[Mesa-dev] [PATCH 1/2] i965: Use true AA line distance on G45/Ironlake.

[Kenneth Graunke]

On Wednesday, April 26, 2017 3:45:00 PM PDT Francisco Jerez wrote:
> Kenneth Graunke <kenneth at whitecape.org> writes:
> 
> > The original Broadwater and Crestline platforms computed antialiased
> > line distances using "manhattan" distance, aka a + b = c.  Eaglelake
> > and Cantiga added "true" distance, aka a^2 + b^2 = c^2, which is
> > obviously superior.
> >
> 
> The hardware docs are incredibly optimistic calling the improved AA line
> distance mode "true", in reality the strips and fans unit does something
> along the lines of 'max(a, b) + min(a, b) / 4' in "true" distance mode
> in order to avoid calculating the square root.  At any rate, it's still
> better than manhattan.  Series is:
> 
> Reviewed-by: Francisco Jerez <currojerez at riseup.net>

Oh, right, this is True(tm) distance...I'd forgotten about that.
Thanks for the reminder!  I've removed the pythagoreon theorem from the
commit message and replaced it with yours, and dropped the "obviously"
part of the comment :)

--Ken
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