Edit Mesh: optimize common use-cases for partial updates

Skip updating normals & tessellation for contiguous geometry regions
for operations such as translate & uniform scale.

This means when all geometry is selected, no updates are needed
as the relative locations of vertices aren't being modified.

Performance:

As this is skipping a multi-threaded operation,
larger improvements are noticeable on systems with fewer cores.

- ~1.15x to ~1.3x overall gain for 32 cores.
- ~1.7x to ~2.2x overall gain for 1 core (limited using `-t 1` argument).

Details:

- Rotate & non-uniform scale only skip tessellation.

- Proportional editing and axis-mirror have special handling
  ensure geometry is properly grouped before considering
  a face part of a single group that can be skipped.

- Loose vertices always need their normals to be recalculated
  since they're calculated based on the location.

- Non-affine transform operations such as shrink-fatten & bend,
  don't take advantage of this optimization.

- Snap projection also disables the optimization.

1 files changed, 15 insertions, 4 deletions

diff --git a/source/blender/bmesh/intern/bmesh_mesh_partial_update.h b/source/blender/bmesh/intern/bmesh_mesh_partial_update.h
index 3dbfb985e92..cf4eab22836 100644
--- a/source/blender/bmesh/intern/bmesh_mesh_partial_update.h
+++ b/source/blender/bmesh/intern/bmesh_mesh_partial_update.h
@@ -54,9 +54,20 @@ typedef struct BMPartialUpdate {
 
 BMPartialUpdate *BM_mesh_partial_create_from_verts(BMesh *bm,
                                                    const BMPartialUpdate_Params *params,
-                                                   const int verts_len,
-                                                   bool (*filter_fn)(BMVert *, void *user_data),
-                                                   void *user_data)
-    ATTR_NONNULL(1, 2, 4) ATTR_WARN_UNUSED_RESULT;
+                                                   const unsigned int *verts_mask,
+                                                   const int verts_mask_count)
+    ATTR_NONNULL(1, 2, 3) ATTR_WARN_UNUSED_RESULT;
+
+BMPartialUpdate *BM_mesh_partial_create_from_verts_group_single(
+    BMesh *bm,
+    const BMPartialUpdate_Params *params,
+    const unsigned int *verts_mask,
+    const int verts_mask_count) ATTR_NONNULL(1, 2, 3) ATTR_WARN_UNUSED_RESULT;
+
+BMPartialUpdate *BM_mesh_partial_create_from_verts_group_multi(
+    BMesh *bm,
+    const BMPartialUpdate_Params *params,
+    const int *verts_group,
+    const int verts_group_count) ATTR_NONNULL(1, 2, 3) ATTR_WARN_UNUSED_RESULT;
 
 void BM_mesh_partial_destroy(BMPartialUpdate *bmpinfo) ATTR_NONNULL(1);