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, 52 insertions, 62 deletions

diff --git a/source/blender/modifiers/intern/MOD_solidify_nonmanifold.c b/source/blender/modifiers/intern/MOD_solidify_nonmanifold.c
index 29adbd70198..0bce954a67a 100644
--- a/source/blender/modifiers/intern/MOD_solidify_nonmanifold.c
+++ b/source/blender/modifiers/intern/MOD_solidify_nonmanifold.c
@@ -76,7 +76,7 @@ static float clamp_nonzero(const float value, const float epsilon)
 /* Data structures for manifold solidify. */
 
 typedef struct NewFaceRef {
-  MPoly *face;
+  const MPoly *face;
   uint index;
   bool reversed;
   struct NewEdgeRef **link_edges;
@@ -137,10 +137,6 @@ Mesh *MOD_solidify_nonmanifold_modifyMesh(ModifierData *md,
   Mesh *result;
   const SolidifyModifierData *smd = (SolidifyModifierData *)md;
 
-  MVert *mv, *mvert, *orig_mvert;
-  MEdge *ed, *medge, *orig_medge;
-  MLoop *ml, *mloop, *orig_mloop;
-  MPoly *mp, *mpoly, *orig_mpoly;
   const uint verts_num = (uint)mesh->totvert;
   const uint edges_num = (uint)mesh->totedge;
   const uint polys_num = (uint)mesh->totpoly;
@@ -178,7 +174,7 @@ Mesh *MOD_solidify_nonmanifold_modifyMesh(ModifierData *md,
 
   const float bevel_convex = smd->bevel_convex;
 
-  MDeformVert *dvert;
+  const MDeformVert *dvert;
   const bool defgrp_invert = (smd->flag & MOD_SOLIDIFY_VGROUP_INV) != 0;
   int defgrp_index;
   const int shell_defgrp_index = BKE_id_defgroup_name_index(&mesh->id, smd->shell_defgrp_name);
@@ -188,10 +184,10 @@ Mesh *MOD_solidify_nonmanifold_modifyMesh(ModifierData *md,
 
   const bool do_flat_faces = dvert && (smd->flag & MOD_SOLIDIFY_NONMANIFOLD_FLAT_FACES);
 
-  orig_mvert = mesh->mvert;
-  orig_medge = mesh->medge;
-  orig_mloop = mesh->mloop;
-  orig_mpoly = mesh->mpoly;
+  const MVert *orig_mvert = BKE_mesh_vertices(mesh);
+  const MEdge *orig_medge = BKE_mesh_edges(mesh);
+  const MPoly *orig_mpoly = BKE_mesh_polygons(mesh);
+  const MLoop *orig_mloop = BKE_mesh_loops(mesh);
 
   uint new_verts_num = 0;
   uint new_edges_num = 0;
@@ -213,11 +209,11 @@ Mesh *MOD_solidify_nonmanifold_modifyMesh(ModifierData *md,
   uint largest_ngon = 3;
   /* Calculate face to #NewFaceRef map. */
   {
-    mp = orig_mpoly;
+    const MPoly *mp = orig_mpoly;
     for (uint i = 0; i < polys_num; i++, mp++) {
       /* Make normals for faces without area (should really be avoided though). */
       if (len_squared_v3(poly_nors[i]) < 0.5f) {
-        MEdge *e = orig_medge + orig_mloop[mp->loopstart].e;
+        const MEdge *e = orig_medge + orig_mloop[mp->loopstart].e;
         float edgedir[3];
         sub_v3_v3v3(edgedir, orig_mvert[e->v2].co, orig_mvert[e->v1].co);
         if (fabsf(edgedir[2]) < fabsf(edgedir[1])) {
@@ -254,9 +250,9 @@ Mesh *MOD_solidify_nonmanifold_modifyMesh(ModifierData *md,
       edges_num, sizeof(*edge_adj_faces_len), "edge_adj_faces_len in solidify");
   /* Count for each edge how many faces it has adjacent. */
   {
-    mp = orig_mpoly;
+    const MPoly *mp = orig_mpoly;
     for (uint i = 0; i < polys_num; i++, mp++) {
-      ml = orig_mloop + mp->loopstart;
+      const MLoop *ml = orig_mloop + mp->loopstart;
       for (uint j = 0; j < mp->totloop; j++, ml++) {
         edge_adj_faces_len[ml->e]++;
       }
@@ -304,9 +300,9 @@ Mesh *MOD_solidify_nonmanifold_modifyMesh(ModifierData *md,
 
