Fix T96356: artefacts with GPU subdivision and vertex paint mask

The lines paint mask IBO extraction was not implemented for GPU subdivision.
For it to work, we also now need to preserve the subdivision loop to
subdivision edge map, which until now was overwritten to store coarse edges
(the map to coarse edges is still preserved).

Also the paint flag stored in the 4th dimension of the loop normal buffer
was not properly set for flat shaded faces, leading to other kind of
artefacts and render issues.

1 files changed, 2 insertions, 0 deletions

diff --git a/source/blender/draw/intern/draw_subdivision.h b/source/blender/draw/intern/draw_subdivision.h
index 41d177a644a..8d7bc3dc495 100644
--- a/source/blender/draw/intern/draw_subdivision.h
+++ b/source/blender/draw/intern/draw_subdivision.h
@@ -130,6 +130,8 @@ typedef struct DRWSubdivCache {
 
   /* Maps subdivision loop to subdivided vertex index. */
   int *subdiv_loop_subdiv_vert_index;
+  /* Maps subdivision loop to subdivided edge index. */
+  int *subdiv_loop_subdiv_edge_index;
   /* Maps subdivision loop to original coarse poly index. */
   int *subdiv_loop_poly_index;