[Mesa-dev] [PATCH 2/2] gallium: Replaced gl_rasterization_rules with lower_left_origin and half_pixel_center.

[Jose Fonseca]

----- Original Message -----
> ----- Original Message -----
> > I have managed to make the triangle-rasterization test pass. Let's
> > forget about what the origin is, because it's not really important.
> > What is actually important is what happens when an edge falls exactly
> > on a sample point. Radeons have a state which determines what happens
> > for the left, right, top, and bottom edge, and it does not affect the
> > coordinate system, which is always top-left. So the issue is fixable
> > for radeon drivers as long as the origin is always top-left (i.e. no
> > changes are made to the viewport and scissor states).
> > 
> > Registers:
> > r300 - SC_EDGERULE
> > r600 - PA_SC_EDGERULE
> > 
> > Marek
> > 
> 
> That's great.
> 
> Spite the name, this was precisely the intent of "lower_left_origin" --
> whether top edges (horizontal edges exactly along the sample point) are
> inclusive or exclusive.  I'm open for better name suggestions.

Actually, it's not just horizontal edges -- the rule also applies to any edge < 45 degrees.

Jose