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/**********************************************************************
*
* PostGIS - Spatial Types for PostgreSQL
* http://postgis.net
*
* PostGIS 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.
*
* PostGIS 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 PostGIS. If not, see <http://www.gnu.org/licenses/>.
*
**********************************************************************
*
* Copyright (C) 2015-2024 Sandro Santilli <strk@kbt.io>
*
**********************************************************************
*
* Topology Polygonizer
*
**********************************************************************/
#include "../postgis_config.h"
/*#define POSTGIS_DEBUG_LEVEL 1*/
#include "lwgeom_log.h"
#include "liblwgeom_internal.h"
#include "liblwgeom_topo_internal.h"
#include "lwgeom_geos.h"
/* An array of pointers to EDGERING structures */
typedef struct LWT_ISO_EDGE_TABLE_T {
LWT_ISO_EDGE *edges;
int size;
} LWT_ISO_EDGE_TABLE;
static int
compare_iso_edges_by_id(const void *si1, const void *si2)
{
int a = ((LWT_ISO_EDGE *)si1)->edge_id;
int b = ((LWT_ISO_EDGE *)si2)->edge_id;
if ( a < b )
return -1;
else if ( a > b )
return 1;
else
return 0;
}
static LWT_ISO_EDGE *
_lwt_getIsoEdgeById(LWT_ISO_EDGE_TABLE *tab, LWT_ELEMID id)
{
LWT_ISO_EDGE key;
key.edge_id = id;
void *match = bsearch( &key, tab->edges, tab->size,
sizeof(LWT_ISO_EDGE),
compare_iso_edges_by_id);
return match;
}
typedef struct LWT_EDGERING_ELEM_T {
/* externally owned */
LWT_ISO_EDGE *edge;
/* 0 if false, 1 if true */
int left;
} LWT_EDGERING_ELEM;
/* A ring of edges */
typedef struct LWT_EDGERING_T {
/* Signed edge identifiers
* positive ones are walked in their direction, negative ones
* in the opposite direction */
LWT_EDGERING_ELEM **elems;
/* Number of edges in the ring */
int size;
int capacity;
/* Bounding box of the ring */
GBOX *env;
/* Bounding box of the ring in GEOS format (for STRTree) */
GEOSGeometry *genv;
} LWT_EDGERING;
#define LWT_EDGERING_INIT(a) { \
(a)->size = 0; \
(a)->capacity = 1; \
(a)->elems = lwalloc(sizeof(LWT_EDGERING_ELEM *) * (a)->capacity); \
(a)->env = NULL; \
(a)->genv = NULL; \
}
#define LWT_EDGERING_PUSH(a, r) { \
if ( (a)->size + 1 > (a)->capacity ) { \
(a)->capacity *= 2; \
(a)->elems = lwrealloc((a)->elems, sizeof(LWT_EDGERING_ELEM *) * (a)->capacity); \
} \
/* lwdebug(1, "adding elem %d (%p) of edgering %p", (a)->size, (r), (a)); */ \
(a)->elems[(a)->size++] = (r); \
}
#define LWT_EDGERING_CLEAN(a) { \
int i; for (i=0; i<(a)->size; ++i) { \
if ( (a)->elems[i] ) { \
/* lwdebug(1, "freeing elem %d (%p) of edgering %p", i, (a)->elems[i], (a)); */ \
lwfree((a)->elems[i]); \
} \
} \
if ( (a)->elems ) { lwfree((a)->elems); (a)->elems = NULL; } \
(a)->size = 0; \
(a)->capacity = 0; \
if ( (a)->env ) { lwfree((a)->env); (a)->env = NULL; } \
if ( (a)->genv ) { GEOSGeom_destroy((a)->genv); (a)->genv = NULL; } \
}
/* An array of pointers to EDGERING structures */
typedef struct LWT_EDGERING_ARRAY_T {
LWT_EDGERING **rings;
int size;
int capacity;
