Merge branch 'master' into soc-2021-uv-edge-select-support

1 files changed, 2271 insertions, 0 deletions

diff --git a/source/blender/blenkernel/intern/mesh.cc b/source/blender/blenkernel/intern/mesh.cc
new file mode 100644
index 00000000000..73e0c2cfa74
--- /dev/null
+++ b/source/blender/blenkernel/intern/mesh.cc
@@ -0,0 +1,2271 @@
+/*
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ * The Original Code is Copyright (C) 2001-2002 by NaN Holding BV.
+ * All rights reserved.
+ */
+
+/** \file
+ * \ingroup bke
+ */
+
+#include "MEM_guardedalloc.h"
+
+/* Allow using deprecated functionality for .blend file I/O. */
+#define DNA_DEPRECATED_ALLOW
+
+#include "DNA_defaults.h"
+#include "DNA_key_types.h"
+#include "DNA_material_types.h"
+#include "DNA_mesh_types.h"
+#include "DNA_meshdata_types.h"
+#include "DNA_object_types.h"
+
+#include "BLI_bitmap.h"
+#include "BLI_edgehash.h"
+#include "BLI_endian_switch.h"
+#include "BLI_ghash.h"
+#include "BLI_hash.h"
+#include "BLI_linklist.h"
+#include "BLI_listbase.h"
+#include "BLI_math.h"
+#include "BLI_memarena.h"
+#include "BLI_string.h"
+#include "BLI_utildefines.h"
+
+#include "BLT_translation.h"
+
+#include "BKE_anim_data.h"
+#include "BKE_deform.h"
+#include "BKE_editmesh.h"
+#include "BKE_global.h"
+#include "BKE_idtype.h"
+#include "BKE_key.h"
+#include "BKE_lib_id.h"
+#include "BKE_lib_query.h"
+#include "BKE_main.h"
+#include "BKE_material.h"
+#include "BKE_mesh.h"
+#include "BKE_mesh_runtime.h"
+#include "BKE_mesh_wrapper.h"
+#include "BKE_modifier.h"
+#include "BKE_multires.h"
+#include "BKE_object.h"
+
+#include "PIL_time.h"
+
+#include "DEG_depsgraph.h"
+#include "DEG_depsgraph_query.h"
+
+#include "BLO_read_write.h"
+
+static void mesh_clear_geometry(Mesh *mesh);
+static void mesh_tessface_clear_intern(Mesh *mesh, int free_customdata);
+
+static void mesh_init_data(ID *id)
+{
+  Mesh *mesh = (Mesh *)id;
+
+  BLI_assert(MEMCMP_STRUCT_AFTER_IS_ZERO(mesh, id));
+
+  MEMCPY_STRUCT_AFTER(mesh, DNA_struct_default_get(Mesh), id);
+
+  CustomData_reset(&mesh->vdata);
+  CustomData_reset(&mesh->edata);
+  CustomData_reset(&mesh->fdata);
+  CustomData_reset(&mesh->pdata);
+  CustomData_reset(&mesh->ldata);
+
+  BKE_mesh_runtime_init_data(mesh);
+
+  mesh->face_sets_color_seed = BLI_hash_int(PIL_check_seconds_timer_i() & UINT_MAX);
+}
+
+static void mesh_copy_data(Main *bmain, ID *id_dst, const ID *id_src, const int flag)
+{
+  Mesh *mesh_dst = (Mesh *)id_dst;
+  const Mesh *mesh_src = (const Mesh *)id_src;
+
+  BKE_mesh_runtime_reset_on_copy(mesh_dst, flag);
+  if ((mesh_src->id.tag & LIB_TAG_NO_MAIN) == 0) {
+    /* This is a direct copy of a main mesh, so for now it has the same topology. */
+    mesh_dst->runtime.deformed_only = true;
+  }
+  /* This option is set for run-time meshes that have been copied from the current objects mode.
+   * Currently this is used for edit-mesh although it could be used for sculpt or other
+   * kinds of data specific to an objects mode.
+   *
+   * The flag signals that the mesh hasn't been modified from the data that generated it,
+   * allowing us to use the object-mode data for drawing.
+   *
+   * While this could be the callers responsibility, keep here since it's
+   * highly unlikely we want to create a duplicate and not use it for drawing. */
+  mesh_dst->runtime.is_original = false;
+
+  /* Only do tessface if we have no polys. */
+  const bool do_tessface = ((mesh_src->totface != 0) && (mesh_src->totpoly == 0));
+
+  CustomData_MeshMasks mask = CD_MASK_MESH;
+
+  if (mesh_src->id.tag & LIB_TAG_NO_MAIN) {
+    /* For copies in depsgraph, keep data like origindex and orco. */
+    CustomData_MeshMasks_update(&mask, &CD_MASK_DERIVEDMESH);
+  }
+
+  mesh_dst->mat = (Material **)MEM_dupallocN(mesh_src->mat);
+
+  BKE_defgroup_copy_list(&mesh_dst->vertex_group_names, &mesh_src->vertex_group_names);
+
+  const eCDAllocType alloc_type = (flag & LIB_ID_COPY_CD_REFERENCE) ? CD_REFERENCE : CD_DUPLICATE;
+  CustomData_copy(&mesh_src->vdata, &mesh_dst->vdata, mask.vmask, alloc_type, mesh_dst->totvert);
+  CustomData_copy(&mesh_src->edata, &mesh_dst->edata, mask.emask, alloc_type, mesh_dst->totedge);
+  CustomData_copy(&mesh_src->ldata, &mesh_dst->ldata, mask.lmask, alloc_type, mesh_dst->totloop);
+  CustomData_copy(&mesh_src->pdata, &mesh_dst->pdata, mask.pmask, alloc_type, mesh_dst->totpoly);
+  if (do_tessface) {
+    CustomData_copy(&mesh_src->fdata, &mesh_dst->fdata, mask.fmask, alloc_type, mesh_dst->totface);
+  }
+  else {
+    mesh_tessface_clear_intern(mesh_dst, false);
+  }
+
+  BKE_mesh_update_customdata_pointers(mesh_dst, do_tessface);
+
+  mesh_dst->edit_mesh = nullptr;
+
+  mesh_dst->mselect = (MSelect *)MEM_dupallocN(mesh_dst->mselect);
+
+  /* TODO: Do we want to add flag to prevent this? */
+  if (mesh_src->key && (flag & LIB_ID_COPY_SHAPEKEY)) {
+    BKE_id_copy_ex(bmain, &mesh_src->key->id, (ID **)&mesh_dst->key, flag);
+    /* XXX This is not nice, we need to make BKE_id_copy_ex fully re-entrant... */
+    mesh_dst->key->from = &mesh_dst->id;
+  }
+}
+
+static void mesh_free_data(ID *id)
+{
+  Mesh *mesh = (Mesh *)id;
+
+  BLI_freelistN(&mesh->vertex_group_names);
+
+  if (mesh->edit_mesh) {
+    if (mesh->edit_mesh->is_shallow_copy == false) {
+      BKE_editmesh_free_data(mesh->edit_mesh);
+    }
+    MEM_freeN(mesh->edit_mesh);
+    mesh->edit_mesh = nullptr;
+  }
+
+  BKE_mesh_runtime_free_data(mesh);
+  mesh_clear_geometry(mesh);
+  MEM_SAFE_FREE(mesh->mat);
+}
+
+static void mesh_foreach_id(ID *id, LibraryForeachIDData *data)
+{
+  Mesh *mesh = (Mesh *)id;
+  BKE_LIB_FOREACHID_PROCESS_IDSUPER(data, mesh->texcomesh, IDWALK_CB_NEVER_SELF);
+  BKE_LIB_FOREACHID_PROCESS_IDSUPER(data, mesh->key, IDWALK_CB_USER);
+  for (int i = 0; i < mesh->totcol; i++) {
+    BKE_LIB_FOREACHID_PROCESS_IDSUPER(data, mesh->mat[i], IDWALK_CB_USER);
+  }
+}
+
+static void mesh_blend_write(BlendWriter *writer, ID *id, const void *id_address)
+{
+  Mesh *mesh = (Mesh *)id;
+  const bool is_undo = BLO_write_is_undo(writer);
+
+  CustomDataLayer *vlayers = nullptr, vlayers_buff[CD_TEMP_CHUNK_SIZE];
+  CustomDataLayer *elayers = nullptr, elayers_buff[CD_TEMP_CHUNK_SIZE];
+  CustomDataLayer *flayers = nullptr, flayers_buff[CD_TEMP_CHUNK_SIZE];
+  CustomDataLayer *llayers = nullptr, llayers_buff[CD_TEMP_CHUNK_SIZE];
+  CustomDataLayer *players = nullptr, players_buff[CD_TEMP_CHUNK_SIZE];
+
+  /* cache only - don't write */
+  mesh->mface = nullptr;
+  mesh->totface = 0;
+  memset(&mesh->fdata, 0, sizeof(mesh->fdata));
+  memset(&mesh->runtime, 0, sizeof(mesh->runtime));
+  flayers = flayers_buff;
+
+  /* Do not store actual geometry data in case this is a library override ID. */
+  if (ID_IS_OVERRIDE_LIBRARY(mesh) && !is_undo) {
+    mesh->mvert = nullptr;
+    mesh->totvert = 0;
+    memset(&mesh->vdata, 0, sizeof(mesh->vdata));
+    vlayers = vlayers_buff;
+
+    mesh->medge = nullptr;
+    mesh->totedge = 0;
+    memset(&mesh->edata, 0, sizeof(mesh->edata));
+    elayers = elayers_buff;
+
+    mesh->mloop = nullptr;
+    mesh->totloop = 0;
+    memset(&mesh->ldata, 0, sizeof(mesh->ldata));
+    llayers = llayers_buff;
+
+    mesh->mpoly = nullptr;
+    mesh->totpoly = 0;
+    memset(&mesh->pdata, 0, sizeof(mesh->pdata));
+    players = players_buff;
+  }
+  else {
+    CustomData_blend_write_prepare(&mesh->vdata, &vlayers, vlayers_buff, ARRAY_SIZE(vlayers_buff));
+    CustomData_blend_write_prepare(&mesh->edata, &elayers, elayers_buff, ARRAY_SIZE(elayers_buff));
+    CustomData_blend_write_prepare(&mesh->ldata, &llayers, llayers_buff, ARRAY_SIZE(llayers_buff));
+    CustomData_blend_write_prepare(&mesh->pdata, &players, players_buff, ARRAY_SIZE(players_buff));
+  }
+
+  BLO_write_id_struct(writer, Mesh, id_address, &mesh->id);
+  BKE_id_blend_write(writer, &mesh->id);
+
+  /* direct data */
+  if (mesh->adt) {
+    BKE_animdata_blend_write(writer, mesh->adt);
+  }
+
+  BKE_defbase_blend_write(writer, &mesh->vertex_group_names);
+
+  BLO_write_pointer_array(writer, mesh->totcol, mesh->mat);
+  BLO_write_raw(writer, sizeof(MSelect) * mesh->totselect, mesh->mselect);
+
+  CustomData_blend_write(
+      writer, &mesh->vdata, vlayers, mesh->totvert, CD_MASK_MESH.vmask, &mesh->id);
+  CustomData_blend_write(
+      writer, &mesh->edata, elayers, mesh->totedge, CD_MASK_MESH.emask, &mesh->id);
+  /* fdata is really a dummy - written so slots align */
+  CustomData_blend_write(
+      writer, &mesh->fdata, flayers, mesh->totface, CD_MASK_MESH.fmask, &mesh->id);
+  CustomData_blend_write(
+      writer, &mesh->ldata, llayers, mesh->totloop, CD_MASK_MESH.lmask, &mesh->id);
+  CustomData_blend_write(
+      writer, &mesh->pdata, players, mesh->totpoly, CD_MASK_MESH.pmask, &mesh->id);
+
+  /* Free temporary data */
+
+  /* Free custom-data layers, when not assigned a buffer value. */
+#define CD_LAYERS_FREE(id) \
+  if (id && id != id##_buff) { \
+    MEM_freeN(id); \
+  } \
+  ((void)0)
+
+  CD_LAYERS_FREE(vlayers);
