Transformation functions for 3x3/3x2 matrices (2d matrices)

[WebFreak001]

It would be nice to have rotate, translate and scale in 2d aswell

[extrawurst]

afaik they apply on mat3 awell:

static if((rows == cols) && (rows >= 3)) {
        static if(isFloatingPoint!mt) {
            /// Returns an identity matrix with an applied rotate_axis around an arbitrary axis (nxn matrices, n >= 3).
            static Matrix rotation(real alpha, Vector!(mt, 3) axis) {......

see: https://github.com/Dav1dde/gl3n/blob/master/gl3n/linalg.d#L1444

[Dav1dde]

A 2x2 rotation matrix is indeed missing, not sure how useful it would be (but I wouldnt be against adding it anyways), since you normally work with homogeneous coordinates anyways (correct me if I am wrong!). 3x3 rotation/translation/scale matrices are supported (as @Extrawurst stated), 3x2 aren't, if you give me a good resource why they are needed and what they do, I am all for adding them.

[WebFreak001]

There is D2D1_MATRIX_3X2 in Direct2D for 2D transformation.

https://msdn.microsoft.com/en-us/library/windows/desktop/dd372275(v=vs.85).aspx

[Dav1dde]

Ok, but why is it important to have a 3x2 matrix, instead of a 3x3. How does it work? I was looking for something more mathematical, since I've never seen a use for a 3x2 matrix.

[WebFreak001]

Not mathematical but it saves 12 bytes in ram for each matrix

[Dav1dde]

Which is irrelevant. You don't create millions of matrices and keep these in memory. Also you don't send them to the GPU with every vertex, but once via uniform.