move mesh evaluation functions (normal, mapping, smooth group... etc, calculations) into mesh_evaluate.c.

mesh.c was over 4k lines and complex functions mixed in with general library management.

1 files changed, 2017 insertions, 0 deletions

diff --git a/source/blender/blenkernel/intern/mesh_evaluate.c b/source/blender/blenkernel/intern/mesh_evaluate.c
new file mode 100644
index 00000000000..d35d91cc45a
--- /dev/null
+++ b/source/blender/blenkernel/intern/mesh_evaluate.c
@@ -0,0 +1,2017 @@
+/*
+ * ***** 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) 2001-2002 by NaN Holding BV.
+ * All rights reserved.
+ *
+ * Contributor(s): Blender Foundation
+ *
+ * ***** END GPL LICENSE BLOCK *****
+ */
+
+/** \file blender/blenkernel/intern/mesh_evaluate.c
+ *  \ingroup bke
+ *
+ * Functions to evaluate mesh data.
+ */
+
+#include "MEM_guardedalloc.h"
+
+#include "DNA_object_types.h"
+#include "DNA_mesh_types.h"
+#include "DNA_meshdata_types.h"
+
+#include "BLI_utildefines.h"
+#include "BLI_memarena.h"
+#include "BLI_math.h"
+#include "BLI_edgehash.h"
+#include "BLI_bitmap.h"
+#include "BLI_scanfill.h"
+#include "BLI_alloca.h"
+#include "BLI_array.h"
+
+#include "BKE_customdata.h"
+#include "BKE_mesh.h"
+#include "BKE_multires.h"
+
+
+/* -------------------------------------------------------------------- */
+
+/** \name Mesh Normal Calculation
+ * \{ */
+
+/**
+ * Call when there are no polygons.
+ */
+static void mesh_calc_normals_vert_fallback(MVert *mverts, int numVerts)
+{
+	int i;
+	for (i = 0; i < numVerts; i++) {
+		MVert *mv = &mverts[i];
+		float no[3];
+
+		normalize_v3_v3(no, mv->co);
+		normal_float_to_short_v3(mv->no, no);
+	}
+}
+
+/* Calculate vertex and face normals, face normals are returned in *faceNors_r if non-NULL
+ * and vertex normals are stored in actual mverts.
+ */
+void BKE_mesh_calc_normals_mapping(MVert *mverts, int numVerts,
+                                   MLoop *mloop, MPoly *mpolys, int numLoops, int numPolys, float (*polyNors_r)[3],
+                                   MFace *mfaces, int numFaces, int *origIndexFace, float (*faceNors_r)[3])
+{
+	BKE_mesh_calc_normals_mapping_ex(mverts, numVerts, mloop, mpolys,
+	                                 numLoops, numPolys, polyNors_r, mfaces, numFaces,
+	                                 origIndexFace, faceNors_r, FALSE);
+}
+/* extended version of 'BKE_mesh_calc_normals_poly' with option not to calc vertex normals */
+void BKE_mesh_calc_normals_mapping_ex(
+        MVert *mverts, int numVerts,
+        MLoop *mloop, MPoly *mpolys,
+        int numLoops, int numPolys, float (*polyNors_r)[3],
+        MFace *mfaces, int numFaces, int *origIndexFace, float (*faceNors_r)[3],
+        const bool only_face_normals)
+{
+	float (*pnors)[3] = polyNors_r, (*fnors)[3] = faceNors_r;
+	int i;
+	MFace *mf;
+	MPoly *mp;
+
+	if (numPolys == 0) {
+		if (only_face_normals == FALSE) {
+			mesh_calc_normals_vert_fallback(mverts, numVerts);
+		}
+		return;
+	}
+
+	/* if we are not calculating verts and no verts were passes then we have nothing to do */
+	if ((only_face_normals == TRUE) && (polyNors_r == NULL) && (faceNors_r == NULL)) {
+		printf("%s: called with nothing to do\n", __func__);
+		return;
+	}
+
+	if (!pnors) pnors = MEM_callocN(sizeof(float) * 3 * numPolys, "poly_nors mesh.c");
+	/* if (!fnors) fnors = MEM_callocN(sizeof(float) * 3 * numFaces, "face nors mesh.c"); */ /* NO NEED TO ALLOC YET */
+
+
+	if (only_face_normals == FALSE) {
+		/* vertex normals are optional, they require some extra calculations,
+		 * so make them optional */
+		BKE_mesh_calc_normals_poly(mverts, numVerts, mloop, mpolys, numLoops, numPolys, pnors, false);
+	}
+	else {
+		/* only calc poly normals */
+		mp = mpolys;
+		for (i = 0; i < numPolys; i++, mp++) {
+			BKE_mesh_calc_poly_normal(mp, mloop + mp->loopstart, mverts, pnors[i]);
+		}
+	}
+
+	if (origIndexFace &&
+	    /* fnors == faceNors_r */ /* NO NEED TO ALLOC YET */
+	    fnors != NULL &&
+	    numFaces)
+	{
+		mf = mfaces;
+		for (i = 0; i < numFaces; i++, mf++, origIndexFace++) {
+			if (*origIndexFace < numPolys) {
+				copy_v3_v3(fnors[i], pnors[*origIndexFace]);
+			}
+			else {
+				/* eek, we're not corresponding to polys */
+				printf("error in %s: tessellation face indices are incorrect.  normals may look bad.\n", __func__);
+			}
+		}
+	}
+
+	if (pnors != polyNors_r) MEM_freeN(pnors);
+	/* if (fnors != faceNors_r) MEM_freeN(fnors); */ /* NO NEED TO ALLOC YET */
+
+	fnors = pnors = NULL;
+	
+}
+
+static void mesh_calc_normals_poly_accum(MPoly *mp, MLoop *ml,
+                                         MVert *mvert, float polyno[3], float (*tnorms)[3])
+{
+	const int nverts = mp->totloop;
+	float (*edgevecbuf)[3] = BLI_array_alloca(edgevecbuf, nverts);
+	int i;
+
+	/* Polygon Normal and edge-vector */
+	/* inline version of #BKE_mesh_calc_poly_normal, also does edge-vectors */
+	{
+		int i_prev = nverts - 1;
+		float const *v_prev = mvert[ml[i_prev].v].co;
+		float const *v_curr;
+
+		zero_v3(polyno);
+		/* Newell's Method */
+		for (i = 0; i < nverts; i++) {
+			v_curr = mvert[ml[i].v].co;
+			add_newell_cross_v3_v3v3(polyno, v_prev, v_curr);
+
+			/* Unrelated to normalize, calcualte edge-vector */
+			sub_v3_v3v3(edgevecbuf[i_prev], v_prev, v_curr);
+			normalize_v3(edgevecbuf[i_prev]);
+			i_prev = i;
+
+			v_prev = v_curr;
+		}
+		if (UNLIKELY(normalize_v3(polyno) == 0.0f)) {
+			polyno[2] = 1.0f; /* other axis set to 0.0 */
+		}
+	}
+
+	/* accumulate angle weighted face normal */
+	/* inline version of #accumulate_vertex_normals_poly */
+	{
+		const float *prev_edge = edgevecbuf[nverts - 1];
+
+		for (i = 0; i < nverts; i++) {
+			const float *cur_edge = edgevecbuf[i];
+
+			/* calculate angle between the two poly edges incident on
+			 * this vertex */
+			const float fac = saacos(-dot_v3v3(cur_edge, prev_edge));
+
+			/* accumulate */
+			madd_v3_v3fl(tnorms[ml[i].v], polyno, fac);
+			prev_edge = cur_edge;
+		}
+	}
+
+}
+
+void BKE_mesh_calc_normals_poly(MVert *mverts, int numVerts, MLoop *mloop, MPoly *mpolys,
+                                int UNUSED(numLoops), int numPolys, float (*r_polynors)[3],
+                                const bool only_face_normals)
+{
+	float (*pnors)[3] = r_polynors;
+	float (*tnorms)[3];
+	int i;
+	MPoly *mp;
+
+	if (only_face_normals) {
+		BLI_assert(pnors != NULL);
+
+#pragma omp parallel for if (numPolys > BM_OMP_LIMIT)
+		for (i = 0; i < numPolys; i++) {
+			BKE_mesh_calc_poly_normal(&mpolys[i], mloop + mpolys[i].loopstart, mverts, pnors[i]);
+		}
+		return;
+	}
+
+	/* first go through and calculate normals for all the polys */
+	tnorms = MEM_callocN(sizeof(*tnorms) * numVerts, __func__);
+
+	if (pnors) {
+		mp = mpolys;
+		for (i = 0; i < numPolys; i++, mp++) {
+			mesh_calc_normals_poly_accum(mp, mloop + mp->loopstart, mverts, pnors[i], tnorms);
+		}
+	}
+	else {
+		float tpnor[3];  /* temp poly normal */
+		mp = mpolys;
+		for (i = 0; i < numPolys; i++, mp++) {
+			mesh_calc_normals_poly_accum(mp, mloop + mp->loopstart, mverts, tpnor, tnorms);
+		}
+	}
+
+	/* following Mesh convention; we use vertex coordinate itself for normal in this case */
+	for (i = 0; i < numVerts; i++) {
+		MVert *mv = &mverts[i];
+		float *no = tnorms[i];
+
+		if (UNLIKELY(normalize_v3(no) == 0.0f)) {
+			normalize_v3_v3(no, mv->co);
+		}
+
+		normal_float_to_short_v3(mv->no, no);
+	}
+
+	MEM_freeN(tnorms);
+}
+
+void BKE_mesh_calc_normals(Mesh *mesh)
+{
+	BKE_mesh_calc_normals_poly(mesh->mvert, mesh->totvert,
+	                           mesh->mloop, mesh->mpoly, mesh->totloop, mesh->totpoly,
+	                           NULL, false);
+}
+
+void BKE_mesh_calc_normals_tessface(MVert *mverts, int numVerts, MFace *mfaces, int numFaces, float (*faceNors_r)[3])
+{
+	float (*tnorms)[3] = MEM_callocN(numVerts * sizeof(*tnorms), "tnorms");
+	float (*fnors)[3] = (faceNors_r) ? faceNors_r : MEM_callocN(sizeof(*fnors) * numFaces, "meshnormals");
+	int i;
+
+	for (i = 0; i < numFaces; i++) {
+		MFace *mf = &mfaces[i];
+		float *f_no = fnors[i];
+		float *n4 = (mf->v4) ? tnorms[mf->v4] : NULL;
+		float *c4 = (mf->v4) ? mverts[mf->v4].co : NULL;
+
+		if (mf->v4)
+			normal_quad_v3(f_no, mverts[mf->v1].co, mverts[mf->v2].co, mverts[mf->v3].co, mverts[mf->v4].co);
+		else
+			normal_tri_v3(f_no, mverts[mf->v1].co, mverts[mf->v2].co, mverts[mf->v3].co);
+
+		accumulate_vertex_normals(tnorms[mf->v1], tnorms[mf->v2], tnorms[mf->v3], n4,
+		                          f_no, mverts[mf->v1].co, mverts[mf->v2].co, mverts[mf->v3].co, c4);
+	}
+
+	/* following Mesh convention; we use vertex coordinate itself for normal in this case */
+	for (i = 0; i < numVerts; i++) {
+		MVert *mv = &mverts[i];
+		float *no = tnorms[i];
+		
+		if (UNLIKELY(normalize_v3(no) == 0.0f)) {
+			normalize_v3_v3(no, mv->co);
+		}
+
+		normal_float_to_short_v3(mv->no, no);
+	}
+	
+	MEM_freeN(tnorms);
+
+	if (fnors != faceNors_r)
+		MEM_freeN(fnors);
+}
+/** \} */
+
+
+/* -------------------------------------------------------------------- */
+
+/** \name Polygon Calculations
+ * \{ */
+
+/*
+ * COMPUTE POLY NORMAL
+ *
+ * Computes the normal of a planar
+ * polygon See Graphics Gems for
+ * computing newell normal.
