[Mesa-dev] [PATCH v2] i965: do not round line width when multisampling or antialiaing are enabled

[Kenneth Graunke]

On Wednesday, June 10, 2015 09:07:32 AM Iago Toral Quiroga wrote:
> In commit fe74fee8fa721a we rounded the line width to the nearest integer to
> match the GLES3 spec requirements stated in section 13.4.2.1, but that seems
> to break a dEQP test that renders wide lines in some multisampling scenarios.
> 
> Ian noted that the Open 4.4 spec has the following similar text:
> 
>     "The actual width of non-antialiased lines is determined by rounding the
>     supplied width to the nearest integer, then clamping it to the
>     implementation-dependent maximum non-antialiased line width."
> 
> and suggested that when ES removed antialiased lines, they removed
> "non-antialised" from that paragraph but probably should not have.
> 
> Going by that note, this patch restricts the quantization implemented in
> fe74fee8fa721a only to regular aliased lines. This seems to keep the
> tests fixed with that commit passing while fixing the broken test.
> 
> v2:
>   - Drop one of the clamps (Ken, Marius)
>   - Add a rule to prevent advertising line widths that when rounded go beyond
>     the limits allowed by the hardware (Ken)
>   - Update comments in the code accordingly (Ian)
>   - Put the code in a utility function (Ian)
> 
> Fixes:
> dEQP-GLES3.functional.rasterization.fbo.rbo_multisample_max.primitives.lines_wide
> 
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=90749

Looks good to me.  Thanks for doing this!

Reviewed-by: Kenneth Graunke <kenneth at whitecape.org>

By the way, I noticed that Marius' line-width < 1.5 code never got added
to gen8_sf_state.c, so a couple Piglit tests fail still.  It might be
nice to put that in the helper function too.  Feel like making a
follow-up patch?
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