path: root/source/blender/blenkernel/intern/shrinkwrap.c

/*
 * ***** BEGIN GPL LICENSE BLOCK *****
 *
 * 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) Blender Foundation.
 * All rights reserved.
 *
 * The Original Code is: all of this file.
 *
 * Contributor(s): Andr Pinto
 *
 * ***** END GPL LICENSE BLOCK *****
 */

/** \file blender/blenkernel/intern/shrinkwrap.c
 *  \ingroup bke
 */

#include <string.h>
#include <float.h>
#include <math.h>
#include <memory.h>
#include <stdio.h>
#include <time.h>
#include <assert.h>

#include "DNA_object_types.h"
#include "DNA_modifier_types.h"
#include "DNA_meshdata_types.h"
#include "DNA_mesh_types.h"

#include "BLI_math.h"
#include "BLI_utildefines.h"
#include "BLI_task.h"

#include "BKE_shrinkwrap.h"
#include "BKE_DerivedMesh.h"
#include "BKE_lattice.h"

#include "BKE_deform.h"
#include "BKE_editmesh.h"
#include "BKE_mesh.h"  /* for OMP limits. */
#include "BKE_subsurf.h"

#include "BLI_strict_flags.h"

/* for timing... */
#if 0
#  include "PIL_time_utildefines.h"
#else
#  define TIMEIT_BENCH(expr, id) (expr)
#endif

/* Util macros */
#define OUT_OF_MEMORY() ((void)printf("Shrinkwrap: Out of memory\n"))

typedef struct ShrinkwrapCalcCBData {
	ShrinkwrapCalcData *calc;

	void *treeData;
	void *auxData;
	BVHTree *targ_tree;
	BVHTree *aux_tree;
	void *targ_callback;
	void *aux_callback;

	float *proj_axis;
	SpaceTransform *local2aux;
} ShrinkwrapCalcCBData;

/*
 * Shrinkwrap to the nearest vertex
 *
 * it builds a kdtree of vertexs we can attach to and then
 * for each vertex performs a nearest vertex search on the tree
 */
static void shrinkwrap_calc_nearest_vertex_cb_ex(
        void *__restrict userdata,
        const int i,
        const ParallelRangeTLS *__restrict tls)
{
	ShrinkwrapCalcCBData *data = userdata;

	ShrinkwrapCalcData *calc = data->calc;
	BVHTreeFromMesh *treeData = data->treeData;
	BVHTreeNearest *nearest = tls->userdata_chunk;

	float *co = calc->vertexCos[i];
	float tmp_co[3];
	float weight = defvert_array_find_weight_safe(calc->dvert, i, calc->vgroup);

	if (calc->invert_vgroup) {
		weight = 1.0f - weight;
	}

	if (weight == 0.0f) {
		return;
	}

	/* Convert the vertex to tree coordinates */
	if (calc->vert) {
		copy_v3_v3(tmp_co, calc->vert[i].co);
	}
	else {
		copy_v3_v3(tmp_co, co);
	}
	BLI_space_transform_apply(&calc->local2target, tmp_co);

	/* Use local proximity heuristics (to reduce the nearest search)
	 *
	 * If we already had an hit before.. we assume this vertex is going to have a close hit to that other vertex
	 * so we can initiate the "nearest.dist" with the expected value to that last hit.
	 * This will lead in pruning of the search tree. */
	if (nearest->index != -1)
		nearest->dist_sq = len_squared_v3v3(tmp_co, nearest->co);
	else
		nearest->dist_sq = FLT_MAX;

	BLI_bvhtree_find_nearest(treeData->tree, tmp_co, nearest, treeData->nearest_callback, treeData);


	/* Found the nearest vertex */
	if (nearest->index != -1) {
		/* Adjusting the vertex weight,
		 * so that after interpolating it keeps a certain distance from the nearest position */
		if (nearest->dist_sq > FLT_EPSILON) {
			const float dist = sqrtf(nearest->dist_sq);
			weight *= (dist - calc->keepDist) / dist;
		}

		/* Convert the coordinates back to mesh coordinates */
		copy_v3_v3(tmp_co, nearest->co);
		BLI_space_transform_invert(&calc->local2target, tmp_co);

		interp_v3_v3v3(co, co, tmp_co, weight);  /* linear interpolation */
	}
}

static void shrinkwrap_calc_nearest_vertex(ShrinkwrapCalcData *calc)
{
	BVHTreeFromMesh treeData = NULL_BVHTreeFromMesh;
	BVHTreeNearest nearest  = NULL_BVHTreeNearest;

	if (calc->target != NULL && calc->target->getNumVerts(calc->target) == 0) {
		return;
	}

