transform_convert_mesh.cc

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/* SPDX-FileCopyrightText: 2001-2002 NaN Holding BV. All rights reserved.
 *
 * SPDX-License-Identifier: GPL-2.0-or-later */
 
#include "DNA_mesh_types.h"
 
#include "MEM_guardedalloc.h"
 
#include "BLI_alloca.h"
#include "BLI_bitmap.h"
#include "BLI_linklist_stack.h"
#include "BLI_math_geom.h"
#include "BLI_math_matrix.h"
#include "BLI_math_rotation.h"
#include "BLI_math_vector.h"
#include "BLI_memarena.h"
#include "BLI_utildefines_stack.h"
 
#include "BKE_context.hh"
#include "BKE_crazyspace.hh"
#include "BKE_editmesh.hh"
#include "BKE_mesh.hh"
#include "BKE_modifier.hh"
#include "BKE_scene.hh"
 
#include "ED_mesh.hh"
#include "ED_object.hh"
 
#include "DEG_depsgraph_query.hh"
 
#include "transform.hh"
#include "transform_orientations.hh"
#include "transform_snap.hh"
 
#include "transform_convert.hh"
 
using namespace blender;
 
/* -------------------------------------------------------------------- */
static void mesh_customdata_free_fn(TransInfo *t,
                                    TransDataContainer *tc,
                                    TransCustomData *custom_data);
 
struct TransCustomDataLayer;
static void mesh_customdatacorrect_free(TransCustomDataLayer *tcld);
 
struct TransCustomData_PartialUpdate {
  BMPartialUpdate *cache;
 
  float prop_size;
  float prop_size_prev;
};
 
enum ePartialType {
  PARTIAL_NONE = -1,
  PARTIAL_TYPE_GROUP = 0,
  PARTIAL_TYPE_ALL = 1,
};
 
#define PARTIAL_TYPE_MAX 2
 
struct PartialTypeState {
  ePartialType for_looptris;
  ePartialType for_normals;
};
 
struct TransCustomDataMesh {
  TransCustomDataLayer *cd_layer_correct;
  TransCustomData_PartialUpdate partial_update[PARTIAL_TYPE_MAX];
  PartialTypeState partial_update_state_prev;
};
 
static TransCustomDataMesh *mesh_customdata_ensure(TransDataContainer *tc)
{
  TransCustomDataMesh *tcmd = static_cast<TransCustomDataMesh *>(tc->custom.type.data);
  BLI_assert(tc->custom.type.data == nullptr ||
             tc->custom.type.free_cb == mesh_customdata_free_fn);
  if (tc->custom.type.data == nullptr) {
    tc->custom.type.data = MEM_callocN(sizeof(TransCustomDataMesh), __func__);
    tc->custom.type.free_cb = mesh_customdata_free_fn;
    tcmd = static_cast<TransCustomDataMesh *>(tc->custom.type.data);
    tcmd->partial_update_state_prev.for_looptris = PARTIAL_NONE;
    tcmd->partial_update_state_prev.for_normals = PARTIAL_NONE;
  }
  return tcmd;
}
 
static void mesh_customdata_free(TransCustomDataMesh *tcmd)
{
  if (tcmd->cd_layer_correct != nullptr) {
    mesh_customdatacorrect_free(tcmd->cd_layer_correct);
  }
 
  for (int i = 0; i < ARRAY_SIZE(tcmd->partial_update); i++) {
    if (tcmd->partial_update[i].cache != nullptr) {
      BM_mesh_partial_destroy(tcmd->partial_update[i].cache);
    }
  }
 
  MEM_freeN(tcmd);
}
 
static void mesh_customdata_free_fn(TransInfo * /*t*/,
                                    TransDataContainer * /*tc*/,
                                    TransCustomData *custom_data)
{
  TransCustomDataMesh *tcmd = static_cast<TransCustomDataMesh *>(custom_data->data);
  mesh_customdata_free(tcmd);
  custom_data->data = nullptr;
}
 
/* -------------------------------------------------------------------- */
struct TransCustomDataMergeGroup {
  LinkNode **cd_loop_groups;
};
 
struct TransCustomDataLayer {
  BMesh *bm;
  MemArena *arena;
 
  GHash *origfaces;
  BMesh *bm_origfaces;
 
  /* Special handle for multi-resolution. */
  int cd_loop_mdisp_offset;
 
  /* Optionally merge custom-data groups (this keeps UVs connected for example). */
  struct {
    GHash *origverts;
    TransCustomDataMergeGroup *data;
    int data_len;
    int *customdatalayer_map;
    int customdatalayer_map_len;
  } merge_group;
 
  bool use_merge_group;
};
 
#define USE_FACE_SUBSTITUTE
#ifdef USE_FACE_SUBSTITUTE
#  define FACE_SUBSTITUTE_INDEX INT_MIN
 
static BMFace *mesh_customdatacorrect_find_best_face_substitute(BMFace *f)
{
  BMFace *best_face = nullptr;
  BMLoop *l;
  BMIter liter;
  BM_ITER_ELEM (l, &liter, f, BM_LOOPS_OF_FACE) {
    BMLoop *l_radial_next = l->radial_next;
    BMFace *f_test = l_radial_next->f;
    if (f_test == f) {
      continue;
    }
    if (is_zero_v3(f_test->no)) {
      continue;
    }
 
    /* Check the loops edge isn't selected. */
    if (!BM_elem_flag_test(l_radial_next->v, BM_ELEM_SELECT) &&
        !BM_elem_flag_test(l_radial_next->next->v, BM_ELEM_SELECT))
    {
      /* Prefer edges with unselected vertices.
       * Useful for extrude. */
      best_face = f_test;
      break;
    }
    if (best_face == nullptr) {
      best_face = f_test;
    }
  }
  return best_face;
}
 
static void mesh_customdatacorrect_face_substitute_set(TransCustomDataLayer *tcld,
                                                       BMFace *f,
                                                       BMFace *f_copy)
{
  BLI_assert(is_zero_v3(f->no));
  BMesh *bm = tcld->bm;
 
  const BMCustomDataCopyMap cd_face_map = CustomData_bmesh_copy_map_calc(
      bm->pdata, tcld->bm_origfaces->pdata);
  const BMCustomDataCopyMap cd_loop_map = CustomData_bmesh_copy_map_calc(
      bm->ldata, tcld->bm_origfaces->ldata);
 
  /* It is impossible to calculate the loops weights of a face without area.
   * Find a substitute. */
  BMFace *f_substitute = mesh_customdatacorrect_find_best_face_substitute(f);
  if (f_substitute) {
    /* Copy the custom-data from the substitute face. */
    BMLoop *l_iter, *l_first;
    l_iter = l_first = BM_FACE_FIRST_LOOP(f);
    do {
      BM_loop_interp_from_face(bm, l_iter, f_substitute, false, false);
    } while ((l_iter = l_iter->next) != l_first);
 
    /* Use the substitute face as the reference during the transformation. */
    BMFace *f_substitute_copy = BM_face_copy(
        tcld->bm_origfaces, cd_face_map, cd_loop_map, f_substitute, true, true);
 
    /* Hack: reference substitute face in `f_copy->no`.
     * `tcld->origfaces` is already used to restore the initial value. */
    BM_elem_index_set(f_copy, FACE_SUBSTITUTE_INDEX);
    *((BMFace **)&f_copy->no[0]) = f_substitute_copy;
  }
}
 
static BMFace *mesh_customdatacorrect_face_substitute_get(BMFace *f_copy)
{
  BLI_assert(BM_elem_index_get(f_copy) == FACE_SUBSTITUTE_INDEX);
  return *((BMFace **)&f_copy->no[0]);
}
 
#endif /* USE_FACE_SUBSTITUTE */
 
static void mesh_customdatacorrect_init_vert(TransCustomDataLayer *tcld,
                                             TransDataBasic *td,
                                             const int index)
{
  BMesh *bm = tcld->bm;
  BMVert *v = static_cast<BMVert *>(td->extra);
  BMIter liter;
  int j, l_num;
  float *loop_weights;
 
  const BMCustomDataCopyMap cd_face_map = CustomData_bmesh_copy_map_calc(
      bm->pdata, tcld->bm_origfaces->pdata);
  const BMCustomDataCopyMap cd_loop_map = CustomData_bmesh_copy_map_calc(
      bm->ldata, tcld->bm_origfaces->ldata);
 
  // BM_ITER_ELEM (l, &liter, sv->v, BM_LOOPS_OF_VERT) {
  BM_iter_init(&liter, bm, BM_LOOPS_OF_VERT, v);
  l_num = liter.count;
  loop_weights = tcld->use_merge_group ?
                     static_cast<float *>(BLI_array_alloca(loop_weights, l_num)) :
                     nullptr;
  for (j = 0; j < l_num; j++) {
    BMLoop *l = static_cast<BMLoop *>(BM_iter_step(&liter));
    BMLoop *l_prev, *l_next;
 
    /* Generic custom-data correction. Copy face data. */
    void **val_p;
    if (!BLI_ghash_ensure_p(tcld->origfaces, l->f, &val_p)) {
      BMFace *f_copy = BM_face_copy(
          tcld->bm_origfaces, cd_face_map, cd_loop_map, l->f, true, true);
      *val_p = f_copy;
#ifdef USE_FACE_SUBSTITUTE
      if (is_zero_v3(l->f->no)) {
        mesh_customdatacorrect_face_substitute_set(tcld, l->f, f_copy);
      }
#endif
    }
 
    if (tcld->use_merge_group) {
      if ((l_prev = BM_loop_find_prev_nodouble(l, l->next, FLT_EPSILON)) &&
          (l_next = BM_loop_find_next_nodouble(l, l_prev, FLT_EPSILON)))
      {
        loop_weights[j] = angle_v3v3v3(l_prev->v->co, l->v->co, l_next->v->co);
      }
      else {
        loop_weights[j] = 0.0f;
      }
    }
  }
 
  if (tcld->use_merge_group) {
    /* Store cd_loop_groups. */
    TransCustomDataMergeGroup *merge_data = &tcld->merge_group.data[index];
    if (l_num != 0) {
      merge_data->cd_loop_groups = static_cast<LinkNode **>(BLI_memarena_alloc(
          tcld->arena, tcld->merge_group.customdatalayer_map_len * sizeof(void *)));
      for (j = 0; j < tcld->merge_group.customdatalayer_map_len; j++) {
        const int layer_nr = tcld->merge_group.customdatalayer_map[j];
        merge_data->cd_loop_groups[j] = BM_vert_loop_groups_data_layer_create(
            bm, v, layer_nr, loop_weights, tcld->arena);
      }
    }
    else {
      merge_data->cd_loop_groups = nullptr;
    }
 
    BLI_ghash_insert(tcld->merge_group.origverts, v, td);
  }
}
 
static void mesh_customdatacorrect_init_container_generic(TransDataContainer * /*tc*/,
                                                          TransCustomDataLayer *tcld)
{
  BMesh *bm = tcld->bm;
 
  GHash *origfaces = BLI_ghash_ptr_new(__func__);
  BMeshCreateParams params{};
  params.use_toolflags = false;
  BMesh *bm_origfaces = BM_mesh_create(&bm_mesh_allocsize_default, &params);
 
  /* We need to have matching loop custom-data. */
  BM_mesh_copy_init_customdata_all_layers(bm_origfaces, bm, BM_LOOP, nullptr);
 
  tcld->origfaces = origfaces;
  tcld->bm_origfaces = bm_origfaces;
 
  bmesh_edit_begin(bm, BMO_OPTYPE_FLAG_UNTAN_MULTIRES);
  tcld->cd_loop_mdisp_offset = CustomData_get_offset(&bm->ldata, CD_MDISPS);
}
 
static void mesh_customdatacorrect_init_container_merge_group(TransDataContainer *tc,
                                                              TransCustomDataLayer *tcld)
{
  BMesh *bm = tcld->bm;
  BLI_assert(CustomData_has_math(&bm->ldata));
 
  /* TODO: We don't need `layer_math_map` when there are no loops linked
   * to one of the sliding vertices. */
 