     /* Create link_faces for edges. */
     {
-      mp = orig_mpoly;
+      const MPoly *mp = orig_mpoly;
       for (uint i = 0; i < polys_num; i++, mp++) {
-        ml = orig_mloop + mp->loopstart;
+        const MLoop *ml = orig_mloop + mp->loopstart;
         for (uint j = 0; j < mp->totloop; j++, ml++) {
           const uint edge = ml->e;
           const bool reversed = orig_medge[edge].v2 != ml->v;
@@ -353,7 +349,7 @@ Mesh *MOD_solidify_nonmanifold_modifyMesh(ModifierData *md,
       uint *combined_verts = MEM_calloc_arrayN(
           verts_num, sizeof(*combined_verts), "combined_verts in solidify");
 
-      ed = orig_medge;
+      const MEdge *ed = orig_medge;
       for (uint i = 0; i < edges_num; i++, ed++) {
         if (edge_adj_faces_len[i] > 0) {
           uint v1 = vm[ed->v1];
@@ -377,7 +373,7 @@ Mesh *MOD_solidify_nonmanifold_modifyMesh(ModifierData *md,
               if (k != i && edge_adj_faces_len[k] > 0 &&
                   (ELEM(vm[orig_medge[k].v1], v1, v2) != ELEM(vm[orig_medge[k].v2], v1, v2))) {
                 for (uint j = 0; j < edge_adj_faces[k]->faces_len && can_merge; j++) {
-                  mp = orig_mpoly + edge_adj_faces[k]->faces[j];
+                  const MPoly *mp = orig_mpoly + edge_adj_faces[k]->faces[j];
                   uint changes = 0;
                   int cur = mp->totloop - 1;
                   for (int next = 0; next < mp->totloop && changes <= 2; next++) {
@@ -473,7 +469,7 @@ Mesh *MOD_solidify_nonmanifold_modifyMesh(ModifierData *md,
 
     /* Create vert_adj_edges for verts. */
     {
-      ed = orig_medge;
+      const MEdge *ed = orig_medge;
       for (uint i = 0; i < edges_num; i++, ed++) {
         if (edge_adj_faces_len[i] > 0) {
           const uint vs[2] = {vm[ed->v1], vm[ed->v2]};
@@ -592,7 +588,7 @@ Mesh *MOD_solidify_nonmanifold_modifyMesh(ModifierData *md,
 
     /* Filter duplicate polys. */
     {
-      ed = orig_medge;
+      const MEdge *ed = orig_medge;
       /* Iterate over edges and only check the faces around an edge for duplicates
        * (performance optimization). */
       for (uint i = 0; i < edges_num; i++, ed++) {
@@ -615,7 +611,7 @@ Mesh *MOD_solidify_nonmanifold_modifyMesh(ModifierData *md,
                 /* Find first face first loop vert in second face loops. */
                 const int k_loopstart = orig_mpoly[adj_faces->faces[k]].loopstart;
                 int l;
-                ml = orig_mloop + k_loopstart;
+                const MLoop *ml = orig_mloop + k_loopstart;
                 for (l = 0; l < totloop && vm[ml->v] != j_first_v; l++, ml++) {
                   /* Pass. */
                 }
@@ -703,7 +699,7 @@ Mesh *MOD_solidify_nonmanifold_modifyMesh(ModifierData *md,
 
