/*
 * 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"

#include "DNA_defaults.h"
#include "DNA_key_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_ghash.h"
#include "BLI_hash.h"
#include "BLI_linklist.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_editmesh.h"
#include "BKE_global.h"
#include "BKE_idtype.h"
#include "BKE_key.h"
#include "BKE_lib_id.h"
#include "BKE_main.h"
#include "BKE_material.h"
#include "BKE_mesh.h"
#include "BKE_mesh_runtime.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"

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_reset(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;
  }
  /* XXX WHAT? Why? Comment, please! And pretty sure this is not valid for regular Mesh copying? */
  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 = MEM_dupallocN(mesh_src->mat);

  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 = NULL;

  mesh_dst->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;

  BKE_mesh_runtime_clear_cache(mesh);
  mesh_clear_geometry(mesh);
  MEM_SAFE_FREE(mesh->mat);
}

IDTypeInfo IDType_ID_ME = {
    .id_code = ID_ME,
    .id_filter = FILTER_ID_ME,
    .main_listbase_index = INDEX_ID_ME,
    .struct_size = sizeof(Mesh),
    .name = "Mesh",
    .name_plural = "meshes",
    .translation_context = BLT_I18NCONTEXT_ID_MESH,
    .flags = 0,

    .init_data = mesh_init_data,
    .copy_data = mesh_copy_data,
    .free_data = mesh_free_data,
    .make_local = NULL,
};

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,
};

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";
    default:
      return "Mesh Comparison Code Unknown";
  }
}

/* thresh is threshold for comparing vertices, uvs, vertex colors,
 * weights, etc.*/
static int customdata_compare(
    CustomData *c1, CustomData *c2, Mesh *m1, Mesh *m2, const float thresh)
{
  const float thresh_sq = thresh * thresh;
  CustomDataLayer *l1, *l2;
  int i, i1 = 0, i2 = 0, tot, j;

  for (i = 0; i < c1->totlayer; i++) {
    if (ELEM(c1->layers[i].type,
             CD_MVERT,
             CD_MEDGE,
             CD_MPOLY,
             CD_MLOOPUV,
             CD_MLOOPCOL,
             CD_MDEFORMVERT)) {
      i1++;
    }
  }

  for (i = 0; i < c2->totlayer; i++) {
    if (ELEM(c2->layers[i].type,
             CD_MVERT,
             CD_MEDGE,
             CD_MPOLY,
             CD_MLOOPUV,
             CD_MLOOPCOL,
             CD_MDEFORMVERT)) {
      i2++;
    }
  }

  if (i1 != i2) {
    return MESHCMP_CDLAYERS_MISMATCH;
  }

  l1 = c1->layers;
  l2 = c2->layers;
  tot = i1;
  i1 = 0;
  i2 = 0;
  for (i = 0; i < tot; i++) {
    while (
        i1 < c1->totlayer &&
        !ELEM(l1->type, CD_MVERT, CD_MEDGE, CD_MPOLY, CD_MLOOPUV, CD_MLOOPCOL, CD_MDEFORMVERT)) {
      i1++;
      l1++;
    }

    while (
        i2 < c2->totlayer &&
        !ELEM(l2->type, CD_MVERT, CD_MEDGE, CD_MPOLY, CD_MLOOPUV, CD_MLOOPCOL, CD_MDEFORMVERT)) {
      i2++;
      l2++;
    }

    if (l1->type == CD_MVERT) {
      MVert *v1 = l1->data;
      MVert *v2 = l2->data;
      int vtot = m1->totvert;

      for (j = 0; j < vtot; j++, v1++, v2++) {
        if (len_squared_v3v3(v1->co, v2->co) > thresh_sq) {
          return MESHCMP_VERTCOMISMATCH;
        }
        /* I don't care about normals, let's just do coordinates */
      }
    }

