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475 lines
10 KiB
C
475 lines
10 KiB
C
/**********************************************************************
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*
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* PostGIS - Spatial Types for PostgreSQL
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* http://postgis.refractions.net
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*
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* Copyright (C) 2001-2006 Refractions Research Inc.
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*
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* This is free software; you can redistribute and/or modify it under
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* the terms of the GNU General Public Licence. See the COPYING file.
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*
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**********************************************************************/
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/* basic LWPOLY manipulation */
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include "liblwgeom_internal.h"
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#include "lwgeom_log.h"
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#define CHECK_POLY_RINGS_ZM 1
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/* construct a new LWPOLY. arrays (points/points per ring) will NOT be copied
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* use SRID=SRID_UNKNOWN for unknown SRID (will have 8bit type's S = 0)
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*/
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LWPOLY*
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lwpoly_construct(int srid, GBOX *bbox, uint32_t nrings, POINTARRAY **points)
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{
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LWPOLY *result;
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int hasz, hasm;
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#ifdef CHECK_POLY_RINGS_ZM
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char zm;
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uint32_t i;
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#endif
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if ( nrings < 1 ) lwerror("lwpoly_construct: need at least 1 ring");
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hasz = FLAGS_GET_Z(points[0]->flags);
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hasm = FLAGS_GET_M(points[0]->flags);
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#ifdef CHECK_POLY_RINGS_ZM
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zm = FLAGS_GET_ZM(points[0]->flags);
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for (i=1; i<nrings; i++)
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{
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if ( zm != FLAGS_GET_ZM(points[i]->flags) )
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lwerror("lwpoly_construct: mixed dimensioned rings");
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}
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#endif
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result = (LWPOLY*) lwalloc(sizeof(LWPOLY));
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result->type = POLYGONTYPE;
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result->flags = gflags(hasz, hasm, 0);
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FLAGS_SET_BBOX(result->flags, bbox?1:0);
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result->srid = srid;
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result->nrings = nrings;
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result->maxrings = nrings;
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result->rings = points;
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result->bbox = bbox;
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return result;
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}
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LWPOLY*
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lwpoly_construct_empty(int srid, char hasz, char hasm)
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{
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LWPOLY *result = lwalloc(sizeof(LWPOLY));
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result->type = POLYGONTYPE;
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result->flags = gflags(hasz,hasm,0);
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result->srid = srid;
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result->nrings = 0;
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result->maxrings = 1; /* Allocate room for ring, just in case. */
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result->rings = lwalloc(result->maxrings * sizeof(POINTARRAY*));
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result->bbox = NULL;
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return result;
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}
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void lwpoly_free(LWPOLY *poly)
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{
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int t;
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if ( poly->bbox )
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lwfree(poly->bbox);
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for (t=0; t<poly->nrings; t++)
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{
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if ( poly->rings[t] )
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ptarray_free(poly->rings[t]);
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}
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if ( poly->rings )
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lwfree(poly->rings);
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lwfree(poly);
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}
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void printLWPOLY(LWPOLY *poly)
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{
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int t;
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lwnotice("LWPOLY {");
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lwnotice(" ndims = %i", (int)FLAGS_NDIMS(poly->flags));
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lwnotice(" SRID = %i", (int)poly->srid);
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lwnotice(" nrings = %i", (int)poly->nrings);
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for (t=0; t<poly->nrings; t++)
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{
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lwnotice(" RING # %i :",t);
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printPA(poly->rings[t]);
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}
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lwnotice("}");
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}
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/* @brief Clone LWLINE object. Serialized point lists are not copied.
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*
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* @see ptarray_clone
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*/
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LWPOLY *
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lwpoly_clone(const LWPOLY *g)
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{
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int i;
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LWPOLY *ret = lwalloc(sizeof(LWPOLY));
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memcpy(ret, g, sizeof(LWPOLY));
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ret->rings = lwalloc(sizeof(POINTARRAY *)*g->nrings);
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for ( i = 0; i < g->nrings; i++ ) {
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ret->rings[i] = ptarray_clone(g->rings[i]);
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}
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if ( g->bbox ) ret->bbox = gbox_copy(g->bbox);
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return ret;
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}
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/* Deep clone LWPOLY object. POINTARRAY are copied, as is ring array */
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LWPOLY *
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lwpoly_clone_deep(const LWPOLY *g)
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{
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int i;
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LWPOLY *ret = lwalloc(sizeof(LWPOLY));
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memcpy(ret, g, sizeof(LWPOLY));
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if ( g->bbox ) ret->bbox = gbox_copy(g->bbox);
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ret->rings = lwalloc(sizeof(POINTARRAY *)*g->nrings);
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for ( i = 0; i < ret->nrings; i++ )
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{
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ret->rings[i] = ptarray_clone_deep(g->rings[i]);
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}
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FLAGS_SET_READONLY(ret->flags,0);
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return ret;
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}
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/**
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* Add a ring to a polygon. Point array will be referenced, not copied.
