Members - Reputation: 1409
Posted 04 May 2000 - 11:54 PM
Backfacing polygons are pols that are not facing you, that''s the ones that you don''t need to render.
Imagine a plane.
It''s define by 2 quads, one for each face.
Do you really want to compute vertex lighting, mapping... on the side you don''t see ?
No, so you do backface culling.
OpenGL (as well as Direct3D) did it for you I think you must activate it (if it''s not the default value) with the glEnable() command.
Notice that OpenGL (and Direct3D) are doing backface 2D culling at the end of the process (just before displaying), you can save extra operations by doing 3D culling using surface normals before the projection as been computed.
In 3d gfx (like anywhere) you must suppress as much stuff as you can as soon as possible.
Hope it helps.
-* Sounds, music and story makes the difference between good and great games *-
Moderators - Reputation: 979
Posted 07 May 2000 - 01:14 AM
You can set glCullFace( GL_FRONT ) , for example,
or use glFrontFace( GL_CCW ) or glFrontFace( GL_CW );
So basically, you can pick which way is forward if you want.
What morgan described is the default setting if you don''t change anything.
#pragma DWIM // Do What I Mean!
~ Mad Keith ~
**I use Software Mode**