  /* Over allocate, only 'math' layers are indexed. */
  int *customdatalayer_map = static_cast<int *>(
      MEM_mallocN(sizeof(int) * bm->ldata.totlayer, __func__));
  int layer_math_map_len = 0;
  for (int i = 0; i < bm->ldata.totlayer; i++) {
    if (CustomData_layer_has_math(&bm->ldata, i)) {
      customdatalayer_map[layer_math_map_len++] = i;
    }
  }
  BLI_assert(layer_math_map_len != 0);
 
  tcld->merge_group.data_len = tc->data_len + tc->data_mirror_len;
  tcld->merge_group.customdatalayer_map = customdatalayer_map;
  tcld->merge_group.customdatalayer_map_len = layer_math_map_len;
  tcld->merge_group.origverts = BLI_ghash_ptr_new_ex(__func__, tcld->merge_group.data_len);
  tcld->merge_group.data = static_cast<TransCustomDataMergeGroup *>(BLI_memarena_alloc(
      tcld->arena, tcld->merge_group.data_len * sizeof(*tcld->merge_group.data)));
}
 
static TransCustomDataLayer *mesh_customdatacorrect_create_impl(TransDataContainer *tc,
                                                                const bool use_merge_group)
{
  BMEditMesh *em = BKE_editmesh_from_object(tc->obedit);
  BMesh *bm = em->bm;
 
  if (bm->shapenr > 1) {
    /* Don't do this at all for non-basis shape keys, too easy to
     * accidentally break uv maps or vertex colors then. */
    /* Create copies of faces for custom-data projection. */
    return nullptr;
  }
  if (!CustomData_has_math(&bm->ldata) && !CustomData_has_layer(&bm->ldata, CD_MDISPS)) {
    /* There is no custom-data to correct. */
    return nullptr;
  }
 
  TransCustomDataLayer *tcld = static_cast<TransCustomDataLayer *>(
      MEM_callocN(sizeof(*tcld), __func__));
  tcld->bm = bm;
  tcld->arena = BLI_memarena_new(BLI_MEMARENA_STD_BUFSIZE, __func__);
 
  /* Init `cd_loop_mdisp_offset` to -1 to avoid problems with a valid index. */
  tcld->cd_loop_mdisp_offset = -1;
  tcld->use_merge_group = use_merge_group;
 
  mesh_customdatacorrect_init_container_generic(tc, tcld);
 
  if (tcld->use_merge_group) {
    mesh_customdatacorrect_init_container_merge_group(tc, tcld);
  }
 
  {
    /* Setup Verts. */
    int i = 0;
 
    TransData *tob = tc->data;
    for (int j = tc->data_len; j--; tob++, i++) {
      mesh_customdatacorrect_init_vert(tcld, (TransDataBasic *)tob, i);
    }
 
    TransDataMirror *td_mirror = tc->data_mirror;
    for (int j = tc->data_mirror_len; j--; td_mirror++, i++) {
      mesh_customdatacorrect_init_vert(tcld, (TransDataBasic *)td_mirror, i);
    }
  }
 
  return tcld;
}
 
static void mesh_customdatacorrect_create(TransDataContainer *tc, const bool use_merge_group)
{
  TransCustomDataLayer *customdatacorrect;
  customdatacorrect = mesh_customdatacorrect_create_impl(tc, use_merge_group);
 
  if (!customdatacorrect) {
    return;
  }
 
  TransCustomDataMesh *tcmd = mesh_customdata_ensure(tc);
  BLI_assert(tcmd->cd_layer_correct == nullptr);
  tcmd->cd_layer_correct = customdatacorrect;
}
 
static void mesh_customdatacorrect_free(TransCustomDataLayer *tcld)
{
  bmesh_edit_end(tcld->bm, BMO_OPTYPE_FLAG_UNTAN_MULTIRES);
 
  if (tcld->bm_origfaces) {
    BM_mesh_free(tcld->bm_origfaces);
  }
  if (tcld->origfaces) {
    BLI_ghash_free(tcld->origfaces, nullptr, nullptr);
  }
  if (tcld->merge_group.origverts) {
    BLI_ghash_free(tcld->merge_group.origverts, nullptr, nullptr);
  }
  if (tcld->arena) {
    BLI_memarena_free(tcld->arena);
  }
  if (tcld->merge_group.customdatalayer_map) {
    MEM_freeN(tcld->merge_group.customdatalayer_map);
  }
 
  MEM_freeN(tcld);
}
 
void transform_convert_mesh_customdatacorrect_init(TransInfo *t)
{
  bool use_merge_group = false;
  if (ELEM(t->mode, TFM_EDGE_SLIDE, TFM_VERT_SLIDE)) {
    if (!(t->settings->uvcalc_flag & UVCALC_TRANSFORM_CORRECT_SLIDE)) {
      /* No custom-data correction. */
      return;
    }
    use_merge_group = true;
  }
  else if (ELEM(t->mode,
                TFM_TRANSLATION,
                TFM_ROTATION,
                TFM_RESIZE,
                TFM_TOSPHERE,
                TFM_SHEAR,
                TFM_BEND,
                TFM_SHRINKFATTEN,
                TFM_TRACKBALL,
                TFM_PUSHPULL,
                TFM_ALIGN))
  {
    {
      if (!(t->settings->uvcalc_flag & UVCALC_TRANSFORM_CORRECT)) {
        /* No custom-data correction. */
        return;
      }
      use_merge_group = (t->settings->uvcalc_flag & UVCALC_TRANSFORM_CORRECT_KEEP_CONNECTED) != 0;
    }
  }
  else {
    return;
  }
 
  FOREACH_TRANS_DATA_CONTAINER (t, tc) {
    if (tc->custom.type.data != nullptr) {
      TransCustomDataMesh *tcmd = static_cast<TransCustomDataMesh *>(tc->custom.type.data);
      if (tcmd && tcmd->cd_layer_correct) {
        mesh_customdatacorrect_free(tcmd->cd_layer_correct);
        tcmd->cd_layer_correct = nullptr;
      }
    }
 
    mesh_customdatacorrect_create(tc, use_merge_group);
  }
}
 
/* -------------------------------------------------------------------- */
static const float *mesh_vert_orig_co_get(TransCustomDataLayer *tcld, BMVert *v)
{
  TransDataBasic *td = static_cast<TransDataBasic *>(
      BLI_ghash_lookup(tcld->merge_group.origverts, v));
  return td ? td->iloc : v->co;
}
 
static void mesh_customdatacorrect_apply_vert(TransCustomDataLayer *tcld,
                                              TransDataBasic *td,
                                              TransCustomDataMergeGroup *merge_data,
                                              bool do_loop_mdisps)
{
  BMesh *bm = tcld->bm;
  BMVert *v = static_cast<BMVert *>(td->extra);
  const float *co_orig_3d = td->iloc;
 
  BMIter liter;
  int j, l_num;
  float *loop_weights;
  const bool is_moved = (len_squared_v3v3(v->co, co_orig_3d) > FLT_EPSILON);
  const bool do_loop_weight = is_moved && tcld->merge_group.customdatalayer_map_len;
  const float *v_proj_axis = v->no;
  /* Original (`l->prev`, `l`, `l->next`) projections for each loop ('l' remains unchanged). */
  float v_proj[3][3];
 
  if (do_loop_weight) {
    project_plane_normalized_v3_v3v3(v_proj[1], co_orig_3d, v_proj_axis);
  }
 
  // BM_ITER_ELEM (l, &liter, sv->v, BM_LOOPS_OF_VERT)
  BM_iter_init(&liter, bm, BM_LOOPS_OF_VERT, v);
  l_num = liter.count;
  loop_weights = do_loop_weight ? static_cast<float *>(BLI_array_alloca(loop_weights, l_num)) :
                                  nullptr;
  for (j = 0; j < l_num; j++) {
    BMFace *f_copy; /* The copy of 'f'. */
    BMLoop *l = static_cast<BMLoop *>(BM_iter_step(&liter));
 
    f_copy = static_cast<BMFace *>(BLI_ghash_lookup(tcld->origfaces, l->f));
 
#ifdef USE_FACE_SUBSTITUTE
    /* In some faces it is not possible to calculate interpolation,
     * so we use a substitute. */
    if (BM_elem_index_get(f_copy) == FACE_SUBSTITUTE_INDEX) {
      f_copy = mesh_customdatacorrect_face_substitute_get(f_copy);
    }
#endif
 
    /* Only loop data, no vertex data since that contains shape keys,
     * and we do not want to mess up other shape keys. */
    BM_loop_interp_from_face(bm, l, f_copy, false, false);
 
    /* Weight the loop. */
    if (do_loop_weight) {
      const float eps = 1.0e-8f;
      const BMLoop *l_prev = l->prev;
      const BMLoop *l_next = l->next;
      const float *co_prev = mesh_vert_orig_co_get(tcld, l_prev->v);
      const float *co_next = mesh_vert_orig_co_get(tcld, l_next->v);
      bool co_prev_ok;
      bool co_next_ok;
 
      /* In the unlikely case that we're next to a zero length edge -
       * walk around the to the next.
       *
       * Since we only need to check if the vertex is in this corner,
       * its not important _which_ loop - as long as its not overlapping
       * 'sv->co_orig_3d', see: #45096. */
      project_plane_normalized_v3_v3v3(v_proj[0], co_prev, v_proj_axis);
      while (UNLIKELY(((co_prev_ok = (len_squared_v3v3(v_proj[1], v_proj[0]) > eps)) == false) &&
                      ((l_prev = l_prev->prev) != l->next)))
      {
        co_prev = mesh_vert_orig_co_get(tcld, l_prev->v);
        project_plane_normalized_v3_v3v3(v_proj[0], co_prev, v_proj_axis);
      }
      project_plane_normalized_v3_v3v3(v_proj[2], co_next, v_proj_axis);
      while (UNLIKELY(((co_next_ok = (len_squared_v3v3(v_proj[1], v_proj[2]) > eps)) == false) &&
                      ((l_next = l_next->next) != l->prev)))
      {
        co_next = mesh_vert_orig_co_get(tcld, l_next->v);
        project_plane_normalized_v3_v3v3(v_proj[2], co_next, v_proj_axis);
      }
 
      if (co_prev_ok && co_next_ok) {
        const float dist = dist_signed_squared_to_corner_v3v3v3(
            v->co, UNPACK3(v_proj), v_proj_axis);
 
        loop_weights[j] = (dist >= 0.0f) ? 1.0f : ((dist <= -eps) ? 0.0f : (1.0f + (dist / eps)));
        if (UNLIKELY(!isfinite(loop_weights[j]))) {
          loop_weights[j] = 0.0f;
        }
      }
      else {
        loop_weights[j] = 0.0f;
      }
    }
  }
 
  if (tcld->use_merge_group) {
    LinkNode **cd_loop_groups = merge_data->cd_loop_groups;
    if (tcld->merge_group.customdatalayer_map_len && cd_loop_groups) {
      if (do_loop_weight) {
        for (j = 0; j < tcld->merge_group.customdatalayer_map_len; j++) {
          BM_vert_loop_groups_data_layer_merge_weights(
              bm, cd_loop_groups[j], tcld->merge_group.customdatalayer_map[j], loop_weights);
        }
      }
      else {
        for (j = 0; j < tcld->merge_group.customdatalayer_map_len; j++) {
          BM_vert_loop_groups_data_layer_merge(
              bm, cd_loop_groups[j], tcld->merge_group.customdatalayer_map[j]);
        }
      }
    }
  }
 
  /* Special handling for multires
   *
   * Interpolate from every other loop (not ideal)
   * However values will only be taken from loops which overlap other mdisps.
   */
  const bool update_loop_mdisps = is_moved && do_loop_mdisps && (tcld->cd_loop_mdisp_offset != -1);
  if (update_loop_mdisps) {
    float(*faces_center)[3] = static_cast<float(*)[3]>(BLI_array_alloca(faces_center, l_num));
    BMLoop *l;
 
    BM_ITER_ELEM_INDEX (l, &liter, v, BM_LOOPS_OF_VERT, j) {
      BM_face_calc_center_median(l->f, faces_center[j]);
    }
 
    BM_ITER_ELEM_INDEX (l, &liter, v, BM_LOOPS_OF_VERT, j) {
      BMFace *f_copy = static_cast<BMFace *>(BLI_ghash_lookup(tcld->origfaces, l->f));
      float f_copy_center[3];
      BMIter liter_other;
      BMLoop *l_other;
      int j_other;
 
