I'm interested in coding a portal rendering engine with DirectX 7, using the utility library. I want to use as much hardware acceleration as possible and I want to try to conform to the existing Direct3D standards wherever possible. Therefore, I would like to use the same parameters to calculate my clipping frustrums as Direct3D uses in the normal world to screen transformation. My question is, what steps are performed by Direct3D to transform my world coordinates to screen coordinates? If I knew what Direct3D does in the graphics pipeline in detail, I could duplicate that functionality to perform the necessary portal clips.

Any help would be much appreciated.