GEOSSTRtree* tree;
} LWT_EDGERING_ARRAY;
#define LWT_EDGERING_ARRAY_INIT(a) { \
(a)->size = 0; \
(a)->capacity = 1; \
(a)->rings = lwalloc(sizeof(LWT_EDGERING *) * (a)->capacity); \
(a)->tree = NULL; \
}
/* WARNING: use of 'j' is intentional, not to clash with
* 'i' used in LWT_EDGERING_CLEAN */
#define LWT_EDGERING_ARRAY_CLEAN(a) { \
int j; for (j=0; j<(a)->size; ++j) { \
LWT_EDGERING_CLEAN((a)->rings[j]); \
} \
if ( (a)->capacity ) lwfree((a)->rings); \
if ( (a)->tree ) { \
GEOSSTRtree_destroy( (a)->tree ); \
(a)->tree = NULL; \
} \
}
#define LWT_EDGERING_ARRAY_PUSH(a, r) { \
if ( (a)->size + 1 > (a)->capacity ) { \
(a)->capacity *= 2; \
(a)->rings = lwrealloc((a)->rings, sizeof(LWT_EDGERING *) * (a)->capacity); \
} \
(a)->rings[(a)->size++] = (r); \
}
typedef struct LWT_EDGERING_POINT_ITERATOR_T {
LWT_EDGERING *ring;
LWT_EDGERING_ELEM *curelem;
int curelemidx;
int curidx;
} LWT_EDGERING_POINT_ITERATOR;
static int
_lwt_EdgeRingIterator_next(LWT_EDGERING_POINT_ITERATOR *it, POINT2D *pt)
{
LWT_EDGERING_ELEM *el = it->curelem;
POINTARRAY *pa;
if ( ! el ) return 0; /* finished */
pa = el->edge->geom->points;
int tonext = 0;
LWDEBUGF(3, "iterator fetching idx %d from pa of %d points", it->curidx, pa->npoints);
getPoint2d_p(pa, it->curidx, pt);
if ( el->left ) {
it->curidx++;
if ( it->curidx >= (int) pa->npoints ) tonext = 1;
} else {
it->curidx--;
if ( it->curidx < 0 ) tonext = 1;
}
if ( tonext )
{
LWDEBUG(3, "iterator moving to next element");
it->curelemidx++;
if ( it->curelemidx < it->ring->size )
{
el = it->curelem = it->ring->elems[it->curelemidx];
it->curidx = el->left ? 0 : el->edge->geom->points->npoints - 1;
}
else
{
it->curelem = NULL;
}
}
return 1;
}
/* Release return with lwfree */
static LWT_EDGERING_POINT_ITERATOR *
_lwt_EdgeRingIterator_begin(LWT_EDGERING *er)
{
LWT_EDGERING_POINT_ITERATOR *ret = lwalloc(sizeof(LWT_EDGERING_POINT_ITERATOR));
ret->ring = er;
if ( er->size ) ret->curelem = er->elems[0];
else ret->curelem = NULL;
ret->curelemidx = 0;
ret->curidx = (ret->curelem == NULL || ret->curelem->left) ? 0 : ret->curelem->edge->geom->points->npoints - 1;
return ret;
}
/* Identifier for a placeholder face that will be
* used to mark hole rings */
#define LWT_HOLES_FACE_PLACEHOLDER INT32_MIN
static int
_lwt_FetchNextUnvisitedEdge(__attribute__((__unused__)) LWT_TOPOLOGY *topo, LWT_ISO_EDGE_TABLE *etab, int from)
{
while (
from < etab->size &&
etab->edges[from].face_left != -1 &&
etab->edges[from].face_right != -1
) from++;
return from < etab->size ? from : -1;
}
static LWT_ISO_EDGE *
_lwt_FetchAllEdges(LWT_TOPOLOGY *topo, int *numedges)
{
LWT_ISO_EDGE *edge;
int fields = LWT_COL_EDGE_ALL;
uint64_t nelems = 1;
edge = lwt_be_getEdgeWithinBox2D( topo, NULL, &nelems, fields, 0);
*numedges = nelems;
if (nelems == UINT64_MAX)
{
PGTOPO_BE_ERROR();
return NULL;
}
return edge;
}
/* Update the side face of given ring edges
*
* Edge identifiers are signed, those with negative identifier
* need to be updated their right_face, those with positive
* identifier need to be updated their left_face.