+ *
+ */
+static void mesh_calc_ngon_normal(MPoly *mpoly, MLoop *loopstart,
+                                  MVert *mvert, float normal[3])
+{
+	const int nverts = mpoly->totloop;
+	float const *v_prev = mvert[loopstart[nverts - 1].v].co;
+	float const *v_curr;
+	int i;
+
+	zero_v3(normal);
+
+	/* Newell's Method */
+	for (i = 0; i < nverts; i++) {
+		v_curr = mvert[loopstart[i].v].co;
+		add_newell_cross_v3_v3v3(normal, v_prev, v_curr);
+		v_prev = v_curr;
+	}
+
+	if (UNLIKELY(normalize_v3(normal) == 0.0f)) {
+		normal[2] = 1.0f; /* other axis set to 0.0 */
+	}
+}
+
+void BKE_mesh_calc_poly_normal(MPoly *mpoly, MLoop *loopstart,
+                               MVert *mvarray, float no[3])
+{
+	if (mpoly->totloop > 4) {
+		mesh_calc_ngon_normal(mpoly, loopstart, mvarray, no);
+	}
+	else if (mpoly->totloop == 3) {
+		normal_tri_v3(no,
+		              mvarray[loopstart[0].v].co,
+		              mvarray[loopstart[1].v].co,
+		              mvarray[loopstart[2].v].co
+		              );
+	}
+	else if (mpoly->totloop == 4) {
+		normal_quad_v3(no,
+		               mvarray[loopstart[0].v].co,
+		               mvarray[loopstart[1].v].co,
+		               mvarray[loopstart[2].v].co,
+		               mvarray[loopstart[3].v].co
+		               );
+	}
+	else { /* horrible, two sided face! */
+		no[0] = 0.0;
+		no[1] = 0.0;
+		no[2] = 1.0;
+	}
+}
+/* duplicate of function above _but_ takes coords rather then mverts */
+static void mesh_calc_ngon_normal_coords(MPoly *mpoly, MLoop *loopstart,
+                                         const float (*vertex_coords)[3], float normal[3])
+{
+	const int nverts = mpoly->totloop;
+	float const *v_prev = vertex_coords[loopstart[nverts - 1].v];
+	float const *v_curr;
+	int i;
+
+	zero_v3(normal);
+
+	/* Newell's Method */
+	for (i = 0; i < nverts; i++) {
+		v_curr = vertex_coords[loopstart[i].v];
+		add_newell_cross_v3_v3v3(normal, v_prev, v_curr);
+		v_prev = v_curr;
+	}
+
+	if (UNLIKELY(normalize_v3(normal) == 0.0f)) {
+		normal[2] = 1.0f; /* other axis set to 0.0 */
+	}
+}
+
+void BKE_mesh_calc_poly_normal_coords(MPoly *mpoly, MLoop *loopstart,
+                                      const float (*vertex_coords)[3], float no[3])
+{
+	if (mpoly->totloop > 4) {
+		mesh_calc_ngon_normal_coords(mpoly, loopstart, vertex_coords, no);
+	}
+	else if (mpoly->totloop == 3) {
+		normal_tri_v3(no,
+		              vertex_coords[loopstart[0].v],
+		              vertex_coords[loopstart[1].v],
+		              vertex_coords[loopstart[2].v]
+		              );
+	}
+	else if (mpoly->totloop == 4) {
+		normal_quad_v3(no,
+		               vertex_coords[loopstart[0].v],
+		               vertex_coords[loopstart[1].v],
+		               vertex_coords[loopstart[2].v],
+		               vertex_coords[loopstart[3].v]
+		               );
+	}
+	else { /* horrible, two sided face! */
+		no[0] = 0.0;
+		no[1] = 0.0;
+		no[2] = 1.0;
+	}
+}
+
+static void mesh_calc_ngon_center(MPoly *mpoly, MLoop *loopstart,
+                                  MVert *mvert, float cent[3])
+{
+	const float w = 1.0f / (float)mpoly->totloop;
+	int i;
+
+	zero_v3(cent);
+
+	for (i = 0; i < mpoly->totloop; i++) {
+		madd_v3_v3fl(cent, mvert[(loopstart++)->v].co, w);
+	}
+}
+
+void BKE_mesh_calc_poly_center(MPoly *mpoly, MLoop *loopstart,
+                               MVert *mvarray, float cent[3])
+{
+	if (mpoly->totloop == 3) {
+		cent_tri_v3(cent,
+		            mvarray[loopstart[0].v].co,
+		            mvarray[loopstart[1].v].co,
+		            mvarray[loopstart[2].v].co
+		            );
+	}
+	else if (mpoly->totloop == 4) {
+		cent_quad_v3(cent,
+		             mvarray[loopstart[0].v].co,
+		             mvarray[loopstart[1].v].co,
+		             mvarray[loopstart[2].v].co,
+		             mvarray[loopstart[3].v].co
+		             );
+	}
+	else {
+		mesh_calc_ngon_center(mpoly, loopstart, mvarray, cent);
+	}
+}
+
+/* note, passing polynormal is only a speedup so we can skip calculating it */
+float BKE_mesh_calc_poly_area(MPoly *mpoly, MLoop *loopstart,
+                              MVert *mvarray, const float polynormal[3])
+{
+	if (mpoly->totloop == 3) {
+		return area_tri_v3(mvarray[loopstart[0].v].co,
+		                   mvarray[loopstart[1].v].co,
+		                   mvarray[loopstart[2].v].co
+		                   );
+	}
+	else if (mpoly->totloop == 4) {
+		return area_quad_v3(mvarray[loopstart[0].v].co,
+		                    mvarray[loopstart[1].v].co,
+		                    mvarray[loopstart[2].v].co,
+		                    mvarray[loopstart[3].v].co
+		                    );
+	}
+	else {
+		int i;
+		MLoop *l_iter = loopstart;
+		float area, polynorm_local[3];
+		float (*vertexcos)[3] = BLI_array_alloca(vertexcos, mpoly->totloop);
+		const float *no = polynormal ? polynormal : polynorm_local;
+
+		/* pack vertex cos into an array for area_poly_v3 */
+		for (i = 0; i < mpoly->totloop; i++, l_iter++) {
+			copy_v3_v3(vertexcos[i], mvarray[l_iter->v].co);
+		}
+
+		/* need normal for area_poly_v3 as well */
+		if (polynormal == NULL) {
+			BKE_mesh_calc_poly_normal(mpoly, loopstart, mvarray, polynorm_local);
+		}
+
+		/* finally calculate the area */
+		area = area_poly_v3(mpoly->totloop, vertexcos, no);
+
+		return area;
+	}
+}
+
+/* note, results won't be correct if polygon is non-planar */
+static float mesh_calc_poly_planar_area_centroid(MPoly *mpoly, MLoop *loopstart, MVert *mvarray, float cent[3])
+{
+	int i;
+	float tri_area;
+	float total_area = 0.0f;
+	float v1[3], v2[3], v3[3], normal[3], tri_cent[3];
+
+	BKE_mesh_calc_poly_normal(mpoly, loopstart, mvarray, normal);
+	copy_v3_v3(v1, mvarray[loopstart[0].v].co);
+	copy_v3_v3(v2, mvarray[loopstart[1].v].co);
+	zero_v3(cent);
+
+	for (i = 2; i < mpoly->totloop; i++) {
+		copy_v3_v3(v3, mvarray[loopstart[i].v].co);
+
+		tri_area = area_tri_signed_v3(v1, v2, v3, normal);
+		total_area += tri_area;
+
+		cent_tri_v3(tri_cent, v1, v2, v3);
+		madd_v3_v3fl(cent, tri_cent, tri_area);
+
+		copy_v3_v3(v2, v3);
+	}
+
+	mul_v3_fl(cent, 1.0f / total_area);
+
+	return total_area;
+}
+
+#if 0 /* slow version of the function below */
+void BKE_mesh_calc_poly_angles(MPoly *mpoly, MLoop *loopstart,
+                               MVert *mvarray, float angles[])