    /*we're order-agnostic for edges here*/
    if (l1->type == CD_MEDGE) {
      MEdge *e1 = l1->data;
      MEdge *e2 = 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, NULL);
    }

    if (l1->type == CD_MPOLY) {
      MPoly *p1 = l1->data;
      MPoly *p2 = 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;
          }
        }
      }
    }
    if (l1->type == CD_MLOOP) {
      MLoop *lp1 = l1->data;
      MLoop *lp2 = l2->data;
      int ltot = m1->totloop;

      for (j = 0; j < ltot; j++, lp1++, lp2++) {
        if (lp1->v != lp2->v) {
          return MESHCMP_LOOPMISMATCH;
        }
      }
    }
    if (l1->type == CD_MLOOPUV) {
      MLoopUV *lp1 = l1->data;
      MLoopUV *lp2 = 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;
        }
      }
    }

    if (l1->type == CD_MLOOPCOL) {
      MLoopCol *lp1 = l1->data;
      MLoopCol *lp2 = l2->data;
      int ltot = m1->totloop;

      for (j = 0; j < ltot; j++, lp1++, lp2++) {
        if (abs(lp1->r - lp2->r) > thresh || abs(lp1->g - lp2->g) > thresh ||
            abs(lp1->b - lp2->b) > thresh || abs(lp1->a - lp2->a) > thresh) {
          return MESHCMP_LOOPCOLMISMATCH;
        }
      }
    }

    if (l1->type == CD_MDEFORMVERT) {
      MDeformVert *dv1 = l1->data;
      MDeformVert *dv2 = 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;
          }
        }
      }
    }
  }

  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, me2, thresh))) {
    return cmpcode_to_str(c);
  }

  if ((c = customdata_compare(&me1->edata, &me2->edata, me1, me2, thresh))) {
    return cmpcode_to_str(c);
  }

  if ((c = customdata_compare(&me1->ldata, &me2->ldata, me1, me2, thresh))) {
    return cmpcode_to_str(c);
  }

  if ((c = customdata_compare(&me1->pdata, &me2->pdata, me1, me2, thresh))) {
    return cmpcode_to_str(c);
  }

  return NULL;
}

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 [#30583]
     *
     * 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: this warning may be un-called for if we are initializing the mesh for the
         * first time from bmesh, rather then 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 - campbell */
        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 : NULL;
  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 = 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 = CustomData_add_layer(&me->vdata, CD_MVERT_SKIN, CD_DEFAULT, NULL, 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 : NULL;
  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, NULL, me->totpoly);
      changed = true;
    }
  }
  return changed;
}

bool BKE_mesh_clear_facemap_customdata(struct Mesh *me)
{
  BMesh *bm = me->edit_mesh ? me->edit_mesh->bm : NULL;
  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 customdata (e.g. mtexpoly and mloopuv and mtface, or
 * mloopcol and mcol) have the same relative active/render/clone/mask indices.
 *
 * note that for undo mesh data we want to skip 'ensure_tess_cd' call since
 * we don't want to store memory for tessface when its only used for older
 * versions of the mesh. - campbell*/
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 = CustomData_get_layer(&me->vdata, CD_MVERT);
  me->dvert = CustomData_get_layer(&me->vdata, CD_MDEFORMVERT);

  me->medge = CustomData_get_layer(&me->edata, CD_MEDGE);

  me->mface = CustomData_get_layer(&me->fdata, CD_MFACE);
  me->mcol = CustomData_get_layer(&me->fdata, CD_MCOL);
  me->mtface = CustomData_get_layer(&me->fdata, CD_MTFACE);

  me->mpoly = CustomData_get_layer(&me->pdata, CD_MPOLY);
  me->mloop = CustomData_get_layer(&me->ldata, CD_MLOOP);

  me->mloopcol = CustomData_get_layer(&me->ldata, CD_MLOOPCOL);
  me->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);
  }
  else {
    return CustomData_has_layer(&me->ldata, CD_CUSTOMLOOPNORMAL);
  }
}

/** Free (or release) any data used by this mesh (does not free the mesh itself). */
void BKE_mesh_free(Mesh *me)
{
  mesh_free_data(&me->id);
}

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);
  MEM_SAFE_FREE(mesh->edit_mesh);

  /* Note that materials and shape keys are not freed here. This is intentional, as freeing
   * shape keys requires tagging the depsgraph for updated relations, which is expensive.
   * Material slots should be kept in sync with the object.*/

