canvas.getContext("2d");
dyl.runTime = 0;
dyl.colorList = "01234567890ABCDEFabcdef".split("");
dyl.colorListLength = dyl.colorList.length;
dyl.arcList = null;
/**
* 得到16进制随机颜色值
*/
dyl.getColor = function() {
var color = "#";
for(var i=0; i<6; i++) {
color += dyl.colorList[Math.floor(Math.random()*dyl.colorListLength)];
}
return color;
};
/**
* 一个随机角度，随机初始速度的斜抛对象
*/
var Arc = function(i) {
// 设置自有属性
this.v = Math.round(Math.random()*100)+50;
this.angle = Math.round(Math.random()*145) + 45;
this.startTime = +new Date();
this._angle = this.angle/180*Math.PI;
this.v_x = this.v*Math.cos(this._angle);
this.v_y_start = this.v*Math.sin(this._angle);
this.color = dyl.getColor();
this.x = 500;
this.g = 250;
this.y = 490;
this.index = i;
var _self = this;
this.run = function() {
var endTime = +new Date();
var timeSpan = (endTime - _self.startTime)/1000;
var v_y_now = _self.v_y_start - 1/2*_self.g*Math.pow(timeSpan, 2);
_self.x = _self.x +_self.v_x * timeSpan;
_self.y = _self.y - (_self.v_y_start * timeSpan - 1/2*_self.g*Math.pow(timeSpan, 2));
return this;
};
return this;
};
/**
* 全局绘制图像
*/
dyl.draw = function() {
var arcList = dyl.arcList;
var ctx = dyl.ctx;
dyl.runTime++;
for(var i=0, length=arcList.length; i<length; i++) {
var arc = arcList[i];
if(!arc) {
continue;
}
arc.run();
ctx.save();
ctx.beginPath();
ctx.fillStyle = arc.color;
ctx.arc(arc.x, arc.y, 2, 0, Math.PI*2);
ctx.fill();
ctx.closePath();
ctx.restore();
}
console.log(dyl.runTime);
if(dyl.runTime >= 25) {
setTimeout(dyl.init, 1050);
} else {
setTimeout(dyl.draw, 20);
}
};
/**
* 初始化整个事件
*/
dyl.init = function() {
dyl.ctx.clearRect(0, 0, 1000, 500);
dyl.arcList = [];
dyl.runTime = 0;
for(var i=0; i<100; i++) {
dyl.arcList.push(new Arc(i));
}
dyl.draw();
};
dyl.init();
</script>
</body>
</html>
更多关于js特效相关内容感兴趣的读者可查看本站专题：《jQuery动画与特效用法总结》及《jQuery常见经典特效汇总》
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希望本文所述对大家JavaScript程序设计有所帮助。
