Environment Multi-texturing

you cant (not that i know off)
i find that an optimized manual multitextureing gives me more control over the end product, with only a tiny performace hit on slower machines.

what you''ll have to do is render the object using two passes instead of the single GL_ARB_multitexture.

How to Multipass
1. Render the First Pass
2. Disable Depthmask
3. Render the Second Pass
4. Restore the Depthmask

Example
this code can be optimized by sorting objects by state and
texture''s, remeber state changes are expensive, so code your
work to minimize the number state changes per frame.

void render(void){
  GLuint _tBase,_tEnv;   
    glBindTexture(GL_TEXTURE_2D,_tBase);
    // render object(s)
  glDepthMask(GL_FALSE);
    glBindTexture(GL_TEXTURE_2D,_tEnv);
    // change state, ie. Enviro Map & blending
    // render same objects again.
  glDepthMask(GL_TRUE);
}
 

Enjor
laters
/silvermace

you can control the blending between two textures, look at Nvidia''s simple mutli-tex. example for one way of doing it.

It can also be used for other effects like specular highlights, check out Nutty''s page on effects using OGL extension ( http://opengl.nutty.org/extensions/index.html ) for details on that