+{
+	MLoop *ml;
+	MLoop *mloop = &loopstart[-mpoly->loopstart];
+
+	int j;
+	for (j = 0, ml = loopstart; j < mpoly->totloop; j++, ml++) {
+		MLoop *ml_prev = ME_POLY_LOOP_PREV(mloop, mpoly, j);
+		MLoop *ml_next = ME_POLY_LOOP_NEXT(mloop, mpoly, j);
+
+		float e1[3], e2[3];
+
+		sub_v3_v3v3(e1, mvarray[ml_next->v].co, mvarray[ml->v].co);
+		sub_v3_v3v3(e2, mvarray[ml_prev->v].co, mvarray[ml->v].co);
+
+		angles[j] = (float)M_PI - angle_v3v3(e1, e2);
+	}
+}
+
+#else /* equivalent the function above but avoid multiple subtractions + normalize */
+
+void BKE_mesh_calc_poly_angles(MPoly *mpoly, MLoop *loopstart,
+                               MVert *mvarray, float angles[])
+{
+	float nor_prev[3];
+	float nor_next[3];
+
+	int i_this = mpoly->totloop - 1;
+	int i_next = 0;
+
+	sub_v3_v3v3(nor_prev, mvarray[loopstart[i_this - 1].v].co, mvarray[loopstart[i_this].v].co);
+	normalize_v3(nor_prev);
+
+	while (i_next < mpoly->totloop) {
+		sub_v3_v3v3(nor_next, mvarray[loopstart[i_this].v].co, mvarray[loopstart[i_next].v].co);
+		normalize_v3(nor_next);
+		angles[i_this] = angle_normalized_v3v3(nor_prev, nor_next);
+
+		/* step */
+		copy_v3_v3(nor_prev, nor_next);
+		i_this = i_next;
+		i_next++;
+	}
+}
+#endif
+
+void BKE_mesh_poly_edgehash_insert(EdgeHash *ehash, const MPoly *mp, const MLoop *mloop)
+{
+	const MLoop *ml, *ml_next;
+	int i = mp->totloop;
+
+	ml_next = mloop;       /* first loop */
+	ml = &ml_next[i - 1];  /* last loop */
+
+	while (i-- != 0) {
+		BLI_edgehash_reinsert(ehash, ml->v, ml_next->v, NULL);
+
+		ml = ml_next;
+		ml_next++;
+	}
+}
+
+void BKE_mesh_poly_edgebitmap_insert(unsigned int *edge_bitmap, const MPoly *mp, const MLoop *mloop)
+{
+	const MLoop *ml;
+	int i = mp->totloop;
+
+	ml = mloop;
+
+	while (i-- != 0) {
+		BLI_BITMAP_SET(edge_bitmap, ml->e);
+		ml++;
+	}
+}
+
+/** \} */
+
+
+/* -------------------------------------------------------------------- */
+
+/** \name Mesh Center Calculation
+ * \{ */
+
+bool BKE_mesh_center_median(Mesh *me, float cent[3])
+{
+	int i = me->totvert;
+	MVert *mvert;
+	zero_v3(cent);
+	for (mvert = me->mvert; i--; mvert++) {
+		add_v3_v3(cent, mvert->co);
+	}
+	/* otherwise we get NAN for 0 verts */
+	if (me->totvert) {
+		mul_v3_fl(cent, 1.0f / (float)me->totvert);
+	}
+
+	return (me->totvert != 0);
+}
+
+bool BKE_mesh_center_bounds(Mesh *me, float cent[3])
+{
+	float min[3], max[3];
+	INIT_MINMAX(min, max);
+	if (BKE_mesh_minmax(me, min, max)) {
+		mid_v3_v3v3(cent, min, max);
+		return true;
+	}
+
+	return false;
+}
+
+bool BKE_mesh_center_centroid(Mesh *me, float cent[3])
+{
+	int i = me->totpoly;
+	MPoly *mpoly;
+	float poly_area;
+	float total_area = 0.0f;
+	float poly_cent[3];
+
+	zero_v3(cent);
+
+	/* calculate a weighted average of polygon centroids */
+	for (mpoly = me->mpoly; i--; mpoly++) {
+		poly_area = mesh_calc_poly_planar_area_centroid(mpoly, me->mloop + mpoly->loopstart, me->mvert, poly_cent);
+
+		madd_v3_v3fl(cent, poly_cent, poly_area);
+		total_area += poly_area;
+	}
+	/* otherwise we get NAN for 0 polys */
+	if (me->totpoly) {
+		mul_v3_fl(cent, 1.0f / total_area);
+	}
+
+	/* zero area faces cause this, fallback to median */
+	if (UNLIKELY(!is_finite_v3(cent))) {
+		return BKE_mesh_center_median(me, cent);
+	}
+
+	return (me->totpoly != 0);
+}
+/** \} */
+
+
+/* -------------------------------------------------------------------- */
+
+/** \name Mesh Connectivity Mapping
+ * \{ */
+
+
+/* ngon version wip, based on EDBM_uv_vert_map_create */
+/* this replaces the non bmesh function (in trunk) which takes MTFace's, if we ever need it back we could
+ * but for now this replaces it because its unused. */
+
+UvVertMap *BKE_mesh_uv_vert_map_create(struct MPoly *mpoly, struct MLoop *mloop, struct MLoopUV *mloopuv,
+                                       unsigned int totpoly, unsigned int totvert, int selected, float *limit)
+{
+	UvVertMap *vmap;
+	UvMapVert *buf;
+	MPoly *mp;
+	unsigned int a;
+	int i, totuv, nverts;
+
+	totuv = 0;
+
+	/* generate UvMapVert array */
+	mp = mpoly;
+	for (a = 0; a < totpoly; a++, mp++)
+		if (!selected || (!(mp->flag & ME_HIDE) && (mp->flag & ME_FACE_SEL)))
+			totuv += mp->totloop;
+
+	if (totuv == 0)
+		return NULL;
+
+	vmap = (UvVertMap *)MEM_callocN(sizeof(*vmap), "UvVertMap");
+	if (!vmap)
+		return NULL;
+
+	vmap->vert = (UvMapVert **)MEM_callocN(sizeof(*vmap->vert) * totvert, "UvMapVert*");
+	buf = vmap->buf = (UvMapVert *)MEM_callocN(sizeof(*vmap->buf) * totuv, "UvMapVert");
+
+	if (!vmap->vert || !vmap->buf) {
+		BKE_mesh_uv_vert_map_free(vmap);
+		return NULL;
+	}
+
+	mp = mpoly;
+	for (a = 0; a < totpoly; a++, mp++) {
+		if (!selected || (!(mp->flag & ME_HIDE) && (mp->flag & ME_FACE_SEL))) {
+			nverts = mp->totloop;
+
+			for (i = 0; i < nverts; i++) {
+				buf->tfindex = i;
+				buf->f = a;
+				buf->separate = 0;
+				buf->next = vmap->vert[mloop[mp->loopstart + i].v];
+				vmap->vert[mloop[mp->loopstart + i].v] = buf;
+				buf++;
+			}
+		}
+	}
+
+	/* sort individual uvs for each vert */
+	for (a = 0; a < totvert; a++) {
+		UvMapVert *newvlist = NULL, *vlist = vmap->vert[a];
+		UvMapVert *iterv, *v, *lastv, *next;
+		float *uv, *uv2, uvdiff[2];
+
+		while (vlist) {
+			v = vlist;
+			vlist = vlist->next;
+			v->next = newvlist;
+			newvlist = v;
+
+			uv = mloopuv[mpoly[v->f].loopstart + v->tfindex].uv;
+			lastv = NULL;
+			iterv = vlist;
+
+			while (iterv) {
+				next = iterv->next;
+
+				uv2 = mloopuv[mpoly[iterv->f].loopstart + iterv->tfindex].uv;
+				sub_v2_v2v2(uvdiff, uv2, uv);
+
+
+				if (fabsf(uv[0] - uv2[0]) < limit[0] && fabsf(uv[1] - uv2[1]) < limit[1]) {
+					if (lastv) lastv->next = next;
+					else vlist = next;
+					iterv->next = newvlist;
+					newvlist = iterv;
+				}
+				else
+					lastv = iterv;
+
+				iterv = next;
+			}
+
+			newvlist->separate = 1;
+		}
+
+		vmap->vert[a] = newvlist;
+	}
+
+	return vmap;
+}
+
+UvMapVert *BKE_mesh_uv_vert_map_get_vert(UvVertMap *vmap, unsigned int v)
+{
+	return vmap->vert[v];
+}
+
+void BKE_mesh_uv_vert_map_free(UvVertMap *vmap)
+{
+	if (vmap) {
+		if (vmap->vert) MEM_freeN(vmap->vert);
+		if (vmap->buf) MEM_freeN(vmap->buf);
+		MEM_freeN(vmap);
+	}
+}
+
+/* Generates a map where the key is the vertex and the value is a list
