rotated coordinates

Question

when i rotate an image how do i get the new cordinates of the image.This image is rotated around 0,0 but what is the coordinates of the other corners now it os rotated?img1.rotation=_angle;

Kenneth Kawamoto · Accepted Answer

The new coordination after the rotation would be:

x' = x*cosθ - y*sinθ

y' = x*sinθ + y*cosθ

So the AS equivalent would be something like:

        private function rotatedPoint(originalPoint:Point, rotation:Number):Point {
            return new Point(originalPoint.x*Math.cos(rotation) - originalPoint.y*Math.sin(rotation), originalPoint.x*Math.sin(rotation) + originalPoint.y*Math.cos(rotation));
        }

So Point(0, 20) after 10 degrees rotation would be:

trace(rotatedPoint(new Point(0, 20), 10*Math.PI/180));
// (x=-3.4729635533386065, y=19.69615506024416)

Sounds about right...?

May be better to round off the number:

        private function rotatedPoint(originalPoint:Point, rotation:Number):Point {
            var p:Point = new Point(originalPoint.x*Math.cos(rotation) - originalPoint.y*Math.sin(rotation), originalPoint.x*Math.sin(rotation) + originalPoint.y*Math.cos(rotation));
            p.x = Math.round(p.x*100)/100;
            p.y = Math.round(p.y*100)/100;
            return p;
        }

Anonymous · Answer

with Math.sin and Math.cos

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