Hey guys

I am having some trouble with a project i am working on and the maths is killing me

basically i have a projector which is pointed at different angles to a screen and i need to correct the skew - keystone effects of what i project via software

i can get the corner coordinates of the polygon that appears on the screen and i can get x.y.z roll pitch, yaw of the projector

i have looked and projection matrices look like the way but i have no idea what so ever on how to make them work

if anyone has any ideas i would be much much appreciative

thanks in advance