+  CD_LAYERS_FREE(elayers);
+  // CD_LAYER_FREE(flayers); /* Never allocated. */
+  CD_LAYERS_FREE(llayers);
+  CD_LAYERS_FREE(players);
+
+#undef CD_LAYERS_FREE
+}
+
+static void mesh_blend_read_data(BlendDataReader *reader, ID *id)
+{
+  Mesh *mesh = (Mesh *)id;
+  BLO_read_pointer_array(reader, (void **)&mesh->mat);
+
+  BLO_read_data_address(reader, &mesh->mvert);
+  BLO_read_data_address(reader, &mesh->medge);
+  BLO_read_data_address(reader, &mesh->mface);
+  BLO_read_data_address(reader, &mesh->mloop);
+  BLO_read_data_address(reader, &mesh->mpoly);
+  BLO_read_data_address(reader, &mesh->tface);
+  BLO_read_data_address(reader, &mesh->mtface);
+  BLO_read_data_address(reader, &mesh->mcol);
+  BLO_read_data_address(reader, &mesh->dvert);
+  BLO_read_data_address(reader, &mesh->mloopcol);
+  BLO_read_data_address(reader, &mesh->mloopuv);
+  BLO_read_data_address(reader, &mesh->mselect);
+
+  /* animdata */
+  BLO_read_data_address(reader, &mesh->adt);
+  BKE_animdata_blend_read_data(reader, mesh->adt);
+
+  /* Normally BKE_defvert_blend_read should be called in CustomData_blend_read,
+   * but for backwards compatibility in do_versions to work we do it here. */
+  BKE_defvert_blend_read(reader, mesh->totvert, mesh->dvert);
+  BLO_read_list(reader, &mesh->vertex_group_names);
+
+  CustomData_blend_read(reader, &mesh->vdata, mesh->totvert);
+  CustomData_blend_read(reader, &mesh->edata, mesh->totedge);
+  CustomData_blend_read(reader, &mesh->fdata, mesh->totface);
+  CustomData_blend_read(reader, &mesh->ldata, mesh->totloop);
+  CustomData_blend_read(reader, &mesh->pdata, mesh->totpoly);
+
+  mesh->texflag &= ~ME_AUTOSPACE_EVALUATED;
+  mesh->edit_mesh = nullptr;
+
+  memset(&mesh->runtime, 0, sizeof(mesh->runtime));
+  BKE_mesh_runtime_init_data(mesh);
+
+  /* happens with old files */
+  if (mesh->mselect == nullptr) {
+    mesh->totselect = 0;
+  }
+
+  if (BLO_read_requires_endian_switch(reader) && mesh->tface) {
+    TFace *tf = mesh->tface;
+    for (int i = 0; i < mesh->totface; i++, tf++) {
+      BLI_endian_switch_uint32_array(tf->col, 4);
+    }
+  }
+}
+
+static void mesh_blend_read_lib(BlendLibReader *reader, ID *id)
+{
+  Mesh *me = (Mesh *)id;
+  /* this check added for python created meshes */
+  if (me->mat) {
+    for (int i = 0; i < me->totcol; i++) {
+      BLO_read_id_address(reader, me->id.lib, &me->mat[i]);
+    }
+  }
+  else {
+    me->totcol = 0;
+  }
+
+  BLO_read_id_address(reader, me->id.lib, &me->ipo);  // XXX: deprecated: old anim sys
+  BLO_read_id_address(reader, me->id.lib, &me->key);
+  BLO_read_id_address(reader, me->id.lib, &me->texcomesh);
+}
+
+static void mesh_read_expand(BlendExpander *expander, ID *id)
+{
+  Mesh *me = (Mesh *)id;
+  for (int a = 0; a < me->totcol; a++) {
+    BLO_expand(expander, me->mat[a]);
+  }
+
+  BLO_expand(expander, me->key);
+  BLO_expand(expander, me->texcomesh);
+}
+
+IDTypeInfo IDType_ID_ME = {
+    ID_ME,
+    FILTER_ID_ME,
+    INDEX_ID_ME,
+    sizeof(Mesh),
+    "Mesh",
+    "meshes",
+    BLT_I18NCONTEXT_ID_MESH,
+    IDTYPE_FLAGS_APPEND_IS_REUSABLE,
+
+    mesh_init_data,
+    mesh_copy_data,
+    mesh_free_data,
+    nullptr,
+    mesh_foreach_id,
+    nullptr,
+    nullptr,
+    mesh_blend_write,
+    mesh_blend_read_data,
+    mesh_blend_read_lib,
+    mesh_read_expand,
+    nullptr,
+    nullptr,
+};
+
+enum {
+  MESHCMP_DVERT_WEIGHTMISMATCH = 1,
+  MESHCMP_DVERT_GROUPMISMATCH,
+  MESHCMP_DVERT_TOTGROUPMISMATCH,
+  MESHCMP_LOOPCOLMISMATCH,
+  MESHCMP_LOOPUVMISMATCH,
+  MESHCMP_LOOPMISMATCH,
+  MESHCMP_POLYVERTMISMATCH,
+  MESHCMP_POLYMISMATCH,
+  MESHCMP_EDGEUNKNOWN,
+  MESHCMP_VERTCOMISMATCH,
+  MESHCMP_CDLAYERS_MISMATCH,
+  MESHCMP_ATTRIBUTE_VALUE_MISMATCH,
+};
+
+static const char *cmpcode_to_str(int code)
+{
+  switch (code) {
+    case MESHCMP_DVERT_WEIGHTMISMATCH:
+      return "Vertex Weight Mismatch";
+    case MESHCMP_DVERT_GROUPMISMATCH:
+      return "Vertex Group Mismatch";
+    case MESHCMP_DVERT_TOTGROUPMISMATCH:
+      return "Vertex Doesn't Belong To Same Number Of Groups";
+    case MESHCMP_LOOPCOLMISMATCH:
+      return "Vertex Color Mismatch";
+    case MESHCMP_LOOPUVMISMATCH:
+      return "UV Mismatch";
+    case MESHCMP_LOOPMISMATCH:
+      return "Loop Mismatch";
+    case MESHCMP_POLYVERTMISMATCH:
+      return "Loop Vert Mismatch In Poly Test";
+    case MESHCMP_POLYMISMATCH:
+      return "Loop Vert Mismatch";
+    case MESHCMP_EDGEUNKNOWN:
+      return "Edge Mismatch";
+    case MESHCMP_VERTCOMISMATCH:
+      return "Vertex Coordinate Mismatch";
+    case MESHCMP_CDLAYERS_MISMATCH:
+      return "CustomData Layer Count Mismatch";
+    case MESHCMP_ATTRIBUTE_VALUE_MISMATCH:
+      return "Attribute Value Mismatch";
+    default:
+      return "Mesh Comparison Code Unknown";
+  }
+}
+
+/** Thresh is threshold for comparing vertices, UV's, vertex colors, weights, etc. */
+static int customdata_compare(
+    CustomData *c1, CustomData *c2, const int total_length, Mesh *m1, Mesh *m2, const float thresh)
+{
+  const float thresh_sq = thresh * thresh;
+  CustomDataLayer *l1, *l2;
+  int layer_count1 = 0, layer_count2 = 0, j;
+  const uint64_t cd_mask_non_generic = CD_MASK_MVERT | CD_MASK_MEDGE | CD_MASK_MPOLY |
+                                       CD_MASK_MLOOPUV | CD_MASK_MLOOPCOL | CD_MASK_MDEFORMVERT;
+  const uint64_t cd_mask_all_attr = CD_MASK_PROP_ALL | cd_mask_non_generic;
+
+  for (int i = 0; i < c1->totlayer; i++) {
+    if (CD_TYPE_AS_MASK(c1->layers[i].type) & cd_mask_all_attr) {
+      layer_count1++;
+    }
+  }
+
+  for (int i = 0; i < c2->totlayer; i++) {
+    if (CD_TYPE_AS_MASK(c2->layers[i].type) & cd_mask_all_attr) {
+      layer_count2++;
+    }
+  }
+
+  if (layer_count1 != layer_count2) {
+    return MESHCMP_CDLAYERS_MISMATCH;
+  }
+
+  l1 = c1->layers;
+  l2 = c2->layers;
+
+  for (int i1 = 0; i1 < c1->totlayer; i1++) {
+    l1 = c1->layers + i1;
+    for (int i2 = 0; i2 < c2->totlayer; i2++) {
+      l2 = c2->layers + i2;
+      if (l1->type != l2->type || !STREQ(l1->name, l2->name)) {
+        continue;
+      }
+      /* At this point `l1` and `l2` have the same name and type, so they should be compared. */
+
+      switch (l1->type) {
+
+        case CD_MVERT: {
+          MVert *v1 = (MVert *)l1->data;
+          MVert *v2 = (MVert *)l2->data;
+          int vtot = m1->totvert;
+
+          for (j = 0; j < vtot; j++, v1++, v2++) {
+            for (int k = 0; k < 3; k++) {
+              if (compare_threshold_relative(v1->co[k], v2->co[k], thresh)) {
+                return MESHCMP_VERTCOMISMATCH;
+              }
+            }
+            /* I don't care about normals, let's just do coordinates. */
+          }
+          break;
+        }
+
+        /* We're order-agnostic for edges here. */
+        case CD_MEDGE: {
+          MEdge *e1 = (MEdge *)l1->data;
+          MEdge *e2 = (MEdge *)l2->data;
+          int etot = m1->totedge;
+          EdgeHash *eh = BLI_edgehash_new_ex(__func__, etot);
+
+          for (j = 0; j < etot; j++, e1++) {
+            BLI_edgehash_insert(eh, e1->v1, e1->v2, e1);
+          }
+
+          for (j = 0; j < etot; j++, e2++) {
+            if (!BLI_edgehash_lookup(eh, e2->v1, e2->v2)) {
+              return MESHCMP_EDGEUNKNOWN;
+            }
+          }
+          BLI_edgehash_free(eh, nullptr);
+          break;
+        }
+        case CD_MPOLY: {
+          MPoly *p1 = (MPoly *)l1->data;
+          MPoly *p2 = (MPoly *)l2->data;
+          int ptot = m1->totpoly;
+
+          for (j = 0; j < ptot; j++, p1++, p2++) {
+            MLoop *lp1, *lp2;
+            int k;
+
+            if (p1->totloop != p2->totloop) {
+              return MESHCMP_POLYMISMATCH;
+            }
+
+            lp1 = m1->mloop + p1->loopstart;
+            lp2 = m2->mloop + p2->loopstart;
+
+            for (k = 0; k < p1->totloop; k++, lp1++, lp2++) {
+              if (lp1->v != lp2->v) {
+                return MESHCMP_POLYVERTMISMATCH;
+              }
+            }
+          }
+          break;
+        }
+        case CD_MLOOP: {
+          MLoop *lp1 = (MLoop *)l1->data;
+          MLoop *lp2 = (MLoop *)l2->data;
+          int ltot = m1->totloop;
+
+          for (j = 0; j < ltot; j++, lp1++, lp2++) {
+            if (lp1->v != lp2->v) {
+              return MESHCMP_LOOPMISMATCH;
+            }
+          }
+          break;
+        }
+        case CD_MLOOPUV: {
+          MLoopUV *lp1 = (MLoopUV *)l1->data;
+          MLoopUV *lp2 = (MLoopUV *)l2->data;
+          int ltot = m1->totloop;
+
+          for (j = 0; j < ltot; j++, lp1++, lp2++) {
+            if (len_squared_v2v2(lp1->uv, lp2->uv) > thresh_sq) {
+              return MESHCMP_LOOPUVMISMATCH;
+            }
+          }
+          break;
+        }
+        case CD_MLOOPCOL: {
+          MLoopCol *lp1 = (MLoopCol *)l1->data;
+          MLoopCol *lp2 = (MLoopCol *)l2->data;
+          int ltot = m1->totloop;
+
+          for (j = 0; j < ltot; j++, lp1++, lp2++) {