     /* Create #NewEdgeRef array. */
     {
-      ed = orig_medge;
+      const MEdge *ed = orig_medge;
       for (uint i = 0; i < edges_num; i++, ed++) {
         const uint v1 = vm[ed->v1];
         const uint v2 = vm[ed->v2];
@@ -848,7 +844,7 @@ Mesh *MOD_solidify_nonmanifold_modifyMesh(ModifierData *md,
             new_edges[j] = edge_data;
             for (uint k = 0; k < 2; k++) {
               if (faces[k] != NULL) {
-                ml = orig_mloop + faces[k]->face->loopstart;
+                const MLoop *ml = orig_mloop + faces[k]->face->loopstart;
                 for (int l = 0; l < faces[k]->face->totloop; l++, ml++) {
                   if (edge_adj_faces[ml->e] == edge_adj_faces[i]) {
                     if (ml->e != i && orig_edge_data_arr[ml->e] == NULL) {
@@ -1377,13 +1373,13 @@ Mesh *MOD_solidify_nonmanifold_modifyMesh(ModifierData *md,
     if (do_flat_faces) {
       face_weight = MEM_malloc_arrayN(polys_num, sizeof(*face_weight), "face_weight in solidify");
 
-      mp = orig_mpoly;
+      const MPoly *mp = orig_mpoly;
       for (uint i = 0; i < polys_num; i++, mp++) {
         float scalar_vgroup = 1.0f;
         int loopend = mp->loopstart + mp->totloop;
-        ml = orig_mloop + mp->loopstart;
+        const MLoop *ml = orig_mloop + mp->loopstart;
         for (int j = mp->loopstart; j < loopend; j++, ml++) {
-          MDeformVert *dv = &dvert[ml->v];
+          const MDeformVert *dv = &dvert[ml->v];
           if (defgrp_invert) {
             scalar_vgroup = min_ff(1.0f - BKE_defvert_find_weight(dv, defgrp_index),
                                    scalar_vgroup);
@@ -1397,7 +1393,7 @@ Mesh *MOD_solidify_nonmanifold_modifyMesh(ModifierData *md,
       }
     }
 
-    mv = orig_mvert;
+    const MVert *mv = orig_mvert;
     gs_ptr = orig_vert_groups_arr;
     for (uint i = 0; i < verts_num; i++, mv++, gs_ptr++) {
       if (*gs_ptr) {
@@ -1655,9 +1651,9 @@ Mesh *MOD_solidify_nonmanifold_modifyMesh(ModifierData *md,
 
