Javascript Canvas繪制一個八邊形
[英]Javascript Canvas drawing an octagon
問題描述
使用Javascript Canvas繪制一個八邊形，我具有此功能和代碼，但是由於某種原因，它無法正常工作。 有任何想法嗎？
function drawMe()
{
var numberOfSides = 8;
size = 10;
Xcenter = 100;
Ycenter = 100;
cxt.beginPath();
cxt.moveTo (Xcenter + size * Math.cos(0), Ycenter + size * Math.sin(0));
for (var i = 1; i <= numberOfSides; i += 1)
{
cxt.lineTo (Xcenter + size * Math.cos(i * 2 * Math.PI / numberOfSides), Ycenter + size * Math.sin(i * 2 * Math.PI / numberOfSides));
}
cxt.strokeStyle = "#000000";
cxt.lineWidth = 1;
cxt.stroke();
}
2 個解決方案
解決方案1
0 2014-04-07 02:05:26
只要cxt是對canvas上下文的有效引用，您的代碼就會成功繪制一個六邊形（我假設您會將6更改為8）。
如果未繪制六邊形，請確保您對上下文有有效的引用。
示例代碼：
<!doctype html>
<html>
<head>
<link rel="stylesheet" type="text/css" media="all" href="css/reset.css" /> <!-- reset css -->
<script type="text/javascript" src="http://code.jquery.com/jquery.min.js"></script>
<style>
body{ background-color: ivory; }
canvas{border:1px solid red;}
</style>
<script>
$(function(){
var canvas=document.getElementById("canvas");
var cxt=canvas.getContext("2d");
var numberOfSides = 6;
size = 10;
Xcenter = 100;
Ycenter = 100;
cxt.beginPath();
cxt.moveTo (Xcenter + size * Math.cos(0), Ycenter + size * Math.sin(0));
for (var i = 1; i <= numberOfSides; i += 1)
{
cxt.lineTo (Xcenter + size * Math.cos(i * 2 * Math.PI / numberOfSides), Ycenter + size * Math.sin(i * 2 * Math.PI / numberOfSides));
}
cxt.strokeStyle = "#000000";
cxt.lineWidth = 1;
cxt.stroke();
}); // end $(function(){});
</script>
</head>
<body>
<canvas id="canvas" width=300 height=300></canvas>
</body>
</html>
解決方案2
0 2015-10-02 21:13:03
<!DOCTYPE html>
<html>
<body>
<canvas id="canvas"></canvas>
<script>
var canvas = document.getElementById("canvas");
var ctx = canvas.getContext("2d");
ctx.strokeStyle = "#000000";
ctx.lineWidth = 1;
function drawMe()
{
var numberOfSides = 8,
size = 10,
Xcenter = 100,
Ycenter = 100;
ctx.beginPath();
ctx.moveTo (Xcenter + size * Math.cos(0), Ycenter + size * Math.sin(0));
for (var i = 1; i <= numberOfSides; i += 1)
{
ctx.lineTo (Xcenter + size * Math.cos(i * 2 * Math.PI / numberOfSides), Ycenter + size * Math.sin(i * 2 * Math.PI / numberOfSides));
}
ctx.stroke();
}
drawMe();
</script>
</body>
</html>
精靈未在畫布上繪制（JavaScript）
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