This allows drivers to provide consistent flat shading for quads.
Otherwise a driver that only supported tris would have to force last
provoking vertex when drawing quads (and would have to say that quads
don't follow the provoking vertex convention).
Signed-off-by: Ilia Mirkin <imir...@alum.mit.edu>
---
vmware folks -- Please test this out with svga. I see that you might
have a similar issue with how you determine api_pv as
u_primconvert. Also if you don't expect quads to follow, you can
always just pass in pv == LAST, but then you still end up having to
force your rast state to pv = LAST too, for quads.
A good piglit to play with is:
bin/arb-provoking-vertex-render
src/gallium/auxiliary/indices/u_indices_gen.py | 13 ++++++++++---
1 file changed, 10 insertions(+), 3 deletions(-)
diff --git a/src/gallium/auxiliary/indices/u_indices_gen.py
b/src/gallium/auxiliary/indices/u_indices_gen.py
index 687a717..97c8e0d 100644
--- a/src/gallium/auxiliary/indices/u_indices_gen.py
+++ b/src/gallium/auxiliary/indices/u_indices_gen.py
@@ -142,8 +142,12 @@ def do_tri( intype, outtype, ptr, v0, v1, v2, inpv, outpv
):
tri( intype, outtype, ptr, v2, v0, v1 )
def do_quad( intype, outtype, ptr, v0, v1, v2, v3, inpv, outpv ):
- do_tri( intype, outtype, ptr+'+0', v0, v1, v3, inpv, outpv );
- do_tri( intype, outtype, ptr+'+3', v1, v2, v3, inpv, outpv );
+ if inpv == LAST:
+ do_tri( intype, outtype, ptr+'+0', v0, v1, v3, inpv, outpv );
+ do_tri( intype, outtype, ptr+'+3', v1, v2, v3, inpv, outpv );
+ else:
+ do_tri( intype, outtype, ptr+'+0', v0, v1, v2, inpv, outpv );
+ do_tri( intype, outtype, ptr+'+3', v0, v2, v3, inpv, outpv );
def name(intype, outtype, inpv, outpv, pr, prim):
if intype == GENERATE:
@@ -331,7 +335,10 @@ def quadstrip(intype, outtype, inpv, outpv, pr):
print ' i += 4;'
print ' goto restart;'
print ' }'
- do_quad( intype, outtype, 'out+j', 'i+2', 'i+0', 'i+1', 'i+3', inpv, outpv
);
+ if inpv == LAST:
+ do_quad( intype, outtype, 'out+j', 'i+2', 'i+0', 'i+1', 'i+3', inpv,
outpv );
+ else:
+ do_quad( intype, outtype, 'out+j', 'i+0', 'i+1', 'i+3', 'i+2', inpv,
outpv );
print ' }'
postamble()
--
2.0.5
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