Re: [PATCH 1/2] wined3d: Try to detect the polygon offset scale value.

[Henri Verbeet]

On 30 July 2015 at 12:00, Stefan Dösinger <stefan(a)codeweavers.com> wrote:
> +                if (depth->format_flags & WINED3DFMT_FLAG_FLOAT)
> +                    scale = gl_info->float_polyoffset_scale;
> +                else
> +                    scale = gl_info->fixed_polyoffset_scale;
> Ideally this would be a format property. In practice it probably works
> because we only use 24 and 32 bit depth formats, and the hardware
> probably either only distinguishes between 16 and 24/32, or just
> doesn't support 32.
> +    while(1)
> I would have preferred that as "for (;;)"
> +    return powf(2, cur);
> It seems the compiler is smart enough to work it out, but strictly
> speaking powf() takes floating point arguments.

[PATCH 1/2] wined3d: Try to detect the polygon offset scale value.

[Stefan Dösinger]

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Am 2015-07-30 um 13:56 schrieb Henri Verbeet:
> Ideally this would be a format property. In practice it probably
> works because we only use 24 and 32 bit depth formats, and the
> hardware probably either only distinguishes between 16 and 24/32,
> or just doesn't support 32.
> I'm actually quite happy that we don't have to run this test for every
> format, mostly due to startup performance concerns...

Some Mesa drivers (r300g if I remember right) have some 16 vs 24 bit
code in glPolygonOffset, but in practise it didn't matter. I haven't
really debugged the driver to find out what's going wrong. (r200 has a
suspiciously commented out offset *= 2, which is probably why it ends
up wanting 2^24 instead of 2^23 like all the other drivers)

One suspicion I checked is that the driver looks at the GLX format
instead of the FBO format, but changing the GLX format we request
didn't influence the outcome.

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