query capabilities

in GLview I saw that they can query what tex_env_combine functions are possible on the system.
testing the engine on multiple systems so far I saw that a sis640 (nightmare !!) based graphic card claims that it supports tex_env_combine but then had to find out it doesnt support interpolate function

how do they query in GLview what modes for tex_env_combine are allowed ?
do they just test all and check with glerror ?

I looked up ext_tex_env paper on sgi but couldnt find anything how one could get these infos with glGet

sorry for double topic, but seems like its too advanced for beginner forum

Two ways I can think of:

  1. set the mode

  2. call glGetError()

  3. set the mode

  4. render something

  5. read back a pixel you know what the color of should be

thanks :slight_smile: