MATRIXLF Structure for Shearing

For vertical shear transformation, the matrix element M11 contains the horizontal shear component, and the element M21 contains the vertical shear component, as follows:

                          ┌                         ┐
                          │   1     -tan (theta)  0 │
[ x' y' 1 ] = [ x y 1 ] * │   0           1       0 │
                          │   0           0       1 │
                          └                         ┘

For horizontal shear transformation, the matrix element M21 contains the horizontal shear component, and the matrix element M22 contains the vertical shear component, as follows:

                          ┌                    ┐
                          │   1           0  0 │
[ x' y' 1 ] = [ x y 1 ] * │  -tan theta   1  0 │
                          │   0           0  1 │
                          └                    ┘