PostGIS  2.5.1dev-r@@SVN_REVISION@@

◆ _lwt_MakeRingShell()

static LWPOLY* _lwt_MakeRingShell ( LWT_TOPOLOGY topo,
LWT_ELEMID signed_edge_ids,
int  num_signed_edge_ids 
)
static

Definition at line 1743 of file lwgeom_topo.c.

References _lwt_release_edges(), LWT_TOPOLOGY_T::be_iface, LWT_ISO_EDGE::geom, lwalloc(), LWDEBUGF, lwerror(), lwfree(), lwpoly_construct(), lwt_be_getEdgeById(), lwt_be_lastErrorMessage(), LWT_COL_EDGE_EDGE_ID, LWT_COL_EDGE_GEOM, LWTFMT_ELEMID, LWLINE::points, ptarray_append_ptarray(), ptarray_clone_deep(), ptarray_free(), and ptarray_reverse_in_place().

Referenced by _lwt_AddFaceSplit().

1744 {
1745  LWT_ELEMID *edge_ids;
1746  int numedges, i, j;
1747  LWT_ISO_EDGE *ring_edges;
1748 
1749  /* Construct a polygon using edges of the ring */
1750  numedges = 0;
1751  edge_ids = lwalloc(sizeof(LWT_ELEMID)*num_signed_edge_ids);
1752  for (i=0; i<num_signed_edge_ids; ++i) {
1753  int absid = llabs(signed_edge_ids[i]);
1754  int found = 0;
1755  /* Do not add the same edge twice */
1756  for (j=0; j<numedges; ++j) {
1757  if ( edge_ids[j] == absid ) {
1758  found = 1;
1759  break;
1760  }
1761  }
1762  if ( ! found ) edge_ids[numedges++] = absid;
1763  }
1764  i = numedges;
1765  ring_edges = lwt_be_getEdgeById(topo, edge_ids, &i,
1767  lwfree( edge_ids );
1768  if ( i == -1 )
1769  {
1770  lwerror("Backend error: %s", lwt_be_lastErrorMessage(topo->be_iface));
1771  return NULL;
1772  }
1773  else if ( i != numedges )
1774  {
1775  lwfree( signed_edge_ids );
1776  _lwt_release_edges(ring_edges, numedges);
1777  lwerror("Unexpected error: %d edges found when expecting %d", i, numedges);
1778  return NULL;
1779  }
1780 
1781  /* Should now build a polygon with those edges, in the order
1782  * given by GetRingEdges.
1783  */
1784  POINTARRAY *pa = NULL;
1785  for ( i=0; i<num_signed_edge_ids; ++i )
1786  {
1787  LWT_ELEMID eid = signed_edge_ids[i];
1788  LWDEBUGF(2, "Edge %d in ring is edge %" LWTFMT_ELEMID, i, eid);
1789  LWT_ISO_EDGE *edge = NULL;
1790  POINTARRAY *epa;
1791  for ( j=0; j<numedges; ++j )
1792  {
1793  if ( ring_edges[j].edge_id == llabs(eid) )
1794  {
1795  edge = &(ring_edges[j]);
1796  break;
1797  }
1798  }
1799  if ( edge == NULL )
1800  {
1801  _lwt_release_edges(ring_edges, numedges);
1802  lwerror("missing edge that was found in ring edges loop");
1803  return NULL;
1804  }
1805 
1806  if ( pa == NULL )
1807  {
1808  pa = ptarray_clone_deep(edge->geom->points);
1809  if ( eid < 0 ) ptarray_reverse_in_place(pa);
1810  }
1811  else
1812  {
1813  if ( eid < 0 )
1814  {
1815  epa = ptarray_clone_deep(edge->geom->points);
1817  ptarray_append_ptarray(pa, epa, 0);
1818  ptarray_free(epa);
1819  }
1820  else
1821  {
1822  /* avoid a clone here */
1823  ptarray_append_ptarray(pa, edge->geom->points, 0);
1824  }
1825  }
1826  }
1827  _lwt_release_edges(ring_edges, numedges);
1828  POINTARRAY **points = lwalloc(sizeof(POINTARRAY*));
1829  points[0] = pa;
1830 
1831  /* NOTE: the ring may very well have collapsed components,
1832  * which would make it topologically invalid
1833  */
1834  LWPOLY* shell = lwpoly_construct(0, 0, 1, points);
1835  return shell;
1836 }
void lwfree(void *mem)
Definition: lwutil.c:244
void ptarray_free(POINTARRAY *pa)
Definition: ptarray.c:328
LWLINE * geom
LWT_ISO_EDGE * lwt_be_getEdgeById(LWT_TOPOLOGY *topo, const LWT_ELEMID *ids, int *numelems, int fields)
Definition: lwgeom_topo.c:225
LWPOLY * lwpoly_construct(int srid, GBOX *bbox, uint32_t nrings, POINTARRAY **points)
Definition: lwpoly.c:43
const LWT_BE_IFACE * be_iface
int ptarray_append_ptarray(POINTARRAY *pa1, POINTARRAY *pa2, double gap_tolerance)
Append a POINTARRAY, pa2 to the end of an existing POINTARRAY, pa1.
Definition: ptarray.c:187
POINTARRAY * ptarray_clone_deep(const POINTARRAY *ptarray)
Deep clone a pointarray (also clones serialized pointlist)
Definition: ptarray.c:628
void ptarray_reverse_in_place(POINTARRAY *pa)
Definition: ptarray.c:341
#define LWT_COL_EDGE_EDGE_ID
Edge fields.
static void _lwt_release_edges(LWT_ISO_EDGE *edges, int num_edges)
Definition: lwgeom_topo.c:457
LWT_INT64 LWT_ELEMID
Identifier of topology element.
#define LWT_COL_EDGE_GEOM
void * lwalloc(size_t size)
Definition: lwutil.c:229
#define LWDEBUGF(level, msg,...)
Definition: lwgeom_log.h:88
const char * lwt_be_lastErrorMessage(const LWT_BE_IFACE *be)
Definition: lwgeom_topo.c:120
void lwerror(const char *fmt,...)
Write a notice out to the error handler.
Definition: lwutil.c:190
#define LWTFMT_ELEMID
Definition: lwgeom_topo.c:44
POINTARRAY * points
Definition: liblwgeom.h:424
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