围绕一个点旋转矩形 [英] Rotate rectangle around a point

问题描述

如何让 4 个点围绕指针旋转一定度数以形成矩形?我可以围绕一个点旋转一个点，但我不能通过偏移它来制作一个不变形的矩形.

How would I get 4 points rotated a certain degrees around a pointer to form a rectangle? I can rotate a point around a point, but I can't offset it to make a rectangle that isn't distorted.

推荐答案

如果你可以围绕一个点旋转一个点，那么旋转一个矩形应该很容易——你只需要旋转 4 个点.

If you can rotate a point around a point then it should be easy to rotate a rectangle - you just rotate 4 points.

这是一个绕原点旋转一个点的js函数:

Here is a js function to rotate a point around an origin:

function rotate_point(pointX, pointY, originX, originY, angle) {
    angle = angle * Math.PI / 180.0;
    return {
        x: Math.cos(angle) * (pointX-originX) - Math.sin(angle) * (pointY-originY) + originX,
        y: Math.sin(angle) * (pointX-originX) + Math.cos(angle) * (pointY-originY) + originY
    };
}

然后你可以对每个点都这样做.这是一个例子:http://jsfiddle.net/dahousecat/4TtvU/

And then you can do this to each point. Here is an example: http://jsfiddle.net/dahousecat/4TtvU/

改变角度并点击运行以查看结果...

Change the angle and hit run to see the result...

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