                       if (smd->nonmanifold_offset_mode ==
                           MOD_SOLIDIFY_NONMANIFOLD_OFFSET_MODE_EVEN) {
-                        MLoop *ml_next = orig_mloop + face->face->loopstart;
-                        ml = ml_next + (face->face->totloop - 1);
-                        MLoop *ml_prev = ml - 1;
+                        const MLoop *ml_next = orig_mloop + face->face->loopstart;
+                        const MLoop *ml = ml_next + (face->face->totloop - 1);
+                        const MLoop *ml_prev = ml - 1;
                         for (int m = 0; m < face->face->totloop && vm[ml->v] != i;
                              m++, ml_next++) {
                           ml_prev = ml;
@@ -1766,7 +1762,7 @@ Mesh *MOD_solidify_nonmanifold_modifyMesh(ModifierData *md,
               float tmp[3];
               int k;
               for (k = 1; k + 1 < g->edges_len; k++, edge_ptr++) {
-                MEdge *e = orig_medge + (*edge_ptr)->old_edge;
+                const MEdge *e = orig_medge + (*edge_ptr)->old_edge;
                 sub_v3_v3v3(tmp, orig_mvert_co[vm[e->v1] == i ? e->v2 : e->v1], orig_mvert_co[i]);
                 add_v3_v3(move_nor, tmp);
               }
@@ -1781,8 +1777,8 @@ Mesh *MOD_solidify_nonmanifold_modifyMesh(ModifierData *md,
             if (!disable_boundary_fix) {
               /* Constraint normal, nor * constr_nor == 0 after this fix. */
               float constr_nor[3];
-              MEdge *e0_edge = orig_medge + g->edges[0]->old_edge;
-              MEdge *e1_edge = orig_medge + g->edges[g->edges_len - 1]->old_edge;
+              const MEdge *e0_edge = orig_medge + g->edges[0]->old_edge;
+              const MEdge *e1_edge = orig_medge + g->edges[g->edges_len - 1]->old_edge;
               float e0[3];
               float e1[3];
               sub_v3_v3v3(e0,
@@ -1831,7 +1827,7 @@ Mesh *MOD_solidify_nonmanifold_modifyMesh(ModifierData *md,
             float scalar_vgroup = 1;
             /* Use vertex group. */
             if (dvert && !do_flat_faces) {
-              MDeformVert *dv = &dvert[i];
+              const MDeformVert *dv = &dvert[i];
               if (defgrp_invert) {
                 scalar_vgroup = 1.0f - BKE_defvert_find_weight(dv, defgrp_index);
               }
@@ -1961,10 +1957,10 @@ Mesh *MOD_solidify_nonmanifold_modifyMesh(ModifierData *md,
                                              (int)(new_loops_num),
                                              (int)(new_polys_num));
 
-  mpoly = result->mpoly;
-  mloop = result->mloop;
-  medge = result->medge;
-  mvert = result->mvert;
+  MVert *mvert = BKE_mesh_vertices_for_write(result);
+  MEdge *medge = BKE_mesh_edges_for_write(result);
+  MPoly *mpoly = BKE_mesh_polygons_for_write(result);
+  MLoop *mloop = BKE_mesh_loops_for_write(result);
 
   int *origindex_edge = CustomData_get_layer(&result->edata, CD_ORIGINDEX);
   int *origindex_poly = CustomData_get_layer(&result->pdata, CD_ORIGINDEX);
@@ -1975,15 +1971,9 @@ Mesh *MOD_solidify_nonmanifold_modifyMesh(ModifierData *md,
   }
 
   /* Checks that result has dvert data. */
+  MDeformVert *dst_dvert = NULL;
   if (shell_defgrp_index != -1 || rim_defgrp_index != -1) {
-    dvert = CustomData_duplicate_referenced_layer(&result->vdata, CD_MDEFORMVERT, result->totvert);
-    /* If no vertices were ever added to an object's vgroup, dvert might be NULL. */
-    if (dvert == NULL) {
-      /* Add a valid data layer! */
-      dvert = CustomData_add_layer(
-          &result->vdata, CD_MDEFORMVERT, CD_SET_DEFAULT, NULL, result->totvert);
-    }
-    result->dvert = dvert;
+    dst_dvert = BKE_mesh_deform_verts_for_write(result);
   }
 
   /* Get vertex crease layer and ensure edge creases are active if vertex creases are found, since
@@ -2114,7 +2104,7 @@ Mesh *MOD_solidify_nonmanifold_modifyMesh(ModifierData *md,
   /* Make boundary edges/faces. */
   {
     gs_ptr = orig_vert_groups_arr;
-    mv = orig_mvert;
+    const MVert *mv = orig_mvert;
     for (uint i = 0; i < verts_num; i++, gs_ptr++, mv++) {
       EdgeGroup *gs = *gs_ptr;
       if (gs) {
@@ -2147,7 +2137,7 @@ Mesh *MOD_solidify_nonmanifold_modifyMesh(ModifierData *md,
             }
             else {
               for (uint k = 1; k < g->edges_len - 1; k++) {
-                ed = orig_medge + g->edges[k]->old_edge;
+                const MEdge *ed = orig_medge + g->edges[k]->old_edge;
                 if (ed->crease > max_crease) {
                   max_crease = ed->crease;
                 }
@@ -2279,8 +2269,8 @@ Mesh *MOD_solidify_nonmanifold_modifyMesh(ModifierData *md,
 