*
* @param face identifier of the face bound by the ring
* @return 0 on success, -1 on error
*/
static int
_lwt_UpdateEdgeRingSideFace(LWT_TOPOLOGY *topo, LWT_EDGERING *ring,
LWT_ELEMID face)
{
LWT_ISO_EDGE *forward_edges = NULL;
int forward_edges_count = 0;
LWT_ISO_EDGE *backward_edges = NULL;
int backward_edges_count = 0;
int i, ret;
/* Make a list of forward_edges and backward_edges */
forward_edges = lwalloc(sizeof(LWT_ISO_EDGE) * ring->size);
forward_edges_count = 0;
backward_edges = lwalloc(sizeof(LWT_ISO_EDGE) * ring->size);
backward_edges_count = 0;
for ( i=0; i<ring->size; ++i )
{
LWT_EDGERING_ELEM *elem = ring->elems[i];
LWT_ISO_EDGE *edge = elem->edge;
LWT_ELEMID id = edge->edge_id;
if ( elem->left )
{
LWDEBUGF(3, "Forward edge %d is %d", forward_edges_count, id);
forward_edges[forward_edges_count].edge_id = id;
forward_edges[forward_edges_count++].face_left = face;
edge->face_left = face;
}
else
{
LWDEBUGF(3, "Backward edge %d is %d", forward_edges_count, id);
backward_edges[backward_edges_count].edge_id = id;
backward_edges[backward_edges_count++].face_right = face;
edge->face_right = face;
}
}
/* Update forward edges */
if ( forward_edges_count )
{
ret = lwt_be_updateEdgesById(topo, forward_edges,
forward_edges_count,
LWT_COL_EDGE_FACE_LEFT);
if ( ret == -1 )
{
lwfree( forward_edges );
lwfree( backward_edges );
PGTOPO_BE_ERROR();
return -1;
}
if ( ret != forward_edges_count )
{
lwfree( forward_edges );
lwfree( backward_edges );
lwerror("Unexpected error: %d edges updated when expecting %d (forward)",
ret, forward_edges_count);
return -1;
}
}
/* Update backward edges */
if ( backward_edges_count )
{
ret = lwt_be_updateEdgesById(topo, backward_edges,
backward_edges_count,
LWT_COL_EDGE_FACE_RIGHT);
if ( ret == -1 )
{
lwfree( forward_edges );
lwfree( backward_edges );
PGTOPO_BE_ERROR();
return -1;
}
if ( ret != backward_edges_count )
{
lwfree( forward_edges );
lwfree( backward_edges );
lwerror("Unexpected error: %d edges updated when expecting %d (backward)",
ret, backward_edges_count);
return -1;
}
}
lwfree( forward_edges );
lwfree( backward_edges );
return 0;
}
/*
* @param side 1 for left side, -1 for right side
*/
static LWT_EDGERING *
_lwt_BuildEdgeRing(__attribute__((__unused__)) LWT_TOPOLOGY *topo, LWT_ISO_EDGE_TABLE *edges,
LWT_ISO_EDGE *edge, int side)
{
LWT_EDGERING *ring;
LWT_EDGERING_ELEM *elem;
LWT_ISO_EDGE *cur;
int curside;
ring = lwalloc(sizeof(LWT_EDGERING));
LWT_EDGERING_INIT(ring);
cur = edge;
curside = side;
LWDEBUGF(2, "Building rings for edge %d (side %d)", cur->edge_id, side);
do {
LWT_ELEMID next;
elem = lwalloc(sizeof(LWT_EDGERING_ELEM));
elem->edge = cur;
elem->left = ( curside == 1 );
/* Mark edge as "visited" */
if ( elem->left ) cur->face_left = LWT_HOLES_FACE_PLACEHOLDER;
