when I call =>
glDepthMask(GL_FALSE); glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
depth buffer is not clearing properly (or isn’t clearing at all).
But in spec about glClear(), there is written:
"The pixel-ownership test, the scissor test, dithering, and the buffer writemasks affect
the operation of glClear. The scissor box bounds the cleared region. The alpha function,
blend function, logical operation, stenciling, texture mapping, and z-buffering are ignored by
This is not problem for my, I can just enable depth masking before glClear, but I am curious
if this is correct behavior or error in drivers.
I have tested it on Detonator 6.5 and 10.80. My card is Inno3D Geforce2 GTS 64Mb, Windows 2000 SP1.
If you want, I can try it on Radeon, Riva TNT…
PS: I have uploaded demo in http://www.abc.sk/OpenGL/Matrox_DepthMasking.zip
In file matrox.cpp on line 223 you can enable/disable depth masking and see this effect.