lwpsurface.c

Go to the documentation of this file.

/**********************************************************************
 *
 * 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) 2001-2006 Refractions Research Inc.
 *
 **********************************************************************/


#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "liblwgeom_internal.h"
#include "lwgeom_log.h"


LWPSURFACE* lwpsurface_add_lwpoly(LWPSURFACE *mobj, const LWPOLY *obj)
{
        return (LWPSURFACE*)lwcollection_add_lwgeom((LWCOLLECTION*)mobj, (LWGEOM*)obj);
}


void lwpsurface_free(LWPSURFACE *psurf)
{
        int i;
        if ( ! psurf ) return;
        if ( psurf->bbox )
                lwfree(psurf->bbox);

        for ( i = 0; i < psurf->ngeoms; i++ )
                if ( psurf->geoms && psurf->geoms[i] )
                        lwpoly_free(psurf->geoms[i]);

        if ( psurf->geoms )
                lwfree(psurf->geoms);

        lwfree(psurf);
}


void printLWPSURFACE(LWPSURFACE *psurf)
{
        int i, j;
        LWPOLY *patch;

        if (psurf->type != POLYHEDRALSURFACETYPE)
                lwerror("printLWPSURFACE called with something else than a POLYHEDRALSURFACE");

        lwnotice("LWPSURFACE {");
        lwnotice("    ndims = %i", (int)FLAGS_NDIMS(psurf->flags));
        lwnotice("    SRID = %i", (int)psurf->srid);
        lwnotice("    ngeoms = %i", (int)psurf->ngeoms);

        for (i=0; i<psurf->ngeoms; i++)
        {
                patch = (LWPOLY *) psurf->geoms[i];
                for (j=0; j<patch->nrings; j++)
                {
                        lwnotice("    RING # %i :",j);
                        printPA(patch->rings[j]);
                }
        }
        lwnotice("}");
}




/*
 * TODO rewrite all this stuff to be based on a truly topological model
 */

struct struct_psurface_arcs
{
        double ax, ay, az;
        double bx, by, bz;
        int cnt, face;
};
typedef struct struct_psurface_arcs *psurface_arcs;

/* We supposed that the geometry is valid
   we could have wrong result if not */
int lwpsurface_is_closed(const LWPSURFACE *psurface)
{
        int i, j, k;
        int narcs, carc;
        int found;
        psurface_arcs arcs;
        POINT4D pa, pb;
        LWPOLY *patch;

        /* If surface is not 3D, it's can't be closed */
        if (!FLAGS_GET_Z(psurface->flags)) return 0;

        /* If surface is less than 4 faces hard to be closed too */
        if (psurface->ngeoms < 4) return 0;

        /* Max theorical arcs number if no one is shared ... */
        for (i=0, narcs=0 ; i < psurface->ngeoms ; i++)
        {
                patch = (LWPOLY *) psurface->geoms[i];
                narcs += patch->rings[0]->npoints - 1;
        }

        arcs = lwalloc(sizeof(struct struct_psurface_arcs) * narcs);
        for (i=0, carc=0; i < psurface->ngeoms ; i++)
        {

                patch = (LWPOLY *) psurface->geoms[i];
                for (j=0; j < patch->rings[0]->npoints - 1; j++)
                {

                        getPoint4d_p(patch->rings[0], j,   &pa);
                        getPoint4d_p(patch->rings[0], j+1, &pb);

                        /* remove redundant points if any */
                        if (pa.x == pb.x && pa.y == pb.y && pa.z == pb.z) continue;

                        /* Make sure to order the 'lower' point first */
                        if ( (pa.x > pb.x) ||
                                (pa.x == pb.x && pa.y > pb.y) ||
                                (pa.x == pb.x && pa.y == pb.y && pa.z > pb.z) )
                        {
                                pa = pb;
                                getPoint4d_p(patch->rings[0], j, &pb);
                        }

                        for (found=0, k=0; k < carc ; k++)
                        {

                                if (  ( arcs[k].ax == pa.x && arcs[k].ay == pa.y &&
                                        arcs[k].az == pa.z && arcs[k].bx == pb.x &&
                                        arcs[k].by == pb.y && arcs[k].bz == pb.z &&
                                        arcs[k].face != i) )
                                {
                                        arcs[k].cnt++;
                                        found = 1;

                                        /* Look like an invalid PolyhedralSurface
                                              anyway not a closed one */
                                        if (arcs[k].cnt > 2)
                                        {
                                                lwfree(arcs);
                                                return 0;
                                        }
                                }
                        }

                        if (!found)
                        {
                                arcs[carc].cnt=1;
                                arcs[carc].face=i;
                                arcs[carc].ax = pa.x;
                                arcs[carc].ay = pa.y;
                                arcs[carc].az = pa.z;
                                arcs[carc].bx = pb.x;
                                arcs[carc].by = pb.y;
                                arcs[carc].bz = pb.z;
                                carc++;

                                /* Look like an invalid PolyhedralSurface
                                      anyway not a closed one */
                                if (carc > narcs)
                                {
                                        lwfree(arcs);
                                        return 0;
                                }
                        }
                }
        }

        /* A polyhedron is closed if each edge
               is shared by exactly 2 faces */
        for (k=0; k < carc ; k++)
        {
                if (arcs[k].cnt != 2)
                {
                        lwfree(arcs);
                        return 0;
                }
        }
        lwfree(arcs);

        /* Invalid Polyhedral case */
        if (carc < psurface->ngeoms) return 0;

        return 1;
}