+            if (lp1->r != lp2->r || lp1->g != lp2->g || lp1->b != lp2->b || lp1->a != lp2->a) {
+              return MESHCMP_LOOPCOLMISMATCH;
+            }
+          }
+          break;
+        }
+        case CD_MDEFORMVERT: {
+          MDeformVert *dv1 = (MDeformVert *)l1->data;
+          MDeformVert *dv2 = (MDeformVert *)l2->data;
+          int dvtot = m1->totvert;
+
+          for (j = 0; j < dvtot; j++, dv1++, dv2++) {
+            int k;
+            MDeformWeight *dw1 = dv1->dw, *dw2 = dv2->dw;
+
+            if (dv1->totweight != dv2->totweight) {
+              return MESHCMP_DVERT_TOTGROUPMISMATCH;
+            }
+
+            for (k = 0; k < dv1->totweight; k++, dw1++, dw2++) {
+              if (dw1->def_nr != dw2->def_nr) {
+                return MESHCMP_DVERT_GROUPMISMATCH;
+              }
+              if (fabsf(dw1->weight - dw2->weight) > thresh) {
+                return MESHCMP_DVERT_WEIGHTMISMATCH;
+              }
+            }
+          }
+          break;
+        }
+        case CD_PROP_FLOAT: {
+          const float *l1_data = (float *)l1->data;
+          const float *l2_data = (float *)l2->data;
+
+          for (int i = 0; i < total_length; i++) {
+            if (compare_threshold_relative(l1_data[i], l2_data[i], thresh)) {
+              return MESHCMP_ATTRIBUTE_VALUE_MISMATCH;
+            }
+          }
+          break;
+        }
+        case CD_PROP_FLOAT2: {
+          const float(*l1_data)[2] = (float(*)[2])l1->data;
+          const float(*l2_data)[2] = (float(*)[2])l2->data;
+
+          for (int i = 0; i < total_length; i++) {
+            if (compare_threshold_relative(l1_data[i][0], l2_data[i][0], thresh)) {
+              return MESHCMP_ATTRIBUTE_VALUE_MISMATCH;
+            }
+            if (compare_threshold_relative(l1_data[i][1], l2_data[i][1], thresh)) {
+              return MESHCMP_ATTRIBUTE_VALUE_MISMATCH;
+            }
+          }
+          break;
+        }
+        case CD_PROP_FLOAT3: {
+          const float(*l1_data)[3] = (float(*)[3])l1->data;
+          const float(*l2_data)[3] = (float(*)[3])l2->data;
+
+          for (int i = 0; i < total_length; i++) {
+            if (compare_threshold_relative(l1_data[i][0], l2_data[i][0], thresh)) {
+              return MESHCMP_ATTRIBUTE_VALUE_MISMATCH;
+            }
+            if (compare_threshold_relative(l1_data[i][1], l2_data[i][1], thresh)) {
+              return MESHCMP_ATTRIBUTE_VALUE_MISMATCH;
+            }
+            if (compare_threshold_relative(l1_data[i][2], l2_data[i][2], thresh)) {
+              return MESHCMP_ATTRIBUTE_VALUE_MISMATCH;
+            }
+          }
+          break;
+        }
+        case CD_PROP_INT32: {
+          const int *l1_data = (int *)l1->data;
+          const int *l2_data = (int *)l2->data;
+
+          for (int i = 0; i < total_length; i++) {
+            if (l1_data[i] != l2_data[i]) {
+              return MESHCMP_ATTRIBUTE_VALUE_MISMATCH;
+            }
+          }
+          break;
+        }
+        case CD_PROP_BOOL: {
+          const bool *l1_data = (bool *)l1->data;
+          const bool *l2_data = (bool *)l2->data;
+
+          for (int i = 0; i < total_length; i++) {
+            if (l1_data[i] != l2_data[i]) {
+              return MESHCMP_ATTRIBUTE_VALUE_MISMATCH;
+            }
+          }
+          break;
+        }
+        case CD_PROP_COLOR: {
+          const MPropCol *l1_data = (MPropCol *)l1->data;
+          const MPropCol *l2_data = (MPropCol *)l2->data;
+
+          for (int i = 0; i < total_length; i++) {
+            for (j = 0; j < 4; j++) {
+              if (compare_threshold_relative(l1_data[i].color[j], l2_data[i].color[j], thresh)) {
+                return MESHCMP_ATTRIBUTE_VALUE_MISMATCH;
+              }
+            }
+          }
+          break;
+        }
+        default: {
+          break;
+        }
+      }
+    }
+  }
+
+  return 0;
+}
+
+/**
+ * Used for unit testing; compares two meshes, checking only
+ * differences we care about.  should be usable with leaf's
+ * testing framework I get RNA work done, will use hackish
+ * testing code for now.
+ */
+const char *BKE_mesh_cmp(Mesh *me1, Mesh *me2, float thresh)
+{
+  int c;
+
+  if (!me1 || !me2) {
+    return "Requires two input meshes";
+  }
+
+  if (me1->totvert != me2->totvert) {
+    return "Number of verts don't match";
+  }
+
+  if (me1->totedge != me2->totedge) {
+    return "Number of edges don't match";
+  }
+
+  if (me1->totpoly != me2->totpoly) {
+    return "Number of faces don't match";
+  }
+
+  if (me1->totloop != me2->totloop) {
+    return "Number of loops don't match";
+  }
+
+  if ((c = customdata_compare(&me1->vdata, &me2->vdata, me1->totvert, me1, me2, thresh))) {
+    return cmpcode_to_str(c);
+  }
+
+  if ((c = customdata_compare(&me1->edata, &me2->edata, me1->totedge, me1, me2, thresh))) {
+    return cmpcode_to_str(c);
+  }
+
+  if ((c = customdata_compare(&me1->ldata, &me2->ldata, me1->totloop, me1, me2, thresh))) {
+    return cmpcode_to_str(c);
+  }
+
+  if ((c = customdata_compare(&me1->pdata, &me2->pdata, me1->totpoly, me1, me2, thresh))) {
+    return cmpcode_to_str(c);
+  }
+
+  return nullptr;
+}
+
+static void mesh_ensure_tessellation_customdata(Mesh *me)
+{
+  if (UNLIKELY((me->totface != 0) && (me->totpoly == 0))) {
+    /* Pass, otherwise this function  clears 'mface' before
+     * versioning 'mface -> mpoly' code kicks in T30583.
+     *
+     * Callers could also check but safer to do here - campbell */
+  }
+  else {
+    const int tottex_original = CustomData_number_of_layers(&me->ldata, CD_MLOOPUV);
+    const int totcol_original = CustomData_number_of_layers(&me->ldata, CD_MLOOPCOL);
+
+    const int tottex_tessface = CustomData_number_of_layers(&me->fdata, CD_MTFACE);
+    const int totcol_tessface = CustomData_number_of_layers(&me->fdata, CD_MCOL);
+
+    if (tottex_tessface != tottex_original || totcol_tessface != totcol_original) {
+      BKE_mesh_tessface_clear(me);
+
+      CustomData_from_bmeshpoly(&me->fdata, &me->ldata, me->totface);
+
+      /* TODO: add some `--debug-mesh` option. */
+      if (G.debug & G_DEBUG) {
+        /* NOTE(campbell): this warning may be un-called for if we are initializing the mesh for
+         * the first time from #BMesh, rather than giving a warning about this we could be smarter
+         * and check if there was any data to begin with, for now just print the warning with
+         * some info to help troubleshoot what's going on. */
+        printf(
+            "%s: warning! Tessellation uvs or vcol data got out of sync, "
+            "had to reset!\n    CD_MTFACE: %d != CD_MLOOPUV: %d || CD_MCOL: %d != CD_MLOOPCOL: "
+            "%d\n",
+            __func__,
+            tottex_tessface,
+            tottex_original,
+            totcol_tessface,
+            totcol_original);
+      }
+    }
+  }
+}
+
+void BKE_mesh_ensure_skin_customdata(Mesh *me)
+{
+  BMesh *bm = me->edit_mesh ? me->edit_mesh->bm : nullptr;
+  MVertSkin *vs;
+
+  if (bm) {
+    if (!CustomData_has_layer(&bm->vdata, CD_MVERT_SKIN)) {
+      BMVert *v;
+      BMIter iter;
+
+      BM_data_layer_add(bm, &bm->vdata, CD_MVERT_SKIN);
+
+      /* Mark an arbitrary vertex as root */
+      BM_ITER_MESH (v, &iter, bm, BM_VERTS_OF_MESH) {
+        vs = (MVertSkin *)CustomData_bmesh_get(&bm->vdata, v->head.data, CD_MVERT_SKIN);
+        vs->flag |= MVERT_SKIN_ROOT;
+        break;
+      }
+    }
+  }
+  else {
+    if (!CustomData_has_layer(&me->vdata, CD_MVERT_SKIN)) {
+      vs = (MVertSkin *)CustomData_add_layer(
+          &me->vdata, CD_MVERT_SKIN, CD_DEFAULT, nullptr, me->totvert);
+
+      /* Mark an arbitrary vertex as root */
+      if (vs) {
+        vs->flag |= MVERT_SKIN_ROOT;
+      }
+    }
+  }
+}
+
+bool BKE_mesh_ensure_facemap_customdata(struct Mesh *me)
+{
+  BMesh *bm = me->edit_mesh ? me->edit_mesh->bm : nullptr;
+  bool changed = false;
+  if (bm) {
+    if (!CustomData_has_layer(&bm->pdata, CD_FACEMAP)) {
+      BM_data_layer_add(bm, &bm->pdata, CD_FACEMAP);
+      changed = true;
+    }
+  }
+  else {
+    if (!CustomData_has_layer(&me->pdata, CD_FACEMAP)) {
+      CustomData_add_layer(&me->pdata, CD_FACEMAP, CD_DEFAULT, nullptr, me->totpoly);
+      changed = true;
+    }
+  }
+  return changed;
+}
+
+bool BKE_mesh_clear_facemap_customdata(struct Mesh *me)
+{
+  BMesh *bm = me->edit_mesh ? me->edit_mesh->bm : nullptr;
+  bool changed = false;
+  if (bm) {
+    if (CustomData_has_layer(&bm->pdata, CD_FACEMAP)) {
+      BM_data_layer_free(bm, &bm->pdata, CD_FACEMAP);
+      changed = true;
+    }
+  }
+  else {
+    if (CustomData_has_layer(&me->pdata, CD_FACEMAP)) {
+      CustomData_free_layers(&me->pdata, CD_FACEMAP, me->totpoly);
+      changed = true;
+    }
+  }
+  return changed;
+}
+
+/**
+ * This ensures grouped custom-data (e.g. #CD_MLOOPUV and #CD_MTFACE, or
+ * #CD_MLOOPCOL and #CD_MCOL) have the same relative active/render/clone/mask indices.
