Portals With Hardware
The Fountain Of Knowledge has been updated with a response to the following question on using clipping with OpenGL for a portal engine:
I'm working on a small portal engine in OpenGL.
Now I wonder, what is better for the view frustum clipping? I use 6 planes for the normal view, and when I find a portal, I will have to adjust these planes so clipping is done according to the portal.
OpenGL has it's "view frustum" (glFrustum), which I've read somewhere should NOT to be changed during run time. Additionally, OpenGL can use "extra clipping planes", so, I assume I COULD use these for my portalclipper.
But, will this be extremely slow? Will it be speeded up with hardware T&L, or should I stick to my own software clipping? "