HTML5 Canvas实现玫瑰曲线和心形图案的代码实例-巨人网络通讯

效果图：
提示：把代码复制到一个html文件中并保存，直接打开即可看到效果。
实现代码：
<!DOCTYPE html>
<html>
<head>
<meta charset = "gbk">
<title>HTML5 Demo</title>
<style type="text/css">
#apDiv1 {
position:absolute;
width:120px;
height:300px;
z-index:1;
left: 840px;
top: 80px;
}
</style>
</head>
<body>
<canvas id="canvas" width="800" height="600" style="border:1px solid #c3c3c3;"> 
Your browser does not support the canvas element. </canvas> 
<div id="apDiv1">
<form>
玫瑰曲线方程：<br>
r=a+bsin(m/n*x)<br><br>
选择参数：<br><br>
m: <input type="number" name="m" min="2" max="29" value="29"/><br><br>
n: <input type="number" name="n" min="1" max="12" value="11"/><br><br>
a: <input type="number" name="a" min="0" max="5" value="1"/><br><br>
b: <input type="number" name="b" min="1" max="7" value="5"/><br><br>
<input type="button" value=" 画 图 " onClick="draw();"><br><br>
<hr><br>
<input type="button" value=" 画 图 2 " onClick="draw2();"><br><br>
<hr><br>
<input type="button" value=" 心形图 " onClick="draw3();"><br>
</form>
</div>
<script type="text/javascript"> 
function draw() { 
var ctx = document.getElementById('canvas').getContext('2d'); 
ctx.save(); 
ctx.translate(400,300); 
ctx.clearRect(-400,-300,800,600);
ctx.strokeStyle = "#cc0000"; 
var a = 0, b = 1, m = 6, n = 1;
m = document.forms[0].m.value;
n = document.forms[0].n.value;
a = document.forms[0].a.value; 
b = document.forms[0].b.value; 
drawRose(ctx,a,b,m,n); 
ctx.restore(); 
} 
function drawRose(ctx,a,b,m,n){ 
ctx.beginPath(); 
var e = 0, c = 120; 
var k = 2 * Math.PI / 360;
do { 
var r = a/b + Math.sin( m * e / n * k);
r = r * c; 
var x = r * Math.cos( e * k );
var y = r * Math.sin( e * k );
e += 0.1; 
ctx.lineTo(x,y); 
} while ( e <= 4320 ); 
ctx.stroke(); 
} 
function draw2(){ 
var ctx = document.getElementById('canvas').getContext('2d'); 
ctx.save(); 
ctx.translate(400,300); 
ctx.clearRect(-400,-300,800,600);
ctx.strokeStyle = "#cc0000"; 
ctx.beginPath(); //ctx.moveTo(0,0);
var e = 0, c = 150; 
var k = 2 * Math.PI / 360;
do { 
x = 150*Math.cos( 5/2 * e*k ) + 50*Math.cos( 15/16 * 5/2 * e*k ); 
y = 150*Math.sin( 5/2 * e*k ) - 50*Math.sin( 15/16 * 5/2 * e*k ); 
e += 0.1; 
ctx.lineTo(x,y); 
} while ( e <= 3600 ); 
ctx.stroke(); 
ctx.restore();
} 
function draw3(){ 
var ctx = document.getElementById('canvas').getContext('2d'); 
ctx.save(); 
ctx.translate(400,300); 
ctx.clearRect(-400,-300,800,600);
ctx.strokeStyle = "#ff0000"; 
ctx.beginPath(); 
var x = 1, y;
do { 
y = -80*(Math.sqrt(1-x*x) + Math.pow(x*x,1/3)); 
x -= 0.001; 
ctx.lineTo(100*x,y); 
} while ( x >= -1 ); 

do { 
y = 80*(Math.sqrt(1-x*x) - Math.pow(x*x,1/3)); 
x += 0.001; 
ctx.lineTo(100*x,y); 
} while ( x <= 1 );
ctx.closePath(); 

var grad = ctx.createRadialGradient(-40,-60,10,-40,-40,200);
grad.addColorStop(0, "#ffcc00"); 
grad.addColorStop(1, "#ff0000"); 
ctx.fillStyle = grad;
ctx.fill();
// ctx.stroke(); 
ctx.restore();
} 
window.onload = function (){ 
draw();
} 
</script>
</body>
</html>
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