Mesh: Remove redundant custom data pointers

For copy-on-write, we want to share attribute arrays between meshes
where possible. Mutable pointers like `Mesh.mvert` make that difficult
by making ownership vague. They also make code more complex by adding
redundancy.

The simplest solution is just removing them and retrieving layers from
`CustomData` as needed. Similar changes have already been applied to
curves and point clouds (e9f82d3dc7ee, 410a6efb747f). Removing use of
the pointers generally makes code more obvious and more reusable.

Mesh data is now accessed with a C++ API (`Mesh::edges()` or
`Mesh::edges_for_write()`), and a C API (`BKE_mesh_edges(mesh)`).

The CoW changes this commit makes possible are described in T95845
and T95842, and started in D14139 and D14140. The change also simplifies
the ongoing mesh struct-of-array refactors from T95965.

**RNA/Python Access Performance**
Theoretically, accessing mesh elements with the RNA API may become
slower, since the layer needs to be found on every random access.
However, overhead is already high enough that this doesn't make a
noticible differenc, and performance is actually improved in some
cases. Random access can be up to 10% faster, but other situations
might be a bit slower. Generally using `foreach_get/set` are the best
way to improve performance. See the differential revision for more
discussion about Python performance.

Cycles has been updated to use raw pointers and the internal Blender
mesh types, mostly because there is no sense in having this overhead
when it's already compiled with Blender. In my tests this roughly
halves the Cycles mesh creation time (0.19s to 0.10s for a 1 million
face grid).

Differential Revision: https://developer.blender.org/D15488

1 files changed, 11 insertions, 11 deletions

diff --git a/source/blender/modifiers/intern/MOD_correctivesmooth.c b/source/blender/modifiers/intern/MOD_correctivesmooth.c
index 4df0479372f..30afb993cc7 100644
--- a/source/blender/modifiers/intern/MOD_correctivesmooth.c
+++ b/source/blender/modifiers/intern/MOD_correctivesmooth.c
@@ -109,7 +109,7 @@ static void requiredDataMask(Object *UNUSED(ob),
 }
 
 /* check individual weights for changes and cache values */
-static void mesh_get_weights(MDeformVert *dvert,
+static void mesh_get_weights(const MDeformVert *dvert,
                              const int defgrp_index,
                              const uint verts_num,
                              const bool use_invert_vgroup,
@@ -131,9 +131,9 @@ static void mesh_get_weights(MDeformVert *dvert,
 
 static void mesh_get_boundaries(Mesh *mesh, float *smooth_weights)
 {
-  const MPoly *mpoly = mesh->mpoly;
-  const MLoop *mloop = mesh->mloop;
-  const MEdge *medge = mesh->medge;
+  const MEdge *medge = BKE_mesh_edges(mesh);
+  const MPoly *mpoly = BKE_mesh_polygons(mesh);
+  const MLoop *mloop = BKE_mesh_loops(mesh);
   uint mpoly_num, medge_num, i;
   ushort *boundaries;
 
@@ -178,7 +178,7 @@ static void smooth_iter__simple(CorrectiveSmoothModifierData *csmd,
   uint i;
 
   const uint edges_num = (uint)mesh->totedge;
-  const MEdge *edges = mesh->medge;
+  const MEdge *edges = BKE_mesh_edges(mesh);
   float *vertex_edge_count_div;
 
   struct SmoothingData_Simple {
@@ -255,7 +255,7 @@ static void smooth_iter__length_weight(CorrectiveSmoothModifierData *csmd,
   /* NOTE: the way this smoothing method works, its approx half as strong as the simple-smooth,
    * and 2.0 rarely spikes, double the value for consistent behavior. */
   const float lambda = csmd->lambda * 2.0f;
-  const MEdge *edges = mesh->medge;
+  const MEdge *edges = BKE_mesh_edges(mesh);
   float *vertex_edge_count;
   uint i;
 
@@ -358,7 +358,7 @@ static void smooth_iter(CorrectiveSmoothModifierData *csmd,
 
 static void smooth_verts(CorrectiveSmoothModifierData *csmd,
                          Mesh *mesh,
-                         MDeformVert *dvert,
+                         const MDeformVert *dvert,
                          const int defgrp_index,
                          float (*vertexCos)[3],
                          uint verts_num)
@@ -452,8 +452,8 @@ static void calc_tangent_spaces(Mesh *mesh, float (*vertexCos)[3], float (*r_tan
 #ifndef USE_TANGENT_CALC_INLINE
   const uint mvert_num = (uint)dm->getNumVerts(dm);
 #endif
-  const MPoly *mpoly = mesh->mpoly;
-  const MLoop *mloop = mesh->mloop;
+  const MPoly *mpoly = BKE_mesh_polygons(mesh);
+  const MLoop *mloop = BKE_mesh_loops(mesh);
   uint i;
 
   for (i = 0; i < mpoly_num; i++) {
@@ -519,7 +519,7 @@ static bool cache_settings_equal(CorrectiveSmoothModifierData *csmd)
  */
 static void calc_deltas(CorrectiveSmoothModifierData *csmd,
                         Mesh *mesh,
-                        MDeformVert *dvert,
+                        const MDeformVert *dvert,
                         const int defgrp_index,
                         const float (*rest_coords)[3],
                         uint verts_num)
@@ -579,7 +579,7 @@ static void correctivesmooth_modifier_do(ModifierData *md,
        (((ID *)ob->data)->recalc & ID_RECALC_ALL));
 
   bool use_only_smooth = (csmd->flag & MOD_CORRECTIVESMOOTH_ONLY_SMOOTH) != 0;
-  MDeformVert *dvert = NULL;
+  const MDeformVert *dvert = NULL;
   int defgrp_index;
 
   MOD_get_vgroup(ob, mesh, csmd->defgrp_name, &dvert, &defgrp_index);