在 canvas 上绘制多边形时出现间隙

Question

我正在使用以下方法在 html canvas 上绘制多边形：

var canvas = document.getElementById("mycanvas");
var ctx = canvas.getContext("2d");

var numberOfSides = 6,
    size = 20,
    Xcenter = 25,
    Ycenter = 25;

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.strokeStyle = "#000000";
ctx.lineWidth = 10;
ctx.stroke();

不幸的是，它在多边形的末端留下了一个缺口。知道如何解决这个问题吗？

Jsfiddle here

Answer 1

尝试再画一条边来填补空白：

for (var i = 1; i <= numberOfSides+1;i += 1) {
    ctx.lineTo (Xcenter + size * Math.cos(i * 2 * Math.PI / numberOfSides), Ycenter + size * Math.sin(i * 2 * Math.PI / numberOfSides));
}

Answer 2

不是画到所有 6 个点，而是只画到前 5 个点，然后调用 ctx.closePath();

http://jsfiddle.net/757mavjb/2/

var canvas = document.getElementById("mycanvas");
var ctx = canvas.getContext("2d");

var numberOfSides = 6,
    size = 20,
    Xcenter = 25,
    Ycenter = 25;

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.closePath();

ctx.strokeStyle = "#000000";
ctx.lineWidth = 10;
ctx.stroke();

（注意从 i <= numberOfSides 到 i < numberOfSides 的变化）

在 canvas 上绘制多边形时出现间隙

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