	TIMEIT_BENCH(bvhtree_from_mesh_get(&treeData, calc->target, BVHTREE_FROM_VERTS, 2), bvhtree_verts);
	if (treeData.tree == NULL) {
		OUT_OF_MEMORY();
		return;
	}

	/* Setup nearest */
	nearest.index = -1;
	nearest.dist_sq = FLT_MAX;

	ShrinkwrapCalcCBData data = {.calc = calc, .treeData = &treeData};
	ParallelRangeSettings settings;
	BLI_parallel_range_settings_defaults(&settings);
	settings.use_threading = (calc->numVerts > BKE_MESH_OMP_LIMIT);
	settings.userdata_chunk = &nearest;
	settings.userdata_chunk_size = sizeof(nearest);
	BLI_task_parallel_range(0, calc->numVerts,
	                        &data, shrinkwrap_calc_nearest_vertex_cb_ex,
	                        &settings);

	free_bvhtree_from_mesh(&treeData);
}


/*
 * This function raycast a single vertex and updates the hit if the "hit" is considered valid.
 * Returns true if "hit" was updated.
 * Opts control whether an hit is valid or not
 * Supported options are:
 * - MOD_SHRINKWRAP_CULL_TARGET_FRONTFACE (front faces hits are ignored)
 * - MOD_SHRINKWRAP_CULL_TARGET_BACKFACE (back faces hits are ignored)
 */
bool BKE_shrinkwrap_project_normal(
        char options, const float vert[3], const float dir[3],
        const float ray_radius, const SpaceTransform *transf,
        BVHTree *tree, BVHTreeRayHit *hit,
        BVHTree_RayCastCallback callback, void *userdata)
{
	/* don't use this because this dist value could be incompatible
	 * this value used by the callback for comparing prev/new dist values.
	 * also, at the moment there is no need to have a corrected 'dist' value */
// #define USE_DIST_CORRECT

	float tmp_co[3], tmp_no[3];
	const float *co, *no;
	BVHTreeRayHit hit_tmp;

	/* Copy from hit (we need to convert hit rays from one space coordinates to the other */
	memcpy(&hit_tmp, hit, sizeof(hit_tmp));

	/* Apply space transform (TODO readjust dist) */
	if (transf) {
		copy_v3_v3(tmp_co, vert);
		BLI_space_transform_apply(transf, tmp_co);
		co = tmp_co;

		copy_v3_v3(tmp_no, dir);
		BLI_space_transform_apply_normal(transf, tmp_no);
		no = tmp_no;

#ifdef USE_DIST_CORRECT
		hit_tmp.dist *= mat4_to_scale(((SpaceTransform *)transf)->local2target);
#endif
	}
	else {
		co = vert;
		no = dir;
	}

	hit_tmp.index = -1;

	BLI_bvhtree_ray_cast(tree, co, no, ray_radius, &hit_tmp, callback, userdata);

	if (hit_tmp.index != -1) {
		/* invert the normal first so face culling works on rotated objects */
		if (transf) {
			BLI_space_transform_invert_normal(transf, hit_tmp.no);
		}

		if (options & (MOD_SHRINKWRAP_CULL_TARGET_FRONTFACE | MOD_SHRINKWRAP_CULL_TARGET_BACKFACE)) {
			/* apply backface */
			const float dot = dot_v3v3(dir, hit_tmp.no);
			if (((options & MOD_SHRINKWRAP_CULL_TARGET_FRONTFACE) && dot <= 0.0f) ||
			    ((options & MOD_SHRINKWRAP_CULL_TARGET_BACKFACE)  && dot >= 0.0f))
			{
				return false;  /* Ignore hit */
			}
		}

		if (transf) {
			/* Inverting space transform (TODO make coeherent with the initial dist readjust) */
			BLI_space_transform_invert(transf, hit_tmp.co);
#ifdef USE_DIST_CORRECT
			hit_tmp.dist = len_v3v3(vert, hit_tmp.co);
#endif
		}

		BLI_assert(hit_tmp.dist <= hit->dist);

		memcpy(hit, &hit_tmp, sizeof(hit_tmp));
		return true;
	}
	return false;
}

static void shrinkwrap_calc_normal_projection_cb_ex(
        void *__restrict userdata,
        const int i,
        const ParallelRangeTLS *__restrict tls)
{
	ShrinkwrapCalcCBData *data = userdata;

	ShrinkwrapCalcData *calc = data->calc;
	void *treeData = data->treeData;
	void *auxData = data->auxData;
	BVHTree *targ_tree = data->targ_tree;
	BVHTree *aux_tree = data->aux_tree;
	void *targ_callback = data->targ_callback;
	void *aux_callback = data->aux_callback;

	float *proj_axis = data->proj_axis;
	SpaceTransform *local2aux = data->local2aux;

	BVHTreeRayHit *hit = tls->userdata_chunk;

	const float proj_limit_squared = calc->smd->projLimit * calc->smd->projLimit;
	float *co = calc->vertexCos[i];
	float tmp_co[3], tmp_no[3];
	float weight = defvert_array_find_weight_safe(calc->dvert, i, calc->vgroup);

	if (calc->invert_vgroup) {
		weight = 1.0f - weight;
	}

	if (weight == 0.0f) {
		return;
	}

	if (calc->vert) {
		/* calc->vert contains verts from derivedMesh  */
		/* this coordinated are deformed by vertexCos only for normal projection (to get correct normals) */
		/* for other cases calc->varts contains undeformed coordinates and vertexCos should be used */
		if (calc->smd->projAxis == MOD_SHRINKWRAP_PROJECT_OVER_NORMAL) {
			copy_v3_v3(tmp_co, calc->vert[i].co);
			normal_short_to_float_v3(tmp_no, calc->vert[i].no);
		}
		else {
			copy_v3_v3(tmp_co, co);
			copy_v3_v3(tmp_no, proj_axis);
		}
	}
	else {
		copy_v3_v3(tmp_co, co);
		copy_v3_v3(tmp_no, proj_axis);
	}


	hit->index = -1;
	hit->dist = BVH_RAYCAST_DIST_MAX; /* TODO: we should use FLT_MAX here, but sweepsphere code isn't prepared for that */

	/* Project over positive direction of axis */
	if (calc->smd->shrinkOpts & MOD_SHRINKWRAP_PROJECT_ALLOW_POS_DIR) {
		if (aux_tree) {
			BKE_shrinkwrap_project_normal(
			        0, tmp_co, tmp_no, 0.0,
			        local2aux, aux_tree, hit,
			        aux_callback, auxData);
		}

		BKE_shrinkwrap_project_normal(
		        calc->smd->shrinkOpts, tmp_co, tmp_no, 0.0,
		        &calc->local2target, targ_tree, hit,
		        targ_callback, treeData);
	}

	/* Project over negative direction of axis */
	if (calc->smd->shrinkOpts & MOD_SHRINKWRAP_PROJECT_ALLOW_NEG_DIR) {
		float inv_no[3];
		negate_v3_v3(inv_no, tmp_no);

		if (aux_tree) {
			BKE_shrinkwrap_project_normal(
			        0, tmp_co, inv_no, 0.0,
			        local2aux, aux_tree, hit,
			        aux_callback, auxData);
		}

		BKE_shrinkwrap_project_normal(
		        calc->smd->shrinkOpts, tmp_co, inv_no, 0.0,
		        &calc->local2target, targ_tree, hit,
		        targ_callback, treeData);
	}

	/* don't set the initial dist (which is more efficient),
	 * because its calculated in the targets space, we want the dist in our own space */
	if (proj_limit_squared != 0.0f) {
		if (len_squared_v3v3(hit->co, co) > proj_limit_squared) {
			hit->index = -1;
		}
	}

	if (hit->index != -1) {
		madd_v3_v3v3fl(hit->co, hit->co, tmp_no, calc->keepDist);
		interp_v3_v3v3(co, co, hit->co, weight);
	}
}

static void shrinkwrap_calc_normal_projection(ShrinkwrapCalcData *calc, bool for_render)
{
	/* Options about projection direction */
	float proj_axis[3]      = {0.0f, 0.0f, 0.0f};

	/* Raycast and tree stuff */

	/** \note 'hit.dist' is kept in the targets space, this is only used
	 * for finding the best hit, to get the real dist,
	 * measure the len_v3v3() from the input coord to hit.co */
	BVHTreeRayHit hit;
	void *treeData = NULL;

	/* auxiliary target */
	DerivedMesh *auxMesh    = NULL;
	void *auxData = NULL;
	SpaceTransform local2aux;

	/* If the user doesn't allows to project in any direction of projection axis
	 * then there's nothing todo. */
	if ((calc->smd->shrinkOpts & (MOD_SHRINKWRAP_PROJECT_ALLOW_POS_DIR | MOD_SHRINKWRAP_PROJECT_ALLOW_NEG_DIR)) == 0)
		return;

	if (calc->target != NULL && calc->target->getNumPolys(calc->target) == 0) {
		return;
	}

	/* Prepare data to retrieve the direction in which we should project each vertex */
	if (calc->smd->projAxis == MOD_SHRINKWRAP_PROJECT_OVER_NORMAL) {
		if (calc->vert == NULL) return;
	}
	else {
		/* The code supports any axis that is a combination of X,Y,Z
		 * although currently UI only allows to set the 3 different axis */
		if (calc->smd->projAxis & MOD_SHRINKWRAP_PROJECT_OVER_X_AXIS) proj_axis[0] = 1.0f;
		if (calc->smd->projAxis & MOD_SHRINKWRAP_PROJECT_OVER_Y_AXIS) proj_axis[1] = 1.0f;
		if (calc->smd->projAxis & MOD_SHRINKWRAP_PROJECT_OVER_Z_AXIS) proj_axis[2] = 1.0f;

		normalize_v3(proj_axis);

		/* Invalid projection direction */
		if (len_squared_v3(proj_axis) < FLT_EPSILON) {
			return;
		}
	}

	if (calc->smd->auxTarget) {
		auxMesh = object_get_derived_final(calc->smd->auxTarget, for_render);
		if (!auxMesh)
			return;
		BLI_SPACE_TRANSFORM_SETUP(&local2aux, calc->ob, calc->smd->auxTarget);
	}

	/* use editmesh to avoid array allocation */
	BMEditMesh *emtarget = NULL, *emaux = NULL;
	union {
		BVHTreeFromEditMesh emtreedata;
		BVHTreeFromMesh dmtreedata;
	} treedata_stack, auxdata_stack;

	BVHTree *targ_tree;
	void *targ_callback;
	if (calc->smd->target && calc->target->type == DM_TYPE_EDITBMESH) {
		emtarget = BKE_editmesh_from_object(calc->smd->target);
		if ((targ_tree = bvhtree_from_editmesh_looptri(
		         &treedata_stack.emtreedata, emtarget, 0.0, 4, 6, &calc->target->bvhCache)))
		{
			targ_callback = treedata_stack.emtreedata.raycast_callback;
			treeData = &treedata_stack.emtreedata;
		}
	}
	else {
		if ((targ_tree = bvhtree_from_mesh_get(
		             &treedata_stack.dmtreedata, calc->target, BVHTREE_FROM_LOOPTRI, 4)))
		{
			targ_callback = treedata_stack.dmtreedata.raycast_callback;
			treeData = &treedata_stack.dmtreedata;
		}
	}
	if (targ_tree) {
		BVHTree *aux_tree = NULL;
		void *aux_callback = NULL;
		if (auxMesh != NULL && auxMesh->getNumPolys(auxMesh) != 0) {
			/* use editmesh to avoid array allocation */
			if (calc->smd->auxTarget && auxMesh->type == DM_TYPE_EDITBMESH) {
				emaux = BKE_editmesh_from_object(calc->smd->auxTarget);
				if ((aux_tree = bvhtree_from_editmesh_looptri(
				         &auxdata_stack.emtreedata, emaux, 0.0, 4, 6, &auxMesh->bvhCache)))
				{
					aux_callback = auxdata_stack.emtreedata.raycast_callback;
					auxData = &auxdata_stack.emtreedata;
				}
			}
			else {
				if ((aux_tree = bvhtree_from_mesh_get(
				        &auxdata_stack.dmtreedata, auxMesh, BVHTREE_FROM_LOOPTRI, 4)) != NULL)
				{
					aux_callback = auxdata_stack.dmtreedata.raycast_callback;
					auxData = &auxdata_stack.dmtreedata;
				}
			}
		}
		/* After sucessufuly build the trees, start projection vertexs */
		ShrinkwrapCalcCBData data = {
			.calc = calc,
			.treeData = treeData, .targ_tree = targ_tree, .targ_callback = targ_callback,
			.auxData = auxData, .aux_tree = aux_tree, .aux_callback = aux_callback,
			.proj_axis = proj_axis, .local2aux = &local2aux,
		};
		ParallelRangeSettings settings;
		BLI_parallel_range_settings_defaults(&settings);
		settings.use_threading = (calc->numVerts > BKE_MESH_OMP_LIMIT);
		settings.userdata_chunk = &hit;
		settings.userdata_chunk_size = sizeof(hit);
		BLI_task_parallel_range(0, calc->numVerts,
		                        &data,
		                        shrinkwrap_calc_normal_projection_cb_ex,
		                        &settings);
	}

	/* free data structures */
	if (treeData) {
		if (emtarget) {
			free_bvhtree_from_editmesh(treeData);
		}
		else {
			free_bvhtree_from_mesh(treeData);
		}
	}

	if (auxData) {
		if (emaux) {
			free_bvhtree_from_editmesh(auxData);
		}
		else {
			free_bvhtree_from_mesh(auxData);
		}
	}
}

/*
 * Shrinkwrap moving vertexs to the nearest surface point on the target
 *
 * it builds a BVHTree from the target mesh and then performs a
 * NN matches for each vertex
 */
static void shrinkwrap_calc_nearest_surface_point_cb_ex(
        void *__restrict userdata,
        const int i,
        const ParallelRangeTLS *__restrict tls)
{
	ShrinkwrapCalcCBData *data = userdata;

	ShrinkwrapCalcData *calc = data->calc;
	BVHTreeFromMesh *treeData = data->treeData;
	BVHTreeNearest *nearest = tls->userdata_chunk;

	float *co = calc->vertexCos[i];
	float tmp_co[3];
	float weight = defvert_array_find_weight_safe(calc->dvert, i, calc->vgroup);

	if (calc->invert_vgroup) {
		weight = 1.0f - weight;
	}

	if (weight == 0.0f) {
		return;
	}

	/* Convert the vertex to tree coordinates */
	if (calc->vert) {
		copy_v3_v3(tmp_co, calc->vert[i].co);
	}
	else {
		copy_v3_v3(tmp_co, co);
	}
	BLI_space_transform_apply(&calc->local2target, tmp_co);

	/* Use local proximity heuristics (to reduce the nearest search)
	 *
	 * If we already had an hit before.. we assume this vertex is going to have a close hit to that other vertex
	 * so we can initiate the "nearest.dist" with the expected value to that last hit.
	 * This will lead in pruning of the search tree. */
	if (nearest->index != -1)
		nearest->dist_sq = len_squared_v3v3(tmp_co, nearest->co);
	else
		nearest->dist_sq = FLT_MAX;

	BLI_bvhtree_find_nearest(treeData->tree, tmp_co, nearest, treeData->nearest_callback, treeData);

	/* Found the nearest vertex */
	if (nearest->index != -1) {
		if (calc->smd->shrinkOpts & MOD_SHRINKWRAP_KEEP_ABOVE_SURFACE) {
			/* Make the vertex stay on the front side of the face */
			madd_v3_v3v3fl(tmp_co, nearest->co, nearest->no, calc->keepDist);
		}
		else {
			/* Adjusting the vertex weight,
			 * so that after interpolating it keeps a certain distance from the nearest position */
			const float dist = sasqrt(nearest->dist_sq);
			if (dist > FLT_EPSILON) {
				/* linear interpolation */
				interp_v3_v3v3(tmp_co, tmp_co, nearest->co, (dist - calc->keepDist) / dist);
			}
			else {
				copy_v3_v3(tmp_co, nearest->co);
			}
		}

		/* Convert the coordinates back to mesh coordinates */
		BLI_space_transform_invert(&calc->local2target, tmp_co);
		interp_v3_v3v3(co, co, tmp_co, weight);  /* linear interpolation */
	}
}

static void shrinkwrap_calc_nearest_surface_point(ShrinkwrapCalcData *calc)
{
	BVHTreeFromMesh treeData = NULL_BVHTreeFromMesh;
	BVHTreeNearest nearest  = NULL_BVHTreeNearest;

	if (calc->target->getNumPolys(calc->target) == 0) {
		return;
	}

	/* Create a bvh-tree of the given target */
	bvhtree_from_mesh_get(&treeData, calc->target, BVHTREE_FROM_LOOPTRI, 2);
	if (treeData.tree == NULL) {
		OUT_OF_MEMORY();
		return;
	}

	/* Setup nearest */
	nearest.index = -1;
	nearest.dist_sq = FLT_MAX;

	/* Find the nearest vertex */
	ShrinkwrapCalcCBData data = {.calc = calc, .treeData = &treeData};
	ParallelRangeSettings settings;
	BLI_parallel_range_settings_defaults(&settings);
	settings.use_threading = (calc->numVerts > BKE_MESH_OMP_LIMIT);
	settings.userdata_chunk = &nearest;
	settings.userdata_chunk_size = sizeof(nearest);
	BLI_task_parallel_range(0, calc->numVerts,
	                        &data,
	                        shrinkwrap_calc_nearest_surface_point_cb_ex,
	                        &settings);

	free_bvhtree_from_mesh(&treeData);
}

/* Main shrinkwrap function */
void shrinkwrapModifier_deform(ShrinkwrapModifierData *smd, Object *ob, DerivedMesh *dm,
                               float (*vertexCos)[3], int numVerts, bool for_render)
{

	DerivedMesh *ss_mesh    = NULL;
	ShrinkwrapCalcData calc = NULL_ShrinkwrapCalcData;

	/* remove loop dependencies on derived meshes (TODO should this be done elsewhere?) */
	if (smd->target == ob) smd->target = NULL;
	if (smd->auxTarget == ob) smd->auxTarget = NULL;


	/* Configure Shrinkwrap calc data */
	calc.smd = smd;
	calc.ob = ob;
	calc.numVerts = numVerts;
	calc.vertexCos = vertexCos;
	calc.invert_vgroup = (smd->shrinkOpts & MOD_SHRINKWRAP_INVERT_VGROUP) != 0;

	/* DeformVertex */
	calc.vgroup = defgroup_name_index(calc.ob, calc.smd->vgroup_name);
	if (dm) {
		calc.dvert = dm->getVertDataArray(dm, CD_MDEFORMVERT);
	}
	else if (calc.ob->type == OB_LATTICE) {
		calc.dvert = BKE_lattice_deform_verts_get(calc.ob);
	}


	if (smd->target) {
		calc.target = object_get_derived_final(smd->target, for_render);

		/* TODO there might be several "bugs" on non-uniform scales matrixs
		 * because it will no longer be nearest surface, not sphere projection
		 * because space has been deformed */
		BLI_SPACE_TRANSFORM_SETUP(&calc.local2target, ob, smd->target);

		/* TODO: smd->keepDist is in global units.. must change to local */
		calc.keepDist = smd->keepDist;
	}



	calc.vgroup = defgroup_name_index(calc.ob, smd->vgroup_name);

	if (dm != NULL && smd->shrinkType == MOD_SHRINKWRAP_PROJECT) {
		/* Setup arrays to get vertexs positions, normals and deform weights */
		calc.vert   = dm->getVertDataArray(dm, CD_MVERT);
		calc.dvert  = dm->getVertDataArray(dm, CD_MDEFORMVERT);

		/* Using vertexs positions/normals as if a subsurface was applied */
		if (smd->subsurfLevels) {
			SubsurfModifierData ssmd = {{NULL}};
			ssmd.subdivType = ME_CC_SUBSURF;        /* catmull clark */
			ssmd.levels     = smd->subsurfLevels;   /* levels */

			ss_mesh = subsurf_make_derived_from_derived(dm, &ssmd, NULL, (ob->mode & OB_MODE_EDIT) ? SUBSURF_IN_EDIT_MODE : 0);

			if (ss_mesh) {
				calc.vert = ss_mesh->getVertDataArray(ss_mesh, CD_MVERT);
				if (calc.vert) {
					/* TRICKY: this code assumes subsurface will have the transformed original vertices
					 * in their original order at the end of the vert array. */
					calc.vert = calc.vert + ss_mesh->getNumVerts(ss_mesh) - dm->getNumVerts(dm);
				}
			}

			/* Just to make sure we are not leaving any memory behind */
			assert(ssmd.emCache == NULL);
			assert(ssmd.mCache == NULL);
		}
	}

	/* Projecting target defined - lets work! */
	if (calc.target) {
		switch (smd->shrinkType) {
			case MOD_SHRINKWRAP_NEAREST_SURFACE:
				TIMEIT_BENCH(shrinkwrap_calc_nearest_surface_point(&calc), deform_surface);
				break;

			case MOD_SHRINKWRAP_PROJECT:
				TIMEIT_BENCH(shrinkwrap_calc_normal_projection(&calc, for_render), deform_project);
				break;

			case MOD_SHRINKWRAP_NEAREST_VERTEX:
				TIMEIT_BENCH(shrinkwrap_calc_nearest_vertex(&calc), deform_vertex);
				break;
		}
	}

	/* free memory */
	if (ss_mesh)
		ss_mesh->release(ss_mesh);
}