+ * of polys that use that vertex as a corner. The lists are allocated
+ * from one memory pool. */
+void BKE_mesh_vert_poly_map_create(MeshElemMap **r_map, int **r_mem,
+                                   const MPoly *mpoly, const MLoop *mloop,
+                                   int totvert, int totpoly, int totloop)
+{
+	MeshElemMap *map = MEM_callocN(sizeof(MeshElemMap) * totvert, "vert poly map");
+	int *indices, *index_iter;
+	int i, j;
+
+	indices = index_iter = MEM_mallocN(sizeof(int) * totloop, "vert poly map mem");
+
+	/* Count number of polys for each vertex */
+	for (i = 0; i < totpoly; i++) {
+		const MPoly *p = &mpoly[i];
+
+		for (j = 0; j < p->totloop; j++)
+			map[mloop[p->loopstart + j].v].count++;
+	}
+
+	/* Assign indices mem */
+	for (i = 0; i < totvert; i++) {
+		map[i].indices = index_iter;
+		index_iter += map[i].count;
+
+		/* Reset 'count' for use as index in last loop */
+		map[i].count = 0;
+	}
+
+	/* Find the users */
+	for (i = 0; i < totpoly; i++) {
+		const MPoly *p = &mpoly[i];
+
+		for (j = 0; j < p->totloop; j++) {
+			int v = mloop[p->loopstart + j].v;
+
+			map[v].indices[map[v].count] = i;
+			map[v].count++;
+		}
+	}
+
+	*r_map = map;
+	*r_mem = indices;
+}
+
+/* Generates a map where the key is the vertex and the value is a list
+ * of edges that use that vertex as an endpoint. The lists are allocated
+ * from one memory pool. */
+void BKE_mesh_vert_edge_map_create(MeshElemMap **r_map, int **r_mem,
+                                   const MEdge *medge, int totvert, int totedge)
+{
+	MeshElemMap *map = MEM_callocN(sizeof(MeshElemMap) * totvert, "vert-edge map");
+	int *indices = MEM_mallocN(sizeof(int) * totedge * 2, "vert-edge map mem");
+	int *i_pt = indices;
+
+	int i;
+
+	/* Count number of edges for each vertex */
+	for (i = 0; i < totedge; i++) {
+		map[medge[i].v1].count++;
+		map[medge[i].v2].count++;
+	}
+
+	/* Assign indices mem */
+	for (i = 0; i < totvert; i++) {
+		map[i].indices = i_pt;
+		i_pt += map[i].count;
+
+		/* Reset 'count' for use as index in last loop */
+		map[i].count = 0;
+	}
+
+	/* Find the users */
+	for (i = 0; i < totedge; i++) {
+		const int v[2] = {medge[i].v1, medge[i].v2};
+
+		map[v[0]].indices[map[v[0]].count] = i;
+		map[v[1]].indices[map[v[1]].count] = i;
+
+		map[v[0]].count++;
+		map[v[1]].count++;
+	}
+
+	*r_map = map;
+	*r_mem = indices;
+}
+
+void BKE_mesh_edge_poly_map_create(MeshElemMap **r_map, int **r_mem,
+                                   const MEdge *UNUSED(medge), const int totedge,
+                                   const MPoly *mpoly, const int totpoly,
+                                   const MLoop *mloop, const int totloop)
+{
+	MeshElemMap *map = MEM_callocN(sizeof(MeshElemMap) * totedge, "edge-poly map");
+	int *indices = MEM_mallocN(sizeof(int) * totloop, "edge-poly map mem");
+	int *index_step;
+	const MPoly *mp;
+	int i;
+
+	/* count face users */
+	for (i = 0, mp = mpoly; i < totpoly; mp++, i++) {
+		const MLoop *ml;
+		int j = mp->totloop;
+		for (ml = &mloop[mp->loopstart]; j--; ml++) {
+			map[ml->e].count++;
+		}
+	}
+
+	/* create offsets */
+	index_step = indices;
+	for (i = 0; i < totedge; i++) {
+		map[i].indices = index_step;
+		index_step += map[i].count;
+
+		/* re-count, using this as an index below */
+		map[i].count = 0;
+
+	}
+
+	/* assign poly-edge users */
+	for (i = 0, mp = mpoly; i < totpoly; mp++, i++) {
+		const MLoop *ml;
+		int j = mp->totloop;
+		for (ml = &mloop[mp->loopstart]; j--; ml++) {
+			MeshElemMap *map_ele = &map[ml->e];
+			map_ele->indices[map_ele->count++] = i;
+		}
+	}
+
+	*r_map = map;
+	*r_mem = indices;
+}
+
+
+/** \} */
+
+
+/* -------------------------------------------------------------------- */
+
+/** \name NGon Tessellation (NGon/Tessface Conversion)
+ * \{ */
+
+/**
+ * Convert a triangle or quadrangle of loop/poly data to tessface data
+ */
+void BKE_mesh_loops_to_mface_corners(
+        CustomData *fdata, CustomData *ldata,
+        CustomData *pdata, int lindex[4], int findex,
+        const int polyindex,
+        const int mf_len, /* 3 or 4 */
+
+        /* cache values to avoid lookups every time */
+        const int numTex, /* CustomData_number_of_layers(pdata, CD_MTEXPOLY) */
+        const int numCol, /* CustomData_number_of_layers(ldata, CD_MLOOPCOL) */
+        const bool hasPCol, /* CustomData_has_layer(ldata, CD_PREVIEW_MLOOPCOL) */
+        const bool hasOrigSpace /* CustomData_has_layer(ldata, CD_ORIGSPACE_MLOOP) */
+)
+{
+	MTFace *texface;
+	MTexPoly *texpoly;
+	MCol *mcol;
+	MLoopCol *mloopcol;
+	MLoopUV *mloopuv;
+	int i, j;
+
+	for (i = 0; i < numTex; i++) {
+		texface = CustomData_get_n(fdata, CD_MTFACE, findex, i);
+		texpoly = CustomData_get_n(pdata, CD_MTEXPOLY, polyindex, i);
+
+		ME_MTEXFACE_CPY(texface, texpoly);
+
+		for (j = 0; j < mf_len; j++) {
+			mloopuv = CustomData_get_n(ldata, CD_MLOOPUV, lindex[j], i);
+			copy_v2_v2(texface->uv[j], mloopuv->uv);
+		}
+	}
+
+	for (i = 0; i < numCol; i++) {
+		mcol = CustomData_get_n(fdata, CD_MCOL, findex, i);
+
+		for (j = 0; j < mf_len; j++) {
+			mloopcol = CustomData_get_n(ldata, CD_MLOOPCOL, lindex[j], i);
+			MESH_MLOOPCOL_TO_MCOL(mloopcol, &mcol[j]);
+		}
+	}
+
+	if (hasPCol) {
+		mcol = CustomData_get(fdata,  findex, CD_PREVIEW_MCOL);
+
+		for (j = 0; j < mf_len; j++) {
+			mloopcol = CustomData_get(ldata, lindex[j], CD_PREVIEW_MLOOPCOL);
+			MESH_MLOOPCOL_TO_MCOL(mloopcol, &mcol[j]);
+		}
+	}
+
+	if (hasOrigSpace) {
+		OrigSpaceFace *of = CustomData_get(fdata, findex, CD_ORIGSPACE);
+		OrigSpaceLoop *lof;
+
+		for (j = 0; j < mf_len; j++) {
+			lof = CustomData_get(ldata, lindex[j], CD_ORIGSPACE_MLOOP);
+			copy_v2_v2(of->uv[j], lof->uv);
+		}
+	}
+}
+
+/**
+ * Recreate tessellation.
+ *
+ * use_poly_origindex sets whether or not the tessellation faces' origindex
+ * layer should point to original poly indices or real poly indices.
+ *
+ * use_face_origindex sets the tessellation faces' origindex layer
+ * to point to the tessellation faces themselves, not the polys.
+ *
+ * if both of the above are 0, it'll use the indices of the mpolys of the MPoly
+ * data in pdata, and ignore the origindex layer altogether.
+ *
+ * \return number of tessellation faces.