      BM_face_calc_center_median(f_copy, f_copy_center);
 
      BM_ITER_ELEM_INDEX (l_other, &liter_other, v, BM_LOOPS_OF_VERT, j_other) {
        BM_face_interp_multires_ex(bm,
                                   l_other->f,
                                   f_copy,
                                   faces_center[j_other],
                                   f_copy_center,
                                   tcld->cd_loop_mdisp_offset);
      }
    }
  }
}
 
static void mesh_customdatacorrect_apply(TransDataContainer *tc, bool is_final)
{
  TransCustomDataMesh *tcmd = static_cast<TransCustomDataMesh *>(tc->custom.type.data);
  TransCustomDataLayer *tcld = tcmd ? tcmd->cd_layer_correct : nullptr;
  if (tcld == nullptr) {
    return;
  }
  const bool use_merge_group = tcld->use_merge_group;
 
  TransCustomDataMergeGroup *merge_data = tcld->merge_group.data;
  TransData *tob = tc->data;
  for (int i = tc->data_len; i--; tob++) {
    mesh_customdatacorrect_apply_vert(tcld, (TransDataBasic *)tob, merge_data, is_final);
 
    if (use_merge_group) {
      merge_data++;
    }
  }
 
  TransDataMirror *td_mirror = tc->data_mirror;
  for (int i = tc->data_mirror_len; i--; td_mirror++) {
    mesh_customdatacorrect_apply_vert(tcld, (TransDataBasic *)td_mirror, merge_data, is_final);
 
    if (use_merge_group) {
      merge_data++;
    }
  }
}
 
/* -------------------------------------------------------------------- */
static void mesh_customdatacorrect_restore(TransInfo *t)
{
  FOREACH_TRANS_DATA_CONTAINER (t, tc) {
    TransCustomDataMesh *tcmd = static_cast<TransCustomDataMesh *>(tc->custom.type.data);
    TransCustomDataLayer *tcld = tcmd ? tcmd->cd_layer_correct : nullptr;
    if (!tcld) {
      continue;
    }
 
    BMesh *bm = tcld->bm;
    BMesh *bm_copy = tcld->bm_origfaces;
    const BMCustomDataCopyMap cd_loop_map = CustomData_bmesh_copy_map_calc(bm_copy->ldata,
                                                                           bm->ldata);
 
    GHashIterator gh_iter;
    GHASH_ITER (gh_iter, tcld->origfaces) {
      BMFace *f = static_cast<BMFace *>(BLI_ghashIterator_getKey(&gh_iter));
      BMFace *f_copy = static_cast<BMFace *>(BLI_ghashIterator_getValue(&gh_iter));
      BLI_assert(f->len == f_copy->len);
 
      BMLoop *l_iter, *l_first, *l_copy;
      l_iter = l_first = BM_FACE_FIRST_LOOP(f);
      l_copy = BM_FACE_FIRST_LOOP(f_copy);
      do {
        /* TODO: Restore only the elements that transform. */
        BM_elem_attrs_copy(bm, cd_loop_map, l_copy, l_iter);
        l_copy = l_copy->next;
      } while ((l_iter = l_iter->next) != l_first);
    }
  }
}
 
/* -------------------------------------------------------------------- */
void transform_convert_mesh_islands_calc(BMEditMesh *em,
                                         const bool calc_single_islands,
                                         const bool calc_island_center,
                                         const bool calc_island_axismtx,
                                         TransIslandData *r_island_data)
{
  TransIslandData data = {nullptr};
 
  BMesh *bm = em->bm;
  char htype;
  char itype;
  int i;
 
  /* Group variables. */
  int *groups_array = nullptr;
  int(*group_index)[2] = nullptr;
 
  bool has_only_single_islands = bm->totedgesel == 0 && bm->totfacesel == 0;
  if (has_only_single_islands && !calc_single_islands) {
    return;
  }
 
  data.island_vert_map = static_cast<int *>(
      MEM_mallocN(sizeof(*data.island_vert_map) * bm->totvert, __func__));
  /* We shouldn't need this, but with incorrect selection flushing
   * its possible we have a selected vertex that's not in a face,
   * for now best not crash in that case. */
  copy_vn_i(data.island_vert_map, bm->totvert, -1);
 
  if (!has_only_single_islands) {
    if (em->selectmode & (SCE_SELECT_VERTEX | SCE_SELECT_EDGE)) {
      groups_array = static_cast<int *>(
          MEM_mallocN(sizeof(*groups_array) * bm->totedgesel, __func__));
      data.island_tot = BM_mesh_calc_edge_groups(
          bm, groups_array, &group_index, nullptr, nullptr, BM_ELEM_SELECT);
 
      htype = BM_EDGE;
      itype = BM_VERTS_OF_EDGE;
    }
    else { /* `bm->selectmode & SCE_SELECT_FACE`. */
      groups_array = static_cast<int *>(
          MEM_mallocN(sizeof(*groups_array) * bm->totfacesel, __func__));
      data.island_tot = BM_mesh_calc_face_groups(
          bm, groups_array, &group_index, nullptr, nullptr, nullptr, BM_ELEM_SELECT, BM_VERT);
 
      htype = BM_FACE;
      itype = BM_VERTS_OF_FACE;
    }
 
    BLI_assert(data.island_tot);
    if (calc_island_center) {
      data.center = static_cast<float(*)[3]>(
          MEM_mallocN(sizeof(*data.center) * data.island_tot, __func__));
    }
 
    if (calc_island_axismtx) {
      data.axismtx = static_cast<float(*)[3][3]>(
          MEM_mallocN(sizeof(*data.axismtx) * data.island_tot, __func__));
    }
 
    BM_mesh_elem_table_ensure(bm, htype);
 
    void **ele_array;
    ele_array = (htype == BM_FACE) ? (void **)bm->ftable : (void **)bm->etable;
 
    BM_mesh_elem_index_ensure(bm, BM_VERT);
 
    /* May be an edge OR a face array. */
    for (i = 0; i < data.island_tot; i++) {
      BMEditSelection ese = {nullptr};
 
      const int fg_sta = group_index[i][0];
      const int fg_len = group_index[i][1];
      float co[3], no[3], tangent[3];
      int j;
 
      zero_v3(co);
      zero_v3(no);
      zero_v3(tangent);
 
      ese.htype = htype;
 
      /* Loop on each face or edge in this group:
       * - Assign `r_vert_map`.
       * - Calculate (`co`, `no`).
       */
      for (j = 0; j < fg_len; j++) {
        ese.ele = static_cast<BMElem *>(ele_array[groups_array[fg_sta + j]]);
 
        if (data.center) {
          float tmp_co[3];
          BM_editselection_center(&ese, tmp_co);
          add_v3_v3(co, tmp_co);
        }
 
        if (data.axismtx) {
          float tmp_no[3], tmp_tangent[3];
          BM_editselection_normal(&ese, tmp_no);
          BM_editselection_plane(&ese, tmp_tangent);
          add_v3_v3(no, tmp_no);
          add_v3_v3(tangent, tmp_tangent);
        }
 
        {
          /* Setup vertex map. */
          BMIter iter;
          BMVert *v;
 
          /* Connected edge-verts. */
          BM_ITER_ELEM (v, &iter, ese.ele, itype) {
            data.island_vert_map[BM_elem_index_get(v)] = i;
          }
        }
      }
 
      if (data.center) {
        mul_v3_v3fl(data.center[i], co, 1.0f / float(fg_len));
      }
 
      if (data.axismtx) {
        if (createSpaceNormalTangent(data.axismtx[i], no, tangent)) {
          /* Pass. */
        }
        else {
          if (normalize_v3(no) != 0.0f) {
            axis_dominant_v3_to_m3(data.axismtx[i], no);
            invert_m3(data.axismtx[i]);
          }
          else {
            unit_m3(data.axismtx[i]);
          }
        }
      }
    }
 
    MEM_freeN(groups_array);
    MEM_freeN(group_index);
  }
 
  /* For proportional editing we need islands of 1 so connected vertices can use it with
   * #V3D_AROUND_LOCAL_ORIGINS. */
  if (calc_single_islands) {
    BMIter viter;
    BMVert *v;
    int group_tot_single = 0;
 
    BM_ITER_MESH_INDEX (v, &viter, bm, BM_VERTS_OF_MESH, i) {
      if (BM_elem_flag_test(v, BM_ELEM_SELECT) && (data.island_vert_map[i] == -1)) {
        group_tot_single += 1;
      }
    }
 
    if (group_tot_single != 0) {
      if (calc_island_center) {
        data.center = static_cast<float(*)[3]>(MEM_reallocN(
            data.center, sizeof(*data.center) * (data.island_tot + group_tot_single)));
      }
      if (calc_island_axismtx) {
        data.axismtx = static_cast<float(*)[3][3]>(MEM_reallocN(
            data.axismtx, sizeof(*data.axismtx) * (data.island_tot + group_tot_single)));
      }
 
      BM_ITER_MESH_INDEX (v, &viter, bm, BM_VERTS_OF_MESH, i) {
        if (BM_elem_flag_test(v, BM_ELEM_SELECT) && (data.island_vert_map[i] == -1)) {
          data.island_vert_map[i] = data.island_tot;
          if (data.center) {
            copy_v3_v3(data.center[data.island_tot], v->co);
          }
          if (data.axismtx) {
            if (is_zero_v3(v->no) == false) {
              axis_dominant_v3_to_m3(data.axismtx[data.island_tot], v->no);
              invert_m3(data.axismtx[data.island_tot]);
            }
            else {
              unit_m3(data.axismtx[data.island_tot]);
            }
          }
 
          data.island_tot += 1;
        }
      }
    }
  }
 
  *r_island_data = data;
}
 
void transform_convert_mesh_islanddata_free(TransIslandData *island_data)
{
  if (island_data->center) {
    MEM_freeN(island_data->center);
  }
  if (island_data->axismtx) {
    MEM_freeN(island_data->axismtx);
  }
  if (island_data->island_vert_map) {
    MEM_freeN(island_data->island_vert_map);
  }
}
 
/* -------------------------------------------------------------------- */
/* Propagate distance from v1 and v2 to v0. */
static bool bmesh_test_dist_add(BMVert *v0,
                                BMVert *v1,
                                BMVert *v2,
                                float *dists, /* Optionally track original index. */
                                int *index,
                                const float mtx[3][3])
{
  if ((BM_elem_flag_test(v0, BM_ELEM_SELECT) == 0) && (BM_elem_flag_test(v0, BM_ELEM_HIDDEN) == 0))
  {
    const int i0 = BM_elem_index_get(v0);
    const int i1 = BM_elem_index_get(v1);
 
    BLI_assert(dists[i1] != FLT_MAX);
    if (dists[i0] <= dists[i1]) {
      return false;
    }
 
    float dist0;
 
    if (v2) {
      /* Distance across triangle. */
      const int i2 = BM_elem_index_get(v2);
      BLI_assert(dists[i2] != FLT_MAX);
      if (dists[i0] <= dists[i2]) {
        return false;
      }
 
      float vm0[3], vm1[3], vm2[3];
      mul_v3_m3v3(vm0, mtx, v0->co);
      mul_v3_m3v3(vm1, mtx, v1->co);
      mul_v3_m3v3(vm2, mtx, v2->co);
 
      dist0 = geodesic_distance_propagate_across_triangle(vm0, vm1, vm2, dists[i1], dists[i2]);
    }
    else {
      /* Distance along edge. */
      float vec[3];
      sub_v3_v3v3(vec, v1->co, v0->co);
      mul_m3_v3(mtx, vec);
 
      dist0 = dists[i1] + len_v3(vec);
    }
 
    if (dist0 < dists[i0]) {
      dists[i0] = dist0;
      if (index != nullptr) {
        index[i0] = index[i1];
      }
      return true;
    }
  }
 
  return false;
}
 
static bool bmesh_test_loose_edge(BMEdge *edge)
{
  /* Actual loose edge. */
  if (edge->l == nullptr) {
    return true;
  }
 
  /* Loose edge due to hidden adjacent faces. */
  BMIter iter;
  BMFace *face;
  BM_ITER_ELEM (face, &iter, edge, BM_FACES_OF_EDGE) {
    if (BM_elem_flag_test(face, BM_ELEM_HIDDEN) == 0) {
      return false;
    }
  }
  return true;
}
 
void transform_convert_mesh_connectivity_distance(BMesh *bm,
                                                  const float mtx[3][3],
                                                  float *dists,
                                                  int *index)
{
  BLI_LINKSTACK_DECLARE(queue, BMEdge *);
 
