[Mesa-dev] vertex array regression

[Mathias Fröhlich]

Brian,

On Thursday, December 15, 2011 22:36:24 you wrote:
> I found the problem.  It's this chunk in vbo_context.c:
[...]
> For fixed function, the point is to simply place the per-vertex
> material attributes in the generic attribute arrays.  There are 12
> such material attributes.  So there's four slots left over.

Yep, and these map with the old scheme to often used attributes like the 
vertex position.

Thanks to your hints I believe that I found the underlying problem:

If you look at the resulting bitmasks for the enabled vertex program inputs in 
isosurf by commenting out the printf in _mesa_set_varying_vp_inputs you will 
see surprising results with the old numbering. The current checked in 
numbering looks much more plausible.
It turns out that this wrong varying_vp_inputs mask sets the _NEW_ARRAY bit 
through _mesa_set_varying_vp_inputs. That in turn cares for some (by now in my 
debug session untracked) state updates. This helps in the end for isosurf.
If the varying_vp_inputs mask looks plausible the _NEW_ARRAY bit is not set 
and isosurf fails.

This also explaines that only draw paths going through vbo_exec_array.c are 
affected, since the imm variants in vbo_exec_{safe,draw} always set the 
_NEW_ARRAY bit on any draw.

So for me this change

diff --git a/src/mesa/vbo/vbo_exec_array.c b/src/mesa/vbo/vbo_exec_array.c
index a6e41e9..a2851c4 100644
--- a/src/mesa/vbo/vbo_exec_array.c
+++ b/src/mesa/vbo/vbo_exec_array.c
@@ -446,7 +446,7 @@ recalculate_input_bindings(struct gl_context *ctx)
        * to revalidate vertex arrays. Not marking the state as dirty also
        * improves performance (quite significantly in some apps).
        */
-      if (!ctx->VertexProgram._MaintainTnlProgram)
+      /* if (!ctx->VertexProgram._MaintainTnlProgram) */
          ctx->NewState |= _NEW_ARRAY;
       break;

makes isosurf work reliable.

I will prepare a patch for that.

Greetings

Mathias