else cur->face_right = LWT_HOLES_FACE_PLACEHOLDER;
LWT_EDGERING_PUSH(ring, elem);
next = elem->left ? cur->next_left : cur->next_right;
LWDEBUGF(3, " next edge is %d", next);
if ( next > 0 ) curside = 1;
else { curside = -1; next = -next; }
cur = _lwt_getIsoEdgeById(edges, next);
if ( ! cur )
{
lwerror("Could not find edge with id %" LWTFMT_ELEMID, next);
break;
}
} while (cur != edge || curside != side);
LWDEBUGF(1, "Ring for edge %d has %d elems", edge->edge_id*side, ring->size);
return ring;
}
static double
_lwt_EdgeRingSignedArea(LWT_EDGERING_POINT_ITERATOR *it)
{
POINT2D P1;
POINT2D P2;
POINT2D P3;
double sum = 0.0;
double x0, x, y1, y2;
if ( ! _lwt_EdgeRingIterator_next(it, &P1) ) return 0.0;
if ( ! _lwt_EdgeRingIterator_next(it, &P2) ) return 0.0;
LWDEBUG(2, "_lwt_EdgeRingSignedArea");
x0 = P1.x;
while ( _lwt_EdgeRingIterator_next(it, &P3) )
{
x = P2.x - x0;
y1 = P3.y;
y2 = P1.y;
sum += x * (y2-y1);
/* Move forwards! */
P1 = P2;
P2 = P3;
}
return sum / 2.0;
}
/* Return 1 for true, 0 for false */
static int
_lwt_EdgeRingIsCCW(LWT_EDGERING *ring)
{
double sa;
LWDEBUGF(2, "_lwt_EdgeRingIsCCW, ring has %d elems", ring->size);
LWT_EDGERING_POINT_ITERATOR *it = _lwt_EdgeRingIterator_begin(ring);
sa = _lwt_EdgeRingSignedArea(it);
LWDEBUGF(2, "_lwt_EdgeRingIsCCW, signed area is %g", sa);
lwfree(it);
if ( sa >= 0 ) return 0;
else return 1;
}
static int
_lwt_EdgeRingCrossingCount(const POINT2D *p, LWT_EDGERING_POINT_ITERATOR *it)
{
int cn = 0; /* the crossing number counter */
POINT2D v1, v2;
#ifndef RELAX
POINT2D v0;
#endif
if ( ! _lwt_EdgeRingIterator_next(it, &v1) ) return cn;
v0 = v1;
while ( _lwt_EdgeRingIterator_next(it, &v2) )
{
double vt;
/* edge from vertex i to vertex i+1 */
if
(
/* an upward crossing */
((v1.y <= p->y) && (v2.y > p->y))
/* a downward crossing */
|| ((v1.y > p->y) && (v2.y <= p->y))
)
{
vt = (double)(p->y - v1.y) / (v2.y - v1.y);
/* P->x <intersect */
if (p->x < v1.x + vt * (v2.x - v1.x))
{
/* a valid crossing of y=p->y right of p->x */
++cn;
}
}
v1 = v2;
}
LWDEBUGF(3, "_lwt_EdgeRingCrossingCount returning %d", cn);
#ifndef RELAX
if ( memcmp(&v1, &v0, sizeof(POINT2D)) )
{
lwerror("_lwt_EdgeRingCrossingCount: V[n] != V[0] (%g %g != %g %g)",
v1.x, v1.y, v0.x, v0.y);
return -1;
}
#endif
return cn;
}
/* Return 1 for true, 0 for false */
static int
_lwt_EdgeRingContainsPoint(LWT_EDGERING *ring, POINT2D *p)
{
int cn = 0;
LWT_EDGERING_POINT_ITERATOR *it = _lwt_EdgeRingIterator_begin(ring);
cn = _lwt_EdgeRingCrossingCount(p, it);
lwfree(it);
return (cn&1); /* 0 if even (out), and 1 if odd (in) */
}
static GBOX *
_lwt_EdgeRingGetBbox(LWT_EDGERING *ring)
{
int i;
if ( ! ring->env )
{
LWDEBUGF(2, "Computing GBOX for ring %p", ring);
for (i=0; i<ring->size; ++i)
{
LWT_EDGERING_ELEM *elem = ring->elems[i];
LWLINE *g = elem->edge->geom;
