NULL for glTexImage3D = (PFNGLTEXIMAGE3DPROC)wglGetProcAddress("glTexImage3DEXT");

I get a NULL pointer to glTexImage3D after the GL win is open. I have OpenGl 1.2.1 from glGetString(GL_VERSION). Presumably this happens because my card/driver does not support it. How to get the right card/driver? On a Win NT 4.0 I have OpenGL 1.2.0 and a VolPro card. Is there any way to make the code work with that card?

Check whether or not the extension string (glGetString and GL_EXTENSIONS) contains GL_EXT_texture3D. If not, you can’t load “glTexImage3DEXT”. However, if you have OpenGL 1.2 or above, you should be able to load “glTexImage3D” instead.