Hi,
while working on the savage driver I found two problems. One with tnl/t_vb_render.c, the other one with tnl_dd/t_dd_tritmp.h. Both started since I use different hardware primitives for quads and triangles/polygons.
TAG(quad) in t_dd_tritmp.h calls RASTERIZE( GL_TRIANGLES ) directly before QUAD( (v[0]), (v[1]), (v[2]), (v[3]) ). RASTERIZE should be called with GL_QUADS so that the driver selects the correct hardware primitive. Also I believe that we could use the same condition as in TAG(triangle), namely
if (DO_UNFILLED) RASTERIZE( GL_QUADS );
This looks ok.
I wonder when this condition will be true anyway. But without this RASTERIZE is called for every single quad!
The second problem is in t_vb_render.c with clipped primitives. When a clipped primitive is rendered the PrimitiveNotify callback gets called with GL_POLYGON. When the next unclipped primitive is drawn we have to call PrimitiveNotify again with the original primitive type.
I think this is a misunderstanding. Although at a hardware level, you may be rendering with who knows what primitive, at a GL level, you are still attempting to render a TRIANGLE, QUAD, whatever.
The only time a difference between TRIANGLES, QUADS and POLYGONS emerges is if flat shading is active, in which case a different vertex is choosen to provide the color for the whole primitive. Is this the problem you're seeing, or is it something less subtle?
Keith
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