#798 – Rotation Transforms Using Homogeneous Coordinates

You can apply a rotation transform to a 2D point using a 2 x 2 transformation, multiplying it by a 2 x 1 point matrix.  This results in a second 2 x 1 point matrix that represents the transformed (rotated) point.

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In WPF, however, rotation transforms are done using homogeneous coordinates, which means that we multiply a 3 x 3 transformation matrix by a 3 x 1 point matrix.

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In the resulting 3 x 1 matrix, the first and second rows contain the x and y values of the transformed (rotated) point.

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