  /* Any BM_ELEM_TAG'd edge is in 'queue_next', so we don't add in twice. */
  const int tag_queued = BM_ELEM_TAG;
  const int tag_loose = BM_ELEM_TAG_ALT;
 
  BLI_LINKSTACK_DECLARE(queue_next, BMEdge *);
 
  BLI_LINKSTACK_INIT(queue);
  BLI_LINKSTACK_INIT(queue_next);
 
  {
    /* Set indexes and initial distances for selected vertices. */
    BMIter viter;
    BMVert *v;
    int i;
 
    BM_ITER_MESH_INDEX (v, &viter, bm, BM_VERTS_OF_MESH, i) {
      float dist;
      BM_elem_index_set(v, i); /* set_inline */
 
      if (BM_elem_flag_test(v, BM_ELEM_SELECT) == 0 || BM_elem_flag_test(v, BM_ELEM_HIDDEN)) {
        dist = FLT_MAX;
        if (index != nullptr) {
          index[i] = i;
        }
      }
      else {
        dist = 0.0f;
        if (index != nullptr) {
          index[i] = i;
        }
      }
 
      dists[i] = dist;
    }
    bm->elem_index_dirty &= ~BM_VERT;
  }
 
  {
    /* Add edges with at least one selected vertex to the queue. */
    BMIter eiter;
    BMEdge *e;
 
    BM_ITER_MESH (e, &eiter, bm, BM_EDGES_OF_MESH) {
 
      /* Always clear to satisfy the assert, also predictable to leave in cleared state. */
      BM_elem_flag_disable(e, tag_queued);
 
      if (BM_elem_flag_test(e, BM_ELEM_HIDDEN)) {
        continue;
      }
 
      BMVert *v1 = e->v1;
      BMVert *v2 = e->v2;
      int i1 = BM_elem_index_get(v1);
      int i2 = BM_elem_index_get(v2);
 
      if (dists[i1] != FLT_MAX || dists[i2] != FLT_MAX) {
        BLI_LINKSTACK_PUSH(queue, e);
      }
      BM_elem_flag_set(e, tag_loose, bmesh_test_loose_edge(e));
    }
  }
 
  do {
    BMEdge *e;
 
    while ((e = BLI_LINKSTACK_POP(queue))) {
      BMVert *v1 = e->v1;
      BMVert *v2 = e->v2;
      int i1 = BM_elem_index_get(v1);
      int i2 = BM_elem_index_get(v2);
 
      if (BM_elem_flag_test(e, tag_loose) || (dists[i1] == FLT_MAX || dists[i2] == FLT_MAX)) {
        /* Propagate along edge from vertex with smallest to largest distance. */
        if (dists[i1] > dists[i2]) {
          std::swap(i1, i2);
          std::swap(v1, v2);
        }
 
        if (bmesh_test_dist_add(v2, v1, nullptr, dists, index, mtx)) {
          /* Add adjacent loose edges to the queue, or all edges if this is a loose edge.
           * Other edges are handled by propagation across edges below. */
          BMEdge *e_other;
          BMIter eiter;
          BM_ITER_ELEM (e_other, &eiter, v2, BM_EDGES_OF_VERT) {
            if (e_other != e && BM_elem_flag_test(e_other, tag_queued) == 0 &&
                !BM_elem_flag_test(e_other, BM_ELEM_HIDDEN) &&
                (BM_elem_flag_test(e, tag_loose) || BM_elem_flag_test(e_other, tag_loose)))
            {
              BM_elem_flag_enable(e_other, tag_queued);
              BLI_LINKSTACK_PUSH(queue_next, e_other);
            }
          }
        }
      }
 
      if (!BM_elem_flag_test(e, tag_loose)) {
        /* Propagate across edge to vertices in adjacent faces. */
        BMLoop *l;
        BMIter liter;
        BM_ITER_ELEM (l, &liter, e, BM_LOOPS_OF_EDGE) {
          if (BM_elem_flag_test(l->f, BM_ELEM_HIDDEN)) {
            continue;
          }
          /* Don't check hidden edges or vertices in this loop
           * since any hidden edge causes the face to be hidden too. */
          for (BMLoop *l_other = l->next->next; l_other != l; l_other = l_other->next) {
            BMVert *v_other = l_other->v;
            BLI_assert(!ELEM(v_other, v1, v2));
 
            if (bmesh_test_dist_add(v_other, v1, v2, dists, index, mtx)) {
              /* Add adjacent edges to the queue, if they are ready to propagate across/along.
               * Always propagate along loose edges, and for other edges only propagate across
               * if both vertices have a known distances. */
              BMEdge *e_other;
              BMIter eiter;
              BM_ITER_ELEM (e_other, &eiter, v_other, BM_EDGES_OF_VERT) {
                if (e_other != e && BM_elem_flag_test(e_other, tag_queued) == 0 &&
                    !BM_elem_flag_test(e_other, BM_ELEM_HIDDEN) &&
                    (BM_elem_flag_test(e_other, tag_loose) ||
                     dists[BM_elem_index_get(BM_edge_other_vert(e_other, v_other))] != FLT_MAX))
                {
                  BM_elem_flag_enable(e_other, tag_queued);
                  BLI_LINKSTACK_PUSH(queue_next, e_other);
                }
              }
            }
          }
        }
      }
    }
 
    /* Clear for the next loop. */
    for (LinkNode *lnk = queue_next; lnk; lnk = lnk->next) {
      BMEdge *e_link = static_cast<BMEdge *>(lnk->link);
 
      BM_elem_flag_disable(e_link, tag_queued);
    }
 
    BLI_LINKSTACK_SWAP(queue, queue_next);
 
    /* None should be tagged now since 'queue_next' is empty. */
    BLI_assert(BM_iter_mesh_count_flag(BM_EDGES_OF_MESH, bm, tag_queued, true) == 0);
  } while (BLI_LINKSTACK_SIZE(queue));
 
  BLI_LINKSTACK_FREE(queue);
  BLI_LINKSTACK_FREE(queue_next);
}
 
/* -------------------------------------------------------------------- */
/* Used for both mirror epsilon and TD_MIRROR_EDGE_ */
#define TRANSFORM_MAXDIST_MIRROR 0.00002f
 
static bool is_in_quadrant_v3(const float co[3], const int quadrant[3], const float epsilon)
{
  if (quadrant[0] && ((co[0] * quadrant[0]) < -epsilon)) {
    return false;
  }
  if (quadrant[1] && ((co[1] * quadrant[1]) < -epsilon)) {
    return false;
  }
  if (quadrant[2] && ((co[2] * quadrant[2]) < -epsilon)) {
    return false;
  }
  return true;
}
 
void transform_convert_mesh_mirrordata_calc(BMEditMesh *em,
                                            const bool use_select,
                                            const bool use_topology,
                                            const bool mirror_axis[3],
                                            TransMirrorData *r_mirror_data)
{
  MirrorDataVert *vert_map;
 
  BMesh *bm = em->bm;
  BMVert *eve;
  BMIter iter;
  int i, flag, totvert = bm->totvert;
 
  vert_map = static_cast<MirrorDataVert *>(MEM_callocN(totvert * sizeof(*vert_map), __func__));
 
  float select_sum[3] = {0};
  BM_ITER_MESH_INDEX (eve, &iter, bm, BM_VERTS_OF_MESH, i) {
    vert_map[i] = MirrorDataVert{-1, 0};
    if (BM_elem_flag_test(eve, BM_ELEM_HIDDEN)) {
      continue;
    }
    if (BM_elem_flag_test(eve, BM_ELEM_SELECT)) {
      add_v3_v3(select_sum, eve->co);
    }
  }
 
  /* Tag only elements that will be transformed within the quadrant. */
  int quadrant[3];
  for (int a = 0; a < 3; a++) {
    if (mirror_axis[a]) {
      quadrant[a] = select_sum[a] >= 0.0f ? 1 : -1;
    }
    else {
      quadrant[a] = 0;
    }
  }
 
  uint mirror_elem_len = 0;
  int *index[3] = {nullptr, nullptr, nullptr};
  bool is_single_mirror_axis = (mirror_axis[0] + mirror_axis[1] + mirror_axis[2]) == 1;
  bool test_selected_only = use_select && is_single_mirror_axis;
  for (int a = 0; a < 3; a++) {
    if (!mirror_axis[a]) {
      continue;
    }
 
    index[a] = static_cast<int *>(MEM_mallocN(totvert * sizeof(*index[a]), __func__));
    EDBM_verts_mirror_cache_begin_ex(
        em, a, false, test_selected_only, true, use_topology, TRANSFORM_MAXDIST_MIRROR, index[a]);
 
    flag = TD_MIRROR_X << a;
    BM_ITER_MESH_INDEX (eve, &iter, bm, BM_VERTS_OF_MESH, i) {
      int i_mirr = index[a][i];
      if (i_mirr < 0) {
        continue;
      }
      if (BM_elem_flag_test(eve, BM_ELEM_HIDDEN)) {
        continue;
      }
      if (use_select && !BM_elem_flag_test(eve, BM_ELEM_SELECT)) {
        continue;
      }
      if (!is_in_quadrant_v3(eve->co, quadrant, TRANSFORM_MAXDIST_MIRROR)) {
        continue;
      }
      if (vert_map[i_mirr].flag != 0) {
        /* One mirror per element.
         * It can happen when vertices occupy the same position. */
        continue;
      }
      if (vert_map[i].flag & flag) {
        /* It's already a mirror.
         * Avoid a mirror vertex dependency cycle.
         * This can happen when the vertices are within the mirror threshold. */
        continue;
      }
 
      vert_map[i_mirr] = MirrorDataVert{i, flag};
      mirror_elem_len++;
    }
  }
 
  if (!mirror_elem_len) {
    MEM_freeN(vert_map);
    vert_map = nullptr;
  }
  else if (!is_single_mirror_axis) {
    /* Adjustment for elements that are mirrors of mirrored elements. */
    for (int a = 0; a < 3; a++) {
      if (!mirror_axis[a]) {
        continue;
      }
 
      flag = TD_MIRROR_X << a;
      for (i = 0; i < totvert; i++) {
        int i_mirr = index[a][i];
        if (i_mirr < 0) {
          continue;
        }
        if (vert_map[i].index != -1 && !(vert_map[i].flag & flag)) {
          if (vert_map[i_mirr].index == -1) {
            mirror_elem_len++;
          }
          vert_map[i_mirr].index = vert_map[i].index;
          vert_map[i_mirr].flag |= vert_map[i].flag | flag;
        }
      }
    }
  }
 
  MEM_SAFE_FREE(index[0]);
  MEM_SAFE_FREE(index[1]);
  MEM_SAFE_FREE(index[2]);
 
  r_mirror_data->vert_map = vert_map;
  r_mirror_data->mirror_elem_len = mirror_elem_len;
}
 
void transform_convert_mesh_mirrordata_free(TransMirrorData *mirror_data)
{
  if (mirror_data->vert_map) {
    MEM_freeN(mirror_data->vert_map);
  }
}
 
/* -------------------------------------------------------------------- */
void transform_convert_mesh_crazyspace_detect(TransInfo *t,
                                              TransDataContainer *tc,
                                              BMEditMesh *em,
                                              TransMeshDataCrazySpace *r_crazyspace_data)
{
  float(*quats)[4] = nullptr;
  const int prop_mode = (t->flag & T_PROP_EDIT) ? (t->flag & T_PROP_EDIT_ALL) : 0;
  if (BKE_modifiers_get_cage_index(t->scene, tc->obedit, nullptr, true) != -1) {
    blender::Array<blender::float3, 0> defcos;
    int totleft = -1;
    if (BKE_modifiers_is_correctable_deformed(t->scene, tc->obedit)) {
      BKE_scene_graph_evaluated_ensure(t->depsgraph, CTX_data_main(t->context));
 
