text: /*
   * 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) 2005 by the Blender Foundation.
   * All rights reserved.
   */
  
  /** \file
   * \ingroup modifiers
   */
  
  #include "BLI_utildefines.h"
  
  #include "BLI_math.h"
  
  #include "DNA_mesh_types.h"
  #include "DNA_meshdata_types.h"
  #include "DNA_object_types.h"
  
  #include "BKE_action.h"
  #include "BKE_colortools.h"
  #include "BKE_deform.h"
  #include "BKE_editmesh.h"
  #include "BKE_lib_id.h"
  #include "BKE_lib_query.h"
  #include "BKE_mesh.h"
  #include "BKE_modifier.h"
  
  #include "DEG_depsgraph_query.h"
  
  #include "MEM_guardedalloc.h"
  
  #include "MOD_util.h"
  
  static void initData(ModifierData *md)
  {
    HookModifierData *hmd = (HookModifierData *)md;
  
    hmd->force = 1.0;
    hmd->curfalloff = BKE_curvemapping_add(1, 0.0f, 0.0f, 1.0f, 1.0f);
    hmd->falloff_type = eHook_Falloff_Smooth;
    hmd->flag = 0;
  }
  
  static void copyData(const ModifierData *md, ModifierData *target, const int flag)
  {
    const HookModifierData *hmd = (const HookModifierData *)md;
    HookModifierData *thmd = (HookModifierData *)target;
  
    modifier_copyData_generic(md, target, flag);
  
    thmd->curfalloff = BKE_curvemapping_copy(hmd->curfalloff);
  
    thmd->indexar = MEM_dupallocN(hmd->indexar);
  }
  
  static void requiredDataMask(Object *UNUSED(ob),
                               ModifierData *md,
                               CustomData_MeshMasks *r_cddata_masks)
  {
    HookModifierData *hmd = (HookModifierData *)md;
  
    /* ask for vertexgroups if we need them */
    if (hmd->name[0] != '\0') {
      r_cddata_masks->vmask |= CD_MASK_MDEFORMVERT;
    }
    if (hmd->indexar != NULL) {
      /* TODO check which origindex are actually needed? */
      r_cddata_masks->vmask |= CD_MASK_ORIGINDEX;
      r_cddata_masks->emask |= CD_MASK_ORIGINDEX;
      r_cddata_masks->pmask |= CD_MASK_ORIGINDEX;
    }
  }
  
  static void freeData(ModifierData *md)
  {
    HookModifierData *hmd = (HookModifierData *)md;
  
    BKE_curvemapping_free(hmd->curfalloff);
  
    MEM_SAFE_FREE(hmd->indexar);
  }
  
  static bool isDisabled(const struct Scene *UNUSED(scene),
                         ModifierData *md,
                         bool UNUSED(useRenderParams))
  {
    HookModifierData *hmd = (HookModifierData *)md;
  
    return !hmd->object;
  }
  
  static void foreachObjectLink(ModifierData *md, Object *ob, ObjectWalkFunc walk, void *userData)
  {
    HookModifierData *hmd = (HookModifierData *)md;
  
    walk(userData, ob, &hmd->object, IDWALK_CB_NOP);
  }
  
  static void updateDepsgraph(ModifierData *md, const ModifierUpdateDepsgraphContext *ctx)
  {
    HookModifierData *hmd = (HookModifierData *)md;
    if (hmd->object != NULL) {
      if (hmd->subtarget[0]) {
        DEG_add_bone_relation(
            ctx->node, hmd->object, hmd->subtarget, DEG_OB_COMP_BONE, "Hook Modifier");
      }
      DEG_add_object_relation(ctx->node, hmd->object, DEG_OB_COMP_TRANSFORM, "Hook Modifier");
    }
    /* We need own transformation as well. */
    DEG_add_modifier_to_transform_relation(ctx->node, "Hook Modifier");
  }
  
  struct HookData_cb {
    float (*vertexCos)[3];
  
    MDeformVert *dvert;
    int defgrp_index;
  
    struct CurveMapping *curfalloff;
  
    char falloff_type;
    float falloff;
    float falloff_sq;
    float fac_orig;
  
    uint use_falloff : 1;
    uint use_uniform : 1;
  
    float cent[3];
  
    float mat_uniform[3][3];
    float mat[4][4];
  
    bool invert_vgroup;
  };
  
  static float hook_falloff(const struct HookData_cb *hd, const float len_sq)
  {
    BLI_assert(hd->falloff_sq);
    if (len_sq > hd->falloff_sq) {
      return 0.0f;
    }
    else if (len_sq > 0.0f) {
      float fac;
  
      if (hd->falloff_type == eHook_Falloff_Const) {
        fac = 1.0f;
        goto finally;
      }
      else if (hd->falloff_type == eHook_Falloff_InvSquare) {
        /* avoid sqrt below */
        fac = 1.0f - (len_sq / hd->falloff_sq);
        goto finally;
      }
  
      fac = 1.0f - (sqrtf(len_sq) / hd->falloff);
  
      /* closely match PROP_SMOOTH and similar */
      switch (hd->falloff_type) {
  #if 0
        case eHook_Falloff_None:
          fac = 1.0f;
          break;
  #endif
        case eHook_Falloff_Curve:
          fac = BKE_curvemapping_evaluateF(hd->curfalloff, 0, fac);
          break;
        case eHook_Falloff_Sharp:
          fac = fac * fac;
          break;
        case eHook_Falloff_Smooth:
          fac = 3.0f * fac * fac - 2.0f * fac * fac * fac;
          break;
        case eHook_Falloff_Root:
          fac = sqrtf(fac);
          break;
        case eHook_Falloff_Linear:
          /* pass */
          break;
  #if 0
        case eHook_Falloff_Const:
          fac = 1.0f;
          break;
  #endif
        case eHook_Falloff_Sphere:
          fac = sqrtf(2 * fac - fac * fac);
          break;
  #if 0
        case eHook_Falloff_InvSquare:
          fac = fac * (2.0f - fac);
          break;
  #endif
      }
  
    finally:
      return fac * hd->fac_orig;
    }
    else {
      return hd->fac_orig;
    }
  }
  
  static void hook_co_apply(struct HookData_cb *hd, const int j)
  {
    float *co = hd->vertexCos[j];
    float fac;
  
    if (hd->use_falloff) {
      float len_sq;
  
      if (hd->use_uniform) {
        float co_uniform[3];
        mul_v3_m3v3(co_uniform, hd->mat_uniform, co);
        len_sq = len_squared_v3v3(hd->cent, co_uniform);
      }
      else {
        len_sq = len_squared_v3v3(hd->cent, co);
      }
  
      fac = hook_falloff(hd, len_sq);
    }
    else {
      fac = hd->fac_orig;
    }
  
    if (fac) {
      if (hd->dvert) {
        fac *= hd->invert_vgroup ? 1.0f - BKE_defvert_find_weight(&hd->dvert[j], hd->defgrp_index) :
                                   BKE_defvert_find_weight(&hd->dvert[j], hd->defgrp_index);
      }
  
      if (fac) {
        float co_tmp[3];
        mul_v3_m4v3(co_tmp, hd->mat, co);
        interp_v3_v3v3(co, co, co_tmp, fac);
      }
    }
  }
  
  static void deformVerts_do(HookModifierData *hmd,
                             const ModifierEvalContext *UNUSED(ctx),
                             Object *ob,
                             Mesh *mesh,
                             float (*vertexCos)[3],
                             int numVerts)
  {
    Object *ob_target = hmd->object;
    bPoseChannel *pchan = BKE_pose_channel_find_name(ob_target->pose, hmd->subtarget);
    float dmat[4][4];
    int i, *index_pt;
    struct HookData_cb hd;
    const bool invert_vgroup = (hmd->flag & MOD_HOOK_INVERT_VGROUP) != 0;
  
    if (hmd->curfalloff == NULL) {
      /* should never happen, but bad lib linking could cause it */
      hmd->curfalloff = BKE_curvemapping_add(1, 0.0f, 0.0f, 1.0f, 1.0f);
    }
  
    if (hmd->curfalloff) {
      BKE_curvemapping_initialize(hmd->curfalloff);
    }
  
    /* Generic data needed for applying per-vertex calculations (initialize all members) */
    hd.vertexCos = vertexCos;
    MOD_get_vgroup(ob, mesh, hmd->name, &hd.dvert, &hd.defgrp_index);
  
    hd.curfalloff = hmd->curfalloff;
  
    hd.falloff_type = hmd->falloff_type;
    hd.falloff = (hmd->falloff_type == eHook_Falloff_None) ? 0.0f : hmd->falloff;
    hd.falloff_sq = square_f(hd.falloff);
    hd.fac_orig = hmd->force;
  
    hd.use_falloff = (hd.falloff_sq != 0.0f);
    hd.use_uniform = (hmd->flag & MOD_HOOK_UNIFORM_SPACE) != 0;
  
    hd.invert_vgroup = invert_vgroup;
  
    if (hd.use_uniform) {
      copy_m3_m4(hd.mat_uniform, hmd->parentinv);
      mul_v3_m3v3(hd.cent, hd.mat_uniform, hmd->cent);
    }
    else {
      unit_m3(hd.mat_uniform); /* unused */
      copy_v3_v3(hd.cent, hmd->cent);
    }
  