const GBOX *newbox = lwgeom_get_bbox(lwline_as_lwgeom(g));
if ( ! i ) ring->env = gbox_clone( newbox );
else gbox_merge( newbox, ring->env );
}
}
return ring->env;
}
static LWT_ELEMID
_lwt_EdgeRingGetFace(LWT_EDGERING *ring)
{
LWT_EDGERING_ELEM *el = ring->elems[0];
return el->left ? el->edge->face_left : el->edge->face_right;
}
/*
* Register a face on an edge side
*
* Create and register face to shell (CCW) walks,
* register arbitrary negative face_id to CW rings.
*
* Push CCW rings to shells, CW rings to holes.
*
* The ownership of the "geom" and "ids" members of the
* LWT_EDGERING pushed to the given LWT_EDGERING_ARRAYS
* are transferred to caller.
*
* @param side 1 for left side, -1 for right side
*
* @param holes an array where holes will be pushed
*
* @param shells an array where shells will be pushed
*
* @param registered id of registered face. It will be a negative number
* for holes or isolated edge strips (still registered in the face
* table, but only temporary).
*
* @return 0 on success, -1 on error.
*
*/
static int
_lwt_RegisterFaceOnEdgeSide(LWT_TOPOLOGY *topo, LWT_ISO_EDGE *edge,
int side, LWT_ISO_EDGE_TABLE *edges,
LWT_EDGERING_ARRAY *holes,
LWT_EDGERING_ARRAY *shells,
LWT_ELEMID *registered)
{
const LWT_BE_IFACE *iface = topo->be_iface;
/* this is arbitrary, could be taken as parameter */
static const int placeholder_faceid = LWT_HOLES_FACE_PLACEHOLDER;
LWT_EDGERING *ring;
/* Get edge ring */
ring = _lwt_BuildEdgeRing(topo, edges, edge, side);
LWDEBUG(2, "Ring built, calling EdgeRingIsCCW");
/* Compute winding (CW or CCW?) */
int isccw = _lwt_EdgeRingIsCCW(ring);
if ( isccw )
{
/* Create new face */
LWT_ISO_FACE newface;
LWDEBUGF(1, "Ring of edge %d is a shell (shell %d)", edge->edge_id * side, shells->size);
newface.mbr = _lwt_EdgeRingGetBbox(ring);
newface.face_id = -1;
/* Insert the new face */
int ret = lwt_be_insertFaces( topo, &newface, 1 );
newface.mbr = NULL;
if ( ret == -1 )
{
PGTOPO_BE_ERROR();
return -1;
}
if ( ret != 1 )
{
lwerror("Unexpected error: %d faces inserted when expecting 1", ret);
return -1;
}
/* return new face_id */
*registered = newface.face_id;
LWT_EDGERING_ARRAY_PUSH(shells, ring);
/* update ring edges set new face_id on resp. side to *registered */
ret = _lwt_UpdateEdgeRingSideFace(topo, ring, *registered);
if ( ret )
{
lwerror("Errors updating edgering side face: %s",
lwt_be_lastErrorMessage(iface));
return -1;
}
}
else /* cw, so is an hole */
{
LWDEBUGF(1, "Ring of edge %d is a hole (hole %d)", edge->edge_id * side, holes->size);
*registered = placeholder_faceid;
LWT_EDGERING_ARRAY_PUSH(holes, ring);
}
return 0;
}
static void
_lwt_AccumulateCanditates(void* item, void* userdata)
{
LWT_EDGERING_ARRAY *candidates = userdata;
LWT_EDGERING *sring = item;
