[Mesa-dev] [PATCH-RFC] draw: Rewrite primitive decomposer

[Chia-I Wu]

Hi,

While studying the draw module, I noticed that multiple primitive
decomposers exist: draw_pt_vcache_tmp.h, draw_gs_tmp.h,
draw_so_emit_tmp.h, and draw_pt_decompose.h.  The differences between
them are small, yet some of them support primitive modes that others
don't.  So I started the work to add a generic draw_decompose_tmp.h
that can be included by other tmp header files.  You may find the
changes in the attachments, or

  http://cgit.freedesktop.org/~olv/mesa/log/?h=draw-decompose

draw_decompose_tmp.h supports all primitive modes.  While it is a
rewrite, it resembles the existing decomposers a lot.  There are two
changes regarding how PIPE_PRIM_POLYGON and
PIPE_PRIM_TRIANGLE_STRIP_ADJACENCY are decomposed.

When flatshade_first is TRUE, the first triangle of the decomposed
polygon has edge flags 0 and 1 set; the last triangle has edge flags 1
and 2 set;  the other triangles has edge flags 1 set.  This is
different from the existing decomposers, which seem to set the edge
flags wrongly(?).

As for PIPE_PRIM_TRIANGLE_STRIP_ADJACENCY, the GS decomposer does not
seem to follow the vertex ordering of GL_TRIANGLE_STRIP_ADJACENCY.  I
write that part from scratch.  I am not 100% sure here as I don't have
a test case to verify.  It would be great if someone can clarify.

I haven't done a thorough (read: piglit) test yet.  I would like to
get early feedback before continuing.  Suggestions?

-- 
olv at LunarG.com
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