绕一个点的矩形 [英] Rotate rectangle around a point

问题描述

如何将得到4分绕一个指针一定程度，以形成一个矩形？我可以绕一个点一个点，但我不能抵消它使未变形的矩形。

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

如果你可以绕一个点一个点，那么你就应该很容易旋转矩形 - 你只需旋转4个

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

下面是一个js函数来绕原点的点：

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
    };
}

然后你就可以做到这一点，以每个点。 这里有一个例子： http://jsfiddle.net/dahousecat/4TtvU/

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

变换角度和命中运行，看看结果......

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

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