[Mesa3d-dev] depth test after texturing

[Alexandr A. <an...@ni...>]

Hi, list.
I'm a newbie in Mesa, and I apologize if this question was asked before.
I have got an obsolete Mesa-4.0.3 source, but i think that nothing is 
changed in new
Mesa-5.x.

The fast_persp_span() function (and others) puts a texture on a span 
(scan line of triangle)
and then do clipping, alpha, depth and other tests. I think that In 
hardware this sequence
is justified because of pipeline architecture, where this approach 
provides avoiding of
conditional branches, but in the software, performance can be improved 
if do these tests
before texturing. Why Mesa works so? What is the secret?

Please, can you point me to any documentation or discussions in this list?

Thanks in advance.