It turns out the user planes handed to the driver are already in clip space.
Hence, we no longer need to transform incoming vertices before computing the
clip distance, and no longer need to change the interface provided by
gallium. Yay :)
The clip state change handling could be better, but this works.
Encode edgeflags (and reset_stipple info) into the top two bits of the
fetch elements. This info could be moved elsewhere, but for now we
can live with a 1<<30 maximum element size...
Also use the primitive decomposition code from draw_prim.c verbatim, as
it includes all this stuff and is known to work.
Also, implement support in the draw module. We were hardwiring these
to one for quite a long time...
Currently using a draw_set_edgeflags() function, may be better to push
the argument into the draw_arrays() function. TBD.
Previously all drivers were in twosided mode since they checked for
stencil.enable[1] flag which was a copy of stencil.enable[0]. Note that drivers
should not reference stencil[1] state (other than the enable) if twosided
stenciling is disabled (for now the stencil state is still copied but for
instance clear_with_quads won't provide useful values in there).
Also, use _TestTwoSide instead of TestTwoSide since results would be
bogus otherwise if using APIs with implicit two side stencil enable
(i.e. core ogl 2.0).
This handles the case where bypass_vs is set, but vertices need to go
through the pipeline for some reason - eg unfilled polygon mode.
Demonstrates how to drive the pipeline from inside one of these things.
Leaving it until 'run' is bad as the primitive is pretty much state
for some drivers and so needs to get set early. In some drivers
this is used to determine things like vertex format, etc -- by the
time we get to 'run', it's too late to change this.
Use this to set up hardware rasterization (if your hardware can
do it) or otherwise turn on various tweaks in the draw module.
Currently only hooked up to point biasing code.
