How can u tell OpenGL that f.i. GL_TEXTURE1_ARB is mapped on GL_TEXTURE0_ARB with a transperency of 0.7f or 0.2f etc. ? I can only achieve that both textures are mixed equally on my primitive…

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Use the combine extension GL_ARB_texture_env_combine you also have NV_texture_env_combine4 for nvidia cards.

What is f.i.?

f.i. = for instance

Can you please tell me how to use the func?? And the use of an alpha-value?

There’s a complete reference of register combiners in the newest nVidia OpenGL SDK Documentation(in the extensions specification), and it’s downloadable from


Using register combiners (if you have a GeForce) can be great for more advanced stuff. For simpler things is it a overkill and probably not the easiest way to do it.

You will find some information in the NeHe tutorial 22. Zed has some samples on his page

also check the ati developer website there used to be a utility there that’ll demonstrate the tex_env_combine extension