LWT_EDGERING_ARRAY_PUSH(candidates, sring);
}
static LWT_ELEMID
_lwt_FindFaceContainingRing(LWT_TOPOLOGY* topo, LWT_EDGERING *ring,
LWT_EDGERING_ARRAY *shells)
{
LWT_ELEMID foundInFace = -1;
int i;
const GBOX *minenv = NULL;
POINT2D pt;
const GBOX *testbox;
GEOSGeometry *ghole;
getPoint2d_p( ring->elems[0]->edge->geom->points, 0, &pt );
testbox = _lwt_EdgeRingGetBbox(ring);
/* Create a GEOS Point from a vertex of the hole ring */
{
LWPOINT *point = lwpoint_make2d(topo->srid, pt.x, pt.y);
ghole = LWGEOM2GEOS( lwpoint_as_lwgeom(point), 1 );
lwpoint_free(point);
if ( ! ghole ) {
lwerror("Could not convert edge geometry to GEOS: %s", lwgeom_geos_errmsg);
return -1;
}
}
/* Build STRtree of shell envelopes */
if ( ! shells->tree )
{
static const int STRTREE_NODE_CAPACITY = 10;
LWDEBUG(1, "Building STRtree");
shells->tree = GEOSSTRtree_create(STRTREE_NODE_CAPACITY);
if (shells->tree == NULL)
{
lwerror("Could not create GEOS STRTree: %s", lwgeom_geos_errmsg);
return -1;
}
for (i=0; i<shells->size; ++i)
{
LWT_EDGERING *sring = shells->rings[i];
const GBOX* shellbox = _lwt_EdgeRingGetBbox(sring);
LWDEBUGF(2, "GBOX of shell %p for edge %d is %g %g,%g %g",
sring, sring->elems[0]->edge->edge_id, shellbox->xmin,
shellbox->ymin, shellbox->xmax, shellbox->ymax);
POINTARRAY *pa = ptarray_construct(0, 0, 2);
POINT4D pt;
LWLINE *diag;
pt.x = shellbox->xmin;
pt.y = shellbox->ymin;
ptarray_set_point4d(pa, 0, &pt);
pt.x = shellbox->xmax;
pt.y = shellbox->ymax;
ptarray_set_point4d(pa, 1, &pt);
diag = lwline_construct(topo->srid, NULL, pa);
/* Record just envelope in ggeom */
/* making valid, probably not needed */
sring->genv = LWGEOM2GEOS( lwline_as_lwgeom(diag), 1 );
lwline_free(diag);
GEOSSTRtree_insert(shells->tree, sring->genv, sring);
}
LWDEBUG(1, "STRtree build completed");
}
LWT_EDGERING_ARRAY candidates;
LWT_EDGERING_ARRAY_INIT(&candidates);
GEOSSTRtree_query(shells->tree, ghole, &_lwt_AccumulateCanditates, &candidates);
LWDEBUGF(1, "Found %d candidate shells containing first point of ring's originating edge %d",
candidates.size, ring->elems[0]->edge->edge_id * ( ring->elems[0]->left ? 1 : -1 ) );
/* TODO: sort candidates by bounding box size */
for (i=0; i<candidates.size; ++i)
{
LWT_EDGERING *sring = candidates.rings[i];
const GBOX* shellbox = _lwt_EdgeRingGetBbox(sring);
int contains = 0;
if ( sring->elems[0]->edge->edge_id == ring->elems[0]->edge->edge_id )
{
LWDEBUGF(1, "Shell %d is on other side of ring",
_lwt_EdgeRingGetFace(sring));
continue;
}
/* The hole envelope cannot equal the shell envelope */
if ( gbox_same(shellbox, testbox) )
{
LWDEBUGF(1, "Bbox of shell %d equals that of hole ring",
_lwt_EdgeRingGetFace(sring));
continue;
}
/* Skip if ring box is not in shell box */
if ( ! gbox_contains_2d(shellbox, testbox) )
{
