BMesh: remove unit-length edge-vector cache from normal calculation

Bypass stored edge-vectors for ~16% performance gains.

While this increases unit-length edge-vector calculations by around ~4x
the overhead of a parallel loop over all edges makes it worthwhile.

Note that caching edge-vectors per-vertex performs better and may be
worth investigating further, although in my tests this increases code
complexity with barley measurable benefits over not using cache at all.

Details about performance and possible optimizations are noted in
bm_vert_calc_normals_impl.

1 files changed, 2 insertions, 41 deletions

diff --git a/source/blender/bmesh/intern/bmesh_mesh_partial_update.c b/source/blender/bmesh/intern/bmesh_mesh_partial_update.c
index 7b01b61d4fa..267705aa7c7 100644
--- a/source/blender/bmesh/intern/bmesh_mesh_partial_update.c
+++ b/source/blender/bmesh/intern/bmesh_mesh_partial_update.c
@@ -79,20 +79,6 @@ BLI_INLINE bool partial_elem_vert_ensure(BMPartialUpdate *bmpinfo,
   return false;
 }
 
-BLI_INLINE bool partial_elem_edge_ensure(BMPartialUpdate *bmpinfo,
-                                         BLI_bitmap *edges_tag,
-                                         BMEdge *e)
-{
-  const int i = BM_elem_index_get(e);
-  if (!BLI_BITMAP_TEST(edges_tag, i)) {
-    BLI_BITMAP_ENABLE(edges_tag, i);
-    GROW_ARRAY_AS_NEEDED(bmpinfo->edges, bmpinfo->edges_len_alloc, bmpinfo->edges_len);
-    bmpinfo->edges[bmpinfo->edges_len++] = e;
-    return true;
-  }
-  return false;
-}
-
 BLI_INLINE bool partial_elem_face_ensure(BMPartialUpdate *bmpinfo,
                                          BLI_bitmap *faces_tag,
                                          BMFace *f)
@@ -121,17 +107,15 @@ BMPartialUpdate *BM_mesh_partial_create_from_verts(BMesh *bm,
   /* Reserve more edges than vertices since it's common for a grid topology
    * to use around twice as many edges as vertices. */
   const int default_verts_len_alloc = verts_len;
-  const int default_edges_len_alloc = min_ii(bm->totedge, verts_len * 2);
   const int default_faces_len_alloc = min_ii(bm->totface, verts_len);
 
   /* Allocate tags instead of using #BM_ELEM_TAG because the caller may already be using tags.
    * Further, walking over all geometry to clear the tags isn't so efficient. */
   BLI_bitmap *verts_tag = NULL;
-  BLI_bitmap *edges_tag = NULL;
   BLI_bitmap *faces_tag = NULL;
 
   /* Set vert inline. */
-  BM_mesh_elem_index_ensure(bm, (BM_EDGE | BM_FACE));
+  BM_mesh_elem_index_ensure(bm, BM_FACE);
 
   if (params->do_normals || params->do_tessellate) {
     /* - Extend to all vertices connected faces:
@@ -197,29 +181,12 @@ BMPartialUpdate *BM_mesh_partial_create_from_verts(BMesh *bm,
       verts_tag = BLI_BITMAP_NEW((size_t)bm->totvert, __func__);
     }
 
-    /* Edges. */
-    if (bmpinfo->edges == NULL) {
-      bmpinfo->edges_len_alloc = default_edges_len_alloc;
-      bmpinfo->edges = MEM_mallocN((sizeof(BMEdge *) * bmpinfo->edges_len_alloc), __func__);
-      edges_tag = BLI_BITMAP_NEW((size_t)bm->totedge, __func__);
-    }
-
     for (int i = 0; i < bmpinfo->faces_len; i++) {
       BMFace *f = bmpinfo->faces[i];
       BMLoop *l_iter, *l_first;
       l_iter = l_first = BM_FACE_FIRST_LOOP(f);
       do {
-        if (!partial_elem_vert_ensure(bmpinfo, verts_tag, l_iter->v)) {
-          continue;
-        }
-        BMVert *v = l_iter->v;
-        BMEdge *e_first = v->e;
-        BMEdge *e_iter = e_first;
-        do {
-          if (e_iter->l) {
-            partial_elem_edge_ensure(bmpinfo, edges_tag, e_iter);
-          }
-        } while ((e_iter = BM_DISK_EDGE_NEXT(e_iter, v)) != e_first);
+        partial_elem_vert_ensure(bmpinfo, verts_tag, l_iter->v);
       } while ((l_iter = l_iter->next) != l_first);
     }
   }
@@ -227,9 +194,6 @@ BMPartialUpdate *BM_mesh_partial_create_from_verts(BMesh *bm,
   if (verts_tag) {
     MEM_freeN(verts_tag);
   }
-  if (edges_tag) {
-    MEM_freeN(edges_tag);
-  }
   if (faces_tag) {
     MEM_freeN(faces_tag);
   }
@@ -244,9 +208,6 @@ void BM_mesh_partial_destroy(BMPartialUpdate *bmpinfo)
   if (bmpinfo->verts) {
     MEM_freeN(bmpinfo->verts);
   }
-  if (bmpinfo->edges) {
-    MEM_freeN(bmpinfo->edges);
-  }
   if (bmpinfo->faces) {
     MEM_freeN(bmpinfo->faces);
   }