      /* Use evaluated state because we need b-bone cache. */
      Scene *scene_eval = (Scene *)DEG_get_evaluated_id(t->depsgraph, &t->scene->id);
      Object *obedit_eval = (Object *)DEG_get_evaluated_id(t->depsgraph, &tc->obedit->id);
      BMEditMesh *em_eval = BKE_editmesh_from_object(obedit_eval);
      /* Check if we can use deform matrices for modifier from the
       * start up to stack, they are more accurate than quats. */
      totleft = BKE_crazyspace_get_first_deform_matrices_editbmesh(
          t->depsgraph, scene_eval, obedit_eval, em_eval, r_crazyspace_data->defmats, defcos);
    }
 
    /* If we still have more modifiers, also do crazy-space
     * correction with \a quats, relative to the coordinates after
     * the modifiers that support deform matrices \a defcos. */
 
#if 0 /* TODO(@ideasman42): fix crazy-space & extrude so it can be enabled for general use. */
    if ((totleft > 0) || (totleft == -1))
#else
    if (totleft > 0)
#endif
    {
      const blender::Array<blender::float3> mappedcos = BKE_crazyspace_get_mapped_editverts(
          t->depsgraph, tc->obedit);
      quats = static_cast<float(*)[4]>(
          MEM_mallocN(em->bm->totvert * sizeof(*quats), "crazy quats"));
      BKE_crazyspace_set_quats_editmesh(em, defcos, mappedcos, quats, !prop_mode);
    }
  }
  r_crazyspace_data->quats = quats;
}
 
void transform_convert_mesh_crazyspace_transdata_set(const float mtx[3][3],
                                                     const float smtx[3][3],
                                                     const float defmat[3][3],
                                                     const float quat[4],
                                                     TransData *r_td)
{
  /* CrazySpace. */
  if (quat || defmat) {
    float mat[3][3], qmat[3][3], imat[3][3];
 
    /* Use both or either quat and defmat correction. */
    if (quat) {
      quat_to_mat3(qmat, quat);
 
      if (defmat) {
        mul_m3_series(mat, defmat, qmat, mtx);
      }
      else {
        mul_m3_m3m3(mat, mtx, qmat);
      }
    }
    else {
      mul_m3_m3m3(mat, mtx, defmat);
    }
 
    invert_m3_m3(imat, mat);
 
    copy_m3_m3(r_td->smtx, imat);
    copy_m3_m3(r_td->mtx, mat);
  }
  else {
    copy_m3_m3(r_td->smtx, smtx);
    copy_m3_m3(r_td->mtx, mtx);
  }
}
 
void transform_convert_mesh_crazyspace_free(TransMeshDataCrazySpace *r_crazyspace_data)
{
  if (r_crazyspace_data->quats) {
    MEM_freeN(r_crazyspace_data->quats);
  }
}
 
/* -------------------------------------------------------------------- */
static void mesh_transdata_center_copy(const TransIslandData *island_data,
                                       const int island_index,
                                       const float iloc[3],
                                       float r_center[3])
{
  if (island_data->center && island_index != -1) {
    copy_v3_v3(r_center, island_data->center[island_index]);
  }
  else {
    copy_v3_v3(r_center, iloc);
  }
}
 
/* Way to overwrite what data is edited with transform. */
static void VertsToTransData(TransInfo *t,
                             TransData *td,
                             TransDataExtension *tx,
                             BMEditMesh *em,
                             BMVert *eve,
                             const TransIslandData *island_data,
                             const int island_index)
{
  float *no, _no[3];
  BLI_assert(BM_elem_flag_test(eve, BM_ELEM_HIDDEN) == 0);
 
  td->flag = 0;
  // if (key)
  //  td->loc = key->co;
  // else
  td->loc = eve->co;
  copy_v3_v3(td->iloc, td->loc);
 
  if ((t->mode == TFM_SHRINKFATTEN) && (em->selectmode & SCE_SELECT_FACE) &&
      BM_elem_flag_test(eve, BM_ELEM_SELECT) && BM_vert_calc_normal_ex(eve, BM_ELEM_SELECT, _no))
  {
    no = _no;
  }
  else {
    no = eve->no;
  }
 
  mesh_transdata_center_copy(island_data, island_index, td->iloc, td->center);
 
  if ((island_index != -1) && island_data->axismtx) {
    copy_m3_m3(td->axismtx, island_data->axismtx[island_index]);
  }
  else if (t->around == V3D_AROUND_LOCAL_ORIGINS) {
    createSpaceNormal(td->axismtx, no);
  }
  else {
    /* Setting normals. */
    copy_v3_v3(td->axismtx[2], no);
    td->axismtx[0][0] = td->axismtx[0][1] = td->axismtx[0][2] = td->axismtx[1][0] =
        td->axismtx[1][1] = td->axismtx[1][2] = 0.0f;
  }
 
  td->ext = nullptr;
  td->val = nullptr;
  td->extra = eve;
  if (t->mode == TFM_SHRINKFATTEN) {
    td->ext = tx;
    tx->isize[0] = BM_vert_calc_shell_factor_ex(eve, no, BM_ELEM_SELECT);
  }
}
 
static void createTransEditVerts(bContext * /*C*/, TransInfo *t)
{
  FOREACH_TRANS_DATA_CONTAINER (t, tc) {
    TransDataExtension *tx = nullptr;
    BMEditMesh *em = BKE_editmesh_from_object(tc->obedit);
    Mesh *mesh = static_cast<Mesh *>(tc->obedit->data);
    BMesh *bm = em->bm;
    BMVert *eve;
    BMIter iter;
    float mtx[3][3], smtx[3][3];
    int a;
    const int prop_mode = (t->flag & T_PROP_EDIT) ? (t->flag & T_PROP_EDIT_ALL) : 0;
 
    TransIslandData island_data = {nullptr};
    TransMirrorData mirror_data = {nullptr};
    TransMeshDataCrazySpace crazyspace_data = {};
 
    /* Avoid editing locked shapes. */
    if (t->mode != TFM_DUMMY &&
        blender::ed::object::shape_key_report_if_locked(tc->obedit, t->reports))
    {
      continue;
    }
 
    /* Support other objects using proportional editing to adjust these, unless connected is
     * enabled. */
    if ((!prop_mode || (prop_mode & T_PROP_CONNECTED)) && (bm->totvertsel == 0)) {
      continue;
    }
 
    int data_len = 0;
    if (prop_mode) {
      BM_ITER_MESH (eve, &iter, bm, BM_VERTS_OF_MESH) {
        if (!BM_elem_flag_test(eve, BM_ELEM_HIDDEN)) {
          data_len++;
        }
      }
    }
    else {
      data_len = bm->totvertsel;
    }
 
    if (data_len == 0) {
      continue;
    }
 
    /* Snap rotation along normal needs a common axis for whole islands,
     * otherwise one get random crazy results, see #59104.
     * However, we do not want to use the island center for the pivot/translation reference. */
    const bool is_snap_rotate = ((t->mode == TFM_TRANSLATION) &&
                                 /* There is not guarantee that snapping
                                  * is initialized yet at this point... */
                                 (usingSnappingNormal(t) ||
                                  (t->settings->snap_flag & SCE_SNAP_ROTATE) != 0) &&
                                 (t->around != V3D_AROUND_LOCAL_ORIGINS));
 
    /* Even for translation this is needed because of island-orientation, see: #51651. */
    const bool is_island_center = (t->around == V3D_AROUND_LOCAL_ORIGINS) || is_snap_rotate;
    if (is_island_center) {
      /* In this specific case, near-by vertices will need to know
       * the island of the nearest connected vertex. */
      const bool calc_single_islands = ((prop_mode & T_PROP_CONNECTED) &&
                                        (t->around == V3D_AROUND_LOCAL_ORIGINS) &&
                                        (em->selectmode & SCE_SELECT_VERTEX));
 
      const bool calc_island_center = !is_snap_rotate;
      /* The island axismtx is only necessary in some modes.
       * TODO(Germano): Extend the list to exclude other modes. */
      const bool calc_island_axismtx = !ELEM(t->mode, TFM_SHRINKFATTEN);
 
      transform_convert_mesh_islands_calc(
          em, calc_single_islands, calc_island_center, calc_island_axismtx, &island_data);
    }
 
    copy_m3_m4(mtx, tc->obedit->object_to_world().ptr());
    /* We use a pseudo-inverse so that when one of the axes is scaled to 0,
     * matrix inversion still works and we can still moving along the other. */
    pseudoinverse_m3_m3(smtx, mtx, PSEUDOINVERSE_EPSILON);
 
    /* Original index of our connected vertex when connected distances are calculated.
     * Optional, allocate if needed. */
    int *dists_index = nullptr;
    float *dists = nullptr;
    if (prop_mode & T_PROP_CONNECTED) {
      dists = static_cast<float *>(MEM_mallocN(bm->totvert * sizeof(float), __func__));
      if (is_island_center) {
        dists_index = static_cast<int *>(MEM_mallocN(bm->totvert * sizeof(int), __func__));
      }
      transform_convert_mesh_connectivity_distance(em->bm, mtx, dists, dists_index);
    }
 
    /* Create TransDataMirror. */
    if (tc->use_mirror_axis_any) {
      bool use_topology = (mesh->editflag & ME_EDIT_MIRROR_TOPO) != 0;
      bool use_select = (t->flag & T_PROP_EDIT) == 0;
      const bool mirror_axis[3] = {
          bool(tc->use_mirror_axis_x), bool(tc->use_mirror_axis_y), bool(tc->use_mirror_axis_z)};
      transform_convert_mesh_mirrordata_calc(
          em, use_select, use_topology, mirror_axis, &mirror_data);
 
      if (mirror_data.vert_map) {
        tc->data_mirror_len = mirror_data.mirror_elem_len;
        tc->data_mirror = static_cast<TransDataMirror *>(
            MEM_callocN(mirror_data.mirror_elem_len * sizeof(*tc->data_mirror), __func__));
 
        BM_ITER_MESH_INDEX (eve, &iter, bm, BM_VERTS_OF_MESH, a) {
          if (prop_mode || BM_elem_flag_test(eve, BM_ELEM_SELECT)) {
            if (mirror_data.vert_map[a].index != -1) {
              data_len--;
            }
          }
        }
      }
    }
 
    /* Detect CrazySpace [tm]. */
    transform_convert_mesh_crazyspace_detect(t, tc, em, &crazyspace_data);
 
    /* Create TransData. */
    BLI_assert(data_len >= 1);
    tc->data_len = data_len;
    tc->data = static_cast<TransData *>(
        MEM_callocN(data_len * sizeof(TransData), "TransObData(Mesh EditMode)"));
    if (t->mode == TFM_SHRINKFATTEN) {
      /* Warning: this is overkill, we only need 2 extra floats,
       * but this stores loads of extra stuff, for TFM_SHRINKFATTEN its even more overkill
       * since we may not use the 'alt' transform mode to maintain shell thickness,
       * but with generic transform code its hard to lazy init variables. */
      tx = tc->data_ext = static_cast<TransDataExtension *>(
          MEM_callocN(tc->data_len * sizeof(TransDataExtension), "TransObData ext"));
    }
 
    TransData *tob = tc->data;
    TransDataMirror *td_mirror = tc->data_mirror;
    BM_ITER_MESH_INDEX (eve, &iter, bm, BM_VERTS_OF_MESH, a) {
      if (BM_elem_flag_test(eve, BM_ELEM_HIDDEN)) {
        continue;
      }
 
      int island_index = -1;
      if (island_data.island_vert_map) {
        const int connected_index = (dists_index && dists_index[a] != -1) ? dists_index[a] : a;
        island_index = island_data.island_vert_map[connected_index];
      }
 
      if (mirror_data.vert_map && mirror_data.vert_map[a].index != -1) {
        int elem_index = mirror_data.vert_map[a].index;
        BMVert *v_src = BM_vert_at_index(bm, elem_index);
 
        if (BM_elem_flag_test(eve, BM_ELEM_SELECT)) {
          mirror_data.vert_map[a].flag |= TD_SELECTED;
        }
 
        td_mirror->extra = eve;
        td_mirror->loc = eve->co;
        copy_v3_v3(td_mirror->iloc, eve->co);
        td_mirror->flag = mirror_data.vert_map[a].flag;
        td_mirror->loc_src = v_src->co;
        mesh_transdata_center_copy(&island_data, island_index, td_mirror->iloc, td_mirror->center);
 
        td_mirror++;
      }
      else if (prop_mode || BM_elem_flag_test(eve, BM_ELEM_SELECT)) {
        /* Do not use the island center in case we are using islands
         * only to get axis for snap/rotate to normal... */
        VertsToTransData(t, tob, tx, em, eve, &island_data, island_index);
        if (tx) {
          tx++;
        }
 
