Hi Nicolai,

On Saturday 29 January 2005 18:35, you wrote:
> The fact is, *all* 3D APIs expose their depth buffer. OpenGL (and
> Direct3D) specify a Z-buffer. Applications can read this Z-buffer -
> for example using glReadBuffer, but there are probably less
> straightforward ways to do it. So we *MUST* be able to produce
> compliant Z values. There's simply no way around it.

OK, it occurs to me that the way glReadPixels is defined we don't have a 
problem.  For each render frame, W differs from Z only by a simple 
offset, so we can recover Z from 1/W with some simple arithmetic on the 
host side where we've got access to plenty of divide power.  Unless 
I've missed something else, this allows us to rely on 1/W buffering if 
that is the superior approach.

Regards,

Daniel
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