javascript 围绕一个点旋转矩形
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Rotate rectangle around a point
提问by Anonymous
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.
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，但我不能偏移它来制作一个不变形的矩形。
回答by Felix Eve
If you can rotate a point around a point then it should be easy to rotate a rectangle - you just rotate 4 points.
如果您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——您只需旋转 4 个点。
Here is a js function to rotate a point around an origin:
这是一个围绕原点旋转点的js函数：
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
};
}
And then you can do this to each point. Here is an example: http://jsfiddle.net/dahousecat/4TtvU/
然后你可以对每个点都这样做。这是一个例子：http: //jsfiddle.net/dahousecat/4TtvU/
Change the angle and hit run to see the result...
改变角度并点击运行以查看结果......