        /* Selected. */
        if (BM_elem_flag_test(eve, BM_ELEM_SELECT)) {
          tob->flag |= TD_SELECTED;
        }
 
        if (prop_mode) {
          if (prop_mode & T_PROP_CONNECTED) {
            tob->dist = dists[a];
          }
          else {
            tob->dist = FLT_MAX;
          }
        }
 
        /* CrazySpace. */
        transform_convert_mesh_crazyspace_transdata_set(
            mtx,
            smtx,
            !crazyspace_data.defmats.is_empty() ? crazyspace_data.defmats[a].ptr() : nullptr,
            crazyspace_data.quats && BM_elem_flag_test(eve, BM_ELEM_TAG) ?
                crazyspace_data.quats[a] :
                nullptr,
            tob);
 
        if (tc->use_mirror_axis_any) {
          if (tc->use_mirror_axis_x && fabsf(tob->loc[0]) < TRANSFORM_MAXDIST_MIRROR) {
            tob->flag |= TD_MIRROR_EDGE_X;
          }
          if (tc->use_mirror_axis_y && fabsf(tob->loc[1]) < TRANSFORM_MAXDIST_MIRROR) {
            tob->flag |= TD_MIRROR_EDGE_Y;
          }
          if (tc->use_mirror_axis_z && fabsf(tob->loc[2]) < TRANSFORM_MAXDIST_MIRROR) {
            tob->flag |= TD_MIRROR_EDGE_Z;
          }
        }
 
        tob++;
      }
    }
 
    transform_convert_mesh_islanddata_free(&island_data);
    transform_convert_mesh_mirrordata_free(&mirror_data);
    transform_convert_mesh_crazyspace_free(&crazyspace_data);
    if (dists) {
      MEM_freeN(dists);
    }
    if (dists_index) {
      MEM_freeN(dists_index);
    }
 
    /* WORKAROUND: The transform operators rely on looptris being up-to-date.
     * However, this is not always the case, especially when called from scripts.
     * If this happens, to prevent update issues, make sure the size of #BMEditMesh::looptris
     * arrays aligns with the number looptris to update. */
    const bool looptri_is_dirty = em->looptris.size() !=
                                  poly_to_tri_count(bm->totface, bm->totloop);
    if (looptri_is_dirty) {
      BKE_editmesh_looptris_calc(em);
    }
  }
}
 
/* -------------------------------------------------------------------- */
static BMPartialUpdate *mesh_partial_ensure(TransInfo *t,
                                            TransDataContainer *tc,
                                            enum ePartialType partial_type)
{
  TransCustomDataMesh *tcmd = mesh_customdata_ensure(tc);
 
  TransCustomData_PartialUpdate *pupdate = &tcmd->partial_update[partial_type];
 
  if (pupdate->cache) {
 
    /* Recalculate partial update data when the proportional editing size changes.
     *
     * Note that decreasing the proportional editing size requires the existing
     * partial data is used before recreating this partial data at the smaller size.
     * Since excluding geometry from being transformed requires an update.
     *
     * Extra logic is needed to account for this situation. */
 
    bool recalc;
    if (pupdate->prop_size_prev < t->prop_size) {
      /* Size increase, simply recalculate. */
      recalc = true;
    }
    else if (pupdate->prop_size_prev > t->prop_size) {
      /* Size decreased, first use this partial data since reducing the size will transform
       * geometry which needs recalculating. */
      pupdate->prop_size_prev = t->prop_size;
      recalc = false;
    }
    else if (pupdate->prop_size != t->prop_size) {
      BLI_assert(pupdate->prop_size > pupdate->prop_size_prev);
      recalc = true;
    }
    else {
      BLI_assert(t->prop_size == pupdate->prop_size_prev);
      recalc = false;
    }
 
    if (!recalc) {
      return pupdate->cache;
    }
 
    BM_mesh_partial_destroy(pupdate->cache);
    pupdate->cache = nullptr;
  }
 
  BMEditMesh *em = BKE_editmesh_from_object(tc->obedit);
 
  BM_mesh_elem_index_ensure(em->bm, BM_VERT);
 
  /* Only use `verts_group` or `verts_mask`. */
  int *verts_group = nullptr;
  int verts_group_count = 0; /* Number of non-zero elements in `verts_group`. */
 
  BLI_bitmap *verts_mask = nullptr;
  int verts_mask_count = 0; /* Number of elements enabled in `verts_mask`. */
 
  if ((partial_type == PARTIAL_TYPE_GROUP) && ((t->flag & T_PROP_EDIT) || tc->use_mirror_axis_any))
  {
    verts_group = static_cast<int *>(
        MEM_callocN(sizeof(*verts_group) * em->bm->totvert, __func__));
    int i;
    TransData *td;
    for (i = 0, td = tc->data; i < tc->data_len; i++, td++) {
      if (td->factor == 0.0f) {
        continue;
      }
      const BMVert *v = (BMVert *)td->extra;
      const int v_index = BM_elem_index_get(v);
      BLI_assert(verts_group[v_index] == 0);
      if (td->factor < 1.0f) {
        /* Don't use grouping logic with the factor is under 1.0. */
        verts_group[v_index] = -1;
      }
      else {
        BLI_assert(td->factor == 1.0f);
        verts_group[v_index] = 1;
        if (tc->use_mirror_axis_any) {
          /* Use bits 2-4 for central alignment (don't overlap the first bit). */
          const int flag = td->flag & (TD_MIRROR_EDGE_X | TD_MIRROR_EDGE_Y | TD_MIRROR_EDGE_Z);
          verts_group[v_index] |= (flag >> TD_MIRROR_EDGE_AXIS_SHIFT) << 1;
        }
      }
      verts_mask_count += 1;
    }
 
    TransDataMirror *td_mirror = tc->data_mirror;
    for (i = 0; i < tc->data_mirror_len; i++, td_mirror++) {
      BMVert *v_mirr = (BMVert *)POINTER_OFFSET(td_mirror->loc_src, -offsetof(BMVert, co));
      /* The equality check is to account for the case when topology mirror moves
       * the vertex from it's original location to match it's symmetrical position,
       * with proportional editing enabled. */
      const int v_mirr_index = BM_elem_index_get(v_mirr);
      if (verts_group[v_mirr_index] == 0 && equals_v3v3(td_mirror->loc, td_mirror->iloc)) {
        continue;
      }
 
      BMVert *v_mirr_other = (BMVert *)td_mirror->extra;
      /* This assert should never fail since there is no overlap
       * between mirrored vertices and non-mirrored. */
      BLI_assert(verts_group[BM_elem_index_get(v_mirr_other)] == 0);
      const int v_mirr_other_index = BM_elem_index_get(v_mirr_other);
 
      if (verts_group[v_mirr_index] == -1) {
        verts_group[v_mirr_other_index] = -1;
      }
      else {
        /* Use bits 5-8 for mirror (don't overlap previous bits). */
        const int flag = td_mirror->flag & (TD_MIRROR_X | TD_MIRROR_Y | TD_MIRROR_Z);
        verts_group[v_mirr_other_index] |= (flag >> TD_MIRROR_EDGE_AXIS_SHIFT) << 4;
      }
      verts_mask_count += 1;
    }
  }
  else {
    /* See the body of the comments in the previous block for details. */
    verts_mask = BLI_BITMAP_NEW(em->bm->totvert, __func__);
    int i;
    TransData *td;
    for (i = 0, td = tc->data; i < tc->data_len; i++, td++) {
      if (td->factor == 0.0f) {
        continue;
      }
      const BMVert *v = (BMVert *)td->extra;
      const int v_index = BM_elem_index_get(v);
      BLI_assert(!BLI_BITMAP_TEST(verts_mask, v_index));
      BLI_BITMAP_ENABLE(verts_mask, v_index);
      verts_mask_count += 1;
    }
 
    TransDataMirror *td_mirror = tc->data_mirror;
    for (i = 0; i < tc->data_mirror_len; i++, td_mirror++) {
      BMVert *v_mirr = (BMVert *)POINTER_OFFSET(td_mirror->loc_src, -offsetof(BMVert, co));
      if (!BLI_BITMAP_TEST(verts_mask, BM_elem_index_get(v_mirr)) &&
          equals_v3v3(td_mirror->loc, td_mirror->iloc))
      {
        continue;
      }
 
      BMVert *v_mirr_other = (BMVert *)td_mirror->extra;
      BLI_assert(!BLI_BITMAP_TEST(verts_mask, BM_elem_index_get(v_mirr_other)));
      const int v_mirr_other_index = BM_elem_index_get(v_mirr_other);
      BLI_BITMAP_ENABLE(verts_mask, v_mirr_other_index);
      verts_mask_count += 1;
    }
  }
 
  switch (partial_type) {
    case PARTIAL_TYPE_ALL: {
      BMPartialUpdate_Params params{};
      params.do_tessellate = true;
      params.do_normals = true;
      pupdate->cache = BM_mesh_partial_create_from_verts(
          em->bm, &params, verts_mask, verts_mask_count);
      break;
    }
    case PARTIAL_TYPE_GROUP: {
      BMPartialUpdate_Params params{};
      params.do_tessellate = true;
      params.do_normals = true;
      pupdate->cache = (verts_group ? BM_mesh_partial_create_from_verts_group_multi(
                                          em->bm, &params, verts_group, verts_group_count) :
                                      BM_mesh_partial_create_from_verts_group_single(
                                          em->bm, &params, verts_mask, verts_mask_count));
      break;
    }
    case PARTIAL_NONE: {
      BLI_assert_unreachable();
    }
  }
 
  if (verts_group) {
    MEM_freeN(verts_group);
  }
  else {
    MEM_freeN(verts_mask);
  }
 
  pupdate->prop_size_prev = t->prop_size;
  pupdate->prop_size = t->prop_size;
 
  return pupdate->cache;
}
 
static void mesh_partial_types_calc(TransInfo *t, PartialTypeState *r_partial_state)
{
  /* Calculate the kind of partial updates which can be performed. */
  enum ePartialType partial_for_normals = PARTIAL_NONE;
  enum ePartialType partial_for_looptris = PARTIAL_NONE;
 
  /* Note that operations such as #TFM_CREASE are not handled here
   * (if they were, leaving as #PARTIAL_NONE would be appropriate). */
  switch (t->mode) {
    case TFM_TRANSLATION: {
      partial_for_looptris = PARTIAL_TYPE_GROUP;
      partial_for_normals = PARTIAL_TYPE_GROUP;
      /* Translation can rotate when snapping to normal. */
      if (transform_snap_is_active(t) && usingSnappingNormal(t) && validSnappingNormal(t)) {
        partial_for_normals = PARTIAL_TYPE_ALL;
      }
      break;
    }
    case TFM_ROTATION: {
      partial_for_looptris = PARTIAL_TYPE_GROUP;
      partial_for_normals = PARTIAL_TYPE_ALL;
      break;
    }
    case TFM_RESIZE: {
      partial_for_looptris = PARTIAL_TYPE_GROUP;
      partial_for_normals = PARTIAL_TYPE_GROUP;
      /* Non-uniform scale needs to recalculate all normals
       * since their relative locations change.
       * Uniform negative scale can keep normals as-is since the faces are flipped,
       * normals remain unchanged. */
      if ((t->con.mode & CON_APPLY) ||
          (t->values_final[0] != t->values_final[1] || t->values_final[0] != t->values_final[2]))
      {
        partial_for_normals = PARTIAL_TYPE_ALL;
      }
      break;
    }
    default: {
      partial_for_looptris = PARTIAL_TYPE_ALL;
      partial_for_normals = PARTIAL_TYPE_ALL;
      break;
    }
  }
 
  /* With projection, transform isn't affine. */
  if (transform_snap_project_individual_is_active(t)) {
    if (partial_for_looptris == PARTIAL_TYPE_GROUP) {
      partial_for_looptris = PARTIAL_TYPE_ALL;
    }
    if (partial_for_normals == PARTIAL_TYPE_GROUP) {
      partial_for_normals = PARTIAL_TYPE_ALL;
    }
  }
 
  r_partial_state->for_looptris = partial_for_looptris;
  r_partial_state->for_normals = partial_for_normals;
}
 
static void mesh_partial_update(TransInfo *t,
                                TransDataContainer *tc,
                                const PartialTypeState *partial_state)
{
  BMEditMesh *em = BKE_editmesh_from_object(tc->obedit);
 
