lwpsurface_is_closed()

int lwpsurface_is_closed

(

const LWPSURFACE *

psurface

)

Definition at line 99 of file lwpsurface.c.

{
        uint32_t i, j, k;
        uint32_t 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 theoretical 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;
}

References struct_psurface_arcs::ax, struct_psurface_arcs::ay, struct_psurface_arcs::az, struct_psurface_arcs::bx, struct_psurface_arcs::by, struct_psurface_arcs::bz, struct_psurface_arcs::cnt, struct_psurface_arcs::face, LWPSURFACE::flags, FLAGS_GET_Z, LWPSURFACE::geoms, getPoint4d_p(), lwalloc(), lwfree(), LWPSURFACE::ngeoms, POINTARRAY::npoints, LWPOLY::rings, POINT4D::x, POINT4D::y, and POINT4D::z.

Referenced by lwgeom_dimension(), and lwgeom_is_closed().

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