+ */
+int BKE_mesh_recalc_tessellation(CustomData *fdata,
+                                 CustomData *ldata, CustomData *pdata,
+                                 MVert *mvert, int totface, int totloop,
+                                 int totpoly,
+                                 /* when tessellating to recalculate normals after
+                                  * we can skip copying here */
+                                 const bool do_face_nor_cpy)
+{
+	/* use this to avoid locking pthread for _every_ polygon
+	 * and calling the fill function */
+
+#define USE_TESSFACE_SPEEDUP
+#define USE_TESSFACE_QUADS // NEEDS FURTHER TESTING
+
+#define TESSFACE_SCANFILL (1 << 0)
+#define TESSFACE_IS_QUAD  (1 << 1)
+
+	const int looptris_tot = poly_to_tri_count(totpoly, totloop);
+
+	MPoly *mp, *mpoly;
+	MLoop *ml, *mloop;
+	MFace *mface, *mf;
+	ScanFillContext sf_ctx;
+	ScanFillVert *sf_vert, *sf_vert_last, *sf_vert_first;
+	ScanFillFace *sf_tri;
+	MemArena *sf_arena = NULL;
+	int *mface_to_poly_map;
+	int lindex[4]; /* only ever use 3 in this case */
+	int poly_index, j, mface_index;
+
+	const int numTex = CustomData_number_of_layers(pdata, CD_MTEXPOLY);
+	const int numCol = CustomData_number_of_layers(ldata, CD_MLOOPCOL);
+	const bool hasPCol = CustomData_has_layer(ldata, CD_PREVIEW_MLOOPCOL);
+	const bool hasOrigSpace = CustomData_has_layer(ldata, CD_ORIGSPACE_MLOOP);
+
+	mpoly = CustomData_get_layer(pdata, CD_MPOLY);
+	mloop = CustomData_get_layer(ldata, CD_MLOOP);
+
+	/* allocate the length of totfaces, avoid many small reallocs,
+	 * if all faces are tri's it will be correct, quads == 2x allocs */
+	/* take care. we are _not_ calloc'ing so be sure to initialize each field */
+	mface_to_poly_map = MEM_mallocN(sizeof(*mface_to_poly_map) * looptris_tot, __func__);
+	mface             = MEM_mallocN(sizeof(*mface) *             looptris_tot, __func__);
+
+	mface_index = 0;
+	mp = mpoly;
+	for (poly_index = 0; poly_index < totpoly; poly_index++, mp++) {
+		if (mp->totloop < 3) {
+			/* do nothing */
+		}
+
+#ifdef USE_TESSFACE_SPEEDUP
+
+#define ML_TO_MF(i1, i2, i3)                                                  \
+		mface_to_poly_map[mface_index] = poly_index;                          \
+		mf = &mface[mface_index];                                             \
+		/* set loop indices, transformed to vert indices later */             \
+		mf->v1 = mp->loopstart + i1;                                          \
+		mf->v2 = mp->loopstart + i2;                                          \
+		mf->v3 = mp->loopstart + i3;                                          \
+		mf->v4 = 0;                                                           \
+		mf->mat_nr = mp->mat_nr;                                              \
+		mf->flag = mp->flag;                                                  \
+		mf->edcode = 0;                                                       \
+		(void)0
+
+/* ALMOST IDENTICAL TO DEFINE ABOVE (see EXCEPTION) */
+#define ML_TO_MF_QUAD()                                                       \
+		mface_to_poly_map[mface_index] = poly_index;                          \
+		mf = &mface[mface_index];                                             \
+		/* set loop indices, transformed to vert indices later */             \
+		mf->v1 = mp->loopstart + 0; /* EXCEPTION */                           \
+		mf->v2 = mp->loopstart + 1; /* EXCEPTION */                           \
+		mf->v3 = mp->loopstart + 2; /* EXCEPTION */                           \
+		mf->v4 = mp->loopstart + 3; /* EXCEPTION */                           \
+		mf->mat_nr = mp->mat_nr;                                              \
+		mf->flag = mp->flag;                                                  \
+		mf->edcode = TESSFACE_IS_QUAD; /* EXCEPTION */                        \
+		(void)0
+
+
+		else if (mp->totloop == 3) {
+			ML_TO_MF(0, 1, 2);
+			mface_index++;
+		}
+		else if (mp->totloop == 4) {
+#ifdef USE_TESSFACE_QUADS
+			ML_TO_MF_QUAD();
+			mface_index++;
+#else
+			ML_TO_MF(0, 1, 2);
+			mface_index++;
+			ML_TO_MF(0, 2, 3);
+			mface_index++;
+#endif
+		}
+#endif /* USE_TESSFACE_SPEEDUP */
+		else {
+#define USE_TESSFACE_CALCNORMAL
+
+			int totfilltri;
+
+#ifdef USE_TESSFACE_CALCNORMAL
+			float normal[3];
+			zero_v3(normal);
+#endif
+			ml = mloop + mp->loopstart;
+
+			if (UNLIKELY(sf_arena == NULL)) {
+				sf_arena = BLI_memarena_new(BLI_SCANFILL_ARENA_SIZE, __func__);
+			}
+
+			BLI_scanfill_begin_arena(&sf_ctx, sf_arena);
+			sf_vert_first = NULL;
+			sf_vert_last = NULL;
+			for (j = 0; j < mp->totloop; j++, ml++) {
+				sf_vert = BLI_scanfill_vert_add(&sf_ctx, mvert[ml->v].co);
+
+				sf_vert->keyindex = mp->loopstart + j;
+
+				if (sf_vert_last) {
+					BLI_scanfill_edge_add(&sf_ctx, sf_vert_last, sf_vert);
+#ifdef USE_TESSFACE_CALCNORMAL
+					add_newell_cross_v3_v3v3(normal, sf_vert_last->co, sf_vert->co);
+#endif
+				}
+
+				if (!sf_vert_first)
+					sf_vert_first = sf_vert;
+				sf_vert_last = sf_vert;
+			}
+			BLI_scanfill_edge_add(&sf_ctx, sf_vert_last, sf_vert_first);
+#ifdef USE_TESSFACE_CALCNORMAL
+			add_newell_cross_v3_v3v3(normal, sf_vert_last->co, sf_vert_first->co);
+			if (UNLIKELY(normalize_v3(normal) == 0.0f)) {
+				normal[2] = 1.0f;
+			}
+			totfilltri = BLI_scanfill_calc_ex(&sf_ctx, 0, normal);
+#else
+			totfilltri = BLI_scanfill_calc(&sf_ctx, 0);
+#endif
+			BLI_assert(totfilltri <= mp->totloop - 2);
+			(void)totfilltri;
+
+			for (sf_tri = sf_ctx.fillfacebase.first; sf_tri; sf_tri = sf_tri->next, mf++) {
+				mface_to_poly_map[mface_index] = poly_index;
+				mf = &mface[mface_index];
+
+				/* set loop indices, transformed to vert indices later */
+				mf->v1 = sf_tri->v1->keyindex;
+				mf->v2 = sf_tri->v2->keyindex;
+				mf->v3 = sf_tri->v3->keyindex;
+				mf->v4 = 0;
+
+				mf->mat_nr = mp->mat_nr;
+				mf->flag = mp->flag;
+
+#ifdef USE_TESSFACE_SPEEDUP
+				mf->edcode = TESSFACE_SCANFILL; /* tag for sorting loop indices */
+#endif
+
+				mface_index++;
+			}
+
+			BLI_scanfill_end_arena(&sf_ctx, sf_arena);
+
+#undef USE_TESSFACE_CALCNORMAL
+		}
+	}
+
+	if (sf_arena) {
+		BLI_memarena_free(sf_arena);
+		sf_arena = NULL;
+	}
+
+	CustomData_free(fdata, totface);
+	totface = mface_index;
+
+	BLI_assert(totface <= looptris_tot);
+
+	/* not essential but without this we store over-alloc'd memory in the CustomData layers */
+	if (LIKELY(looptris_tot != totface)) {
+		mface = MEM_reallocN(mface, sizeof(*mface) * totface);
+		mface_to_poly_map = MEM_reallocN(mface_to_poly_map, sizeof(*mface_to_poly_map) * totface);
+	}
+
+	CustomData_add_layer(fdata, CD_MFACE, CD_ASSIGN, mface, totface);
+
+	/* CD_ORIGINDEX will contain an array of indices from tessfaces to the polygons
+	 * they are directly tessellated from */
+	CustomData_add_layer(fdata, CD_ORIGINDEX, CD_ASSIGN, mface_to_poly_map, totface);
+	CustomData_from_bmeshpoly(fdata, pdata, ldata, totface);
+
+	if (do_face_nor_cpy) {
+		/* If polys have a normals layer, copying that to faces can help
+		 * avoid the need to recalculate normals later */
+		if (CustomData_has_layer(pdata, CD_NORMAL)) {
+			float (*pnors)[3] = CustomData_get_layer(pdata, CD_NORMAL);
+			float (*fnors)[3] = CustomData_add_layer(fdata, CD_NORMAL, CD_CALLOC, NULL, totface);
+			for (mface_index = 0; mface_index < totface; mface_index++) {
+				copy_v3_v3(fnors[mface_index], pnors[mface_to_poly_map[mface_index]]);
+			}
+		}
+	}
+
+	mf = mface;
+	for (mface_index = 0; mface_index < totface; mface_index++, mf++) {
+
+#ifdef USE_TESSFACE_QUADS
+		const int mf_len = mf->edcode & TESSFACE_IS_QUAD ? 4 : 3;
+#endif
+
+#ifdef USE_TESSFACE_SPEEDUP
+		/* skip sorting when not using ngons */
+		if (UNLIKELY(mf->edcode & TESSFACE_SCANFILL))
+#endif
+		{
+			/* sort loop indices to ensure winding is correct */
+			if (mf->v1 > mf->v2) SWAP(unsigned int, mf->v1, mf->v2);
+			if (mf->v2 > mf->v3) SWAP(unsigned int, mf->v2, mf->v3);
+			if (mf->v1 > mf->v2) SWAP(unsigned int, mf->v1, mf->v2);
+
+			if (mf->v1 > mf->v2) SWAP(unsigned int, mf->v1, mf->v2);
+			if (mf->v2 > mf->v3) SWAP(unsigned int, mf->v2, mf->v3);
+			if (mf->v1 > mf->v2) SWAP(unsigned int, mf->v1, mf->v2);
+		}
+
+		/* end abusing the edcode */
+#if defined(USE_TESSFACE_QUADS) || defined(USE_TESSFACE_SPEEDUP)
+		mf->edcode = 0;
+#endif
+
+
+		lindex[0] = mf->v1;
+		lindex[1] = mf->v2;
+		lindex[2] = mf->v3;
+#ifdef USE_TESSFACE_QUADS
+		if (mf_len == 4) lindex[3] = mf->v4;
+#endif
+
+		/*transform loop indices to vert indices*/
+		mf->v1 = mloop[mf->v1].v;
+		mf->v2 = mloop[mf->v2].v;
+		mf->v3 = mloop[mf->v3].v;
+#ifdef USE_TESSFACE_QUADS
+		if (mf_len == 4) mf->v4 = mloop[mf->v4].v;
+#endif
+
+		BKE_mesh_loops_to_mface_corners(fdata, ldata, pdata,
+		                                lindex, mface_index, mface_to_poly_map[mface_index],
+#ifdef USE_TESSFACE_QUADS
+		                                mf_len,
+#else
+		                                3,
+#endif
+		                                numTex, numCol, hasPCol, hasOrigSpace);
+
+
+#ifdef USE_TESSFACE_QUADS
+		test_index_face(mf, fdata, mface_index, mf_len);
+#endif
+
+	}
+
+	return totface;
+
+#undef USE_TESSFACE_SPEEDUP
+
+}
+
+
+#ifdef USE_BMESH_SAVE_AS_COMPAT
+
+/**
+ * This function recreates a tessellation.