+ *
+ * NOTE(@campbellbarton): that for undo mesh data we want to skip 'ensure_tess_cd' call since
+ * we don't want to store memory for #MFace data when its only used for older
+ * versions of the mesh.
+ */
+static void mesh_update_linked_customdata(Mesh *me, const bool do_ensure_tess_cd)
+{
+  if (do_ensure_tess_cd) {
+    mesh_ensure_tessellation_customdata(me);
+  }
+
+  CustomData_bmesh_update_active_layers(&me->fdata, &me->ldata);
+}
+
+void BKE_mesh_update_customdata_pointers(Mesh *me, const bool do_ensure_tess_cd)
+{
+  mesh_update_linked_customdata(me, do_ensure_tess_cd);
+
+  me->mvert = (MVert *)CustomData_get_layer(&me->vdata, CD_MVERT);
+  me->dvert = (MDeformVert *)CustomData_get_layer(&me->vdata, CD_MDEFORMVERT);
+
+  me->medge = (MEdge *)CustomData_get_layer(&me->edata, CD_MEDGE);
+
+  me->mface = (MFace *)CustomData_get_layer(&me->fdata, CD_MFACE);
+  me->mcol = (MCol *)CustomData_get_layer(&me->fdata, CD_MCOL);
+  me->mtface = (MTFace *)CustomData_get_layer(&me->fdata, CD_MTFACE);
+
+  me->mpoly = (MPoly *)CustomData_get_layer(&me->pdata, CD_MPOLY);
+  me->mloop = (MLoop *)CustomData_get_layer(&me->ldata, CD_MLOOP);
+
+  me->mloopcol = (MLoopCol *)CustomData_get_layer(&me->ldata, CD_MLOOPCOL);
+  me->mloopuv = (MLoopUV *)CustomData_get_layer(&me->ldata, CD_MLOOPUV);
+}
+
+bool BKE_mesh_has_custom_loop_normals(Mesh *me)
+{
+  if (me->edit_mesh) {
+    return CustomData_has_layer(&me->edit_mesh->bm->ldata, CD_CUSTOMLOOPNORMAL);
+  }
+
+  return CustomData_has_layer(&me->ldata, CD_CUSTOMLOOPNORMAL);
+}
+
+/**
+ * Free (or release) any data used by this mesh (does not free the mesh itself).
+ * Only use for undo, in most cases `BKE_id_free(nullptr, me)` should be used.
+ */
+void BKE_mesh_free_data_for_undo(Mesh *me)
+{
+  mesh_free_data(&me->id);
+}
+
+/**
+ * \note on data that this function intentionally doesn't free:
+ *
+ * - Materials and shape keys are not freed here (#Mesh.mat & #Mesh.key).
+ *   As freeing shape keys requires tagging the depsgraph for updated relations,
+ *   which is expensive.
+ *   Material slots should be kept in sync with the object.
+ *
+ * - Edit-Mesh (#Mesh.edit_mesh)
+ *   Since edit-mesh is tied to the objects mode,
+ *   which crashes when called in edit-mode, see: T90972.
+ */
+static void mesh_clear_geometry(Mesh *mesh)
+{
+  CustomData_free(&mesh->vdata, mesh->totvert);
+  CustomData_free(&mesh->edata, mesh->totedge);
+  CustomData_free(&mesh->fdata, mesh->totface);
+  CustomData_free(&mesh->ldata, mesh->totloop);
+  CustomData_free(&mesh->pdata, mesh->totpoly);
+
+  MEM_SAFE_FREE(mesh->mselect);
+
+  mesh->totvert = 0;
+  mesh->totedge = 0;
+  mesh->totface = 0;
+  mesh->totloop = 0;
+  mesh->totpoly = 0;
+  mesh->act_face = -1;
+  mesh->totselect = 0;
+
+  BKE_mesh_update_customdata_pointers(mesh, false);
+}
+
+void BKE_mesh_clear_geometry(Mesh *mesh)
+{
+  BKE_animdata_free(&mesh->id, false);
+  BKE_mesh_runtime_clear_cache(mesh);
+  mesh_clear_geometry(mesh);
+}
+
+static void mesh_tessface_clear_intern(Mesh *mesh, int free_customdata)
+{
+  if (free_customdata) {
+    CustomData_free(&mesh->fdata, mesh->totface);
+  }
+  else {
+    CustomData_reset(&mesh->fdata);
+  }
+
+  mesh->mface = nullptr;
+  mesh->mtface = nullptr;
+  mesh->mcol = nullptr;
+  mesh->totface = 0;
+}
+
+Mesh *BKE_mesh_add(Main *bmain, const char *name)
+{
+  Mesh *me = (Mesh *)BKE_id_new(bmain, ID_ME, name);
+
+  return me;
+}
+
+/* Custom data layer functions; those assume that totXXX are set correctly. */
+static void mesh_ensure_cdlayers_primary(Mesh *mesh, bool do_tessface)
+{
+  if (!CustomData_get_layer(&mesh->vdata, CD_MVERT)) {
+    CustomData_add_layer(&mesh->vdata, CD_MVERT, CD_CALLOC, nullptr, mesh->totvert);
+  }
+  if (!CustomData_get_layer(&mesh->edata, CD_MEDGE)) {
+    CustomData_add_layer(&mesh->edata, CD_MEDGE, CD_CALLOC, nullptr, mesh->totedge);
+  }
+  if (!CustomData_get_layer(&mesh->ldata, CD_MLOOP)) {
+    CustomData_add_layer(&mesh->ldata, CD_MLOOP, CD_CALLOC, nullptr, mesh->totloop);
+  }
+  if (!CustomData_get_layer(&mesh->pdata, CD_MPOLY)) {
+    CustomData_add_layer(&mesh->pdata, CD_MPOLY, CD_CALLOC, nullptr, mesh->totpoly);
+  }
+
+  if (do_tessface && !CustomData_get_layer(&mesh->fdata, CD_MFACE)) {
+    CustomData_add_layer(&mesh->fdata, CD_MFACE, CD_CALLOC, nullptr, mesh->totface);
+  }
+}
+
+Mesh *BKE_mesh_new_nomain(
+    int verts_len, int edges_len, int tessface_len, int loops_len, int polys_len)
+{
+  Mesh *mesh = (Mesh *)BKE_libblock_alloc(
+      nullptr, ID_ME, BKE_idtype_idcode_to_name(ID_ME), LIB_ID_CREATE_LOCALIZE);
+  BKE_libblock_init_empty(&mesh->id);
+
+  /* Don't use #CustomData_reset because we don't want to touch custom-data. */
+  copy_vn_i(mesh->vdata.typemap, CD_NUMTYPES, -1);
+  copy_vn_i(mesh->edata.typemap, CD_NUMTYPES, -1);
+  copy_vn_i(mesh->fdata.typemap, CD_NUMTYPES, -1);
+  copy_vn_i(mesh->ldata.typemap, CD_NUMTYPES, -1);
+  copy_vn_i(mesh->pdata.typemap, CD_NUMTYPES, -1);
+
+  mesh->totvert = verts_len;
+  mesh->totedge = edges_len;
+  mesh->totface = tessface_len;
+  mesh->totloop = loops_len;
+  mesh->totpoly = polys_len;
+
+  mesh_ensure_cdlayers_primary(mesh, true);
+  BKE_mesh_update_customdata_pointers(mesh, false);
+
+  return mesh;
+}
+
+/**
+ * Copy user editable settings that we want to preserve
+ * when a new mesh is based on an existing mesh.
+ */
+void BKE_mesh_copy_parameters(Mesh *me_dst, const Mesh *me_src)
+{
+  /* Copy general settings. */
+  me_dst->editflag = me_src->editflag;
+  me_dst->flag = me_src->flag;
+  me_dst->smoothresh = me_src->smoothresh;
+  me_dst->remesh_voxel_size = me_src->remesh_voxel_size;
+  me_dst->remesh_voxel_adaptivity = me_src->remesh_voxel_adaptivity;
+  me_dst->remesh_mode = me_src->remesh_mode;
+  me_dst->symmetry = me_src->symmetry;
+
+  me_dst->face_sets_color_seed = me_src->face_sets_color_seed;
+  me_dst->face_sets_color_default = me_src->face_sets_color_default;
+
+  /* Copy texture space. */
+  me_dst->texflag = me_src->texflag;
+  copy_v3_v3(me_dst->loc, me_src->loc);
+  copy_v3_v3(me_dst->size, me_src->size);
+
+  me_dst->vertex_group_active_index = me_src->vertex_group_active_index;
+}
+
+/**
+ * A version of #BKE_mesh_copy_parameters that is intended for evaluated output
+ * (the modifier stack for example).
+ *
+ * \warning User counts are not handled for ID's.
