multiplyByVerticalFlip

Multiplies this matrix by a matrix that flips and shifts the y-axis. The vertical flip matrix maps Y=0 to Y=1 and Y=1 to Y=0. This matrix is usually used to change the coordinate origin from an upper left coordinate origin to a lower left coordinate origin.
This is typically necessary to align the coordinate system of images (top-left origin) with that of OpenGL (bottom-left origin).