效果圖：
提示：把代碼復制到一個html文件中并保存，直接打開即可看到效果。
實現代碼：
<!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>玫瑰曲線方程：<br>r=a+bsin(m/n*x)<br><br>選擇參數：<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=" 畫 圖 " onClick="draw();"><br><br><hr><br><input type="button" value=" 畫 圖 2 " onClick="draw2();"><br><br><hr><br><input type="button" value=" 心形圖 " 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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