+ * returns number of tessellation faces.
+ *
+ * for forwards compat only quad->tri polys to mface, skip ngons.
+ */
+int BKE_mesh_mpoly_to_mface(struct CustomData *fdata, struct CustomData *ldata,
+                            struct CustomData *pdata, int totface, int UNUSED(totloop), int totpoly)
+{
+	MLoop *mloop;
+
+	int lindex[4];
+	int i;
+	int k;
+
+	MPoly *mp, *mpoly;
+	MFace *mface = NULL, *mf;
+	BLI_array_declare(mface);
+
+	const int numTex = CustomData_number_of_layers(pdata, CD_MTEXPOLY);
+	const int numCol = CustomData_number_of_layers(ldata, CD_MLOOPCOL);
+	const bool hasPCol = CustomData_has_layer(ldata, CD_PREVIEW_MLOOPCOL);
+	const bool hasOrigSpace = CustomData_has_layer(ldata, CD_ORIGSPACE_MLOOP);
+
+	mpoly = CustomData_get_layer(pdata, CD_MPOLY);
+	mloop = CustomData_get_layer(ldata, CD_MLOOP);
+
+	mp = mpoly;
+	k = 0;
+	for (i = 0; i < totpoly; i++, mp++) {
+		if (ELEM(mp->totloop, 3, 4)) {
+			BLI_array_grow_one(mface);
+			mf = &mface[k];
+
+			mf->mat_nr = mp->mat_nr;
+			mf->flag = mp->flag;
+
+			mf->v1 = mp->loopstart + 0;
+			mf->v2 = mp->loopstart + 1;
+			mf->v3 = mp->loopstart + 2;
+			mf->v4 = (mp->totloop == 4) ? (mp->loopstart + 3) : 0;
+
+			/* abuse edcode for temp storage and clear next loop */
+			mf->edcode = (char)mp->totloop; /* only ever 3 or 4 */
+
+			k++;
+		}
+	}
+
+	CustomData_free(fdata, totface);
+
+	totface = k;
+
+	CustomData_add_layer(fdata, CD_MFACE, CD_ASSIGN, mface, totface);
+
+	CustomData_from_bmeshpoly(fdata, pdata, ldata, totface);
+
+	mp = mpoly;
+	k = 0;
+	for (i = 0; i < totpoly; i++, mp++) {
+		if (ELEM(mp->totloop, 3, 4)) {
+			mf = &mface[k];
+
+			if (mf->edcode == 3) {
+				/* sort loop indices to ensure winding is correct */
+				/* NO SORT - looks like we can skip this */
+
+				lindex[0] = mf->v1;
+				lindex[1] = mf->v2;
+				lindex[2] = mf->v3;
+				lindex[3] = 0; /* unused */
+
+				/* transform loop indices to vert indices */
+				mf->v1 = mloop[mf->v1].v;
+				mf->v2 = mloop[mf->v2].v;
+				mf->v3 = mloop[mf->v3].v;
+
+				BKE_mesh_loops_to_mface_corners(fdata, ldata, pdata,
+				                                lindex, k, i, 3,
+				                                numTex, numCol, hasPCol, hasOrigSpace);
+				test_index_face(mf, fdata, k, 3);
+			}
+			else {
+				/* sort loop indices to ensure winding is correct */
+				/* NO SORT - looks like we can skip this */
+
+				lindex[0] = mf->v1;
+				lindex[1] = mf->v2;
+				lindex[2] = mf->v3;
+				lindex[3] = mf->v4;
+
+				/* transform loop indices to vert indices */
+				mf->v1 = mloop[mf->v1].v;
+				mf->v2 = mloop[mf->v2].v;
+				mf->v3 = mloop[mf->v3].v;
+				mf->v4 = mloop[mf->v4].v;
+
+				BKE_mesh_loops_to_mface_corners(fdata, ldata, pdata,
+				                                lindex, k, i, 4,
+				                                numTex, numCol, hasPCol, hasOrigSpace);
+				test_index_face(mf, fdata, k, 4);
+			}
+
+			mf->edcode = 0;
+
+			k++;
+		}
+	}
+
+	return k;
+}
+#endif /* USE_BMESH_SAVE_AS_COMPAT */
+
+
+static void bm_corners_to_loops_ex(ID *id, CustomData *fdata, CustomData *ldata, CustomData *pdata,
+                                   MFace *mface, int totloop, int findex, int loopstart, int numTex, int numCol)
+{
+	MTFace *texface;
+	MTexPoly *texpoly;
+	MCol *mcol;
+	MLoopCol *mloopcol;
+	MLoopUV *mloopuv;
+	MFace *mf;
+	int i;
+
+	mf = mface + findex;
+
+	for (i = 0; i < numTex; i++) {
+		texface = CustomData_get_n(fdata, CD_MTFACE, findex, i);
+		texpoly = CustomData_get_n(pdata, CD_MTEXPOLY, findex, i);
+
+		ME_MTEXFACE_CPY(texpoly, texface);
+
+		mloopuv = CustomData_get_n(ldata, CD_MLOOPUV, loopstart, i);
+		copy_v2_v2(mloopuv->uv, texface->uv[0]); mloopuv++;
+		copy_v2_v2(mloopuv->uv, texface->uv[1]); mloopuv++;
+		copy_v2_v2(mloopuv->uv, texface->uv[2]); mloopuv++;
+
+		if (mf->v4) {
+			copy_v2_v2(mloopuv->uv, texface->uv[3]); mloopuv++;
+		}
+	}
+
+	for (i = 0; i < numCol; i++) {
+		mloopcol = CustomData_get_n(ldata, CD_MLOOPCOL, loopstart, i);
+		mcol = CustomData_get_n(fdata, CD_MCOL, findex, i);
+
+		MESH_MLOOPCOL_FROM_MCOL(mloopcol, &mcol[0]); mloopcol++;
+		MESH_MLOOPCOL_FROM_MCOL(mloopcol, &mcol[1]); mloopcol++;
+		MESH_MLOOPCOL_FROM_MCOL(mloopcol, &mcol[2]); mloopcol++;
+		if (mf->v4) {
+			MESH_MLOOPCOL_FROM_MCOL(mloopcol, &mcol[3]); mloopcol++;
+		}
+	}
+
+	if (CustomData_has_layer(fdata, CD_MDISPS)) {
+		MDisps *ld = CustomData_get(ldata, loopstart, CD_MDISPS);
+		MDisps *fd = CustomData_get(fdata, findex, CD_MDISPS);
+		float (*disps)[3] = fd->disps;
+		int tot = mf->v4 ? 4 : 3;
+		int side, corners;
+
+		if (CustomData_external_test(fdata, CD_MDISPS)) {
+			if (id && fdata->external) {
+				CustomData_external_add(ldata, id, CD_MDISPS,
+				                        totloop, fdata->external->filename);
+			}
+		}
+
+		corners = multires_mdisp_corners(fd);
+
+		if (corners == 0) {
+			/* Empty MDisp layers appear in at least one of the sintel.blend files.
+			 * Not sure why this happens, but it seems fine to just ignore them here.
