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/*
* ***** 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.
*
* Contributor(s): Campbell Barton
*
* ***** END GPL LICENSE BLOCK *****
*/
/** \file blender/bmesh/intern/bmesh_decimate_unsubdivide.c
* \ingroup bmesh
*
* BMesh decimator that uses a grid un-subdivide method.
*/
#include "MEM_guardedalloc.h"
#include "BLI_math.h"
#include "bmesh.h"
#include "intern/bmesh_operators_private.h" /* own include */
static int bm_vert_dissolve_fan_test(BMVert *v)
{
/* check if we should walk over these verts */
BMIter iter;
BMEdge *e;
unsigned int tot_edge = 0;
unsigned int tot_edge_boundary = 0;
unsigned int tot_edge_manifold = 0;
unsigned int tot_edge_wire = 0;
BM_ITER_ELEM (e, &iter, v, BM_EDGES_OF_VERT) {
if (BM_edge_is_boundary(e)) {
tot_edge_boundary++;
}
else if (BM_edge_is_manifold(e)) {
tot_edge_manifold++;
}
else if (BM_edge_is_wire(e)) {
tot_edge_wire++;
}
tot_edge++;
}
if ((tot_edge == 4) && (tot_edge_boundary == 0) && (tot_edge_manifold == 4)) {
return TRUE;
}
else if ((tot_edge == 3) && (tot_edge_boundary == 0) && (tot_edge_manifold == 3)) {
return TRUE;
}
else if ((tot_edge == 3) && (tot_edge_boundary == 2) && (tot_edge_manifold == 1)) {
return TRUE;
}
else if ((tot_edge == 2) && (tot_edge_wire == 2)) {
return TRUE;
}
return FALSE;
}
static int bm_vert_dissolve_fan(BMesh *bm, BMVert *v)
{
/* collapse under 2 conditions.
* - vert connects to 4 manifold edges (and 4 faces).
* - vert connecrs to 1 manifold edge, 2 boundary edges (and 2 faces).
*
* This covers boundary verts of a quad grid and center verts.
* note that surrounding faces dont have to be quads.
*/
BMIter iter;
BMEdge *e;
unsigned int tot_loop = 0;
unsigned int tot_edge = 0;
unsigned int tot_edge_boundary = 0;
unsigned int tot_edge_manifold = 0;
unsigned int tot_edge_wire = 0;
BM_ITER_ELEM (e, &iter, v, BM_EDGES_OF_VERT) {
if (BM_edge_is_boundary(e)) {
tot_edge_boundary++;
}
else if (BM_edge_is_manifold(e)) {
tot_edge_manifold++;
}
else if (BM_edge_is_wire(e)) {
tot_edge_wire++;
}
tot_edge++;
}
if (tot_edge == 2) {
/* check for 2 wire verts only */
if (tot_edge_wire == 2) {
return (BM_vert_collapse_edge(bm, v->e, v, TRUE) != NULL);
}
}
else if (tot_edge == 4) {
/* check for 4 faces surrounding */
if (tot_edge_boundary == 0 && tot_edge_manifold == 4) {
/* good to go! */
tot_loop = 4;
}
}
else if (tot_edge == 3) {
/* check for 2 faces surrounding at a boundary */
if (tot_edge_boundary == 2 && tot_edge_manifold == 1) {
/* good to go! */
tot_loop = 2;
}
else if (tot_edge_boundary == 0 && tot_edge_manifold == 3) {
/* good to go! */
tot_loop = 3;
}
}
if (tot_loop) {
BMLoop *f_loop[4];
unsigned int i;
/* ensure there are exactly tot_loop loops */
BLI_assert(BM_iter_at_index(bm, BM_LOOPS_OF_VERT, v, tot_loop) == NULL);
BM_iter_as_array(bm, BM_LOOPS_OF_VERT, v, (void **)f_loop, tot_loop);
for (i = 0; i < tot_loop; i++) {
BMLoop *l = f_loop[i];
if (l->f->len > 3) {
BLI_assert(l->prev->v != l->next->v);
BM_face_split(bm, l->f, l->prev->v, l->next->v, NULL, NULL, TRUE);
}
}
return BM_vert_dissolve(bm, v);
}
return FALSE;
}
enum {
VERT_INDEX_DO_COLLAPSE = -1,
VERT_INDEX_INIT = 0,
VERT_INDEX_IGNORE = 1
};
// #define USE_WALKER /* gives uneven results, disable for now */
/* - BMVert.flag & BM_ELEM_TAG: shows we touched this vert
* - BMVert.index == -1: shows we will remove this vert
*/
/**
* \param tag_only so we can call this from an operator */
void BM_mesh_decimate_unsubdivide_ex(BMesh *bm, const int iterations, const int tag_only)
{
#ifdef USE_WALKER
# define ELE_VERT_TAG 1
#else
BMVert **vert_seek_a = MEM_mallocN(sizeof(BMVert *) * bm->totvert, __func__);
BMVert **vert_seek_b = MEM_mallocN(sizeof(BMVert *) * bm->totvert, __func__);
unsigned vert_seek_a_tot = 0;
unsigned vert_seek_b_tot = 0;
#endif
BMVert *v;
BMIter iter;
