[Mesa-dev] [Bug 71199] [llvmpipe] piglit gl-1.4-polygon-offset regression

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=71199

José Fonseca <jfonseca at vmware.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|[llvmpipe] piglit glean     |[llvmpipe] piglit
                   |polygonOffset regression    |gl-1.4-polygon-offset
                   |                            |regression

--- Comment #4 from José Fonseca <jfonseca at vmware.com> ---
This test was renamed, but the issue is still there:

$ ./bin/gl-1.4-polygon-offset -auto
    Actual MRD is too small (may cause incorrect results)
    Ideal  MRD at near plane is 1.192095e-07 (nominally 2 bits)
    Actual MRD at near plane is 5.960464e-08 (nominally 1 bit)
    Ideal  MRD at infinity is 3.061179e-08 (nominally 1 bit)
    Actual MRD at infinity is 5.960464e-08 (nominally 1 bit)

PIGLIT: {"result": "fail" }

(In reply to Roland Scheidegger from comment #1)
> My guess would be the test is invalid.
> The "mrd" meaning is very precise both in d3d10 and OpenGl, and we were
> being sloppy there before - it really should be exactly one bit (for unorm
> depth formats).
> I quickly looked at the test and I don't quite understand what it does to
> find the ideal mrd. I suspect the math doesn't work out somewhere because
> the float math is right at the limits of depth buffer precision (24 bit in
> this case).

Yes, I also don't understand why the requirement of 2 bits. 

> Do closed source drivers actually pass this (and if so I wonder what their
> calculated ideal/actual mrd values are)?

Yes, they do somehow:

$ glxinfo | grep '^OpenGL \(vendor\|renderer\) string:'
OpenGL vendor string: NVIDIA Corporation
OpenGL renderer string: Quadro K1000M/PCIe/SSE2
$ ./bin/gl-1.4-polygon-offset -auto
    Ideal  MRD at near plane is 1.192089e-07 (nominally 2 bits)
    Actual MRD at near plane is 1.192093e-07 (nominally 2 bits)
    Ideal  MRD at infinity is 1.499423e-08 (nominally 0 bits)
    Actual MRD at infinity is 1.192093e-07 (nominally 2 bits)

PIGLIT: {"result": "pass" }

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