Oblique View Frustum Depth Projection and Clipping
"Mathematics for 3D Game Programming and Computer Graphics" 3rd edition, chapter 5.6.
M is the original projection matrix.
Plane C is the modified near plane, and C'=transpose(inverse(M))*C is the projected plane by M.
Why in NDC the corner Q' of the view frustum lying opposite the plane C' is given by Q'=(Cx, Cy, 1, 1)?