+			 * If (corners == 0) for a non-empty layer though, something went wrong. */
+			BLI_assert(fd->totdisp == 0);
+		}
+		else {
+			side = sqrt(fd->totdisp / corners);
+
+			for (i = 0; i < tot; i++, disps += side * side, ld++) {
+				ld->totdisp = side * side;
+				ld->level = (int)(logf(side - 1.0f) / (float)M_LN2) + 1;
+
+				if (ld->disps)
+					MEM_freeN(ld->disps);
+
+				ld->disps = MEM_mallocN(sizeof(float) * 3 * side * side, "converted loop mdisps");
+				if (fd->disps) {
+					memcpy(ld->disps, disps, sizeof(float) * 3 * side * side);
+				}
+				else {
+					memset(ld->disps, 0, sizeof(float) * 3 * side * side);
+				}
+			}
+		}
+	}
+}
+
+
+void BKE_mesh_convert_mfaces_to_mpolys(Mesh *mesh)
+{
+	BKE_mesh_convert_mfaces_to_mpolys_ex(&mesh->id, &mesh->fdata, &mesh->ldata, &mesh->pdata,
+	                                     mesh->totedge, mesh->totface, mesh->totloop, mesh->totpoly,
+	                                     mesh->medge, mesh->mface,
+	                                     &mesh->totloop, &mesh->totpoly, &mesh->mloop, &mesh->mpoly);
+
+	BKE_mesh_update_customdata_pointers(mesh, true);
+}
+
+/* the same as BKE_mesh_convert_mfaces_to_mpolys but oriented to be used in do_versions from readfile.c
+ * the difference is how active/render/clone/stencil indices are handled here
+ *
+ * normally thay're being set from pdata which totally makes sense for meshes which are already
+ * converted to bmesh structures, but when loading older files indices shall be updated in other
+ * way around, so newly added pdata and ldata would have this indices set based on fdata layer
+ *
+ * this is normally only needed when reading older files, in all other cases BKE_mesh_convert_mfaces_to_mpolys
+ * shall be always used
+ */
+void BKE_mesh_do_versions_convert_mfaces_to_mpolys(Mesh *mesh)
+{
+	BKE_mesh_convert_mfaces_to_mpolys_ex(&mesh->id, &mesh->fdata, &mesh->ldata, &mesh->pdata,
+	                                     mesh->totedge, mesh->totface, mesh->totloop, mesh->totpoly,
+	                                     mesh->medge, mesh->mface,
+	                                     &mesh->totloop, &mesh->totpoly, &mesh->mloop, &mesh->mpoly);
+
+	CustomData_bmesh_do_versions_update_active_layers(&mesh->fdata, &mesh->pdata, &mesh->ldata);
+
+	BKE_mesh_update_customdata_pointers(mesh, true);
+}
+
+void BKE_mesh_convert_mfaces_to_mpolys_ex(ID *id, CustomData *fdata, CustomData *ldata, CustomData *pdata,
+                                          int totedge_i, int totface_i, int totloop_i, int totpoly_i,
+                                          MEdge *medge, MFace *mface,
+                                          int *totloop_r, int *totpoly_r,
+                                          MLoop **mloop_r, MPoly **mpoly_r)
+{
+	MFace *mf;
+	MLoop *ml, *mloop;
+	MPoly *mp, *mpoly;
+	MEdge *me;
+	EdgeHash *eh;
+	int numTex, numCol;
+	int i, j, totloop, totpoly, *polyindex;
+
+	/* just in case some of these layers are filled in (can happen with python created meshes) */
+	CustomData_free(ldata, totloop_i);
+	CustomData_free(pdata, totpoly_i);
+
+	totpoly = totface_i;
+	mpoly = MEM_callocN(sizeof(MPoly) * totpoly, "mpoly converted");
+	CustomData_add_layer(pdata, CD_MPOLY, CD_ASSIGN, mpoly, totpoly);
+
+	numTex = CustomData_number_of_layers(fdata, CD_MTFACE);
+	numCol = CustomData_number_of_layers(fdata, CD_MCOL);
+
+	totloop = 0;
+	mf = mface;
+	for (i = 0; i < totface_i; i++, mf++) {
+		totloop += mf->v4 ? 4 : 3;
+	}
+
+	mloop = MEM_callocN(sizeof(MLoop) * totloop, "mloop converted");
+
+	CustomData_add_layer(ldata, CD_MLOOP, CD_ASSIGN, mloop, totloop);
+
+	CustomData_to_bmeshpoly(fdata, pdata, ldata, totloop, totpoly);
+
+	if (id) {
+		/* ensure external data is transferred */
+		CustomData_external_read(fdata, id, CD_MASK_MDISPS, totface_i);
+	}
+
+	eh = BLI_edgehash_new_ex(__func__, totedge_i);
+
+	/* build edge hash */
+	me = medge;
+	for (i = 0; i < totedge_i; i++, me++) {
+		BLI_edgehash_insert(eh, me->v1, me->v2, SET_INT_IN_POINTER(i));
+
+		/* unrelated but avoid having the FGON flag enabled, so we can reuse it later for something else */
+		me->flag &= ~ME_FGON;
+	}
+
+	polyindex = CustomData_get_layer(fdata, CD_ORIGINDEX);
+
+	j = 0; /* current loop index */
+	ml = mloop;
+	mf = mface;
+	mp = mpoly;
+	for (i = 0; i < totface_i; i++, mf++, mp++) {
+		mp->loopstart = j;
+
+		mp->totloop = mf->v4 ? 4 : 3;
+
+		mp->mat_nr = mf->mat_nr;
+		mp->flag = mf->flag;
+
+#       define ML(v1, v2) { \
+			ml->v = mf->v1; ml->e = GET_INT_FROM_POINTER(BLI_edgehash_lookup(eh, mf->v1, mf->v2)); ml++; j++; \
+		} (void)0
+
+		ML(v1, v2);
+		ML(v2, v3);
+		if (mf->v4) {
+			ML(v3, v4);
+			ML(v4, v1);
+		}
+		else {
+			ML(v3, v1);
+		}
+
+#       undef ML
+
+		bm_corners_to_loops_ex(id, fdata, ldata, pdata, mface, totloop, i, mp->loopstart, numTex, numCol);
+
+		if (polyindex) {
+			*polyindex = i;
+			polyindex++;
+		}
+	}
+
+	/* note, we don't convert NGons at all, these are not even real ngons,
+	 * they have their own UV's, colors etc - its more an editing feature. */
+
+	BLI_edgehash_free(eh, NULL);
+
+	*totpoly_r = totpoly;
+	*totloop_r = totloop;
+	*mpoly_r = mpoly;
+	*mloop_r = mloop;
+}
+/** \} */
+
+
+/* -------------------------------------------------------------------- */
+
+/** \name Mesh Flag Flushing
+ * \{ */
+
+/* update the hide flag for edges and faces from the corresponding
+ * flag in verts */
+void BKE_mesh_flush_hidden_from_verts_ex(const MVert *mvert,
+                                         const MLoop *mloop,
+                                         MEdge *medge, const int totedge,
+                                         MPoly *mpoly, const int totpoly)
+{
+	int i, j;
+
+	for (i = 0; i < totedge; i++) {
+		MEdge *e = &medge[i];
+		if (mvert[e->v1].flag & ME_HIDE ||
+		    mvert[e->v2].flag & ME_HIDE)
+		{
+			e->flag |= ME_HIDE;
+		}
+		else {
+			e->flag &= ~ME_HIDE;
+		}
+	}
+	for (i = 0; i < totpoly; i++) {
+		MPoly *p = &mpoly[i];
+		p->flag &= ~ME_HIDE;
+		for (j = 0; j < p->totloop; j++) {
+			if (mvert[mloop[p->loopstart + j].v].flag & ME_HIDE)
+				p->flag |= ME_HIDE;
+		}
+	}
+}
+void BKE_mesh_flush_hidden_from_verts(Mesh *me)
+{
+	BKE_mesh_flush_hidden_from_verts_ex(me->mvert, me->mloop,
+	                                    me->medge, me->totedge,
+	                                    me->mpoly, me->totpoly);
+}
+
+void BKE_mesh_flush_hidden_from_polys_ex(MVert *mvert,
+                                         const MLoop *mloop,
+                                         MEdge *medge, const int UNUSED(totedge),
+                                         const MPoly *mpoly, const int totpoly)
+{
+	const MPoly *mp;
+	int i;
+
+	i = totpoly;
+	for (mp = mpoly; i--; mp++) {
+		if (mp->flag & ME_HIDE) {
+			const MLoop *ml;
+			int j;
+			j = mp->totloop;
+			for (ml = &mloop[mp->loopstart]; j--; ml++) {
+				mvert[ml->v].flag |= ME_HIDE;
+				medge[ml->e].flag |= ME_HIDE;
+			}
+		}
+	}
+
+	i = totpoly;
+	for (mp = mpoly; i--; mp++) {
+		if ((mp->flag & ME_HIDE) == 0) {
+			const MLoop *ml;
+			int j;
+			j = mp->totloop;
+			for (ml = &mloop[mp->loopstart]; j--; ml++) {
+				mvert[ml->v].flag &= ~ME_HIDE;
+				medge[ml->e].flag &= ~ME_HIDE;
+			}
+		}
+	}
+}
+void BKE_mesh_flush_hidden_from_polys(Mesh *me)
+{
+	BKE_mesh_flush_hidden_from_polys_ex(me->mvert, me->mloop,
+	                                    me->medge, me->totedge,
+	                                    me->mpoly, me->totpoly);
+}
+
+/**
+ * simple poly -> vert/edge selection.