               for (uint k = 0; g2->valid && k < j; g2++) {
                 if ((do_rim && !g2->is_orig_closed) || (do_shell && g2->split)) {
-                  MPoly *face = g2->edges[0]->faces[0]->face;
-                  ml = orig_mloop + face->loopstart;
+                  const MPoly *face = g2->edges[0]->faces[0]->face;
+                  const MLoop *ml = orig_mloop + face->loopstart;
                   for (int l = 0; l < face->totloop; l++, ml++) {
                     if (vm[ml->v] == i) {
                       loops[k] = face->loopstart + l;
@@ -2342,7 +2332,7 @@ Mesh *MOD_solidify_nonmanifold_modifyMesh(ModifierData *md,
         }
 
         const uint orig_face_index = (*new_edges)->faces[0]->index;
-        MPoly *face = &orig_mpoly[orig_face_index];
+        const MPoly *face = (*new_edges)->faces[0]->face;
         CustomData_copy_data(
             &mesh->pdata, &result->pdata, (int)(*new_edges)->faces[0]->index, (int)poly_index, 1);
         mpoly[poly_index].loopstart = (int)loop_index;
@@ -2355,7 +2345,7 @@ Mesh *MOD_solidify_nonmanifold_modifyMesh(ModifierData *md,
 
         int loop1 = -1;
         int loop2 = -1;
-        ml = orig_mloop + face->loopstart;
+        const MLoop *ml = orig_mloop + face->loopstart;
         const uint old_v1 = vm[orig_medge[edge1->old_edge].v1];
         const uint old_v2 = vm[orig_medge[edge1->old_edge].v2];
         for (uint j = 0; j < face->totloop; j++, ml++) {
@@ -2371,7 +2361,7 @@ Mesh *MOD_solidify_nonmanifold_modifyMesh(ModifierData *md,
         uint open_face_edge_index;
         if (!do_flip) {
           if (rim_defgrp_index != -1) {
-            BKE_defvert_ensure_index(&result->dvert[medge[edge1->new_edge].v1], rim_defgrp_index)
+            BKE_defvert_ensure_index(&dst_dvert[medge[edge1->new_edge].v1], rim_defgrp_index)
                 ->weight = 1.0f;
           }
           CustomData_copy_data(&mesh->ldata, &result->ldata, loop1, (int)loop_index, 1);
@@ -2381,7 +2371,7 @@ Mesh *MOD_solidify_nonmanifold_modifyMesh(ModifierData *md,
           if (!v2_singularity) {
             open_face_edge_index = edge1->link_edge_groups[1]->open_face_edge;
             if (rim_defgrp_index != -1) {
-              BKE_defvert_ensure_index(&result->dvert[medge[edge1->new_edge].v2], rim_defgrp_index)
+              BKE_defvert_ensure_index(&dst_dvert[medge[edge1->new_edge].v2], rim_defgrp_index)
                   ->weight = 1.0f;
             }
             CustomData_copy_data(&mesh->ldata, &result->ldata, loop2, (int)loop_index, 1);
@@ -2396,7 +2386,7 @@ Mesh *MOD_solidify_nonmanifold_modifyMesh(ModifierData *md,
           }
 