const unsigned int offset = 0;
const unsigned int nth = 2;
int iter_step;
/* if tag_only is set, we assyme the caller knows what verts to tag
* needed for the operator */
if (tag_only == FALSE) {
BM_ITER_MESH (v, &iter, bm, BM_VERTS_OF_MESH) {
BM_elem_flag_enable(v, BM_ELEM_TAG);
}
}
for (iter_step = 0; iter_step < iterations; iter_step++) {
int iter_done;
BM_ITER_MESH (v, &iter, bm, BM_VERTS_OF_MESH) {
if (BM_elem_flag_test(v, BM_ELEM_TAG) && bm_vert_dissolve_fan_test(v)) {
#ifdef USE_WALKER
BMO_elem_flag_enable(bm, v, ELE_VERT_TAG);
#endif
BM_elem_index_set(v, VERT_INDEX_INIT); /* set_dirty! */
}
else {
BM_elem_index_set(v, VERT_INDEX_IGNORE); /* set_dirty! */
}
}
/* done with selecting tagged verts */
/* main loop, keep tagging until we can't tag any more islands */
while (TRUE) {
#ifdef USE_WALKER
BMWalker walker;
#else
unsigned int depth = 1;
unsigned int i;
#endif
BMVert *v_first = NULL;
BMVert *v;
/* we could avoid iterating from the start each time */
BM_ITER_MESH (v, &iter, bm, BM_VERTS_OF_MESH) {
if (v->e && (BM_elem_index_get(v) == VERT_INDEX_INIT)) {
#ifdef USE_WALKER
if (BMO_elem_flag_test(bm, v, ELE_VERT_TAG))
#endif
{
/* check again incase the topology changed */
if (bm_vert_dissolve_fan_test(v)) {
v_first = v;
}
break;
}
}
}
if (v_first == NULL) {
break;
}
#ifdef USE_WALKER
/* Walk over selected elements starting at active */
BMW_init(&walker, bm, BMW_CONNECTED_VERTEX,
ELE_VERT_TAG, BMW_MASK_NOP, BMW_MASK_NOP,
BMW_FLAG_NOP, /* don't use BMW_FLAG_TEST_HIDDEN here since we want to desel all */
BMW_NIL_LAY);
BLI_assert(walker.order == BMW_BREADTH_FIRST);
for (v = BMW_begin(&walker, v_first); v != NULL; v = BMW_step(&walker)) {
/* Deselect elements that aren't at "nth" depth from active */
if (BM_elem_index_get(v) == VERT_INDEX_INIT) {
if ((offset + BMW_current_depth(&walker)) % nth) {
/* tag for removal */
BM_elem_index_set(v, VERT_INDEX_DO_COLLAPSE); /* set_dirty! */
}
else {
/* works better to allow these verts to be checked again */
//BM_elem_index_set(v, VERT_INDEX_IGNORE); /* set_dirty! */
}
}
}
BMW_end(&walker);
#else
BM_elem_index_set(v_first, (offset + depth) % nth ? VERT_INDEX_IGNORE : VERT_INDEX_DO_COLLAPSE); /* set_dirty! */
vert_seek_b_tot = 0;
vert_seek_b[vert_seek_b_tot++] = v_first;
while (TRUE) {
BMEdge *e;
if ((offset + depth) % nth) {
vert_seek_a_tot = 0;
for (i = 0; i < vert_seek_b_tot; i++) {
v = vert_seek_b[i];
BLI_assert(BM_elem_index_get(v) == VERT_INDEX_IGNORE);
BM_ITER_ELEM (e, &iter, v, BM_EDGES_OF_VERT) {
BMVert *v_other = BM_edge_other_vert(e, v);
if (BM_elem_index_get(v_other) == VERT_INDEX_INIT) {
BM_elem_index_set(v_other, VERT_INDEX_DO_COLLAPSE); /* set_dirty! */
vert_seek_a[vert_seek_a_tot++] = v_other;
}
}
}
if (vert_seek_a_tot == 0) {
break;
}
}
else {
vert_seek_b_tot = 0;
for (i = 0; i < vert_seek_a_tot; i++) {
v = vert_seek_a[i];
BLI_assert(BM_elem_index_get(v) == VERT_INDEX_DO_COLLAPSE);
BM_ITER_ELEM (e, &iter, v, BM_EDGES_OF_VERT) {
BMVert *v_other = BM_edge_other_vert(e, v);
if (BM_elem_index_get(v_other) == VERT_INDEX_INIT) {
BM_elem_index_set(v_other, VERT_INDEX_IGNORE); /* set_dirty! */
vert_seek_b[vert_seek_b_tot++] = v_other;
}
}
}
if (vert_seek_b_tot == 0) {
break;
}
}
depth++;
}
#endif /* USE_WALKER */
}
/* now we tagged all verts -1 for removal, lets loop over and rebuild faces */
iter_done = FALSE;
BM_ITER_MESH (v, &iter, bm, BM_VERTS_OF_MESH) {
if (BM_elem_index_get(v) == VERT_INDEX_DO_COLLAPSE) {
iter_done |= bm_vert_dissolve_fan(bm, v);
}
}
if (iter_done == FALSE) {
break;
}
}
bm->elem_index_dirty |= BM_VERT;
#ifndef USE_WALKER
MEM_freeN(vert_seek_a);
MEM_freeN(vert_seek_b);
#endif
}
void BM_mesh_decimate_unsubdivide(BMesh *bm, const int iterations)
{
BM_mesh_decimate_unsubdivide_ex(bm, iterations, FALSE);
}
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