LWDEBUGF(1, "Bbox of shell %d does not contain bbox of ring point",
_lwt_EdgeRingGetFace(sring));
continue;
}
/* Skip test if a containing shell was already found
* and this shell's bbox is not contained in the other */
if ( minenv && ! gbox_contains_2d(minenv, shellbox) )
{
LWDEBUGF(2, "Bbox of shell %d (face %d) not contained by bbox "
"of last shell found to contain the point",
i, _lwt_EdgeRingGetFace(sring));
continue;
}
contains = _lwt_EdgeRingContainsPoint(sring, &pt);
if ( contains )
{
/* Continue until all shells are tested, as we want to
* use the one with the smallest bounding box */
/* IDEA: sort shells by bbox size, stopping on first match */
LWDEBUGF(1, "Shell %d contains hole of edge %d",
_lwt_EdgeRingGetFace(sring),
ring->elems[0]->edge->edge_id);
minenv = shellbox;
foundInFace = _lwt_EdgeRingGetFace(sring);
}
}
if ( foundInFace == -1 ) foundInFace = 0;
candidates.size = 0; /* Avoid destroying the actual shell rings */
LWT_EDGERING_ARRAY_CLEAN(&candidates);
GEOSGeom_destroy(ghole);
return foundInFace;
}
/*
* @return -1 on error (and report error),
* 1 if faces beside the universal one exist
* 0 otherwise
*/
static int
_lwt_CheckFacesExist(LWT_TOPOLOGY *topo)
{
LWT_ISO_FACE *faces;
int fields = LWT_COL_FACE_FACE_ID;
uint64_t nelems = 1;
GBOX qbox;
qbox.xmin = qbox.ymin = -DBL_MAX;
qbox.xmax = qbox.ymax = DBL_MAX;
faces = lwt_be_getFaceWithinBox2D( topo, &qbox, &nelems, fields, 1);
if (nelems == UINT64_MAX)
{
PGTOPO_BE_ERROR();
return -1;
}
if ( faces )
{
/* we do not call _lwt_release_faces because we are not asking
* for the MBR so there are no nested objects to release */
lwfree(faces);
}
return nelems;
}
int
lwt_Polygonize(LWT_TOPOLOGY* topo)
{
/*
Fetch all edges
Sort edges by edge_id
Mark all edges' left and right face as -1
Iteratively:
Fetch next edge with left or right face == -1
For each side with face == -1:
Find ring on its side
If ring is CCW:
create a new face, assign to the ring edges' appropriate side
If ring is CW (face needs to be same of external):
assign a negative face_id the ring edges' appropriate side
Now for each edge with a negative face_id on the side:
Find containing face (mbr cache and all)
Update with id of containing face
*/
const LWT_BE_IFACE *iface = topo->be_iface;
LWT_ISO_EDGE *edge;
int numfaces = -1;
LWT_ISO_EDGE_TABLE edgetable;
LWT_EDGERING_ARRAY holes, shells;
int i;
int err = 0;
LWT_EDGERING_ARRAY_INIT(&holes);
LWT_EDGERING_ARRAY_INIT(&shells);
initGEOS(lwnotice, lwgeom_geos_error);
/*
Check if Topology already contains some Face
(ignoring the Universal Face)
*/
numfaces = _lwt_CheckFacesExist(topo);
if ( numfaces != 0 ) {
if ( numfaces > 0 ) {
/* Faces exist */
lwerror("Polygonize: face table is not empty.");
}
/* Backend error, message should have been printed already */
return -1;
}
