Fix #28347: VBO's highlights wrong faces when Mirror modifier is in use

Added callback to drawMappedFaces which checks if two faces have got equal draw options.

After discussion with Brecht we found it's nicest solution for now:
- Disabling VBOs in edit mode for this case wouldn't be nicer for this case -
  some additional flag stored in DM should be added in this case.
- Adding new callback in DM isn't nicer that this solution.
- Handling face selection in drawobject would lead to duplicated code
  which is also not nice.

Hopefully, this callback could handle all cases in the future.

Also, Brecht mentioned current VBO implementation isn't perfect, so maybe
when we'll redesign this area dealing with edit mode wouldn't be so tricky.

1 files changed, 2 insertions, 1 deletions

diff --git a/source/blender/blenkernel/BKE_DerivedMesh.h b/source/blender/blenkernel/BKE_DerivedMesh.h
index 46b533f33fd..6e17b056685 100644
--- a/source/blender/blenkernel/BKE_DerivedMesh.h
+++ b/source/blender/blenkernel/BKE_DerivedMesh.h
@@ -283,7 +283,8 @@ struct DerivedMesh {
 							int (*setDrawOptions)(void *userData, int index,
 												  int *drawSmooth_r),
 							void *userData, int useColors,
-							int (*setMaterial)(int, void *attribs));
+							int (*setMaterial)(int, void *attribs),
+							int (*compareDrawOptions)(void *userData, int cur_index, int next_index));
 
 	/* Draw mapped faces using MTFace 
 	 *  o Drawing options too complicated to enumerate, look at code.