+ */
+void BKE_mesh_copy_parameters_for_eval(Mesh *me_dst, const Mesh *me_src)
+{
+  /* User counts aren't handled, don't copy into a mesh from #G_MAIN. */
+  BLI_assert(me_dst->id.tag & (LIB_TAG_NO_MAIN | LIB_TAG_COPIED_ON_WRITE));
+
+  BKE_mesh_copy_parameters(me_dst, me_src);
+
+  /* Copy vertex group names. */
+  BLI_assert(BLI_listbase_is_empty(&me_dst->vertex_group_names));
+  BKE_defgroup_copy_list(&me_dst->vertex_group_names, &me_src->vertex_group_names);
+
+  /* Copy materials. */
+  if (me_dst->mat != nullptr) {
+    MEM_freeN(me_dst->mat);
+  }
+  me_dst->mat = (Material **)MEM_dupallocN(me_src->mat);
+  me_dst->totcol = me_src->totcol;
+}
+
+Mesh *BKE_mesh_new_nomain_from_template_ex(const Mesh *me_src,
+                                           int verts_len,
+                                           int edges_len,
+                                           int tessface_len,
+                                           int loops_len,
+                                           int polys_len,
+                                           CustomData_MeshMasks mask)
+{
+  /* Only do tessface if we are creating tessfaces or copying from mesh with only tessfaces. */
+  const bool do_tessface = (tessface_len || ((me_src->totface != 0) && (me_src->totpoly == 0)));
+
+  Mesh *me_dst = (Mesh *)BKE_id_new_nomain(ID_ME, nullptr);
+
+  me_dst->mselect = (MSelect *)MEM_dupallocN(me_src->mselect);
+
+  me_dst->totvert = verts_len;
+  me_dst->totedge = edges_len;
+  me_dst->totface = tessface_len;
+  me_dst->totloop = loops_len;
+  me_dst->totpoly = polys_len;
+
+  me_dst->cd_flag = me_src->cd_flag;
+  BKE_mesh_copy_parameters_for_eval(me_dst, me_src);
+
+  CustomData_copy(&me_src->vdata, &me_dst->vdata, mask.vmask, CD_CALLOC, verts_len);
+  CustomData_copy(&me_src->edata, &me_dst->edata, mask.emask, CD_CALLOC, edges_len);
+  CustomData_copy(&me_src->ldata, &me_dst->ldata, mask.lmask, CD_CALLOC, loops_len);
+  CustomData_copy(&me_src->pdata, &me_dst->pdata, mask.pmask, CD_CALLOC, polys_len);
+  if (do_tessface) {
+    CustomData_copy(&me_src->fdata, &me_dst->fdata, mask.fmask, CD_CALLOC, tessface_len);
+  }
+  else {
+    mesh_tessface_clear_intern(me_dst, false);
+  }
+
+  /* The destination mesh should at least have valid primary CD layers,
+   * even in cases where the source mesh does not. */
+  mesh_ensure_cdlayers_primary(me_dst, do_tessface);
+  BKE_mesh_update_customdata_pointers(me_dst, false);
+
+  return me_dst;
+}
+
+Mesh *BKE_mesh_new_nomain_from_template(const Mesh *me_src,
+                                        int verts_len,
+                                        int edges_len,
+                                        int tessface_len,
+                                        int loops_len,
+                                        int polys_len)
+{
+  return BKE_mesh_new_nomain_from_template_ex(
+      me_src, verts_len, edges_len, tessface_len, loops_len, polys_len, CD_MASK_EVERYTHING);
+}
+
+void BKE_mesh_eval_delete(struct Mesh *mesh_eval)
+{
+  /* Evaluated mesh may point to edit mesh, but never owns it. */
+  mesh_eval->edit_mesh = nullptr;
+  mesh_free_data(&mesh_eval->id);
+  BKE_libblock_free_data(&mesh_eval->id, false);
+  MEM_freeN(mesh_eval);
+}
+
+Mesh *BKE_mesh_copy_for_eval(const Mesh *source, bool reference)
+{
+  int flags = LIB_ID_COPY_LOCALIZE;
+
+  if (reference) {
+    flags |= LIB_ID_COPY_CD_REFERENCE;
+  }
+
+  Mesh *result = (Mesh *)BKE_id_copy_ex(nullptr, &source->id, nullptr, flags);
+  return result;
+}
+
+BMesh *BKE_mesh_to_bmesh_ex(const Mesh *me,
+                            const struct BMeshCreateParams *create_params,
+                            const struct BMeshFromMeshParams *convert_params)
+{
+  const BMAllocTemplate allocsize = BMALLOC_TEMPLATE_FROM_ME(me);
+
+  BMesh *bm = BM_mesh_create(&allocsize, create_params);
+  BM_mesh_bm_from_me(bm, me, convert_params);
+
+  return bm;
+}
+
+BMesh *BKE_mesh_to_bmesh(Mesh *me,
+                         Object *ob,
+                         const bool add_key_index,
+                         const struct BMeshCreateParams *params)
+{
+  BMeshFromMeshParams bmesh_from_mesh_params{};
+  bmesh_from_mesh_params.calc_face_normal = false;
+  bmesh_from_mesh_params.add_key_index = add_key_index;
+  bmesh_from_mesh_params.use_shapekey = true;
+  bmesh_from_mesh_params.active_shapekey = ob->shapenr;
+  return BKE_mesh_to_bmesh_ex(me, params, &bmesh_from_mesh_params);
+}
+
+Mesh *BKE_mesh_from_bmesh_nomain(BMesh *bm,
+                                 const struct BMeshToMeshParams *params,
+                                 const Mesh *me_settings)
+{
+  BLI_assert(params->calc_object_remap == false);
+  Mesh *mesh = (Mesh *)BKE_id_new_nomain(ID_ME, nullptr);
+  BM_mesh_bm_to_me(nullptr, bm, mesh, params);
+  BKE_mesh_copy_parameters_for_eval(mesh, me_settings);
+  return mesh;
+}
+
+Mesh *BKE_mesh_from_bmesh_for_eval_nomain(BMesh *bm,
+                                          const CustomData_MeshMasks *cd_mask_extra,
+                                          const Mesh *me_settings)
+{
+  Mesh *mesh = (Mesh *)BKE_id_new_nomain(ID_ME, nullptr);
+  BM_mesh_bm_to_me_for_eval(bm, mesh, cd_mask_extra);
+  BKE_mesh_copy_parameters_for_eval(mesh, me_settings);
+  return mesh;
+}
+
+BoundBox *BKE_mesh_boundbox_get(Object *ob)
+{
+  /* This is Object-level data access,
+   * DO NOT touch to Mesh's bb, would be totally thread-unsafe. */
+  if (ob->runtime.bb == nullptr || ob->runtime.bb->flag & BOUNDBOX_DIRTY) {
+    Mesh *me = (Mesh *)ob->data;
+    float min[3], max[3];
+
+    INIT_MINMAX(min, max);
+    if (!BKE_mesh_wrapper_minmax(me, min, max)) {
+      min[0] = min[1] = min[2] = -1.0f;
+      max[0] = max[1] = max[2] = 1.0f;
+    }
+
+    if (ob->runtime.bb == nullptr) {
+      ob->runtime.bb = (BoundBox *)MEM_mallocN(sizeof(*ob->runtime.bb), __func__);
+    }
+    BKE_boundbox_init_from_minmax(ob->runtime.bb, min, max);
+    ob->runtime.bb->flag &= ~BOUNDBOX_DIRTY;
+  }
+
+  return ob->runtime.bb;
+}
+
+void BKE_mesh_texspace_calc(Mesh *me)
+{
+  if (me->texflag & ME_AUTOSPACE) {
+    float min[3], max[3];
+
+    INIT_MINMAX(min, max);
+    if (!BKE_mesh_wrapper_minmax(me, min, max)) {
+      min[0] = min[1] = min[2] = -1.0f;
+      max[0] = max[1] = max[2] = 1.0f;
+    }
+
+    float loc[3], size[3];
+    mid_v3_v3v3(loc, min, max);
+
+    size[0] = (max[0] - min[0]) / 2.0f;
+    size[1] = (max[1] - min[1]) / 2.0f;
+    size[2] = (max[2] - min[2]) / 2.0f;
+
+    for (int a = 0; a < 3; a++) {
+      if (size[a] == 0.0f) {
+        size[a] = 1.0f;
+      }
+      else if (size[a] > 0.0f && size[a] < 0.00001f) {
+        size[a] = 0.00001f;
+      }
+      else if (size[a] < 0.0f && size[a] > -0.00001f) {
+        size[a] = -0.00001f;
+      }
+    }
+
+    copy_v3_v3(me->loc, loc);
+    copy_v3_v3(me->size, size);
+
+    me->texflag |= ME_AUTOSPACE_EVALUATED;
+  }
+}
+
+void BKE_mesh_texspace_ensure(Mesh *me)
+{
+  if ((me->texflag & ME_AUTOSPACE) && !(me->texflag & ME_AUTOSPACE_EVALUATED)) {
+    BKE_mesh_texspace_calc(me);
+  }
+}
+
+void BKE_mesh_texspace_get(Mesh *me, float r_loc[3], float r_size[3])
+{
+  BKE_mesh_texspace_ensure(me);
+
+  if (r_loc) {
+    copy_v3_v3(r_loc, me->loc);
+  }
+  if (r_size) {
+    copy_v3_v3(r_size, me->size);
+  }
+}
+
+void BKE_mesh_texspace_get_reference(Mesh *me, short **r_texflag, float **r_loc, float **r_size)
+{
+  BKE_mesh_texspace_ensure(me);
+
+  if (r_texflag != nullptr) {
+    *r_texflag = &me->texflag;
+  }
+  if (r_loc != nullptr) {
+    *r_loc = me->loc;
+  }
+  if (r_size != nullptr) {
+    *r_size = me->size;
+  }
+}
+
+void BKE_mesh_texspace_copy_from_object(Mesh *me, Object *ob)
+{
+  float *texloc, *texsize;
+  short *texflag;
+
+  if (BKE_object_obdata_texspace_get(ob, &texflag, &texloc, &texsize)) {
+    me->texflag = *texflag;
+    copy_v3_v3(me->loc, texloc);
+    copy_v3_v3(me->size, texsize);
+  }
+}
+
+float (*BKE_mesh_orco_verts_get(Object *ob))[3]
+{
+  Mesh *me = (Mesh *)ob->data;
+  Mesh *tme = me->texcomesh ? me->texcomesh : me;
+
+  /* Get appropriate vertex coordinates */
+  float(*vcos)[3] = (float(*)[3])MEM_calloc_arrayN(me->totvert, sizeof(*vcos), "orco mesh");
+  MVert *mvert = tme->mvert;
+  int totvert = min_ii(tme->totvert, me->totvert);
+
+  for (int a = 0; a < totvert; a++, mvert++) {
+    copy_v3_v3(vcos[a], mvert->co);
+  }
+
+  return vcos;
+}
+
+void BKE_mesh_orco_verts_transform(Mesh *me, float (*orco)[3], int totvert, int invert)
+{
+  float loc[3], size[3];
+
+  BKE_mesh_texspace_get(me->texcomesh ? me->texcomesh : me, loc, size);
+
+  if (invert) {
+    for (int a = 0; a < totvert; a++) {
+      float *co = orco[a];
+      madd_v3_v3v3v3(co, loc, co, size);
+    }
+  }
+  else {
+    for (int a = 0; a < totvert; a++) {
+      float *co = orco[a];
+      co[0] = (co[0] - loc[0]) / size[0];
+      co[1] = (co[1] - loc[1]) / size[1];
+      co[2] = (co[2] - loc[2]) / size[2];
+    }
+  }
+}
+
+/**
+ * Rotates the vertices of a face in case v[2] or v[3] (vertex index) is = 0.
+ * this is necessary to make the if #MFace.v4 check for quads work.
