How lighting effects textured polys

problem! -

Ive got a cube made of triangles. This cube is texture mapped. I have a light in the scene.

When texture mapping is disabled I can see the effect of lighting on my cube. When I enable texture mapping the effects of lighting disapear.

I would like to make my lighting effect the textured polygons appearance as it does the non-textured object polygons, so basically can I set up vertex lighting to effect the textures or will i need to make some form of lightmap routines? Thanks in advance.


You need to make sure your texture environment is set to “GL_MODULATE” it’s prolly set to “GL_DECAL” or “GL_REPLACE” at the moment…


Another thing is that specular lighting in not computed when using textures. You need a card that supports the GL_EXT_separate_specular_color extension or use the two-passes algorithm.




Specular lighting is computed when using textures. The problem is that all lighting components are summed before rasterization so that texturing modulates specular, diffuse and ambient components. GL_EXT_separate_specular_color just interpolates the specular component separately and sums it with the post-texture color.

Hope this helps -

Thanks for the info -

GL_MODULATE did the trick, after fiddling with some glMaterialfv settings (on the vertex structure) i did find no visual change in the textured polys. Ok now so if i set all RGB material values DIFF AMB and SPEC Lighting to 1.0, 1.0, 1.0 i get a massive frame rate hit. something in the realm of 40% mind you i have FRONT_AND_BACK lighting enabled.
Im not really asking questions here but more making a statement on the lighting effects. Feedback would be cool.