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32 bit Depth Buffer...

Started by PepeladZ Jun 12, 2002 at 12:37 PM 3 replies 3.3k views

Original Post

Jun 12, 2002 at 12:37 PM

Hi, How is it possible to make OpenGL use/set 32bit Depth buffer if I don''t need Stencil Buffer at all. I use GeForce2 MX with latest drivers. Here is what I request: dwFlags: PFD_DRAW_TO_WINDOW PFD_SUPPORT_OPENGL PFD_DOUBLEBUFFER iPixelType: PFD_TYPE_RGBA cColorBits: 32 cAlphaBits: 0 cAccumBits: 0 cDepthBits: 32 cStencilBits: 0 cAuxBuffers: 0 iLayerType: 0 Here is what ChoosePixelFormat() returns: dwFlags: PFD_DRAW_TO_WINDOW PFD_SUPPORT_OPENGL PFD_DOUBLEBUFFER iPixelType: PFD_TYPE_RGBA cColorBits: 32 cAlphaBits: 0 cAccumBits: 64 cDepthBits: 16 cStencilBits: 0 cAuxBuffers: 0 iLayerType: 0 Although there is a better format exists: dwFlags: PFD_DRAW_TO_WINDOW PFD_SUPPORT_OPENGL PFD_DOUBLEBUFFER iPixelType: PFD_TYPE_RGBA cColorBits: 32 cAlphaBits: 0 cAccumBits: 64 cDepthBits: 24 cStencilBits: 8 cAuxBuffers: 0 iLayerType: 0 Please advise. Thanks in advance.

siaspete

Jun 12, 2002 at 12:41 PM

Looks like there is no 32-bit depth buffer for that card. It''s 24-bit with optional 8-bit stencil.

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a person

Jun 13, 2002 at 12:30 AM

a 32bit depth buffer ussually measn 24 bit with 8bit stencil. much like a 32 bit color color depth is really 24bit with an 8bit alpha.

like with color depth you dont need to use th alpha channel, but is there to improve performence since everything is dword aligned.

[edited by - a person on June 13, 2002 1:31:52 AM]

Brother Bob

Jun 13, 2002 at 6:11 AM

Since most consumer level cards uses single precision floats internally, which has 23 significat bits in the mantissa, it''s pretty useless to have more than 24 bits in the depth buffer. You can''t have more precision than what the datatype can give you.

PepeladZ

Jun 14, 2002 at 3:38 PM

Many thanks for your help

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