[Mesa-dev] Mesa (master): draw: fix flat shading and screen-space linear interpolation in clipper

[Olivier Galibert]

On Wed, Jul 11, 2012 at 02:19:02PM +0200, Marek Ol??ák wrote:
> On Wed, Jul 11, 2012 at 1:09 PM, Jose Fonseca <jfonseca at vmware.com> wrote:
> > My current plan is to:
> > - make it clear that INSTANCEID/VERTEXID always means integer
> > - require PIPE_SHADER_CAP_INTEGERS to be advertise in the vertex shader stage in order to advertise INSTANCEID/VERTEXID in Mesa statetracker
> > - given that Mesa assumes integer, insert a I2F when loading INSTANCEID/VERTEXID (this meets the new semantics while avoiding a big re-architecture)
> 
> The first two points sound good, but why I2F? Note that softpipe fully
> supports integers while llvmpipe doesn't, and I2F after loading
> INSTANCEID would very likely break softpipe.

I think that would break llvmpipe too.  llvmpipe actually fully
supports integers, it only thinks it doesn't, and least according to
piglit (textureFetch is the only real remaining issue left for glsl
1.30).  And draw-instanced works perfectly well with native integer
llvmpipe (which is why I didn't see the problem before the bug
report).

  OG.