1GL_SGIX_depth_pass_instrument 2https://www.khronos.org/registry/OpenGL/extensions/SGIX/SGIX_depth_pass_instrument.txt 3GL_SGIX_depth_pass_instrument 4 5 GL_DEPTH_PASS_INSTRUMENT_SGIX 0x8310 6 GL_DEPTH_PASS_INSTRUMENT_COUNTERS_SGIX 0x8311 7 GL_DEPTH_PASS_INSTRUMENT_MAX_SGIX 0x8312 8