+ */
+void BKE_mesh_flush_select_from_polys_ex(MVert *mvert,       const int totvert,
+                                         const MLoop *mloop,
+                                         MEdge *medge,       const int totedge,
+                                         const MPoly *mpoly, const int totpoly)
+{
+	MVert *mv;
+	MEdge *med;
+	const MPoly *mp;
+	int i;
+
+	i = totvert;
+	for (mv = mvert; i--; mv++) {
+		mv->flag &= ~SELECT;
+	}
+
+	i = totedge;
+	for (med = medge; i--; med++) {
+		med->flag &= ~SELECT;
+	}
+
+	i = totpoly;
+	for (mp = mpoly; i--; mp++) {
+		/* assume if its selected its not hidden and none of its verts/edges are hidden
+		 * (a common assumption)*/
+		if (mp->flag & ME_FACE_SEL) {
+			const MLoop *ml;
+			int j;
+			j = mp->totloop;
+			for (ml = &mloop[mp->loopstart]; j--; ml++) {
+				mvert[ml->v].flag |= SELECT;
+				medge[ml->e].flag |= SELECT;
+			}
+		}
+	}
+}
+void BKE_mesh_flush_select_from_polys(Mesh *me)
+{
+	BKE_mesh_flush_select_from_polys_ex(me->mvert, me->totvert,
+	                                 me->mloop,
+	                                 me->medge, me->totedge,
+	                                 me->mpoly, me->totpoly);
+}
+
+void BKE_mesh_flush_select_from_verts_ex(const MVert *mvert, const int UNUSED(totvert),
+                                         const MLoop *mloop,
+                                         MEdge *medge,       const int totedge,
+                                         MPoly *mpoly,       const int totpoly)
+{
+	MEdge *med;
+	MPoly *mp;
+	int i;
+
+	/* edges */
+	i = totedge;
+	for (med = medge; i--; med++) {
+		if ((med->flag & ME_HIDE) == 0) {
+			if ((mvert[med->v1].flag & SELECT) && (mvert[med->v2].flag & SELECT)) {
+				med->flag |= SELECT;
+			}
+			else {
+				med->flag &= ~SELECT;
+			}
+		}
+	}
+
+	/* polys */
+	i = totpoly;
+	for (mp = mpoly; i--; mp++) {
+		if ((mp->flag & ME_HIDE) == 0) {
+			int ok = TRUE;
+			const MLoop *ml;
+			int j;
+			j = mp->totloop;
+			for (ml = &mloop[mp->loopstart]; j--; ml++) {
+				if ((mvert[ml->v].flag & SELECT) == 0) {
+					ok = FALSE;
+					break;
+				}
+			}
+
+			if (ok) {
+				mp->flag |= ME_FACE_SEL;
+			}
+			else {
+				mp->flag &= ~ME_FACE_SEL;
+			}
+		}
+	}
+}
+void BKE_mesh_flush_select_from_verts(Mesh *me)
+{
+	BKE_mesh_flush_select_from_verts_ex(me->mvert, me->totvert,
+	                                    me->mloop,
+	                                    me->medge, me->totedge,
+	                                    me->mpoly, me->totpoly);
+}
+/** \} */
+
+
+/* -------------------------------------------------------------------- */
+
+/** \name Mesh Smooth Groups
+ * \{ */
+
+/**
+ * Calculate smooth groups from sharp edges.
+ *
+ * \param r_totgroup The total number of groups, 1 or more.
+ * \return Polygon aligned array of group index values (bitflags if use_bitflags is true), starting at 1.
+ */
+int *BKE_mesh_calc_smoothgroups(const MEdge *medge, const int totedge,
+                                const MPoly *mpoly, const int totpoly,
+                                const MLoop *mloop, const int totloop,
+                                int *r_totgroup, const bool use_bitflags)
+{
+	int *poly_groups;
+	int *poly_stack;
+
+	int poly_prev = 0;
+	const int temp_poly_group_id = 3;  /* Placeholder value. */
+	const int poly_group_id_overflowed = 5;  /* Group we could not find any available bit, will be reset to 0 at end */
+	int tot_group = 0;
+	bool group_id_overflow = false;
+
+	/* map vars */
+	MeshElemMap *edge_poly_map;
+	int *edge_poly_mem;
+
+	if (totpoly == 0) {
+		*r_totgroup = 0;
+		return NULL;
+	}
+
+	BKE_mesh_edge_poly_map_create(&edge_poly_map, &edge_poly_mem,
+	                              medge, totedge,
+	                              mpoly, totpoly,
+	                              mloop, totloop);
+
+	poly_groups = MEM_callocN(sizeof(int) * totpoly, __func__);
+	poly_stack  = MEM_mallocN(sizeof(int) * totpoly, __func__);
+
+	while (true) {
+		int poly;
+		int bit_poly_group_mask = 0;
+		int poly_group_id;
+		int ps_curr_idx = 0, ps_end_idx = 0;  /* stack indices */
+
+		for (poly = poly_prev; poly < totpoly; poly++) {
+			if (poly_groups[poly] == 0) {
+				break;
+			}
+		}
+
+		if (poly == totpoly) {
+			/* all done */
+			break;
+		}
+
+		poly_group_id = use_bitflags ? temp_poly_group_id : ++tot_group;
+
+		/* start searching from here next time */
+		poly_prev = poly + 1;
+
+		poly_groups[poly] = poly_group_id;
+		poly_stack[ps_end_idx++] = poly;
+
+		while (ps_curr_idx != ps_end_idx) {
+			const MPoly *mp;
+			const MLoop *ml;
+			int j;
+
+			poly = poly_stack[ps_curr_idx++];
+			BLI_assert(poly_groups[poly] == poly_group_id);
+
+			mp = &mpoly[poly];
+			for (ml = &mloop[mp->loopstart], j = mp->totloop; j--; ml++) {
+				/* loop over poly users */
+				const MeshElemMap *map_ele = &edge_poly_map[ml->e];
+				int *p = map_ele->indices;
+				int i = map_ele->count;
+				if (!(medge[ml->e].flag & ME_SHARP)) {
+					for (; i--; p++) {
+						/* if we meet other non initialized its a bug */
+						BLI_assert(ELEM(poly_groups[*p], 0, poly_group_id));
+
+						if (poly_groups[*p] == 0) {
+							poly_groups[*p] = poly_group_id;
+							poly_stack[ps_end_idx++] = *p;
+						}
+					}
+				}
+				else if (use_bitflags) {
+					/* Find contiguous smooth groups already assigned, these are the values we can't reuse! */
+					for (; i--; p++) {
+						int bit = poly_groups[*p];
+						if (!ELEM3(bit, 0, poly_group_id, poly_group_id_overflowed) &&
+						    !(bit_poly_group_mask & bit))
+						{
+							bit_poly_group_mask |= bit;
+						}
+					}
+				}
+			}
+		}
+		/* And now, we have all our poly from current group in poly_stack (from 0 to (ps_end_idx - 1)), as well as
+		 * all smoothgroups bits we can't use in bit_poly_group_mask.
+		 */
+		if (use_bitflags) {
+			int i, *p, gid_bit = 0;
+			poly_group_id = 1;
+
+			/* Find first bit available! */
+			for (; (poly_group_id & bit_poly_group_mask) && (gid_bit < 32); gid_bit++) {
+				poly_group_id <<= 1;  /* will 'overflow' on last possible iteration. */
+			}
+			if (UNLIKELY(gid_bit > 31)) {
+				/* All bits used in contiguous smooth groups, we can't do much!
+				 * Note: this is *very* unlikely - theoretically, four groups are enough, I don't think we can reach
+				 *       this goal with such a simple algo, but I don't think either we'll never need all 32 groups!
+				 */
+				printf("Warning, could not find an available id for current smooth group, faces will me marked "
+				       "as out of any smooth group...\n");
+				poly_group_id = poly_group_id_overflowed; /* Can't use 0, will have to set them to this value later. */
+				group_id_overflow = true;
+			}
+			if (gid_bit > tot_group) {
+				tot_group = gid_bit;
+			}
+			/* And assign the final smooth group id to that poly group! */
+			for (i = ps_end_idx, p = poly_stack; i--; p++) {
+				poly_groups[*p] = poly_group_id;
+			}
+		}
+	}
+
+	if (UNLIKELY(group_id_overflow)) {
+		int i = totpoly, *gid = poly_groups;
+		for (; i--; gid++) {
+			if (*gid == poly_group_id_overflowed) {
+				*gid = 0;
+			}
+		}
+	}
+
+	MEM_freeN(edge_poly_map);
+	MEM_freeN(edge_poly_mem);
+	MEM_freeN(poly_stack);
+
+	*r_totgroup = tot_group + 1;
+
+	return poly_groups;
+}
+/** \} */
+
+
+/* -------------------------------------------------------------------- */
+
+/** \name Mesh Spatial Calculation
+ * \{ */
+
+/**
+ * This function takes the difference between 2 vertex-coord-arrays
+ * (\a vert_cos_src, \a vert_cos_dst),
+ * and applies the difference to \a vert_cos_new relative to \a vert_cos_org.
+ *
+ * \param vert_cos_src reference deform source.
+ * \param vert_cos_dst reference deform destination.
+ *
+ * \param vert_cos_org reference for the output location.
+ * \param vert_cos_new resulting coords.
+ */
+void BKE_mesh_calc_relative_deform(
+        const MPoly *mpoly, const int totpoly,
+        const MLoop *mloop, const int totvert,
+
+        const float (*vert_cos_src)[3],
+        const float (*vert_cos_dst)[3],
+
+        const float (*vert_cos_org)[3],
+              float (*vert_cos_new)[3])
+{
+	const MPoly *mp;
+	int i;
+
+	int *vert_accum = MEM_callocN(sizeof(*vert_accum) * totvert, __func__);
+
+	memset(vert_cos_new, '\0', sizeof(*vert_cos_new) * totvert);
+
+	for (i = 0, mp = mpoly; i < totpoly; i++, mp++) {
+		const MLoop *loopstart = mloop + mp->loopstart;
+		int j;
+
+		for (j = 0; j < mp->totloop; j++) {
+			int v_prev = (loopstart + ((mp->totloop + (j - 1)) % mp->totloop))->v;
+			int v_curr = (loopstart + j)->v;
+			int v_next = (loopstart + ((j + 1) % mp->totloop))->v;
+
+			float tvec[3];
+
+			barycentric_transform(
+			            tvec, vert_cos_dst[v_curr],
+			            vert_cos_org[v_prev], vert_cos_org[v_curr], vert_cos_org[v_next],
+			            vert_cos_src[v_prev], vert_cos_src[v_curr], vert_cos_src[v_next]
+			            );
+
+			add_v3_v3(vert_cos_new[v_curr], tvec);
+			vert_accum[v_curr] += 1;
+		}
+	}
+
+	for (i = 0; i < totvert; i++) {
+		if (vert_accum[i]) {
+			mul_v3_fl(vert_cos_new[i], 1.0f / (float)vert_accum[i]);
+		}
+		else {
+			copy_v3_v3(vert_cos_new[i], vert_cos_org[i]);
+		}
+	}
+
+	MEM_freeN(vert_accum);
+}
+/** \} */