+ */
+int BKE_mesh_mface_index_validate(MFace *mface, CustomData *fdata, int mfindex, int nr)
+{
+  /* first test if the face is legal */
+  if ((mface->v3 || nr == 4) && mface->v3 == mface->v4) {
+    mface->v4 = 0;
+    nr--;
+  }
+  if ((mface->v2 || mface->v4) && mface->v2 == mface->v3) {
+    mface->v3 = mface->v4;
+    mface->v4 = 0;
+    nr--;
+  }
+  if (mface->v1 == mface->v2) {
+    mface->v2 = mface->v3;
+    mface->v3 = mface->v4;
+    mface->v4 = 0;
+    nr--;
+  }
+
+  /* Check corrupt cases, bow-tie geometry,
+   * can't handle these because edge data won't exist so just return 0. */
+  if (nr == 3) {
+    if (
+        /* real edges */
+        mface->v1 == mface->v2 || mface->v2 == mface->v3 || mface->v3 == mface->v1) {
+      return 0;
+    }
+  }
+  else if (nr == 4) {
+    if (
+        /* real edges */
+        mface->v1 == mface->v2 || mface->v2 == mface->v3 || mface->v3 == mface->v4 ||
+        mface->v4 == mface->v1 ||
+        /* across the face */
+        mface->v1 == mface->v3 || mface->v2 == mface->v4) {
+      return 0;
+    }
+  }
+
+  /* prevent a zero at wrong index location */
+  if (nr == 3) {
+    if (mface->v3 == 0) {
+      static int corner_indices[4] = {1, 2, 0, 3};
+
+      SWAP(uint, mface->v1, mface->v2);
+      SWAP(uint, mface->v2, mface->v3);
+
+      if (fdata) {
+        CustomData_swap_corners(fdata, mfindex, corner_indices);
+      }
+    }
+  }
+  else if (nr == 4) {
+    if (mface->v3 == 0 || mface->v4 == 0) {
+      static int corner_indices[4] = {2, 3, 0, 1};
+
+      SWAP(uint, mface->v1, mface->v3);
+      SWAP(uint, mface->v2, mface->v4);
+
+      if (fdata) {
+        CustomData_swap_corners(fdata, mfindex, corner_indices);
+      }
+    }
+  }
+
+  return nr;
+}
+
+Mesh *BKE_mesh_from_object(Object *ob)
+{
+  if (ob == nullptr) {
+    return nullptr;
+  }
+  if (ob->type == OB_MESH) {
+    return (Mesh *)ob->data;
+  }
+
+  return nullptr;
+}
+
+void BKE_mesh_assign_object(Main *bmain, Object *ob, Mesh *me)
+{
+  Mesh *old = nullptr;
+
+  if (ob == nullptr) {
+    return;
+  }
+
+  multires_force_sculpt_rebuild(ob);
+
+  if (ob->type == OB_MESH) {
+    old = (Mesh *)ob->data;
+    if (old) {
+      id_us_min(&old->id);
+    }
+    ob->data = me;
+    id_us_plus((ID *)me);
+  }
+
+  BKE_object_materials_test(bmain, ob, (ID *)me);
+
+  BKE_modifiers_test_object(ob);
+}
+
+void BKE_mesh_material_index_remove(Mesh *me, short index)
+{
+  MPoly *mp;
+  MFace *mf;
+  int i;
+
+  for (mp = me->mpoly, i = 0; i < me->totpoly; i++, mp++) {
+    if (mp->mat_nr && mp->mat_nr >= index) {
+      mp->mat_nr--;
+    }
+  }
+
+  for (mf = me->mface, i = 0; i < me->totface; i++, mf++) {
+    if (mf->mat_nr && mf->mat_nr >= index) {
+      mf->mat_nr--;
+    }
+  }
+}
+
+bool BKE_mesh_material_index_used(Mesh *me, short index)
+{
+  MPoly *mp;
+  MFace *mf;
+  int i;
+
+  for (mp = me->mpoly, i = 0; i < me->totpoly; i++, mp++) {
+    if (mp->mat_nr == index) {
+      return true;
+    }
+  }
+
+  for (mf = me->mface, i = 0; i < me->totface; i++, mf++) {
+    if (mf->mat_nr == index) {
+      return true;
+    }
+  }
+
+  return false;
+}
+
+void BKE_mesh_material_index_clear(Mesh *me)
+{
+  MPoly *mp;
+  MFace *mf;
+  int i;
+
+  for (mp = me->mpoly, i = 0; i < me->totpoly; i++, mp++) {
+    mp->mat_nr = 0;
+  }
+
+  for (mf = me->mface, i = 0; i < me->totface; i++, mf++) {
+    mf->mat_nr = 0;
+  }
+}
+
+void BKE_mesh_material_remap(Mesh *me, const uint *remap, uint remap_len)
+{
+  const short remap_len_short = (short)remap_len;
+
+#define MAT_NR_REMAP(n) \
+  if (n < remap_len_short) { \
+    BLI_assert(n >= 0 && remap[n] < remap_len_short); \
+    n = remap[n]; \
+  } \
+  ((void)0)
+
+  if (me->edit_mesh) {
+    BMEditMesh *em = me->edit_mesh;
+    BMIter iter;
+    BMFace *efa;
+
+    BM_ITER_MESH (efa, &iter, em->bm, BM_FACES_OF_MESH) {
+      MAT_NR_REMAP(efa->mat_nr);
+    }
+  }
+  else {
+    int i;
+    for (i = 0; i < me->totpoly; i++) {
+      MAT_NR_REMAP(me->mpoly[i].mat_nr);
+    }
+  }
+
+#undef MAT_NR_REMAP
+}
+
+void BKE_mesh_smooth_flag_set(Mesh *me, const bool use_smooth)
+{
+  if (use_smooth) {
+    for (int i = 0; i < me->totpoly; i++) {
+      me->mpoly[i].flag |= ME_SMOOTH;
+    }
+  }
+  else {
+    for (int i = 0; i < me->totpoly; i++) {
+      me->mpoly[i].flag &= ~ME_SMOOTH;
+    }
+  }
+}
+
+/**
+ * Find the index of the loop in 'poly' which references vertex,
+ * returns -1 if not found
+ */
+int poly_find_loop_from_vert(const MPoly *poly, const MLoop *loopstart, uint vert)
+{
+  for (int j = 0; j < poly->totloop; j++, loopstart++) {
+    if (loopstart->v == vert) {
+      return j;
+    }
+  }
+
+  return -1;
+}
+
+/**
+ * Fill \a r_adj with the loop indices in \a poly adjacent to the
+ * vertex. Returns the index of the loop matching vertex, or -1 if the
+ * vertex is not in \a poly
+ */
+int poly_get_adj_loops_from_vert(const MPoly *poly, const MLoop *mloop, uint vert, uint r_adj[2])
+{
+  int corner = poly_find_loop_from_vert(poly, &mloop[poly->loopstart], vert);
+
+  if (corner != -1) {
+    /* vertex was found */
+    r_adj[0] = ME_POLY_LOOP_PREV(mloop, poly, corner)->v;
+    r_adj[1] = ME_POLY_LOOP_NEXT(mloop, poly, corner)->v;
+  }
+
+  return corner;
+}
+
+/**
+ * Return the index of the edge vert that is not equal to \a v. If
+ * neither edge vertex is equal to \a v, returns -1.
+ */
+int BKE_mesh_edge_other_vert(const MEdge *e, int v)
+{
+  if (e->v1 == v) {
+    return e->v2;
+  }
+  if (e->v2 == v) {
+    return e->v1;
+  }
+
+  return -1;
+}
+
+/**
+ * Sets each output array element to the edge index if it is a real edge, or -1.
+ */
+void BKE_mesh_looptri_get_real_edges(const Mesh *mesh, const MLoopTri *looptri, int r_edges[3])
+{
+  for (int i = 2, i_next = 0; i_next < 3; i = i_next++) {
+    const MLoop *l1 = &mesh->mloop[looptri->tri[i]], *l2 = &mesh->mloop[looptri->tri[i_next]];
+    const MEdge *e = &mesh->medge[l1->e];
+
+    bool is_real = (l1->v == e->v1 && l2->v == e->v2) || (l1->v == e->v2 && l2->v == e->v1);
+
+    r_edges[i] = is_real ? l1->e : -1;
+  }
+}
+
+/* basic vertex data functions */
+bool BKE_mesh_minmax(const Mesh *me, float r_min[3], float r_max[3])
+{
+  int i = me->totvert;
+  MVert *mvert;
+  for (mvert = me->mvert; i--; mvert++) {
+    minmax_v3v3_v3(r_min, r_max, mvert->co);
+  }
+
+  return (me->totvert != 0);
+}
+
+void BKE_mesh_transform(Mesh *me, const float mat[4][4], bool do_keys)
+{
+  int i;
+  MVert *mvert = (MVert *)CustomData_duplicate_referenced_layer(&me->vdata, CD_MVERT, me->totvert);
+  float(*lnors)[3] = (float(*)[3])CustomData_duplicate_referenced_layer(
+      &me->ldata, CD_NORMAL, me->totloop);
+
+  /* If the referenced layer has been re-allocated need to update pointers stored in the mesh. */
+  BKE_mesh_update_customdata_pointers(me, false);
+
+  for (i = 0; i < me->totvert; i++, mvert++) {
+    mul_m4_v3(mat, mvert->co);
+  }
+
+  if (do_keys && me->key) {
+    LISTBASE_FOREACH (KeyBlock *, kb, &me->key->block) {
+      float *fp = (float *)kb->data;
+      for (i = kb->totelem; i--; fp += 3) {
+        mul_m4_v3(mat, fp);
+      }
+    }
+  }
+
+  /* don't update normals, caller can do this explicitly.
+   * We do update loop normals though, those may not be auto-generated
+   * (see e.g. STL import script)! */
+  if (lnors) {
+    float m3[3][3];
+
+    copy_m3_m4(m3, mat);
+    normalize_m3(m3);
+    for (i = 0; i < me->totloop; i++, lnors++) {
+      mul_m3_v3(m3, *lnors);
+    }
+  }
+}
+
+void BKE_mesh_translate(Mesh *me, const float offset[3], const bool do_keys)
+{
+  CustomData_duplicate_referenced_layer(&me->vdata, CD_MVERT, me->totvert);
+  /* If the referenced layer has been re-allocated need to update pointers stored in the mesh. */
+  BKE_mesh_update_customdata_pointers(me, false);
+
+  int i = me->totvert;
+  for (MVert *mvert = me->mvert; i--; mvert++) {
+    add_v3_v3(mvert->co, offset);
+  }
+
+  if (do_keys && me->key) {
+    LISTBASE_FOREACH (KeyBlock *, kb, &me->key->block) {
+      float *fp = (float *)kb->data;
+      for (i = kb->totelem; i--; fp += 3) {
+        add_v3_v3(fp, offset);
+      }
+    }
+  }
+}
+
+void BKE_mesh_tessface_ensure(Mesh *mesh)
+{
+  if (mesh->totpoly && mesh->totface == 0) {
+    BKE_mesh_tessface_calc(mesh);
+  }
+}
+
+void BKE_mesh_tessface_clear(Mesh *mesh)
+{
+  mesh_tessface_clear_intern(mesh, true);
+}
+
+void BKE_mesh_do_versions_cd_flag_init(Mesh *mesh)
+{
+  if (UNLIKELY(mesh->cd_flag)) {
+    return;
+  }
+
+  MVert *mv;
+  MEdge *med;
+  int i;
+
+  for (mv = mesh->mvert, i = 0; i < mesh->totvert; mv++, i++) {
+    if (mv->bweight != 0) {
+      mesh->cd_flag |= ME_CDFLAG_VERT_BWEIGHT;
+      break;
+    }
+  }
+
+  for (med = mesh->medge, i = 0; i < mesh->totedge; med++, i++) {
+    if (med->bweight != 0) {
+      mesh->cd_flag |= ME_CDFLAG_EDGE_BWEIGHT;
+      if (mesh->cd_flag & ME_CDFLAG_EDGE_CREASE) {
+        break;
+      }
+    }
+    if (med->crease != 0) {
+      mesh->cd_flag |= ME_CDFLAG_EDGE_CREASE;
+      if (mesh->cd_flag & ME_CDFLAG_EDGE_BWEIGHT) {
+        break;
+      }
+    }
+  }
+}
+
+/* -------------------------------------------------------------------- */
+/* MSelect functions (currently used in weight paint mode) */
+
+void BKE_mesh_mselect_clear(Mesh *me)
+{
+  MEM_SAFE_FREE(me->mselect);
+  me->totselect = 0;
+}
+
+void BKE_mesh_mselect_validate(Mesh *me)
+{
+  MSelect *mselect_src, *mselect_dst;
+  int i_src, i_dst;
+
+  if (me->totselect == 0) {
+    return;
+  }
+
+  mselect_src = me->mselect;
+  mselect_dst = (MSelect *)MEM_malloc_arrayN(
+      (me->totselect), sizeof(MSelect), "Mesh selection history");
+
+  for (i_src = 0, i_dst = 0; i_src < me->totselect; i_src++) {
+    int index = mselect_src[i_src].index;
+    switch (mselect_src[i_src].type) {
+      case ME_VSEL: {
+        if (me->mvert[index].flag & SELECT) {
+          mselect_dst[i_dst] = mselect_src[i_src];
+          i_dst++;
+        }
+        break;
+      }
+      case ME_ESEL: {
+        if (me->medge[index].flag & SELECT) {
+          mselect_dst[i_dst] = mselect_src[i_src];
+          i_dst++;
+        }
+        break;
+      }
+      case ME_FSEL: {
+        if (me->mpoly[index].flag & SELECT) {
+          mselect_dst[i_dst] = mselect_src[i_src];
+          i_dst++;
+        }
+        break;
+      }
+      default: {
+        BLI_assert(0);
+        break;
+      }
+    }
+  }
+
+  MEM_freeN(mselect_src);
+
+  if (i_dst == 0) {
+    MEM_freeN(mselect_dst);
+    mselect_dst = nullptr;
+  }
+  else if (i_dst != me->totselect) {
+    mselect_dst = (MSelect *)MEM_reallocN(mselect_dst, sizeof(MSelect) * i_dst);
+  }
+
+  me->totselect = i_dst;
+  me->mselect = mselect_dst;
+}
+
+/**
+ * Return the index within me->mselect, or -1
+ */
+int BKE_mesh_mselect_find(Mesh *me, int index, int type)
+{
+  BLI_assert(ELEM(type, ME_VSEL, ME_ESEL, ME_FSEL));
+
+  for (int i = 0; i < me->totselect; i++) {
+    if ((me->mselect[i].index == index) && (me->mselect[i].type == type)) {
+      return i;
+    }
+  }
+
+  return -1;
+}
+
+/**
+ * Return The index of the active element.
