Question

我正在使用以下内容在html画布上绘制多边形：

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，它在多边形的末尾留下了一个间隙。知道如何解决这个问题吗？

Jsfiddle here

Answer 1

而不是绘制到所有6个点，只绘制到前5个，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();

（请注意从i <= numberOfSides到i < numberOfSides的更改）

Answer 2

尝试再画一面以填补空白：

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));
}

在画布上绘制多边形时的间隙

2 个答案: