[Bug 28363] New: [r600c, kms, tiling] shadows wrong in doom3

[Bug 28363] New: [r600c, kms, tiling] shadows wrong in doom3

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https://bugs.freedesktop.org/show_bug.cgi?id=28363

           Summary: [r600c, kms, tiling] shadows wrong in doom3
           Product: DRI
           Version: XOrg CVS
          Platform: x86-64 (AMD64)
        OS/Version: Linux (All)
            Status: NEW
          Severity: normal
          Priority: medium
         Component: DRM/Radeon
        AssignedTo: dri-devel@lists.freedesktop.org
        ReportedBy: liquid.acid@gmx.net


Hi there,

I'm using the most recent drm-radeon-testing kernel which incorporates the
r6xx+ tiling patchset. Both the ddx and mesa are patched so that tiling is used
(ColorTiling=true in xorg.conf).

Both ddx and mesa are also git master (plus the patches, like stated before).

Just tried the doom3 demo and noticed that the shadows are not rendered
correctly, probably some issue with stencil buffering.

Should be reproducable with this version of the demo:
doom3-linux-1.3.1.1304.x86.run

Played around a bit with the ingame graphics settings, but ramping the quality
up and down doesn't have any effect on the issue (when not completly disabling
the shadows). Looks like it always uses the same approach, I think it was
called Carmack's reverse.

Performance is quite good and I don't see any other obvious rendering issues,
so fixing the stencil stuff would make d3 a 'perfectly playable' game on the
OSS driver :)

Greets,
Tobias

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[Bug 28363] [r600c, kms, tiling] shadows wrong in doom3

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https://bugs.freedesktop.org/show_bug.cgi?id=28363

--- Comment #1 from Tobias Jakobi <liquid.acid@gmx.net> 2010-06-02 17:39:52 PDT ---
Forgot to mention my hardware:
01:00.0 VGA compatible controller: ATI Technologies Inc Radeon HD 4770 [RV740]

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[Bug 28363] [r600c, kms, tiling] shadows wrong in doom3

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https://bugs.freedesktop.org/show_bug.cgi?id=28363

--- Comment #2 from Alex Deucher <agd5f@yahoo.com> 2010-06-02 21:52:01 PDT ---
Are you saying this is a regression with the tiling patches?  Does it render
correctly without the tiling patches?  Also, make sure you have the drm patch
in bug 28327.

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[Bug 28363] [r600c, kms, tiling] shadows wrong in doom3

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https://bugs.freedesktop.org/show_bug.cgi?id=28363

--- Comment #3 from Andy Furniss <lists@andyfurniss.entadsl.com> 2010-06-03 02:51:26 PDT ---
(In reply to comment #2)
> Are you saying this is a regression with the tiling patches?  Does it render
> correctly without the tiling patches?  Also, make sure you have the drm patch
> in bug 28327.

Not a regression for me - doom 3 demo has never rendered shadows properly as
long as I have been testing rv670. I thought it was a known issue and would
maybe get better when shadowtex starts working.

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[Bug 28363] [r600c, kms, tiling] shadows wrong in doom3

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https://bugs.freedesktop.org/show_bug.cgi?id=28363

--- Comment #4 from Tobias Jakobi <liquid.acid@gmx.net> 2010-06-03 07:05:48 PDT ---
(In reply to comment #2)
> Are you saying this is a regression with the tiling patches?  Does it render
> correctly without the tiling patches?  Also, make sure you have the drm patch
> in bug 28327.

No, no - like Andy wrote this is no regression introduced by the tiling
patches. The shadows are even wrong without tiling, but of course performance
is worse then.

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[Bug 28363] [r600c, kms] shadows wrong in doom3

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https://bugs.freedesktop.org/show_bug.cgi?id=28363

Alex Deucher <agd5f@yahoo.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|[r600c, kms, tiling]        |[r600c, kms] shadows wrong
                   |shadows wrong in doom3      |in doom3

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[Bug 28363] [r600c, kms] shadows wrong in doom3

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https://bugs.freedesktop.org/show_bug.cgi?id=28363

--- Comment #5 from Alex Deucher <agd5f@yahoo.com> 2010-06-03 08:23:06 PDT ---
Ok, updating the topic appropriately.

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[Bug 28363] [r600c, kms] shadows wrong in doom3

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https://bugs.freedesktop.org/show_bug.cgi?id=28363

--- Comment #6 from Tobias Jakobi <liquid.acid@gmx.net> 2010-06-03 08:28:23 PDT ---
Ok, sry - I see now, adding 'tiling' to the description was of course confusing
:)

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[Bug 28363] [r600c, kms] shadows wrong in doom3

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https://bugs.freedesktop.org/show_bug.cgi?id=28363

Andre Maasikas <amaasikas@gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Product|DRI                         |Mesa
            Version|XOrg CVS                    |git
          Component|DRM/Radeon                  |Mesa core
         AssignedTo|dri-devel@lists.freedesktop |mesa-dev@lists.freedesktop.
                   |.org                        |org

--- Comment #7 from Andre Maasikas <amaasikas@gmail.com> 2010-06-03 12:39:00 PDT ---
I looked it a while back and if i remember correctly this went like:
Doom uses ext_stencil_two_side if available
There's 2 back stencil states: 
1 opengl 2.0
2 ext_stencil_two_side
Mesa sets ctx->Stencil._BackFace to 2 if GL_STENCIL_TEST_TWO_SIDE_EXT
is enabled and to 1 otherwise - this is what r600 and also intel? uses

Doom3 does some stencil setup while
GL_STENCIL_TEST_TWO_SIDE_EXT disabled and the driver uses wrong values then

The spec is imho also inconclusive but i read it as
GL_STENCIL_TEST_TWO_SIDE_EXT
should be 'tested' at rendering time and you can set up backface stencil state
(via glActiveStencilFaceEXT) while this enable is not (yet) set.

2 options, use ctx->Stencil.ActiveFace in driver as in stencil.c
or set ctx->Stencil._BackFace also to 2 in _mesa_ActiveStencilFaceEXT()

I'm setting this to core mesa for comments

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