+ */
+int BKE_mesh_mselect_active_get(Mesh *me, int type)
+{
+  BLI_assert(ELEM(type, ME_VSEL, ME_ESEL, ME_FSEL));
+
+  if (me->totselect) {
+    if (me->mselect[me->totselect - 1].type == type) {
+      return me->mselect[me->totselect - 1].index;
+    }
+  }
+  return -1;
+}
+
+void BKE_mesh_mselect_active_set(Mesh *me, int index, int type)
+{
+  const int msel_index = BKE_mesh_mselect_find(me, index, type);
+
+  if (msel_index == -1) {
+    /* add to the end */
+    me->mselect = (MSelect *)MEM_reallocN(me->mselect, sizeof(MSelect) * (me->totselect + 1));
+    me->mselect[me->totselect].index = index;
+    me->mselect[me->totselect].type = type;
+    me->totselect++;
+  }
+  else if (msel_index != me->totselect - 1) {
+    /* move to the end */
+    SWAP(MSelect, me->mselect[msel_index], me->mselect[me->totselect - 1]);
+  }
+
+  BLI_assert((me->mselect[me->totselect - 1].index == index) &&
+             (me->mselect[me->totselect - 1].type == type));
+}
+
+void BKE_mesh_count_selected_items(const Mesh *mesh, int r_count[3])
+{
+  r_count[0] = r_count[1] = r_count[2] = 0;
+  if (mesh->edit_mesh) {
+    BMesh *bm = mesh->edit_mesh->bm;
+    r_count[0] = bm->totvertsel;
+    r_count[1] = bm->totedgesel;
+    r_count[2] = bm->totfacesel;
+  }
+  /* We could support faces in paint modes. */
+}
+
+void BKE_mesh_vert_coords_get(const Mesh *mesh, float (*vert_coords)[3])
+{
+  const MVert *mv = mesh->mvert;
+  for (int i = 0; i < mesh->totvert; i++, mv++) {
+    copy_v3_v3(vert_coords[i], mv->co);
+  }
+}
+
+float (*BKE_mesh_vert_coords_alloc(const Mesh *mesh, int *r_vert_len))[3]
+{
+  float(*vert_coords)[3] = (float(*)[3])MEM_mallocN(sizeof(float[3]) * mesh->totvert, __func__);
+  BKE_mesh_vert_coords_get(mesh, vert_coords);
+  if (r_vert_len) {
+    *r_vert_len = mesh->totvert;
+  }
+  return vert_coords;
+}
+
+void BKE_mesh_vert_coords_apply(Mesh *mesh, const float (*vert_coords)[3])
+{
+  /* This will just return the pointer if it wasn't a referenced layer. */
+  MVert *mv = (MVert *)CustomData_duplicate_referenced_layer(
+      &mesh->vdata, CD_MVERT, mesh->totvert);
+  mesh->mvert = mv;
+  for (int i = 0; i < mesh->totvert; i++, mv++) {
+    copy_v3_v3(mv->co, vert_coords[i]);
+  }
+  BKE_mesh_normals_tag_dirty(mesh);
+}
+
+void BKE_mesh_vert_coords_apply_with_mat4(Mesh *mesh,
+                                          const float (*vert_coords)[3],
+                                          const float mat[4][4])
+{
+  /* This will just return the pointer if it wasn't a referenced layer. */
+  MVert *mv = (MVert *)CustomData_duplicate_referenced_layer(
+      &mesh->vdata, CD_MVERT, mesh->totvert);
+  mesh->mvert = mv;
+  for (int i = 0; i < mesh->totvert; i++, mv++) {
+    mul_v3_m4v3(mv->co, mat, vert_coords[i]);
+  }
+  BKE_mesh_normals_tag_dirty(mesh);
+}
+
+void BKE_mesh_vert_normals_apply(Mesh *mesh, const short (*vert_normals)[3])
+{
+  /* This will just return the pointer if it wasn't a referenced layer. */
+  MVert *mv = (MVert *)CustomData_duplicate_referenced_layer(
+      &mesh->vdata, CD_MVERT, mesh->totvert);
+  mesh->mvert = mv;
+  for (int i = 0; i < mesh->totvert; i++, mv++) {
+    copy_v3_v3_short(mv->no, vert_normals[i]);
+  }
+  mesh->runtime.cd_dirty_vert &= ~CD_MASK_NORMAL;
+}
+
+/**
+ * Compute 'split' (aka loop, or per face corner's) normals.
+ *
+ * \param r_lnors_spacearr: Allows to get computed loop normal space array.
+ * That data, among other things, contains 'smooth fan' info, useful e.g.
+ * to split geometry along sharp edges...
+ */
+void BKE_mesh_calc_normals_split_ex(Mesh *mesh, MLoopNorSpaceArray *r_lnors_spacearr)
+{
+  float(*r_loopnors)[3];
+  float(*polynors)[3];
+  short(*clnors)[2] = nullptr;
+  bool free_polynors = false;
+
+  /* Note that we enforce computing clnors when the clnor space array is requested by caller here.
+   * However, we obviously only use the auto-smooth angle threshold
+   * only in case auto-smooth is enabled. */
+  const bool use_split_normals = (r_lnors_spacearr != nullptr) ||
+                                 ((mesh->flag & ME_AUTOSMOOTH) != 0);
+  const float split_angle = (mesh->flag & ME_AUTOSMOOTH) != 0 ? mesh->smoothresh : (float)M_PI;
+
+  if (CustomData_has_layer(&mesh->ldata, CD_NORMAL)) {
+    r_loopnors = (float(*)[3])CustomData_get_layer(&mesh->ldata, CD_NORMAL);
+    memset(r_loopnors, 0, sizeof(float[3]) * mesh->totloop);
+  }
+  else {
+    r_loopnors = (float(*)[3])CustomData_add_layer(
+        &mesh->ldata, CD_NORMAL, CD_CALLOC, nullptr, mesh->totloop);
+    CustomData_set_layer_flag(&mesh->ldata, CD_NORMAL, CD_FLAG_TEMPORARY);
+  }
+
+  /* may be nullptr */
+  clnors = (short(*)[2])CustomData_get_layer(&mesh->ldata, CD_CUSTOMLOOPNORMAL);
+
+  if (CustomData_has_layer(&mesh->pdata, CD_NORMAL)) {
+    /* This assume that layer is always up to date, not sure this is the case
+     * (esp. in Edit mode?)... */
+    polynors = (float(*)[3])CustomData_get_layer(&mesh->pdata, CD_NORMAL);
+    free_polynors = false;
+  }
+  else {
+    polynors = (float(*)[3])MEM_malloc_arrayN(mesh->totpoly, sizeof(float[3]), __func__);
+    BKE_mesh_calc_normals_poly_and_vertex(mesh->mvert,
+                                          mesh->totvert,
+                                          mesh->mloop,
+                                          mesh->totloop,
+                                          mesh->mpoly,
+                                          mesh->totpoly,
+                                          polynors,
+                                          nullptr);
+    free_polynors = true;
+  }
+
+  BKE_mesh_normals_loop_split(mesh->mvert,
+                              mesh->totvert,
+                              mesh->medge,
+                              mesh->totedge,
+                              mesh->mloop,
+                              r_loopnors,
+                              mesh->totloop,
+                              mesh->mpoly,
+                              (const float(*)[3])polynors,
+                              mesh->totpoly,
+                              use_split_normals,
+                              split_angle,
+                              r_lnors_spacearr,
+                              clnors,
+                              nullptr);
+
+  if (free_polynors) {
+    MEM_freeN(polynors);
+  }
+
+  mesh->runtime.cd_dirty_vert &= ~CD_MASK_NORMAL;
+  mesh->runtime.cd_dirty_poly &= ~CD_MASK_NORMAL;
+  mesh->runtime.cd_dirty_loop &= ~CD_MASK_NORMAL;
+}
+
+void BKE_mesh_calc_normals_split(Mesh *mesh)
+{
+  BKE_mesh_calc_normals_split_ex(mesh, nullptr);
+}
+
+/* Split faces helper functions. */
+
+struct SplitFaceNewVert {
+  struct SplitFaceNewVert *next;
+  int new_index;
+  int orig_index;
+  float *vnor;
+};
+
+struct SplitFaceNewEdge {
+  struct SplitFaceNewEdge *next;
+  int new_index;
+  int orig_index;
+  int v1;
+  int v2;
+};
+
+/* Detect needed new vertices, and update accordingly loops' vertex indices.
+ * WARNING! Leaves mesh in invalid state. */
+static int split_faces_prepare_new_verts(const Mesh *mesh,
+                                         MLoopNorSpaceArray *lnors_spacearr,
+                                         SplitFaceNewVert **new_verts,
+                                         MemArena *memarena)
+{
+  /* This is now mandatory, trying to do the job in simple way without that data is doomed to fail,
+   * even when only dealing with smooth/flat faces one can find cases that no simple algorithm
+   * can handle properly. */
+  BLI_assert(lnors_spacearr != nullptr);
+
+  const int loops_len = mesh->totloop;
+  int verts_len = mesh->totvert;
+  MVert *mvert = mesh->mvert;
+  MLoop *mloop = mesh->mloop;
+
+  BLI_bitmap *verts_used = BLI_BITMAP_NEW(verts_len, __func__);
+  BLI_bitmap *done_loops = BLI_BITMAP_NEW(loops_len, __func__);
+
+  MLoop *ml = mloop;
+  MLoopNorSpace **lnor_space = lnors_spacearr->lspacearr;
+
+  BLI_assert(lnors_spacearr->data_type == MLNOR_SPACEARR_LOOP_INDEX);
+
+  for (int loop_idx = 0; loop_idx < loops_len; loop_idx++, ml++, lnor_space++) {
+    if (!BLI_BITMAP_TEST(done_loops, loop_idx)) {
+      const int vert_idx = ml->v;
+      const bool vert_used = BLI_BITMAP_TEST_BOOL(verts_used, vert_idx);
+      /* If vert is already used by another smooth fan, we need a new vert for this one. */
+      const int new_vert_idx = vert_used ? verts_len++ : vert_idx;
+
+      BLI_assert(*lnor_space);
+
+      if ((*lnor_space)->flags & MLNOR_SPACE_IS_SINGLE) {
+        /* Single loop in this fan... */
+        BLI_assert(POINTER_AS_INT((*lnor_space)->loops) == loop_idx);
+        BLI_BITMAP_ENABLE(done_loops, loop_idx);
+        if (vert_used) {
+          ml->v = new_vert_idx;
+        }
+      }
+      else {
+        for (LinkNode *lnode = (*lnor_space)->loops; lnode; lnode = lnode->next) {
+          const int ml_fan_idx = POINTER_AS_INT(lnode->link);
+          BLI_BITMAP_ENABLE(done_loops, ml_fan_idx);
+          if (vert_used) {
+            mloop[ml_fan_idx].v = new_vert_idx;
+          }
+        }
+      }
+
+      if (!vert_used) {
+        BLI_BITMAP_ENABLE(verts_used, vert_idx);
+        /* We need to update that vertex's normal here, we won't go over it again. */
+        /* This is important! *DO NOT* set vnor to final computed lnor,
+         * vnor should always be defined to 'automatic normal' value computed from its polys,
+         * not some custom normal.
