lwgeom_subdivide_recursive()

static int lwgeom_subdivide_recursive ( const LWGEOM *  geom, int  maxvertices, int  depth, LWCOLLECTION *  col, const GBOX *  clip  )

static

Definition at line 1943 of file lwgeom.c.

References FP_TOLERANCE, LWCOLLECTION::geoms, lwcollection_add_lwgeom(), lwerror(), lwgeom_clip_by_rect(), lwgeom_clone_deep(), lwgeom_count_vertices(), lwgeom_free(), lwgeom_is_collection(), lwtype_name(), MULTIPOINTTYPE, LWCOLLECTION::ngeoms, POINTTYPE, POLYHEDRALSURFACETYPE, TINTYPE, LWGEOM::type, GBOX::xmax, GBOX::xmin, GBOX::ymax, and GBOX::ymin.

Referenced by lwgeom_grid(), and lwgeom_subdivide().

{
        const int maxdepth = 50;
        int nvertices = 0;
        int i, n = 0;
        double width = clip->xmax - clip->xmin;
        double height = clip->ymax - clip->ymin;
        GBOX subbox1, subbox2;
        LWGEOM *clipped1, *clipped2;

        if ( geom->type == POLYHEDRALSURFACETYPE || geom->type == TINTYPE )
        {
                lwerror("%s: unsupported geometry type '%s'", __func__, lwtype_name(geom->type));
        }

        if ( width == 0.0 && height == 0.0 )
        {
                if ( geom->type == POINTTYPE )
                {
                        lwcollection_add_lwgeom(col, lwgeom_clone_deep(geom));
                        return 1;
                }
                else
                {
                        return 0;
                }
        }

        /* Always just recurse into collections */
        if ( lwgeom_is_collection(geom) && geom->type != MULTIPOINTTYPE )
        {
                LWCOLLECTION *incol = (LWCOLLECTION*)geom;
                int n = 0;
                for ( i = 0; i < incol->ngeoms; i++ )
                {
                        /* Don't increment depth yet, since we aren't actually subdividing geomtries yet */
                        n += lwgeom_subdivide_recursive(incol->geoms[i], maxvertices, depth, col, clip);
                }
                return n;
        }

        /* But don't go too far. 2^50 ~= 10^15, that's enough subdivision */
        /* Just add what's left */
        if ( depth > maxdepth )
        {
                lwcollection_add_lwgeom(col, lwgeom_clone_deep(geom));
                return 1;
        }

        nvertices = lwgeom_count_vertices(geom);
        /* Skip empties entirely */
        if ( nvertices == 0 )
        {
                return 0;
        }

        /* If it is under the vertex tolerance, just add it, we're done */
        if ( nvertices < maxvertices )
        {
                lwcollection_add_lwgeom(col, lwgeom_clone_deep(geom));
                return 1;
        }

        subbox1 = subbox2 = *clip;
        if ( width > height )
        {
                subbox1.xmax = subbox2.xmin = (clip->xmin + clip->xmax)/2;
        }
        else
        {
                subbox1.ymax = subbox2.ymin = (clip->ymin + clip->ymax)/2;
        }

        if ( height == 0 )
        {
                subbox1.ymax += FP_TOLERANCE;
                subbox2.ymax += FP_TOLERANCE;
                subbox1.ymin -= FP_TOLERANCE;
                subbox2.ymin -= FP_TOLERANCE;
        }

        if ( width == 0 )
        {
                subbox1.xmax += FP_TOLERANCE;
                subbox2.xmax += FP_TOLERANCE;
                subbox1.xmin -= FP_TOLERANCE;
                subbox2.xmin -= FP_TOLERANCE;
        }

        clipped1 = lwgeom_clip_by_rect(geom, subbox1.xmin, subbox1.ymin, subbox1.xmax, subbox1.ymax);
        clipped2 = lwgeom_clip_by_rect(geom, subbox2.xmin, subbox2.ymin, subbox2.xmax, subbox2.ymax);

        ++depth;

        if ( clipped1 )
        {
                n += lwgeom_subdivide_recursive(clipped1, maxvertices, depth, col, &subbox1);
                lwgeom_free(clipped1);
        }

        if ( clipped2 )
        {
                n += lwgeom_subdivide_recursive(clipped2, maxvertices, depth, col, &subbox2);
                lwgeom_free(clipped2);
        }

        return n;

}

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