           if (rim_defgrp_index != -1) {
-            BKE_defvert_ensure_index(&result->dvert[medge[edge2->new_edge].v2], rim_defgrp_index)
+            BKE_defvert_ensure_index(&dst_dvert[medge[edge2->new_edge].v2], rim_defgrp_index)
                 ->weight = 1.0f;
           }
           CustomData_copy_data(&mesh->ldata, &result->ldata, loop2, (int)loop_index, 1);
@@ -2406,7 +2396,7 @@ Mesh *MOD_solidify_nonmanifold_modifyMesh(ModifierData *md,
           if (!v1_singularity) {
             open_face_edge_index = edge2->link_edge_groups[0]->open_face_edge;
             if (rim_defgrp_index != -1) {
-              BKE_defvert_ensure_index(&result->dvert[medge[edge2->new_edge].v1], rim_defgrp_index)
+              BKE_defvert_ensure_index(&dst_dvert[medge[edge2->new_edge].v1], rim_defgrp_index)
                   ->weight = 1.0f;
             }
             CustomData_copy_data(&mesh->ldata, &result->ldata, loop1, (int)loop_index, 1);
@@ -2424,7 +2414,7 @@ Mesh *MOD_solidify_nonmanifold_modifyMesh(ModifierData *md,
           if (!v1_singularity) {
             open_face_edge_index = edge1->link_edge_groups[0]->open_face_edge;
             if (rim_defgrp_index != -1) {
-              BKE_defvert_ensure_index(&result->dvert[medge[edge1->new_edge].v1], rim_defgrp_index)
+              BKE_defvert_ensure_index(&dst_dvert[medge[edge1->new_edge].v1], rim_defgrp_index)
                   ->weight = 1.0f;
             }
             CustomData_copy_data(&mesh->ldata, &result->ldata, loop1, (int)loop_index, 1);
@@ -2439,7 +2429,7 @@ Mesh *MOD_solidify_nonmanifold_modifyMesh(ModifierData *md,
           }
 
           if (rim_defgrp_index != -1) {
-            BKE_defvert_ensure_index(&result->dvert[medge[edge2->new_edge].v1], rim_defgrp_index)
+            BKE_defvert_ensure_index(&dst_dvert[medge[edge2->new_edge].v1], rim_defgrp_index)
                 ->weight = 1.0f;
           }
           CustomData_copy_data(&mesh->ldata, &result->ldata, loop1, (int)loop_index, 1);
@@ -2449,7 +2439,7 @@ Mesh *MOD_solidify_nonmanifold_modifyMesh(ModifierData *md,
           if (!v2_singularity) {
             open_face_edge_index = edge2->link_edge_groups[1]->open_face_edge;
             if (rim_defgrp_index != -1) {
-              BKE_defvert_ensure_index(&result->dvert[medge[edge2->new_edge].v2], rim_defgrp_index)
+              BKE_defvert_ensure_index(&dst_dvert[medge[edge2->new_edge].v2], rim_defgrp_index)
                   ->weight = 1.0f;
             }
             CustomData_copy_data(&mesh->ldata, &result->ldata, loop2, (int)loop_index, 1);
@@ -2464,7 +2454,7 @@ Mesh *MOD_solidify_nonmanifold_modifyMesh(ModifierData *md,
           }
 
           if (rim_defgrp_index != -1) {
-            BKE_defvert_ensure_index(&result->dvert[medge[edge1->new_edge].v2], rim_defgrp_index)
+            BKE_defvert_ensure_index(&dst_dvert[medge[edge1->new_edge].v2], rim_defgrp_index)
                 ->weight = 1.0f;
           }
           CustomData_copy_data(&mesh->ldata, &result->ldata, loop2, (int)loop_index, 1);
@@ -2547,8 +2537,8 @@ Mesh *MOD_solidify_nonmanifold_modifyMesh(ModifierData *md,
           if (fr->reversed != do_flip) {
             for (int l = (int)k - 1; l >= 0; l--) {
               if (shell_defgrp_index != -1) {
-                BKE_defvert_ensure_index(&result->dvert[face_verts[l]], shell_defgrp_index)
-                    ->weight = 1.0f;
+                BKE_defvert_ensure_index(&dst_dvert[face_verts[l]], shell_defgrp_index)->weight =
+                    1.0f;
               }
               CustomData_copy_data(
                   &mesh->ldata, &result->ldata, (int)face_loops[l], (int)loop_index, 1);