BMesh: support face-normal calculation in normal & looptri functions

Support calculating face normals when tessellating. When this is done
before updating vertex normals it gives ~20% performance improvement.

Now vertex normal calculation only needs to perform a single pass on the
mesh vertices when called after tessellation.

Extended versions of normal & looptri update functions have been added:

- BM_mesh_calc_tessellation_ex
- BM_mesh_normals_update_ex

Most callers don't need to be aware of this detail by using:

- BKE_editmesh_looptri_and_normals_calc
- BKE_editmesh_looptri_and_normals_calc_with_partial

- EDBM_update also takes advantage of this,
  where calling EDBM_update with calc_looptri & calc_normals
  enabled uses the faster normal updating logic.

1 files changed, 54 insertions, 6 deletions

diff --git a/source/blender/blenkernel/intern/editmesh.c b/source/blender/blenkernel/intern/editmesh.c
index 472de1f3c77..b908df267c4 100644
--- a/source/blender/blenkernel/intern/editmesh.c
+++ b/source/blender/blenkernel/intern/editmesh.c
@@ -96,7 +96,8 @@ BMEditMesh *BKE_editmesh_from_object(Object *ob)
   return ((Mesh *)ob->data)->edit_mesh;
 }
 
-static void editmesh_tessface_calc_intern(BMEditMesh *em)
+static void editmesh_tessface_calc_intern(BMEditMesh *em,
+                                          const struct BMeshCalcTessellation_Params *params)
 {
   /* allocating space before calculating the tessellation */
 
@@ -130,12 +131,13 @@ static void editmesh_tessface_calc_intern(BMEditMesh *em)
   em->tottri = looptris_tot;
 
   /* after allocating the em->looptris, we're ready to tessellate */
-  BM_mesh_calc_tessellation(em->bm, em->looptris);
+  BM_mesh_calc_tessellation_ex(em->bm, em->looptris, params);
 }
 
-void BKE_editmesh_looptri_calc(BMEditMesh *em)
+void BKE_editmesh_looptri_calc_ex(BMEditMesh *em,
+                                  const struct BMeshCalcTessellation_Params *params)
 {
-  editmesh_tessface_calc_intern(em);
+  editmesh_tessface_calc_intern(em, params);
 
   /* commented because editbmesh_build_data() ensures we get tessfaces */
 #if 0
@@ -149,12 +151,58 @@ void BKE_editmesh_looptri_calc(BMEditMesh *em)
 #endif
 }
 
-void BKE_editmesh_looptri_calc_with_partial(BMEditMesh *em, struct BMPartialUpdate *bmpinfo)
+void BKE_editmesh_looptri_calc(BMEditMesh *em)
+{
+  BKE_editmesh_looptri_calc_ex(em,
+                               &(const struct BMeshCalcTessellation_Params){
+                                   .face_normals = false,
+                               });
+}
+
+/**
+ * Performing the face normal calculation at the same time as tessellation
+ * gives a reasonable performance boost (approx ~20% faster).
+ */
+void BKE_editmesh_looptri_and_normals_calc(BMEditMesh *em)
+{
+  BKE_editmesh_looptri_calc_ex(em,
+                               &(const struct BMeshCalcTessellation_Params){
+                                   .face_normals = true,
+                               });
+  BM_mesh_normals_update_ex(em->bm,
+                            &(const struct BMeshNormalsUpdate_Params){
+                                .face_normals = false,
+                            });
+}
+
+void BKE_editmesh_looptri_calc_with_partial_ex(BMEditMesh *em,
+                                               struct BMPartialUpdate *bmpinfo,
+                                               const struct BMeshCalcTessellation_Params *params)
 {
   BLI_assert(em->tottri == poly_to_tri_count(em->bm->totface, em->bm->totloop));
   BLI_assert(em->looptris != NULL);
 
-  BM_mesh_calc_tessellation_with_partial(em->bm, em->looptris, bmpinfo);
+  BM_mesh_calc_tessellation_with_partial_ex(em->bm, em->looptris, bmpinfo, params);
+}
+
+void BKE_editmesh_looptri_calc_with_partial(BMEditMesh *em, struct BMPartialUpdate *bmpinfo)
+{
+  BKE_editmesh_looptri_calc_with_partial_ex(em, bmpinfo, false);
+}
+
+void BKE_editmesh_looptri_and_normals_calc_with_partial(BMEditMesh *em,
+                                                        struct BMPartialUpdate *bmpinfo)
+{
+  BKE_editmesh_looptri_calc_with_partial_ex(em,
+                                            bmpinfo,
+                                            &(const struct BMeshCalcTessellation_Params){
+                                                .face_normals = true,
+                                            });
+  BM_mesh_normals_update_with_partial_ex(em->bm,
+                                         bmpinfo,
+                                         &(const struct BMeshNormalsUpdate_Params){
+                                             .face_normals = false,
+                                         });
 }
 
 void BKE_editmesh_free_derivedmesh(BMEditMesh *em)