  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 = NULL;
  mesh->mtface = NULL;
  mesh->mcol = NULL;
  mesh->totface = 0;
}

Mesh *BKE_mesh_add(Main *bmain, const char *name)
{
  Mesh *me;

  me = BKE_libblock_alloc(bmain, ID_ME, name, 0);

  mesh_init_data(&me->id);

  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, NULL, mesh->totvert);
  }
  if (!CustomData_get_layer(&mesh->edata, CD_MEDGE)) {
    CustomData_add_layer(&mesh->edata, CD_MEDGE, CD_CALLOC, NULL, mesh->totedge);
  }
  if (!CustomData_get_layer(&mesh->ldata, CD_MLOOP)) {
    CustomData_add_layer(&mesh->ldata, CD_MLOOP, CD_CALLOC, NULL, mesh->totloop);
  }
  if (!CustomData_get_layer(&mesh->pdata, CD_MPOLY)) {
    CustomData_add_layer(&mesh->pdata, CD_MPOLY, CD_CALLOC, NULL, mesh->totpoly);
  }

  if (do_tessface && !CustomData_get_layer(&mesh->fdata, CD_MFACE)) {
    CustomData_add_layer(&mesh->fdata, CD_MFACE, CD_CALLOC, NULL, mesh->totface);
  }
}

Mesh *BKE_mesh_new_nomain(
    int verts_len, int edges_len, int tessface_len, int loops_len, int polys_len)
{
  Mesh *mesh = BKE_libblock_alloc(
      NULL, ID_ME, BKE_idtype_idcode_to_name(ID_ME), LIB_ID_COPY_LOCALIZE);
  BKE_libblock_init_empty(&mesh->id);

  /* don't use CustomData_reset(...); because we dont want to touch customdata */
  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 through the modifier stack
 * or operations where a mesh with new topology is created based on another mesh. */
void BKE_mesh_copy_settings(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->face_sets_color_seed = me_src->face_sets_color_seed;

  /* 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);

  /* Copy materials. */
  if (me_dst->mat != NULL) {
    MEM_freeN(me_dst->mat);
  }
  me_dst->mat = 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 = BKE_id_new_nomain(ID_ME, NULL);

  me_dst->mselect = MEM_dupallocN(me_dst->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_settings(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 = NULL;
  BKE_mesh_free(mesh_eval);
  BKE_libblock_free_data(&mesh_eval->id, false);
  MEM_freeN(mesh_eval);
}

Mesh *BKE_mesh_copy_for_eval(struct Mesh *source, bool reference)
{
  int flags = LIB_ID_COPY_LOCALIZE;

  if (reference) {
    flags |= LIB_ID_COPY_CD_REFERENCE;
  }

  Mesh *result;
  BKE_id_copy_ex(NULL, &source->id, (ID **)&result, flags);
  return result;
}

Mesh *BKE_mesh_copy(Main *bmain, const Mesh *me)
{
  Mesh *me_copy;
  BKE_id_copy(bmain, &me->id, (ID **)&me_copy);
  return me_copy;
}

BMesh *BKE_mesh_to_bmesh_ex(const Mesh *me,
                            const struct BMeshCreateParams *create_params,
                            const struct BMeshFromMeshParams *convert_params)
{
  BMesh *bm;
  const BMAllocTemplate allocsize = BMALLOC_TEMPLATE_FROM_ME(me);

  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)
{
  return BKE_mesh_to_bmesh_ex(me,
                              params,
                              &(struct BMeshFromMeshParams){
                                  .calc_face_normal = false,
                                  .add_key_index = add_key_index,
                                  .use_shapekey = true,
                                  .active_shapekey = ob->shapenr,
                              });
}

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 = BKE_id_new_nomain(ID_ME, NULL);
  BM_mesh_bm_to_me(NULL, bm, mesh, params);
  BKE_mesh_copy_settings(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 = BKE_id_new_nomain(ID_ME, NULL);
  BM_mesh_bm_to_me_for_eval(bm, mesh, cd_mask_extra);
  BKE_mesh_copy_settings(mesh, me_settings);
  return mesh;
}

