static void SetSinCos(ref SKMatrix matrix, float sin, float cos)
{
matrix.scaleX = cos;
matrix.skewX = -sin;
matrix.transX = 0;
matrix.skewY = sin;
matrix.scaleY = cos;
matrix.transY = 0;
matrix.persp0 = 0;
matrix.persp1 = 0;
matrix.persp2 = 1;
#if OPTIMIZED_SKMATRIX
matrix.typeMask = Mask.Unknown | Mask.OnlyPerspectiveValid;
#endif
}