[Mesa-dev] [Bug 47375] Blender crash on startup after upgrade to mesa 8.0.1

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=47375

--- Comment #45 from Brian Paul <brian.e.paul at gmail.com> 2012-07-27 15:12:02 PDT ---
(In reply to comment #44)
> (In reply to comment #43)
> > > Also fog fallback shouldn't apply to depth/stencil buffer drawing neither (but
> > > OTOH enabled texturing should cause a fallback for color buffer drawing, even
> > > though I'd guess if some app really does a drawpixels with enabled fog or
> > > texturing it is probably by mistake not intentionally...).
> > 
> > Actually, I believe fog would apply to a glDrawPixels(GL_DEPTH) since we
> > generate fragments with color + Z in that case and the colors would be
> > subjected to fog, just like glDrawPixels(GL_RGB).  But it's a pretty obscure
> > case and I'm not going to worry about it for now.

> Yes but why would the generated color (modified by fog) matter in this case?

I'm only saying that fog (surprisingly?) applies to glDrawPixels(GL_DEPTH)
according to the OpenGL spec.  I'm not saying anything about the meta
implementation.


> Also there's WAY more obscure cases which look handled wrong (I guess that we
> don't see bugs filed about them is a testament that the whole "DrawPixel/Bitmap
> is like ordinary rasterization" is a serious misdesign):
> - enabled ColorSum (secondary color comes from current raster pos) for color
> buffer drawing
> - enabled AlphaTest (when drawing to stencil/depth buffer so color comes from
> raster pos and not the pixel data)
> - enabled texturing
> - enabled fragment program / shader
> - probably way more (crazy things like depth/stencil drawpixels with
> multisampled buffer and alpha_to_coverage?)
> At least I don't see how any of these could work with metaops.

I completely agree that there's probably quite a few corner cases that are
mishandled in the meta DrawPixels/Bitmap/etc code.

Anyway, I think we can close out this particular bug if the above-mentioned
patches look OK to everyone.

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