/**
 * TODO(campbell): support mesh with only an edit-mesh which is lazy initialized.
 */
Mesh *BKE_mesh_from_editmesh_with_coords_thin_wrap(BMEditMesh *em,
                                                   const CustomData_MeshMasks *cd_mask_extra,
                                                   float (*vertexCos)[3],
                                                   const Mesh *me_settings)
{
  Mesh *me = BKE_mesh_from_bmesh_for_eval_nomain(em->bm, cd_mask_extra, me_settings);
  /* Use editmesh directly where possible. */
  me->runtime.is_original = true;
  if (vertexCos) {
    /* We will own this array in the future. */
    BKE_mesh_vert_coords_apply(me, vertexCos);
    MEM_freeN(vertexCos);
    me->runtime.is_original = false;
  }
  return me;
}

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 == NULL || ob->runtime.bb->flag & BOUNDBOX_DIRTY) {
    Mesh *me = ob->data;
    float min[3], max[3];

    INIT_MINMAX(min, max);
    if (!BKE_mesh_minmax(me, min, max)) {
      min[0] = min[1] = min[2] = -1.0f;
      max[0] = max[1] = max[2] = 1.0f;
    }

    if (ob->runtime.bb == NULL) {
      ob->runtime.bb = 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_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 != NULL) {
    *r_texflag = &me->texflag;
  }
  if (r_loc != NULL) {
    *r_loc = me->loc;
  }
  if (r_size != NULL) {
    *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 = ob->data;
  MVert *mvert = NULL;
  Mesh *tme = me->texcomesh ? me->texcomesh : me;
  int a, totvert;
  float(*vcos)[3] = NULL;

  /* Get appropriate vertex coordinates */
  vcos = MEM_calloc_arrayN(me->totvert, sizeof(*vcos), "orco mesh");
  mvert = tme->mvert;
  totvert = min_ii(tme->totvert, me->totvert);

  for (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];
  int a;

  BKE_mesh_texspace_get(me->texcomesh ? me->texcomesh : me, loc, size);

  if (invert) {
    for (a = 0; a < totvert; a++) {
      float *co = orco[a];
      madd_v3_v3v3v3(co, loc, co, size);
    }
  }
  else {
    for (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 test_index_face(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,
   * cant handle these because edge data wont 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(unsigned int, mface->v1, mface->v2);
      SWAP(unsigned int, 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(unsigned int, mface->v1, mface->v3);
      SWAP(unsigned int, mface->v2, mface->v4);

      if (fdata) {
        CustomData_swap_corners(fdata, mfindex, corner_indices);
      }
    }
  }

  return nr;
}

Mesh *BKE_mesh_from_object(Object *ob)
{

  if (ob == NULL) {
    return NULL;
  }
  if (ob->type == OB_MESH) {
    return ob->data;
  }
  else {
    return NULL;
  }
}

void BKE_mesh_assign_object(Main *bmain, Object *ob, Mesh *me)
{
  Mesh *old = NULL;

  if (ob == NULL) {
    return;
  }

  multires_force_sculpt_rebuild(ob);

  if (ob->type == OB_MESH) {
    old = 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);

  test_object_modifiers(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 unsigned int *remap, unsigned int 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)
{
  int j;
  for (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,
                                 unsigned int vert,
                                 unsigned int 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;
  }
  else if (e->v2 == v) {
    return e->v1;
  }
  else {
    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, float mat[4][4], bool do_keys)
{
  int i;
  MVert *mvert = me->mvert;
  float(*lnors)[3] = CustomData_get_layer(&me->ldata, CD_NORMAL);

  for (i = 0; i < me->totvert; i++, mvert++) {
    mul_m4_v3(mat, mvert->co);
  }

  if (do_keys && me->key) {
    KeyBlock *kb;
    for (kb = me->key->block.first; kb; kb = kb->next) {
      float *fp = 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)
{
  int i = me->totvert;
  MVert *mvert;
  for (mvert = me->mvert; i--; mvert++) {
    add_v3_v3(mvert->co, offset);
  }

  if (do_keys && me->key) {
    KeyBlock *kb;
    for (kb = me->key->block.first; kb; kb = kb->next) {
      float *fp = kb->data;
      for (i = kb->totelem; i--; fp += 3) {
        add_v3_v3(fp, offset);
      }
    }
  }
}