    /* get world-space matrix of target, corrected for the space the verts are in */
    if (hmd->subtarget[0] && pchan) {
      /* bone target if there's a matching pose-channel */
      mul_m4_m4m4(dmat, ob_target->obmat, pchan->pose_mat);
    }
    else {
      /* just object target */
      copy_m4_m4(dmat, ob_target->obmat);
    }
    invert_m4_m4(ob->imat, ob->obmat);
    mul_m4_series(hd.mat, ob->imat, dmat, hmd->parentinv);
    /* --- done with 'hd' init --- */
  
    /* Regarding index range checking below.
     *
     * This should always be true and I don't generally like
     * "paranoid" style code like this, but old files can have
     * indices that are out of range because old blender did
     * not correct them on exit edit-mode. - zr
     */
  
    if (hmd->force == 0.0f) {
      /* do nothing, avoid annoying checks in the loop */
    }
    else if (hmd->indexar) { /* vertex indices? */
      const int *origindex_ar;
  
      /* if mesh is present and has original index data, use it */
      if (mesh && (origindex_ar = CustomData_get_layer(&mesh->vdata, CD_ORIGINDEX))) {
        for (i = 0, index_pt = hmd->indexar; i < hmd->totindex; i++, index_pt++) {
          if (*index_pt < numVerts) {
            int j;
  
            for (j = 0; j < numVerts; j++) {
              if (origindex_ar[j] == *index_pt) {
                hook_co_apply(&hd, j);
              }
            }
          }
        }
      }
      else { /* missing mesh or ORIGINDEX */
        for (i = 0, index_pt = hmd->indexar; i < hmd->totindex; i++, index_pt++) {
          if (*index_pt < numVerts) {
            hook_co_apply(&hd, *index_pt);
          }
        }
      }
    }
    else if (hd.dvert) { /* vertex group hook */
      for (i = 0; i < numVerts; i++) {
        hook_co_apply(&hd, i);
      }
    }
  }
  
  static void deformVerts(struct ModifierData *md,
                          const struct ModifierEvalContext *ctx,
                          struct Mesh *mesh,
                          float (*vertexCos)[3],
                          int numVerts)
  {
    HookModifierData *hmd = (HookModifierData *)md;
    Mesh *mesh_src = MOD_deform_mesh_eval_get(ctx->object, NULL, mesh, NULL, numVerts, false, false);
  
    deformVerts_do(hmd, ctx, ctx->object, mesh_src, vertexCos, numVerts);
  
    if (!ELEM(mesh_src, NULL, mesh)) {
      BKE_id_free(NULL, mesh_src);
    }
  }
  
  static void deformVertsEM(struct ModifierData *md,
                            const struct ModifierEvalContext *ctx,
                            struct BMEditMesh *editData,
                            struct Mesh *mesh,
                            float (*vertexCos)[3],
                            int numVerts)
  {
    HookModifierData *hmd = (HookModifierData *)md;
    Mesh *mesh_src = MOD_deform_mesh_eval_get(
        ctx->object, editData, mesh, NULL, numVerts, false, false);
  
    deformVerts_do(hmd, ctx, ctx->object, mesh_src, vertexCos, numVerts);
  
    if (!ELEM(mesh_src, NULL, mesh)) {
      BKE_id_free(NULL, mesh_src);
    }
  }
  
  ModifierTypeInfo modifierType_Hook = {
      /* name */ "Hook",
      /* structName */ "HookModifierData",
      /* structSize */ sizeof(HookModifierData),
      /* type */ eModifierTypeType_OnlyDeform,
      /* flags */ eModifierTypeFlag_AcceptsCVs | eModifierTypeFlag_AcceptsVertexCosOnly |
          eModifierTypeFlag_SupportsEditmode,
      /* copyData */ copyData,
  
      /* deformVerts */ deformVerts,
      /* deformMatrices */ NULL,
      /* deformVertsEM */ deformVertsEM,
      /* deformMatricesEM */ NULL,
      /* modifyMesh */ NULL,
      /* modifyHair */ NULL,
      /* modifyPointCloud */ NULL,
      /* modifyVolume */ NULL,
  
      /* initData */ initData,
      /* requiredDataMask */ requiredDataMask,
      /* freeData */ freeData,
      /* isDisabled */ isDisabled,
      /* updateDepsgraph */ updateDepsgraph,
      /* dependsOnTime */ NULL,
      /* dependsOnNormals */ NULL,
      /* foreachObjectLink */ foreachObjectLink,
      /* foreachIDLink */ NULL,
      /* foreachTexLink */ NULL,
      /* freeRuntimeData */ NULL,
  };
  