Fix issue discovered while investigating T39950:

Sculpt mode drawing fails after deleting a subsurf modifier
in sculpt mode and undoing.

This was quite difficult to spot. Main cause was that mesh data was not
synchronized properly between undo and sculpt code because we generated
a pbvh on derivedmesh invalidation without really refreshing the rest of
the data. This could result in undo and drawing operating on different
data.

To solve this and avoid bad level calls I had to move quite some code
around. Crazyspace is now moved to blenkernel, as did some sculpt calls
that make sure sculpt data are properly refreshed.

1 files changed, 11 insertions, 0 deletions

diff --git a/source/blender/blenkernel/BKE_paint.h b/source/blender/blenkernel/BKE_paint.h
index df72cb988b1..cb521382bd3 100644
--- a/source/blender/blenkernel/BKE_paint.h
+++ b/source/blender/blenkernel/BKE_paint.h
@@ -47,6 +47,7 @@ struct Object;
 struct Paint;
 struct PBVH;
 struct Scene;
+struct Sculpt;
 struct StrokeCache;
 struct Tex;
 struct ImagePool;
@@ -176,4 +177,14 @@ void free_sculptsession(struct Object *ob);
 void free_sculptsession_deformMats(struct SculptSession *ss);
 void sculptsession_bm_to_me(struct Object *ob, bool reorder);
 void sculptsession_bm_to_me_for_render(struct Object *object);
+void sculpt_update_mesh_elements(struct Scene *scene, struct Sculpt *sd, struct Object *ob,
+								 bool need_pmap, bool need_mask);
+struct MultiresModifierData *sculpt_multires_active(struct Scene *scene, struct Object *ob);
+int ED_sculpt_mask_layers_ensure(struct Object *ob,
+								  struct MultiresModifierData *mmd);
+
+enum {
+	ED_SCULPT_MASK_LAYER_CALC_VERT = (1 << 0),
+	ED_SCULPT_MASK_LAYER_CALC_LOOP = (1 << 1)
+};
 #endif