66 lines
1.3 KiB
HTML
66 lines
1.3 KiB
HTML
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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
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<html xmlns="http://www.w3c.org/1999/xhtml">
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<head>
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<title>Random canvas circles</title>
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<style type='text/css'>
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* {
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margin:0;
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padding:0;
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}
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canvas {
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position:absolute;
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top:50%;
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left:50%;
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margin-top:-200px;
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margin-left:-320px;
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border:1px solid #000;
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}
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</style>
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<script type='text/javascript'>
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function ani() {
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var ctx = document.getElementById('canvas').getContext('2d');
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ctx.clearRect(0,0,640,400);
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for (var i=0;i<num;i++) {
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ctx.beginPath();
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ctx.arc(a[i],b[i],c[i],0,Math.PI*2,true);
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ctx.stroke();
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nc=c[i]+Math.floor(Math.random()*3)-1
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if (nc<25) nc=25
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else if (nc>75) nc=75
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c[i]=nc
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nb=b[i]+Math.floor(Math.random()*3)-1
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if (nb<c[i]) nb=c[i]
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else if (nb>400-c[i]) nb=400-c[i]
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b[i]=nb
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na=a[i]+Math.floor(Math.random()*3)-1
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if (na<c[i]) na=c[i]
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else if (na>640-c[i]) na=640-c[i]
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a[i]=na
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}
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setTimeout("ani()",40)
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}
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function load() {
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a=new Array()
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b=new Array()
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c=new Array()
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num=10
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for (var i=0;i<num;i++) {
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c[i]=Math.floor(Math.random()*50)+25
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b[i]=Math.floor(Math.random()*(400-c[i]*2))+c[i]
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a[i]=Math.floor(Math.random()*(640-c[i]*2))+c[i]
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}
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ani()
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}
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window.onload=load
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</script>
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</head>
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<body>
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<canvas id='canvas' width='640' height='400'></canvas>
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</body>
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</html>
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