Fix T77359: Crash adding UV's in edit-mode with linked duplicates

This prevents UV layer mix up in
MeshBatchCache.cd_used/cd_needed/cd_used_over_time which depends on the
extraction method.

One object's mesh can be accessed with MR_EXTRACT_MESH, another object
that uses the same mesh can use MR_EXTRACT_BMESH based on
(Object.mode & OB_MODE_EDIT), this causes a problem as the edit-mesh
and the mesh aren't always in sync, the custom data layers wont
necessarily match up, causing T77359.

Reviewed by @jbakker, @brecht

Ref D8645

3 files changed, 19 insertions, 3 deletions

diff --git a/source/blender/draw/intern/draw_cache_extract.h b/source/blender/draw/intern/draw_cache_extract.h
index b2fea957227..17df13b94f1 100644
--- a/source/blender/draw/intern/draw_cache_extract.h
+++ b/source/blender/draw/intern/draw_cache_extract.h
@@ -254,6 +254,7 @@ void mesh_buffer_cache_create_requested(MeshBatchCache *cache,
                                         Mesh *me,
                                         const bool is_editmode,
                                         const bool is_paint_mode,
+                                        const bool is_mode_active,
                                         const float obmat[4][4],
                                         const bool do_final,
                                         const bool do_uvedit,
diff --git a/source/blender/draw/intern/draw_cache_extract_mesh.c b/source/blender/draw/intern/draw_cache_extract_mesh.c
index 40687306b4e..2ac5a7b018c 100644
--- a/source/blender/draw/intern/draw_cache_extract_mesh.c
+++ b/source/blender/draw/intern/draw_cache_extract_mesh.c
@@ -130,6 +130,7 @@ typedef struct MeshRenderData {
 static MeshRenderData *mesh_render_data_create(Mesh *me,
                                                const bool is_editmode,
                                                const bool is_paint_mode,
+                                               const bool is_mode_active,
                                                const float obmat[4][4],
                                                const bool do_final,
                                                const bool do_uvedit,
@@ -151,9 +152,10 @@ static MeshRenderData *mesh_render_data_create(Mesh *me,
     BLI_assert(me->edit_mesh->mesh_eval_cage && me->edit_mesh->mesh_eval_final);
     mr->bm = me->edit_mesh->bm;
     mr->edit_bmesh = me->edit_mesh;
-    mr->edit_data = me->runtime.edit_data;
+    mr->edit_data = is_mode_active ? mr->me->runtime.edit_data : NULL;
     mr->me = (do_final) ? me->edit_mesh->mesh_eval_final : me->edit_mesh->mesh_eval_cage;
-    bool use_mapped = !do_uvedit && mr->me && !mr->me->runtime.is_original;
+
+    bool use_mapped = is_mode_active && (!do_uvedit && mr->me && !mr->me->runtime.is_original);
 
     int bm_ensure_types = BM_VERT | BM_EDGE | BM_LOOP | BM_FACE;
 
@@ -4605,6 +4607,7 @@ void mesh_buffer_cache_create_requested(MeshBatchCache *cache,
                                         Mesh *me,
                                         const bool is_editmode,
                                         const bool is_paint_mode,
+                                        const bool is_mode_active,
                                         const float obmat[4][4],
                                         const bool do_final,
                                         const bool do_uvedit,
@@ -4669,6 +4672,7 @@ void mesh_buffer_cache_create_requested(MeshBatchCache *cache,
   MeshRenderData *mr = mesh_render_data_create(me,
                                                is_editmode,
                                                is_paint_mode,
+                                               is_mode_active,
                                                obmat,
                                                do_final,
                                                do_uvedit,
diff --git a/source/blender/draw/intern/draw_cache_impl_mesh.c b/source/blender/draw/intern/draw_cache_impl_mesh.c
index 9339927926d..c3014cb9ad4 100644
--- a/source/blender/draw/intern/draw_cache_impl_mesh.c
+++ b/source/blender/draw/intern/draw_cache_impl_mesh.c
@@ -1035,7 +1035,15 @@ void DRW_mesh_batch_cache_create_requested(
     BLI_assert(me->edit_mesh->mesh_eval_final != NULL);
   }
 
-  const bool is_editmode = (me->edit_mesh != NULL) && DRW_object_is_in_edit_mode(ob);
+  /* Don't check `DRW_object_is_in_edit_mode(ob)` here because it means the same mesh
+   * may draw with edit-mesh data and regular mesh data.
+   * In this case the custom-data layers used wont always match in `me->runtime.batch_cache`.
+   * If we want to display regular mesh data, we should have a separate cache for the edit-mesh.
+   * See T77359. */
+  const bool is_editmode = (me->edit_mesh != NULL) /* && DRW_object_is_in_edit_mode(ob) */;
+
+  /* This could be set for paint mode too, currently it's only used for edit-mode. */
+  const bool is_mode_active = is_editmode && DRW_object_is_in_edit_mode(ob);
 
   DRWBatchFlag batch_requested = cache->batch_requested;
   cache->batch_requested = 0;
@@ -1373,6 +1381,7 @@ void DRW_mesh_batch_cache_create_requested(
                                        me,
                                        is_editmode,
                                        is_paint_mode,
+                                       is_mode_active,
                                        ob->obmat,
                                        false,
                                        true,
@@ -1389,6 +1398,7 @@ void DRW_mesh_batch_cache_create_requested(
                                        me,
                                        is_editmode,
                                        is_paint_mode,
+                                       is_mode_active,
                                        ob->obmat,
                                        false,
                                        false,
@@ -1404,6 +1414,7 @@ void DRW_mesh_batch_cache_create_requested(
                                      me,
                                      is_editmode,
                                      is_paint_mode,
+                                     is_mode_active,
                                      ob->obmat,
                                      true,
                                      false,