canvas绘制星空
效果图
html结构
当前浏览器不支持canvas,请更换浏览器后再试
js脚本
_window.onload = function(){
var canvas = document.getElementById("canvas");
canvas.width = 800;
canvas.height = 800;
var context = canvas.getContext("2d");
// context.lineJoin = "bevel";
// context.lineJoin = "round";
// context.lineJoin = "miter";
context.fillStyle = "black";
context.fillRect(0,0,canvas.width,canvas.height);
for(var i = 0;i<200;i++){
var r = Math.random() * 10 + 10;
var x = Math.random() * canvas.width;
var y = Math.random() * canvas.height;
var a = Math.random() * 360;
drawStar(context,r/2.0,r,x,y,a,10,"#fb3","#fb3");
}
}
function drawStar(context,r,R,x,y,rot,lineWidth,strokeStyle,fillStyle){
context.beginPath();
for(var i = 0;i<5;i++){
context.lineTo(Math.cos((18+i*72 - rot)/180 * Math.PI) * R + x,-Math.sin((18+i*72 - rot)/180*Math.PI)*R + y);
context.lineTo(Math.cos((54+i*72 - rot)/180 * Math.PI) * r + x,-Math.sin((54+i*72 - rot)/180*Math.PI)*r + y);
}
context.closePath();
context.fillStyle = fillStyle;
context.strokeStyle = strokeStyle;
context.lineWidth = lineWidth;
context.lineJoin = "miter";
context.fill();
context.stroke();
}