Transform/Snap: EditMesh/BKE_bvhutils API improvements

Separate the creation of trees from EditMesh from the creation of trees from DerivedMesh.
This was meant to simplify the API, but didn't work out so well.

`bvhtree_from_mesh_*` actually is working as `bvhtree_from_derivedmesh_*`.
This is inconsistent with the trees created from EditMesh. Since for create them does not use the DerivedMesh.

In such cases the dm is being used only to cache the tree in the struct DerivedMesh. What is immediately released once
bvhtree is being used in functions that change(tag) the DM cleaning the cache.

- Use a filter function so users of SnapObjectContext can define how edit-mesh elements are handled.
- Remove em_evil.
- bvhtree of EditMesh is now really cached in the snap functions.
- Code becomes organized and easier to maintain.

This is an important patch for future improvements in snapping functions.

1 files changed, 12 insertions, 0 deletions

diff --git a/source/blender/bmesh/intern/bmesh_iterators.h b/source/blender/bmesh/intern/bmesh_iterators.h
index 336e9d88dea..0551d824131 100644
--- a/source/blender/bmesh/intern/bmesh_iterators.h
+++ b/source/blender/bmesh/intern/bmesh_iterators.h
@@ -208,6 +208,18 @@ void    *BMO_iter_as_arrayN(
         int *r_len,
         /* optional args to avoid an alloc (normally stack array) */
         void **stack_array, int stack_array_size);
+
+int BM_iter_mesh_bitmap_from_filter(
+        const char itype, BMesh *bm,
+        unsigned int *bitmap,
+        bool (*test_fn)(BMElem *, void *user_data),
+        void *user_data);
+int BM_iter_mesh_bitmap_from_filter_tessface(
+        BMesh *bm,
+        unsigned int *bitmap,
+        bool (*test_fn)(BMFace *, void *user_data),
+        void *user_data);
+
 int     BM_iter_elem_count_flag(const char itype, void *data, const char hflag, const bool value);
 int     BMO_iter_elem_count_flag(BMesh *bm, const char itype, void *data, const short oflag, const bool value);
 int     BM_iter_mesh_count(const char itype, BMesh *bm);