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*/
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int
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lwpoly_add_ring(LWPOLY *poly, POINTARRAY *pa)
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{
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if( ! poly || ! pa )
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return LW_FAILURE;
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/* We have used up our storage, add some more. */
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if( poly->nrings >= poly->maxrings )
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{
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int new_maxrings = 2 * (poly->nrings + 1);
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poly->rings = lwrealloc(poly->rings, new_maxrings * sizeof(POINTARRAY*));
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}
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/* Add the new ring entry. */
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poly->rings[poly->nrings] = pa;
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poly->nrings++;
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return LW_SUCCESS;
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}
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void
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lwpoly_force_clockwise(LWPOLY *poly)
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{
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int i;
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/* No-op empties */
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if ( lwpoly_is_empty(poly) )
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return;
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/* External ring */
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if ( ptarray_isccw(poly->rings[0]) )
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ptarray_reverse(poly->rings[0]);
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/* Internal rings */
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for (i=1; i<poly->nrings; i++)
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if ( ! ptarray_isccw(poly->rings[i]) )
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ptarray_reverse(poly->rings[i]);
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}
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void
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lwpoly_release(LWPOLY *lwpoly)
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{
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lwgeom_release(lwpoly_as_lwgeom(lwpoly));
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}
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void
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lwpoly_reverse(LWPOLY *poly)
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{
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int i;
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if ( lwpoly_is_empty(poly) ) return;
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for (i=0; i<poly->nrings; i++)
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ptarray_reverse(poly->rings[i]);
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}
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LWPOLY *
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lwpoly_segmentize2d(LWPOLY *poly, double dist)
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{
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POINTARRAY **newrings;
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uint32_t i;
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newrings = lwalloc(sizeof(POINTARRAY *)*poly->nrings);
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for (i=0; i<poly->nrings; i++)
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{
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newrings[i] = ptarray_segmentize2d(poly->rings[i], dist);
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}
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return lwpoly_construct(poly->srid, NULL,
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poly->nrings, newrings);
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}
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/*
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* check coordinate equality
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* ring and coordinate order is considered
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*/
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char
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lwpoly_same(const LWPOLY *p1, const LWPOLY *p2)
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{
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uint32_t i;
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if ( p1->nrings != p2->nrings ) return 0;
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for (i=0; i<p1->nrings; i++)
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{
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if ( ! ptarray_same(p1->rings[i], p2->rings[i]) )
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return 0;
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}
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return 1;
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}
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/*
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* Construct a polygon from a LWLINE being
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* the shell and an array of LWLINE (possibly NULL) being holes.
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* Pointarrays from intput geoms are cloned.
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* SRID must be the same for each input line.
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* Input lines must have at least 4 points, and be closed.
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*/
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LWPOLY *
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lwpoly_from_lwlines(const LWLINE *shell,
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uint32_t nholes, const LWLINE **holes)
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{
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uint32_t nrings;
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POINTARRAY **rings = lwalloc((nholes+1)*sizeof(POINTARRAY *));
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int srid = shell->srid;
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LWPOLY *ret;
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if ( shell->points->npoints < 4 )
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lwerror("lwpoly_from_lwlines: shell must have at least 4 points");
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if ( ! ptarray_isclosed2d(shell->points) )
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lwerror("lwpoly_from_lwlines: shell must be closed");
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rings[0] = ptarray_clone_deep(shell->points);
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for (nrings=1; nrings<=nholes; nrings++)
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{
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const LWLINE *hole = holes[nrings-1];
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if ( hole->srid != srid )
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lwerror("lwpoly_from_lwlines: mixed SRIDs in input lines");
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if ( hole->points->npoints < 4 )
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lwerror("lwpoly_from_lwlines: holes must have at least 4 points");
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if ( ! ptarray_isclosed2d(hole->points) )
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lwerror("lwpoly_from_lwlines: holes must be closed");
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rings[nrings] = ptarray_clone_deep(hole->points);
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}
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ret = lwpoly_construct(srid, NULL, nrings, rings);
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return ret;
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}
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LWGEOM*
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lwpoly_remove_repeated_points(LWPOLY *poly)
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{
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uint32_t i;
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POINTARRAY **newrings;
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newrings = lwalloc(sizeof(POINTARRAY *)*poly->nrings);
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for (i=0; i<poly->nrings; i++)
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{
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newrings[i] = ptarray_remove_repeated_points(poly->rings[i]);
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}
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return (LWGEOM*)lwpoly_construct(poly->srid,
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poly->bbox ? gbox_copy(poly->bbox) : NULL,
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poly->nrings, newrings);
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}
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LWPOLY*
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lwpoly_force_dims(const LWPOLY *poly, int hasz, int hasm)
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{
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LWPOLY *polyout;
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/* Return 2D empty */
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if( lwpoly_is_empty(poly) )
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{
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polyout = lwpoly_construct_empty(poly->srid, hasz, hasm);
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}
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else
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{
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POINTARRAY **rings = NULL;
