AssertGLSL
Break and issue an error message if the given combination of graphics
hardware and graphics hardware driver does not support the
OpenGL Shading
Language (GLSL). This command needs to be executed after opening an
onscreen window, because it needs a valid
OpenGL context to work.
3/29/06 mk wrote it.
Psychtoolbox/PsychOneliners/AssertGLSL.m