  TransCustomDataMesh *tcmd = mesh_customdata_ensure(tc);
 
  const PartialTypeState *partial_state_prev = &tcmd->partial_update_state_prev;
 
  /* Promote the partial update types based on the previous state
   * so the values that no longer modified are reset before being left as-is.
   * Needed for translation which can toggle snap-to-normal during transform. */
  const enum ePartialType partial_for_looptris = std::max(partial_state->for_looptris,
                                                          partial_state_prev->for_looptris);
  const enum ePartialType partial_for_normals = std::max(partial_state->for_normals,
                                                         partial_state_prev->for_normals);
 
  if ((partial_for_looptris == PARTIAL_TYPE_ALL) && (partial_for_normals == PARTIAL_TYPE_ALL) &&
      (em->bm->totvert == em->bm->totvertsel))
  {
    /* The additional cost of generating the partial connectivity data isn't justified
     * when all data needs to be updated.
     *
     * While proportional editing can cause all geometry to need updating with a partial
     * selection. It's impractical to calculate this ahead of time. Further, the down side of
     * using partial updates when their not needed is negligible. */
    BKE_editmesh_looptris_and_normals_calc(em);
  }
  else {
    if (partial_for_looptris != PARTIAL_NONE) {
      BMPartialUpdate *bmpinfo = mesh_partial_ensure(t, tc, partial_for_looptris);
      BMeshCalcTessellation_Params params{};
      params.face_normals = true;
      BKE_editmesh_looptris_calc_with_partial_ex(em, bmpinfo, &params);
    }
 
    if (partial_for_normals != PARTIAL_NONE) {
      BMPartialUpdate *bmpinfo = mesh_partial_ensure(t, tc, partial_for_normals);
      /* While not a large difference, take advantage of existing normals where possible. */
      const bool face_normals = !((partial_for_looptris == PARTIAL_TYPE_ALL) ||
                                  ((partial_for_looptris == PARTIAL_TYPE_GROUP) &&
                                   (partial_for_normals == PARTIAL_TYPE_GROUP)));
      BMeshNormalsUpdate_Params params{};
      params.face_normals = face_normals;
      BM_mesh_normals_update_with_partial_ex(em->bm, bmpinfo, &params);
    }
  }
 
  /* Store the previous requested (not the previous used),
   * since the values used may have been promoted based on the previous types. */
  tcmd->partial_update_state_prev = *partial_state;
}
 
/* -------------------------------------------------------------------- */
static void mesh_transdata_mirror_apply(TransDataContainer *tc)
{
  if (tc->use_mirror_axis_any) {
    int i;
    TransData *td;
    for (i = 0, td = tc->data; i < tc->data_len; i++, td++) {
      if (td->flag & (TD_MIRROR_EDGE_X | TD_MIRROR_EDGE_Y | TD_MIRROR_EDGE_Z)) {
        if (td->flag & TD_MIRROR_EDGE_X) {
          td->loc[0] = 0.0f;
        }
        if (td->flag & TD_MIRROR_EDGE_Y) {
          td->loc[1] = 0.0f;
        }
        if (td->flag & TD_MIRROR_EDGE_Z) {
          td->loc[2] = 0.0f;
        }
      }
    }
 
    TransDataMirror *td_mirror = tc->data_mirror;
    for (i = 0; i < tc->data_mirror_len; i++, td_mirror++) {
      copy_v3_v3(td_mirror->loc, td_mirror->loc_src);
      if (td_mirror->flag & TD_MIRROR_X) {
        td_mirror->loc[0] *= -1;
      }
      if (td_mirror->flag & TD_MIRROR_Y) {
        td_mirror->loc[1] *= -1;
      }
      if (td_mirror->flag & TD_MIRROR_Z) {
        td_mirror->loc[2] *= -1;
      }
    }
  }
}
 
static void recalcData_mesh(TransInfo *t)
{
  bool is_canceling = t->state == TRANS_CANCEL;
  /* Apply corrections. */
  if (!is_canceling) {
    transform_snap_project_individual_apply(t);
 
    bool do_mirror = !(t->flag & T_NO_MIRROR);
    FOREACH_TRANS_DATA_CONTAINER (t, tc) {
      /* Apply clipping after so we never project past the clip plane #25423. */
      transform_convert_clip_mirror_modifier_apply(tc);
 
      if (do_mirror) {
        mesh_transdata_mirror_apply(tc);
      }
 
      mesh_customdatacorrect_apply(tc, false);
    }
  }
  else {
    mesh_customdatacorrect_restore(t);
  }
 
  PartialTypeState partial_state;
  mesh_partial_types_calc(t, &partial_state);
 
  FOREACH_TRANS_DATA_CONTAINER (t, tc) {
    DEG_id_tag_update(static_cast<ID *>(tc->obedit->data), ID_RECALC_GEOMETRY);
 
    mesh_partial_update(t, tc, &partial_state);
  }
}
 
/* -------------------------------------------------------------------- */
static void special_aftertrans_update__mesh(bContext * /*C*/, TransInfo *t)
{
  const bool is_canceling = (t->state == TRANS_CANCEL);
  const bool use_automerge = !is_canceling && (t->flag & (T_AUTOMERGE | T_AUTOSPLIT)) != 0;
 
  if (!is_canceling && ELEM(t->mode, TFM_EDGE_SLIDE, TFM_VERT_SLIDE)) {
    /* NOTE(joeedh): Handle multi-res re-projection,
     * done on transform completion since it's really slow. */
    FOREACH_TRANS_DATA_CONTAINER (t, tc) {
      mesh_customdatacorrect_apply(tc, true);
    }
  }
 
  if (use_automerge) {
    FOREACH_TRANS_DATA_CONTAINER (t, tc) {
      BMEditMesh *em = BKE_editmesh_from_object(tc->obedit);
      BMesh *bm = em->bm;
      char hflag;
      bool has_face_sel = (bm->totfacesel != 0);
 
      if (tc->use_mirror_axis_any) {
        /* Rather than adjusting the selection (which the user would notice)
         * tag all mirrored verts, then auto-merge those. */
        BM_mesh_elem_hflag_disable_all(bm, BM_VERT, BM_ELEM_TAG, false);
 
        TransDataMirror *td_mirror = tc->data_mirror;
        for (int i = tc->data_mirror_len; i--; td_mirror++) {
          BM_elem_flag_enable((BMVert *)td_mirror->extra, BM_ELEM_TAG);
        }
 
        hflag = BM_ELEM_SELECT | BM_ELEM_TAG;
      }
      else {
        hflag = BM_ELEM_SELECT;
      }
 
      if (t->flag & T_AUTOSPLIT) {
        EDBM_automerge_and_split(
            tc->obedit, true, true, true, hflag, t->scene->toolsettings->doublimit);
      }
      else {
        EDBM_automerge(tc->obedit, true, hflag, t->scene->toolsettings->doublimit);
      }
 
      /* Special case, this is needed or faces won't re-select.
       * Flush selected edges to faces. */
      if (has_face_sel && (em->selectmode == SCE_SELECT_FACE)) {
        EDBM_selectmode_flush_ex(em, SCE_SELECT_EDGE);
      }
    }
  }
 
  FOREACH_TRANS_DATA_CONTAINER (t, tc) {
    /* Table needs to be created for each edit command, since vertices can move etc. */
    ED_mesh_mirror_spatial_table_end(tc->obedit);
    /* TODO(@ideasman42): xform: We need support for many mirror objects at once! */
    break;
  }
}
 
/* -------------------------------------------------------------------- */
Array<TransDataVertSlideVert> transform_mesh_vert_slide_data_create(
    const TransDataContainer *tc, Vector<float3> &r_loc_dst_buffer)
{
  int td_selected_len = 0;
  TransData *td = tc->data;
  for (int i = 0; i < tc->data_len; i++, td++) {
    if (!(td->flag & TD_SELECTED)) {
      /* The selected ones are sorted at the beginning. */
      break;
    }
    td_selected_len++;
  }
 
  Array<TransDataVertSlideVert> r_sv(td_selected_len);
 
  r_loc_dst_buffer.reserve(r_sv.size() * 4);
  td = tc->data;
  for (int i = 0; i < tc->data_len; i++, td++) {
    if (!(td->flag & TD_SELECTED)) {
      /* The selected ones are sorted at the beginning. */
      break;
    }
    const int size_prev = r_loc_dst_buffer.size();
 
    BMVert *v = static_cast<BMVert *>(td->extra);
    if (!v->e) {
      r_loc_dst_buffer.append(td->iloc);
    }
    else {
      BMIter eiter;
      BMEdge *e;
      BM_ITER_ELEM (e, &eiter, v, BM_EDGES_OF_VERT) {
        if (BM_elem_flag_test(e, BM_ELEM_HIDDEN)) {
          continue;
        }
        BMVert *v_other = BM_edge_other_vert(e, v);
        r_loc_dst_buffer.append(v_other->co);
      }
    }
 
    TransDataVertSlideVert &sv = r_sv[i];
    sv.td = &tc->data[i];
    /* The buffer address may change as the vector is resized. Avoid setting #Span. */
    // sv.targets = r_loc_dst_buffer.as_span().drop_front(size_prev);
 
    /* Store the buffer size temporarily in `target_curr`. */
    sv.co_link_curr = r_loc_dst_buffer.size() - size_prev;
  }
 
  int start = 0;
  for (TransDataVertSlideVert &sv : r_sv) {
    int size = sv.co_link_curr;
    sv.co_link_orig_3d = r_loc_dst_buffer.as_span().slice(start, size);
    sv.co_link_curr = 0;
    start += size;
  }
 
  return r_sv;
}
 
/* -------------------------------------------------------------------- */
static bool mesh_vert_is_inner(BMVert *v)
{
  return BM_vert_is_edge_pair(v) && !BM_vert_is_boundary(v);
}
 
static bool bm_loop_calc_opposite_co(const BMLoop *l_tmp, const float plane_no[3], float r_co[3])
{
  /* Skip adjacent edges. */
  BMLoop *l_first = l_tmp->next;
  BMLoop *l_last = l_tmp->prev;
  BMLoop *l_iter;
  float dist_sq_best = FLT_MAX;
  bool found = false;
 
  l_iter = l_first;
  do {
    float tvec[3];
    if (isect_line_plane_v3(tvec, l_iter->v->co, l_iter->next->v->co, l_tmp->v->co, plane_no)) {
      const float fac = line_point_factor_v3(tvec, l_iter->v->co, l_iter->next->v->co);
      /* Allow some overlap to avoid missing the intersection because of float precision. */
      if ((fac > -FLT_EPSILON) && (fac < 1.0f + FLT_EPSILON)) {
        /* Likelihood of multiple intersections per ngon is quite low,
         * it would have to loop back on itself, but better support it
         * so check for the closest opposite edge. */
        const float dist_sq_test = len_squared_v3v3(l_tmp->v->co, tvec);
        if (dist_sq_test < dist_sq_best) {
          copy_v3_v3(r_co, tvec);
          dist_sq_best = dist_sq_test;
          found = true;
        }
      }
    }
  } while ((l_iter = l_iter->next) != l_last);
 
  return found;
}
 
static float3 isect_face_dst(const BMLoop *l)
{
  BMFace *f = l->f;
  BMLoop *l_next = l->next;
  if (f->len == 4) {
    /* We could use code below, but in this case
     * sliding diagonally across the quad works well. */
    return l_next->next->v->co;
  }
 
  float3 plane_no;
  BM_loop_calc_face_direction(l, plane_no);
 
  float3 isect_co;
  if (!bm_loop_calc_opposite_co(l, plane_no, isect_co)) {
    /* Rare case. */
    mid_v3_v3v3(isect_co, l->prev->v->co, l_next->v->co);
  }
  return isect_co;
}
 
Array<TransDataEdgeSlideVert> transform_mesh_edge_slide_data_create(const TransDataContainer *tc,
                                                                    int *r_group_len)
{
  BMEditMesh *em = BKE_editmesh_from_object(tc->obedit);
  BMesh *bm = em->bm;
 
  int td_selected_len = 0;
 
