Created
November 4, 2014 15:42
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用 canvas 绘制的一个旋转图案
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| <!DOCTYPE html> | |
| <html lang="en"> | |
| <head> | |
| <meta charset="UTF-8"> | |
| <title>Twister</title> | |
| <style> | |
| body { background: black } | |
| canvas { margin: 0 auto; display: block; padding: 1px; } | |
| </style> | |
| </head> | |
| <body> | |
| <canvas id="canvas1" width="420" height="420"></canvas> | |
| <script type="text/javascript"> | |
| var canvas = document.getElementById("canvas1"); | |
| var ctx = canvas.getContext('2d'); | |
| ctx.lineCap = 'round'; | |
| ctx.strokeStyle = '#FFFF00'; | |
| ctx.lineWidth = 4; | |
| function turnIt() { | |
| ctx.beginPath(); | |
| ctx.moveTo(0, 0); | |
| moveNum = 2; | |
| rotateNum = 0.1 | |
| rads = rotateNum * 2 * Math.PI; | |
| for (i = 1; i <= 100; i++) { | |
| distance = i * moveNum; | |
| turn = i * rads; | |
| x = Math.cos(turn) * distance; | |
| y = Math.sin(turn) * distance; | |
| ctx.lineTo(x, y); | |
| } | |
| } | |
| ctx.translate(ctx.canvas.width / 2, ctx.canvas.height / 2); | |
| setInterval(function() { | |
| ctx.clearRect(-ctx.canvas.width / 2, -ctx.canvas.height / 2, | |
| ctx.canvas.width, ctx.canvas.height); | |
| ctx.rotate(.01); | |
| turnIt.apply(); | |
| ctx.stroke(); | |
| }, 10); | |
| </script> | |
| </body> | |
| </html> |
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