[Mesa-dev] [PATCH] lp_build_lod_selector: Disable brilinear folding on explicit lod.

[Jose Fonseca]

----- Original Message -----
> On Wed, Jun 27, 2012 at 03:17:05AM -0700, Jose Fonseca wrote:
> > I took a look at the results, and it seems to me that bri linear
> > code is fine -- the test is merely too strict, and doesnot forgive
> > the gravitation towards integer lod that brilinear implements.
> 
> Yes, the current code maps [0,.25] to 0, [0.25,0.75] to [0-1] and
> [0.75,1] to 1.  So you you need an error tolerance of 0.20 given how
> the test is done on multiples of 0.2.

Thanks for confirming.
 
> What's your criteria to decide that a precision is "good enough"?

It's subjective.

My suggestion is to set GALLIVM_DEBUG=no_brilinear when running piglit for now, and when time permits, make the brilinear code conditional upon the contents of the textures (i.e., disbale brilinear when successive miplevels have totally different content) which would mean that the error would be visually very small, and that all tests would pass (was they typically don't meet the requirements). I believe this is what other drivers/hardware that uses brilinear also do.

Jose