  /* Ensure valid selection. */
  BMIter iter;
  BMVert *v;
  TransData *td = tc->data;
  for (int i = 0; i < tc->data_len; i++, td++) {
    if (!(td->flag & TD_SELECTED)) {
      /* The selected ones are sorted at the beginning. */
      break;
    }
    v = static_cast<BMVert *>(td->extra);
    int numsel = BM_iter_elem_count_flag(BM_EDGES_OF_VERT, v, BM_ELEM_SELECT, true);
    if (numsel == 0 || numsel > 2) {
      /* Invalid edge selection. */
      return {};
    }
    td_selected_len++;
  }
 
  BMEdge *e;
  BM_ITER_MESH (e, &iter, bm, BM_EDGES_OF_MESH) {
    if (!BM_elem_flag_test(e, BM_ELEM_SELECT)) {
      continue;
    }
    if (!BM_edge_is_manifold(e) && !BM_edge_is_boundary(e)) {
      /* Can edges with at least once face user. */
      return {};
    }
  }
 
  BM_ITER_MESH (v, &iter, bm, BM_VERTS_OF_MESH) {
    BM_elem_index_set(v, -1);
  }
  bm->elem_index_dirty |= BM_VERT;
 
  /* Alloc and initialize the #TransDataEdgeSlideVert. */
 
  Array<TransDataEdgeSlideVert> r_sv(td_selected_len);
  TransDataEdgeSlideVert *sv = &r_sv[0];
  int sv_index = 0;
  td = tc->data;
  for (int i = 0; i < tc->data_len; i++, td++) {
    if (!(td->flag & TD_SELECTED)) {
      continue;
    }
    sv->td = td;
    sv->loop_nr = -1;
    sv->dir_side[0] = float3(0);
    sv->dir_side[1] = float3(0);
 
    /* Identify the #TransDataEdgeSlideVert by the vertex index. */
    v = static_cast<BMVert *>(td->extra);
    BM_elem_index_set(v, sv_index);
    sv_index++;
    sv++;
  }
 
  /* Map indicating the indexes of #TransData connected by edge. */
  Array<int2> td_connected(tc->data_len, int2(-1, -1));
  BM_ITER_MESH (e, &iter, bm, BM_EDGES_OF_MESH) {
    if (!BM_elem_flag_test(e, BM_ELEM_SELECT)) {
      continue;
    }
    int td_index_1 = BM_elem_index_get(e->v1);
    int td_index_2 = BM_elem_index_get(e->v2);
 
    /* This can occur when the mesh has symmetry enabled but is not symmetrical. See #120811. */
    if (ELEM(-1, td_index_1, td_index_2)) {
      continue;
    }
 
    int slot_1 = int(td_connected[td_index_1][0] != -1);
    int slot_2 = int(td_connected[td_index_2][0] != -1);
 
    td_connected[td_index_1][slot_1] = td_index_2;
    td_connected[td_index_2][slot_2] = td_index_1;
  }
 
  /* Compute the sliding groups. */
  int loop_nr = 0;
  for (int i : r_sv.index_range()) {
    TransDataEdgeSlideVert *sv = &r_sv[i];
    if (sv->loop_nr != -1) {
      /* This vertex has already been computed. */
      continue;
    }
 
    /* Start from a vertex connected to just a single edge or any if it doesn't exist. */
    int i_curr = i;
    int i_prev = td_connected[i][1];
    while (!ELEM(i_prev, -1, i)) {
      int tmp = td_connected[i_prev][0] != i_curr ? td_connected[i_prev][0] :
                                                    td_connected[i_prev][1];
      i_curr = i_prev;
      i_prev = tmp;
    }
 
    struct SlideTempDataMesh {
      int i; /* The #TransDataEdgeSlideVert index. */
      TransDataEdgeSlideVert *sv;
      BMVert *v;
      BMEdge *e;
      struct {
        BMFace *f;
        BMVert *v_dst;
        float3 dst;
      } fdata[2];
      bool vert_is_edge_pair;
      int find_best_dir(const SlideTempDataMesh *curr_side_other,
                        const BMFace *f_curr,
                        const BMLoop *l_src,
                        const BMVert *v_dst,
                        bool *r_do_isect_curr_dirs) const
      {
        *r_do_isect_curr_dirs = false;
 
        if (f_curr == curr_side_other->fdata[0].f || v_dst == curr_side_other->fdata[0].v_dst) {
          return 0;
        }
 
        if (f_curr == curr_side_other->fdata[1].f || v_dst == curr_side_other->fdata[1].v_dst) {
          return 1;
        }
 
        if (curr_side_other->fdata[0].f || curr_side_other->fdata[1].f) {
          /* Find the best direction checking the edges that share faces between them. */
          int best_dir = -1;
          const BMLoop *l_edge = l_src->next->v == v_dst ? l_src : l_src->prev;
          const BMLoop *l_other = l_edge->radial_next;
          do {
            if (l_other->f == curr_side_other->fdata[0].f) {
              best_dir = 0;
              break;
            }
            if (l_other->f == curr_side_other->fdata[1].f) {
              best_dir = 1;
              break;
            }
            l_other = (l_other->v == this->v ? l_other->prev : l_other->next)->radial_next;
          } while (l_other->f != l_edge->f);
 
          if (best_dir != -1) {
            *r_do_isect_curr_dirs = true;
            return best_dir;
          }
        }
 
        if (ELEM(nullptr, this->fdata[0].f, this->fdata[1].f)) {
          return int(this->fdata[0].f != nullptr);
        }
 
        /* Find the best direction among those already computed.
         * Prioritizing in order:
         * - Boundary edge that points to the closest direction.
         * - Any edge that points to the closest direction. */
 
        *r_do_isect_curr_dirs = true;
        BMEdge *e0 = this->fdata[0].v_dst ? BM_edge_exists(this->v, this->fdata[0].v_dst) :
                                            nullptr;
        BMEdge *e1 = this->fdata[1].v_dst ? BM_edge_exists(this->v, this->fdata[1].v_dst) :
                                            nullptr;
        const bool is_boundary_0 = e0 && BM_edge_is_boundary(e0);
        const bool is_boundary_1 = e1 && BM_edge_is_boundary(e1);
        if (is_boundary_0 && !is_boundary_1) {
          return 0;
        }
 
        if (is_boundary_1 && !is_boundary_0) {
          return 1;
        }
 
        /* Find the closest direction. */
        float3 src = this->v->co;
        float3 dst = v_dst->co;
        float3 dir_curr = dst - src;
        float3 dir0 = math::normalize(this->fdata[0].dst - src);
        float3 dir1 = math::normalize(this->fdata[1].dst - src);
        float dot0 = math::dot(dir_curr, dir0);
        float dot1 = math::dot(dir_curr, dir1);
        return int(dot0 < dot1);
      }
    } prev = {}, curr = {}, next = {}, next_next = {}, tmp = {};
 
    next.i = td_connected[i_curr][0] != i_prev ? td_connected[i_curr][0] : td_connected[i_curr][1];
    if (next.i != -1) {
      next.sv = &r_sv[next.i];
      next.v = static_cast<BMVert *>(next.sv->td->extra);
      next.vert_is_edge_pair = mesh_vert_is_inner(next.v);
    }
 
    curr.i = i_curr;
    if (curr.i != -1) {
      curr.sv = &r_sv[curr.i];
      curr.v = static_cast<BMVert *>(curr.sv->td->extra);
      curr.vert_is_edge_pair = mesh_vert_is_inner(curr.v);
      if (next.i != -1) {
        curr.e = BM_edge_exists(curr.v, next.v);
      }
    }
 
    /* Do not compute `prev` for now. Let the loop calculate `curr` twice. */
    prev.i = -1;
 
    while (curr.i != -1) {
      if (next.i != -1) {
        next_next.i = td_connected[next.i][0] != curr.i ? td_connected[next.i][0] :
                                                          td_connected[next.i][1];
        if (next_next.i != -1) {
          next_next.sv = &r_sv[next_next.i];
          next_next.v = static_cast<BMVert *>(next_next.sv->td->extra);
          next_next.vert_is_edge_pair = mesh_vert_is_inner(next_next.v);
          next.e = BM_edge_exists(next.v, next_next.v);
        }
 
        tmp = curr;
 
        BMLoop *l;
        BM_ITER_ELEM (l, &iter, curr.e, BM_LOOPS_OF_EDGE) {
          BMFace *f_curr = l->f;
 
          BMVert *v1_dst, *v2_dst;
          BMEdge *l_edge_next;
          BMLoop *l1, *l2;
          if (l->v == curr.v) {
            l1 = l;
            l2 = l->next;
            l_edge_next = l2->e;
            v1_dst = l1->prev->v;
            v2_dst = l2->next->v;
          }
          else {
            l1 = l->next;
            l2 = l;
            l_edge_next = l2->prev->e;
            v1_dst = l1->next->v;
            v2_dst = l2->prev->v;
          }
 
          float3 dst = v1_dst->co;
 
          /* Sometimes the sliding direction may fork (`isect_curr_dirs` is `true`).
           * In this case, the resulting direction is the intersection of the destinations. */
          bool isect_curr_dirs = false;
 
          /* Identify the slot to slide according to the directions already computed in `curr`. */
          int best_dir = curr.find_best_dir(&tmp, f_curr, l1, v1_dst, &isect_curr_dirs);
 
          if (curr.fdata[best_dir].f == nullptr) {
            curr.fdata[best_dir].f = f_curr;
            if (curr.vert_is_edge_pair) {
              curr.fdata[best_dir].dst = isect_face_dst(l1);
            }
            else {
              curr.fdata[best_dir].v_dst = v1_dst;
              curr.fdata[best_dir].dst = v1_dst->co;
            }
          }
 
          /* Compute `next`. */
          next.fdata[best_dir].f = f_curr;
          if (l_edge_next == next.e || next.vert_is_edge_pair) {
            /* Case where the vertex slides over the face. */
            next.fdata[best_dir].v_dst = nullptr;
            next.fdata[best_dir].dst = isect_face_dst(l2);
          }
          else {
            /* Case where the vertex slides over an edge. */
            next.fdata[best_dir].v_dst = v2_dst;
            next.fdata[best_dir].dst = v2_dst->co;
          }
 
          if (isect_curr_dirs) {
            /* The `best_dir` can only have one direction. */
            float3 &dst0 = prev.fdata[best_dir].dst;
            float3 &dst1 = curr.fdata[best_dir].dst;
            float3 &dst2 = dst;
            float3 &dst3 = next.fdata[best_dir].dst;
            float3 isect0, isect1;
            if (isect_line_line_epsilon_v3(dst0, dst1, dst2, dst3, isect0, isect1, FLT_EPSILON) !=
                0)
            {
              curr.fdata[best_dir].dst = math::midpoint(isect0, isect1);
            }
            else {
              curr.fdata[best_dir].dst = math::midpoint(dst1, dst2);
            }
          }
        }
      }
 
      /* The data in `curr` is computed. Use to compute the #TransDataEdgeSlideVert. */
      float3 iloc = curr.sv->td->iloc;
      if (curr.fdata[0].f) {
        curr.sv->dir_side[0] = curr.fdata[0].dst - iloc;
      }
      if (curr.fdata[1].f) {
        curr.sv->dir_side[1] = curr.fdata[1].dst - iloc;
      }
      curr.sv->edge_len = math::distance(curr.sv->dir_side[0], curr.sv->dir_side[1]);
      curr.sv->loop_nr = loop_nr;
 
      if (i_prev != -1 && prev.i == i_prev) {
        /* Cycle returned to the beginning.
         * The data with index `i_curr` was computed twice to make sure the directions are correct
         * the second time. */
        break;
      }
 
      /* Move forward. */
      prev = curr;
      curr = next;
      next = next_next;
    }
    loop_nr++;
  }
  *r_group_len = loop_nr;
  return r_sv;
}
 
TransConvertTypeInfo TransConvertType_Mesh = {
    /*flags*/ (T_EDIT | T_POINTS),
    /*create_trans_data*/ createTransEditVerts,
    /*recalc_data*/ recalcData_mesh,
    /*special_aftertrans_update*/ special_aftertrans_update__mesh,
};