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

[Olivier Galibert]

On Mon, Jun 25, 2012 at 07:31:20PM +0100, Roland Scheidegger wrote:
> Does this fix the test because lp_build_brilinear_lod produces bogus 
> values in this case or just because the test is strict about such 
> filtering optimizations? In the latter case I'm not sure I really see 
> much point.

Bogus.  It does the fractional-part log2 approximation there, which
only makes sense if you called fast_log2 before (and even then the log
bias is going to be strangely applied, but meh).


> I'm surprised it can actually pass in either case since we drop all but 
> the first lod per quad values on the floor anyway so I think you will 
> get neither the right filtering weights between mipmaps nor even the 
> right mip levels (if the integer part of the lod isn't the same) for 
> anything but the first texel per quad.

Luck due to the design of the test.  It's rectangles with a fixed lod
value, so the quads all have the same.  That's pretty much why I
cooked up miplevels-2 (only in vs though, it's much easier there and
the code is shared).

  OG.