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int i;
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rings = lwalloc(sizeof(POINTARRAY*) * poly->nrings);
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for( i = 0; i < poly->nrings; i++ )
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{
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rings[i] = ptarray_force_dims(poly->rings[i], hasz, hasm);
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}
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polyout = lwpoly_construct(poly->srid, NULL, poly->nrings, rings);
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}
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polyout->type = poly->type;
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return polyout;
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}
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int lwpoly_is_empty(const LWPOLY *poly)
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{
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if ( (poly->nrings == 0) || (!poly->rings) )
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return LW_TRUE;
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return LW_FALSE;
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}
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int lwpoly_count_vertices(LWPOLY *poly)
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{
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int i = 0;
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int v = 0; /* vertices */
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assert(poly);
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for ( i = 0; i < poly->nrings; i ++ )
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{
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v += poly->rings[i]->npoints;
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}
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return v;
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}
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LWPOLY* lwpoly_simplify(const LWPOLY *ipoly, double dist)
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{
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int i;
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LWPOLY *opoly = lwpoly_construct_empty(ipoly->srid, FLAGS_GET_Z(ipoly->flags), FLAGS_GET_M(ipoly->flags));
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LWDEBUGF(2, "simplify_polygon3d: simplifying polygon with %d rings", ipoly->nrings);
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if( lwpoly_is_empty(ipoly) )
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return opoly;
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for (i = 0; i < ipoly->nrings; i++)
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{
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POINTARRAY *opts = ptarray_simplify(ipoly->rings[i], dist);
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/* One point implies an error in the ptarray_simplify */
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if ( opts->npoints < 2 )
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{
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lwnotice("ptarray_simplify returned a <2 pts array");
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ptarray_free(opts);
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continue;
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}
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/* Less points than are needed to form a closed ring, we can't use this */
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if ( opts->npoints < 4 )
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{
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LWDEBUGF(3, "ring%d skipped (<4 pts)", i);
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ptarray_free(opts);
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if ( i ) continue;
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else break;
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}
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LWDEBUGF(3, "ring%d simplified from %d to %d points", i, ipoly->rings[i]->npoints, opts->npoints);
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/* Add ring to simplified polygon */
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if( lwpoly_add_ring(opoly, opts) == LW_FAILURE )
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return NULL;
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}
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LWDEBUGF(3, "simplified polygon with %d rings", ipoly->nrings);
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opoly->type = ipoly->type;
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return opoly;
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}
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/**
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* Find the area of the outer ring - sum (area of inner rings).
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* Could use a more numerically stable calculator...
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*/
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double
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lwpoly_area(const LWPOLY *poly)
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{
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double poly_area=0.0;
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int i;
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POINT2D pp;
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POINT2D cp;
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POINT2D np;
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double x0 = cp.x;
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LWDEBUGF(2, "in lwpoly_area (%d rings)", poly->nrings);
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for (i=0; i<poly->nrings; i++)
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{
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int j;
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POINTARRAY *ring = poly->rings[i];
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double ringarea = 0.0;
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LWDEBUGF(4, " rings %d has %d points", i, ring->npoints);
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if ( ! ring->npoints ) continue; /* empty ring */
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getPoint2d_p(ring, 0, &cp);
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getPoint2d_p(ring, 1, &np);
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x0 = cp.x;
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np.x -= x0;
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for (j=0; j<ring->npoints-1; j++)
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{
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pp.y = cp.y;
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cp.x = np.x;
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cp.y = np.y;
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getPoint2d_p(ring, j+1, &np);
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np.x -= x0;
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ringarea += cp.x * (np.y - pp.y);
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}
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ringarea /= 2.0;
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LWDEBUGF(4, " ring 1 has area %lf",ringarea);
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ringarea = fabs(ringarea);
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if (i != 0) /*outer */
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ringarea = -1.0*ringarea ; /* its a hole */
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poly_area += ringarea;
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}
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return poly_area;
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}
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/**
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* Compute the sum of polygon rings length.
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* Could use a more numerically stable calculator...
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*/
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double
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lwpoly_perimeter(const LWPOLY *poly)
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{
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double result=0.0;
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int i;
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LWDEBUGF(2, "in lwgeom_polygon_perimeter (%d rings)", poly->nrings);
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for (i=0; i<poly->nrings; i++)
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result += ptarray_length(poly->rings[i]);
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return result;
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}
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/**
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* Compute the sum of polygon rings length (forcing 2d computation).
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* Could use a more numerically stable calculator...
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*/
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double
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lwpoly_perimeter_2d(const LWPOLY *poly)
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{
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double result=0.0;
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int i;
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LWDEBUGF(2, "in lwgeom_polygon_perimeter (%d rings)", poly->nrings);
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for (i=0; i<poly->nrings; i++)
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result += ptarray_length_2d(poly->rings[i]);
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return result;
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}
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