void BKE_mesh_ensure_navmesh(Mesh *me)
{
  if (!CustomData_has_layer(&me->pdata, CD_RECAST)) {
    int i;
    int polys_len = me->totpoly;
    int *recastData;
    recastData = (int *)MEM_malloc_arrayN(polys_len, sizeof(int), __func__);
    for (i = 0; i < polys_len; i++) {
      recastData[i] = i + 1;
    }
    CustomData_add_layer_named(
        &me->pdata, CD_RECAST, CD_ASSIGN, recastData, polys_len, "recastData");
  }
}

void BKE_mesh_tessface_calc(Mesh *mesh)
{
  mesh->totface = BKE_mesh_tessface_calc_ex(
      &mesh->fdata,
      &mesh->ldata,
      &mesh->pdata,
      mesh->mvert,
      mesh->totface,
      mesh->totloop,
      mesh->totpoly,
      /* calc normals right after, don't copy from polys here */
      false);

  BKE_mesh_update_customdata_pointers(mesh, true);
}

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;
  }
  else {
    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)
{
  if (me->mselect) {
    MEM_freeN(me->mselect);
    me->mselect = NULL;
  }
  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 = 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 = NULL;
  }
  else if (i_dst != me->totselect) {
    mselect_dst = 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)
{
  int i;

  BLI_assert(ELEM(type, ME_VSEL, ME_ESEL, ME_FSEL));

  for (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 = 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] = 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 = 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]);
  }
  mesh->runtime.cd_dirty_vert |= CD_MASK_NORMAL;
}

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 = 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]);
  }
  mesh->runtime.cd_dirty_vert |= CD_MASK_NORMAL;
}

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 = 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] = NULL;
  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 autosmooth angle threshold
   * only in case autosmooth is enabled. */
  const bool use_split_normals = (r_lnors_spacearr != NULL) || ((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 = CustomData_get_layer(&mesh->ldata, CD_NORMAL);
    memset(r_loopnors, 0, sizeof(float[3]) * mesh->totloop);
  }
  else {
    r_loopnors = CustomData_add_layer(&mesh->ldata, CD_NORMAL, CD_CALLOC, NULL, mesh->totloop);
    CustomData_set_layer_flag(&mesh->ldata, CD_NORMAL, CD_FLAG_TEMPORARY);
  }

  /* may be NULL */
  clnors = 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 = CustomData_get_layer(&mesh->pdata, CD_NORMAL);
    free_polynors = false;
  }
  else {
    polynors = MEM_malloc_arrayN(mesh->totpoly, sizeof(float[3]), __func__);
    BKE_mesh_calc_normals_poly(mesh->mvert,
                               NULL,
                               mesh->totvert,
                               mesh->mloop,
                               mesh->mpoly,
                               mesh->totloop,
                               mesh->totpoly,
                               polynors,
                               false);
    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,
                              NULL);

  if (free_polynors) {
    MEM_freeN(polynors);
  }

  mesh->runtime.cd_dirty_vert &= ~CD_MASK_NORMAL;
}

void BKE_mesh_calc_normals_split(Mesh *mesh)
{
  BKE_mesh_calc_normals_split_ex(mesh, NULL);
}

/* Split faces helper functions. */

typedef struct SplitFaceNewVert {
  struct SplitFaceNewVert *next;
  int new_index;
  int orig_index;
  float *vnor;
} SplitFaceNewVert;

typedef struct SplitFaceNewEdge {
  struct SplitFaceNewEdge *next;
  int new_index;
  int orig_index;
  int v1;
  int v2;
} SplitFaceNewEdge;

/* 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 != NULL);

  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 = 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 = 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, NULL);

  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 = {NULL};
  /* 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 = NULL;
  SplitFaceNewEdge *new_edges = NULL;

  /* 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 != NULL) {
    mesh->runtime.mesh_eval->edit_mesh = NULL;
    BKE_id_free(NULL, mesh->runtime.mesh_eval);
    mesh->runtime.mesh_eval = NULL;
  }
  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);
    }
  }
}
