<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title></title>
</head>
<body>
<body style="margin:0px;padding:0px;width:100%;height:100%;overflow:hidden;">
<canvas id="canvas" style="border: 1px solid #aaa" width="1920" height="962">
你的浏览器不支持canvas,请更换浏览器再试!
</canvas>
<script>
var c=document.getElementById("canvas");
c.width=document.body.clientWidth;
c.height=document.body.clientHeight;
window.onload=function(){
if(c.getContext("2d")){
var cxt= c.getContext("2d");
}else{
document.write("你的浏览器不支持canvas,请更换浏览器再试!");
}
//星空背景颜色
var linearCrad=cxt.createLinearGradient(0,0,0, c.height* 0.68);
linearCrad.addColorStop(0.0, '#7ac4e1');
linearCrad.addColorStop(0.2, '#5eb8dd');
linearCrad.addColorStop(1.0, '#b6e2e5');
cxt.fillStyle=linearCrad;
cxt.fillRect(0,0, c.width, c.height);
//循环绘制100颗星星
for(var i=0 ; i<100 ; i++){
var r=Math.random() * 6 + 2;//半径
var x=Math.random() * c.width * 0.98 ; // x偏移量
var y=Math.random() * c.height * 0.6; //y偏移量
var a=Math.random() * 360; //旋转角度
drawStart(cxt , r/2.0 , r , x , y , a);
}
//月亮
fillMoon(cxt ,2, c.width * 0.88 , c.height * 0.24 ,100 ,20 , "#fff");
//绿地
drawLand(cxt);
}
/*
* cxt:绘图环境
* r:小圆半径
* R:大圆半径
* x:x轴偏移量
* y:y轴偏移量
* rot:旋转角度(逆时针)*/
function drawStart(cxt,r,R,x,y,rot){
cxt.beginPath();
cxt.fillStyle="#fff"
cxt.strokeStyle="#88b9dd";
for(var i=0 ; i < 5 ;i++){
cxt.lineTo( Math.cos((18+ i*72 - rot )/180 * Math.PI) * R + x//大圆
, -Math.sin((18 + i*72 - rot)/180 *Math.PI) * R + y);
cxt.lineTo( Math.cos((54+ i*72 - rot )/180 * Math.PI) * r + x//小圆
, -Math.sin((54 + i*72 - rot)/180 *Math.PI) * r + y);
}
cxt.closePath();
cxt.fill();
cxt.stroke();
}
/*
*参数说明
*R: 半径
* rot:旋转角度
*fillColor: 填充颜色
* */
function fillMoon(cxt ,d , x , y , R , rot , fillColor){
cxt.save();
cxt.translate(x , y);
cxt.rotate(rot * Math.PI / 180);
cxt.scale(R , R);
pathMoon(cxt , d);
cxt.fillStyle=fillColor || "#fb5";
cxt.shadowColor = "rgba(58,88,124,0.5)";
cxt.shadowOffsetX = 14 ;
cxt.shadowOffsetY = 14;
cxt.shadowBlur = 30;
cxt.fill();
cxt.restore();
}
/*
d :坐标
*/
function pathMoon(cxt , d){
cxt.beginPath();
/*
*圆心(0,0)
*半径:1
* */
cxt.arc(0 , 0 , 1 , 0.5 * Math.PI , 1.5 * Math.PI , true);
cxt.moveTo(0 , -1);
cxt.arcTo(d , 0 , 0 , 1 , dis(0 , -1 , d , 0) / d);
cxt.closePath();
}
function dis(x1 , y1 ,x2 , y2){
return Math.sqrt( (x1-x2) * (x1-x2) + (y1-y2) * (y1-y2) );
}
/*
* 绿地
* */
function drawLand(cxt){
cxt.save();
cxt.beginPath();
cxt.moveTo(0 , c.height * 0.7);
/*cxt.bezierCurveTo(540 , 400 , 660 , 800 , 1200 , 600);*/
cxt.bezierCurveTo(c.width * 0.4 , c.height * 0.5 , c.width * 0.5 , c.height * 0.9 , c.width , c.height * 0.8);
cxt.lineTo(c.width , c.height);
cxt.lineTo(0 , c.height);
cxt.closePath();
//添加渐变
var landStyle = cxt.createLinearGradient(0 , 800 , 0 ,0);
landStyle.addColorStop(0.0 ,'#7dbf44');
landStyle.addColorStop(0.2 ,'#b9d532');
landStyle.addColorStop(1 ,'#79bd46');
cxt.fillStyle=landStyle;
cxt.fill();
cxt.restore();
}
</script>
</body>
</body>
</html>
星空画布(刷新星星随机)
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转载自blog.csdn.net/gcyqweasd/article/details/107505252
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