+         * Fortunately, that's the loop normal space's 'lnor' reference vector. ;) */
+        normal_float_to_short_v3(mvert[vert_idx].no, (*lnor_space)->vec_lnor);
+      }
+      else {
+        /* Add new vert to list. */
+        SplitFaceNewVert *new_vert = (SplitFaceNewVert *)BLI_memarena_alloc(memarena,
+                                                                            sizeof(*new_vert));
+        new_vert->orig_index = vert_idx;
+        new_vert->new_index = new_vert_idx;
+        new_vert->vnor = (*lnor_space)->vec_lnor; /* See note above. */
+        new_vert->next = *new_verts;
+        *new_verts = new_vert;
+      }
+    }
+  }
+
+  MEM_freeN(done_loops);
+  MEM_freeN(verts_used);
+
+  return verts_len - mesh->totvert;
+}
+
+/* Detect needed new edges, and update accordingly loops' edge indices.
+ * WARNING! Leaves mesh in invalid state. */
+static int split_faces_prepare_new_edges(const Mesh *mesh,
+                                         SplitFaceNewEdge **new_edges,
+                                         MemArena *memarena)
+{
+  const int num_polys = mesh->totpoly;
+  int num_edges = mesh->totedge;
+  MEdge *medge = mesh->medge;
+  MLoop *mloop = mesh->mloop;
+  const MPoly *mpoly = mesh->mpoly;
+
+  BLI_bitmap *edges_used = BLI_BITMAP_NEW(num_edges, __func__);
+  EdgeHash *edges_hash = BLI_edgehash_new_ex(__func__, num_edges);
+
+  const MPoly *mp = mpoly;
+  for (int poly_idx = 0; poly_idx < num_polys; poly_idx++, mp++) {
+    MLoop *ml_prev = &mloop[mp->loopstart + mp->totloop - 1];
+    MLoop *ml = &mloop[mp->loopstart];
+    for (int loop_idx = 0; loop_idx < mp->totloop; loop_idx++, ml++) {
+      void **eval;
+      if (!BLI_edgehash_ensure_p(edges_hash, ml_prev->v, ml->v, &eval)) {
+        const int edge_idx = ml_prev->e;
+
+        /* That edge has not been encountered yet, define it. */
+        if (BLI_BITMAP_TEST(edges_used, edge_idx)) {
+          /* Original edge has already been used, we need to define a new one. */
+          const int new_edge_idx = num_edges++;
+          *eval = POINTER_FROM_INT(new_edge_idx);
+          ml_prev->e = new_edge_idx;
+
+          SplitFaceNewEdge *new_edge = (SplitFaceNewEdge *)BLI_memarena_alloc(memarena,
+                                                                              sizeof(*new_edge));
+          new_edge->orig_index = edge_idx;
+          new_edge->new_index = new_edge_idx;
+          new_edge->v1 = ml_prev->v;
+          new_edge->v2 = ml->v;
+          new_edge->next = *new_edges;
+          *new_edges = new_edge;
+        }
+        else {
+          /* We can re-use original edge. */
+          medge[edge_idx].v1 = ml_prev->v;
+          medge[edge_idx].v2 = ml->v;
+          *eval = POINTER_FROM_INT(edge_idx);
+          BLI_BITMAP_ENABLE(edges_used, edge_idx);
+        }
+      }
+      else {
+        /* Edge already known, just update loop's edge index. */
+        ml_prev->e = POINTER_AS_INT(*eval);
+      }
+
+      ml_prev = ml;
+    }
+  }
+
+  MEM_freeN(edges_used);
+  BLI_edgehash_free(edges_hash, nullptr);
+
+  return num_edges - mesh->totedge;
+}
+
+/* Perform actual split of vertices. */
+static void split_faces_split_new_verts(Mesh *mesh,
+                                        SplitFaceNewVert *new_verts,
+                                        const int num_new_verts)
+{
+  const int verts_len = mesh->totvert - num_new_verts;
+  MVert *mvert = mesh->mvert;
+
+  /* Remember new_verts is a single linklist, so its items are in reversed order... */
+  MVert *new_mv = &mvert[mesh->totvert - 1];
+  for (int i = mesh->totvert - 1; i >= verts_len; i--, new_mv--, new_verts = new_verts->next) {
+    BLI_assert(new_verts->new_index == i);
+    BLI_assert(new_verts->new_index != new_verts->orig_index);
+    CustomData_copy_data(&mesh->vdata, &mesh->vdata, new_verts->orig_index, i, 1);
+    if (new_verts->vnor) {
+      normal_float_to_short_v3(new_mv->no, new_verts->vnor);
+    }
+  }
+}
+
+/* Perform actual split of edges. */
+static void split_faces_split_new_edges(Mesh *mesh,
+                                        SplitFaceNewEdge *new_edges,
+                                        const int num_new_edges)
+{
+  const int num_edges = mesh->totedge - num_new_edges;
+  MEdge *medge = mesh->medge;
+
+  /* Remember new_edges is a single linklist, so its items are in reversed order... */
+  MEdge *new_med = &medge[mesh->totedge - 1];
+  for (int i = mesh->totedge - 1; i >= num_edges; i--, new_med--, new_edges = new_edges->next) {
+    BLI_assert(new_edges->new_index == i);
+    BLI_assert(new_edges->new_index != new_edges->orig_index);
+    CustomData_copy_data(&mesh->edata, &mesh->edata, new_edges->orig_index, i, 1);
+    new_med->v1 = new_edges->v1;
+    new_med->v2 = new_edges->v2;
+  }
+}
+
+/* Split faces based on the edge angle and loop normals.
+ * Matches behavior of face splitting in render engines.
+ *
+ * NOTE: Will leave CD_NORMAL loop data layer which is
+ * used by render engines to set shading up.
+ */
+void BKE_mesh_split_faces(Mesh *mesh, bool free_loop_normals)
+{
+  const int num_polys = mesh->totpoly;
+
+  if (num_polys == 0) {
+    return;
+  }
+  BKE_mesh_tessface_clear(mesh);
+
+  MLoopNorSpaceArray lnors_spacearr = {nullptr};
+  /* Compute loop normals and loop normal spaces (a.k.a. smooth fans of faces around vertices). */
+  BKE_mesh_calc_normals_split_ex(mesh, &lnors_spacearr);
+  /* Stealing memarena from loop normals space array. */
+  MemArena *memarena = lnors_spacearr.mem;
+
+  SplitFaceNewVert *new_verts = nullptr;
+  SplitFaceNewEdge *new_edges = nullptr;
+
+  /* Ensure we own the layers, we need to do this before split_faces_prepare_new_verts as it will
+   * directly assign new indices to existing edges and loops. */
+  CustomData_duplicate_referenced_layers(&mesh->vdata, mesh->totvert);
+  CustomData_duplicate_referenced_layers(&mesh->edata, mesh->totedge);
+  CustomData_duplicate_referenced_layers(&mesh->ldata, mesh->totloop);
+  /* Update pointers in case we duplicated referenced layers. */
+  BKE_mesh_update_customdata_pointers(mesh, false);
+
+  /* Detect loop normal spaces (a.k.a. smooth fans) that will need a new vert. */
+  const int num_new_verts = split_faces_prepare_new_verts(
+      mesh, &lnors_spacearr, &new_verts, memarena);
+
+  if (num_new_verts > 0) {
+    /* Reminder: beyond this point, there is no way out, mesh is in invalid state
+     * (due to early-reassignment of loops' vertex and edge indices to new,
+     * to-be-created split ones). */
+
+    const int num_new_edges = split_faces_prepare_new_edges(mesh, &new_edges, memarena);
+    /* We can have to split a vertex without having to add a single new edge... */
+    const bool do_edges = (num_new_edges > 0);
+
+    /* Reallocate all vert and edge related data. */
+    mesh->totvert += num_new_verts;
+    CustomData_realloc(&mesh->vdata, mesh->totvert);
+    if (do_edges) {
+      mesh->totedge += num_new_edges;
+      CustomData_realloc(&mesh->edata, mesh->totedge);
+    }
+    /* Update pointers to a newly allocated memory. */
+    BKE_mesh_update_customdata_pointers(mesh, false);
+
+    /* Perform actual split of vertices and edges. */
+    split_faces_split_new_verts(mesh, new_verts, num_new_verts);
+    if (do_edges) {
+      split_faces_split_new_edges(mesh, new_edges, num_new_edges);
+    }
+  }
+
+  /* NOTE: after this point mesh is expected to be valid again. */
+
+  /* CD_NORMAL is expected to be temporary only. */
+  if (free_loop_normals) {
+    CustomData_free_layers(&mesh->ldata, CD_NORMAL, mesh->totloop);
+  }
+
+  /* Also frees new_verts/edges temp data, since we used its memarena to allocate them. */
+  BKE_lnor_spacearr_free(&lnors_spacearr);
+
+#ifdef VALIDATE_MESH
+  BKE_mesh_validate(mesh, true, true);
+#endif
+}
+
+/* **** Depsgraph evaluation **** */
+
+void BKE_mesh_eval_geometry(Depsgraph *depsgraph, Mesh *mesh)
+{
+  DEG_debug_print_eval(depsgraph, __func__, mesh->id.name, mesh);
+  BKE_mesh_texspace_calc(mesh);
+  /* We are here because something did change in the mesh. This means we can not trust the existing
+   * evaluated mesh, and we don't know what parts of the mesh did change. So we simply delete the
+   * evaluated mesh and let objects to re-create it with updated settings. */
+  if (mesh->runtime.mesh_eval != nullptr) {
+    mesh->runtime.mesh_eval->edit_mesh = nullptr;
+    BKE_id_free(nullptr, mesh->runtime.mesh_eval);
+    mesh->runtime.mesh_eval = nullptr;
+  }
+  if (DEG_is_active(depsgraph)) {
+    Mesh *mesh_orig = (Mesh *)DEG_get_original_id(&mesh->id);
+    if (mesh->texflag & ME_AUTOSPACE_EVALUATED) {
+      mesh_orig->texflag |= ME_AUTOSPACE_EVALUATED;
+      copy_v3_v3(mesh_orig->loc, mesh->loc);
+      copy_v3_v3(mesh_orig->size, mesh->size);
+    }
+  }
+}