Programmatically rotate shapes using coordinates

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时光说笑
时光说笑 2021-01-23 07:47

If I have some shapes defined using arrays of coordinates e.g.

[[-30, -30], [-30, 30], [30, 30], [30, -30]]

and edges defined using:

         


        
3条回答
  •  悲哀的现实
    2021-01-23 08:11

    Here you go, rotates point x, y around point centerx, centery by degrees degrees. Returns floating values, round if you need to.

    To rotate a shape, rotate all the points. Calculate the center if you need to, this does not do it.

    Desmos link with x as a, y as b, centerx as p, centery as q, and degrees as s

    function rotatePoint(x, y, centerx, centery, degrees) {
        var newx = (x - centerx) * Math.cos(degrees * Math.PI / 180) - (y - centery) * Math.sin(degrees * math.PI / 180) + centerx;
        var newy = (x - centerx) * Math.sin(degrees * Math.PI / 180) + (y - centery) * Math.cos(degrees * math.PI / 180) + centery;
        return [newx, newy];
    }
    

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