edgetable.edges = _lwt_FetchAllEdges(topo, &(edgetable.size));
if ( ! edgetable.edges ) {
if (edgetable.size == 0) {
/* not an error: no Edges */
return 0;
}
/* error should have been printed already */
return -1;
}
/* Sort edges by ID (to allow btree searches) */
qsort(edgetable.edges, edgetable.size, sizeof(LWT_ISO_EDGE), compare_iso_edges_by_id);
/* Mark all edges as unvisited */
for (i=0; i<edgetable.size; ++i)
edgetable.edges[i].face_left = edgetable.edges[i].face_right = -1;
i = 0;
while (1)
{
i = _lwt_FetchNextUnvisitedEdge(topo, &edgetable, i);
if ( i < 0 ) break; /* end of unvisited */
edge = &(edgetable.edges[i]);
LWT_ELEMID newface = -1;
LWDEBUGF(1, "Next face-missing edge has id:%d, face_left:%d, face_right:%d",
edge->edge_id, edge->face_left, edge->face_right);
if ( edge->face_left == -1 )
{
err = _lwt_RegisterFaceOnEdgeSide(topo, edge, 1, &edgetable,
&holes, &shells, &newface);
if ( err ) break;
LWDEBUGF(1, "New face on the left of edge %d is %d",
edge->edge_id, newface);
edge->face_left = newface;
}
if ( edge->face_right == -1 )
{
err = _lwt_RegisterFaceOnEdgeSide(topo, edge, -1, &edgetable,
&holes, &shells, &newface);
if ( err ) break;
LWDEBUGF(1, "New face on the right of edge %d is %d",
edge->edge_id, newface);
edge->face_right = newface;
}
}
if ( err )
{
_lwt_release_edges(edgetable.edges, edgetable.size);
LWT_EDGERING_ARRAY_CLEAN( &holes );
LWT_EDGERING_ARRAY_CLEAN( &shells );
lwerror("Errors fetching or registering face-missing edges: %s",
lwt_be_lastErrorMessage(iface));
return -1;
}
LWDEBUGF(1, "Found %d holes and %d shells", holes.size, shells.size);
/* TODO: sort holes by pt.x, sort shells by bbox.xmin */
/* Assign shells to holes */
for (i=0; i<holes.size; ++i)
{
LWT_ELEMID containing_face;
LWT_EDGERING *ring = holes.rings[i];
containing_face = _lwt_FindFaceContainingRing(topo, ring, &shells);
LWDEBUGF(1, "Ring %d contained by face %" LWTFMT_ELEMID, i, containing_face);
if ( containing_face == -1 )
{
_lwt_release_edges(edgetable.edges, edgetable.size);
LWT_EDGERING_ARRAY_CLEAN( &holes );
LWT_EDGERING_ARRAY_CLEAN( &shells );
lwerror("Errors finding face containing ring: %s",
lwt_be_lastErrorMessage(iface));
return -1;
}
int ret = _lwt_UpdateEdgeRingSideFace(topo, holes.rings[i], containing_face);
if ( ret )
{
_lwt_release_edges(edgetable.edges, edgetable.size);
LWT_EDGERING_ARRAY_CLEAN( &holes );
LWT_EDGERING_ARRAY_CLEAN( &shells );
lwerror("Errors updating edgering side face: %s",
lwt_be_lastErrorMessage(iface));
return -1;
}
}
LWDEBUG(1, "All holes assigned, cleaning up");
_lwt_release_edges(edgetable.edges, edgetable.size);
/* delete all shell and hole EDGERINGS */
LWT_EDGERING_ARRAY_CLEAN( &holes );
LWT_EDGERING_ARRAY_CLEAN( &shells );
return 0;
}
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