geography_measurement_trees.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^
 *
 **********************************************************************/
 
#include "geography_measurement_trees.h"
 
 
/*
* Specific tree types include all the generic slots and
* their own slots for their trees. We put the implementation
* for the CircTreeGeomCache here because we can't shove
* the PgSQL specific bits of the code (fcinfo) back into
* liblwgeom, where most of the circtree logic lives.
*/
typedef struct {
        GeomCache    gcache;
        CIRC_NODE*   index;
} CircTreeGeomCache;
 
 
 
static int
CircTreeBuilder(const LWGEOM* lwgeom, GeomCache* cache)
{
        CircTreeGeomCache* circ_cache = (CircTreeGeomCache*)cache;
        CIRC_NODE* tree = lwgeom_calculate_circ_tree(lwgeom);
 
        if ( circ_cache->index )
        {
                circ_tree_free(circ_cache->index);
                circ_cache->index = 0;
        }
        if ( ! tree )
                return LW_FAILURE;
 
        circ_cache->index = tree;
        return LW_SUCCESS;
}
 
static int
CircTreeFreer(GeomCache* cache)
{
        CircTreeGeomCache* circ_cache = (CircTreeGeomCache*)cache;
        if ( circ_cache->index )
        {
                circ_tree_free(circ_cache->index);
                circ_cache->index = 0;
                circ_cache->gcache.argnum = 0;
        }
        return LW_SUCCESS;
}
 
static GeomCache*
CircTreeAllocator(void)
{
        CircTreeGeomCache* cache = palloc(sizeof(CircTreeGeomCache));
        memset(cache, 0, sizeof(CircTreeGeomCache));
        return (GeomCache*)cache;
}
 
static GeomCacheMethods CircTreeCacheMethods =
{
        CIRC_CACHE_ENTRY,
        CircTreeBuilder,
        CircTreeFreer,
        CircTreeAllocator
};
 
static CircTreeGeomCache *
GetCircTreeGeomCache(FunctionCallInfo fcinfo, const GSERIALIZED *g1, const GSERIALIZED *g2)
{
        return (CircTreeGeomCache*)GetGeomCache(fcinfo, &CircTreeCacheMethods, g1, g2);
}
 
static int
CircTreePIP(const CIRC_NODE* tree1, const GSERIALIZED* g1, const POINT4D* in_point)
{
        int tree1_type = gserialized_get_type(g1);
        GBOX gbox1;
        GEOGRAPHIC_POINT in_gpoint;
        POINT3D in_point3d;
 
        POSTGIS_DEBUGF(3, "tree1_type=%d", tree1_type);
 
        /* If the tree'ed argument is a polygon, do the P-i-P using the tree-based P-i-P */
        if ( tree1_type == POLYGONTYPE || tree1_type == MULTIPOLYGONTYPE )
        {
                POSTGIS_DEBUG(3, "tree is a polygon, using tree PiP");
                /* Need a gbox to calculate an outside point */
                if ( LW_FAILURE == gserialized_get_gbox_p(g1, &gbox1) )
                {
                        LWGEOM* lwgeom1 = lwgeom_from_gserialized(g1);
                        POSTGIS_DEBUG(3, "unable to read gbox from gserialized, calculating from scratch");
                        lwgeom_calculate_gbox_geodetic(lwgeom1, &gbox1);
                        lwgeom_free(lwgeom1);
                }
 
                /* Flip the candidate point into geographics */
                geographic_point_init(in_point->x, in_point->y, &in_gpoint);
                geog2cart(&in_gpoint, &in_point3d);
 
                /* If the candidate isn't in the tree box, it's not in the tree area */
                if ( ! gbox_contains_point3d(&gbox1, &in_point3d) )
                {
                        POSTGIS_DEBUG(3, "in_point3d is not inside the tree gbox, CircTreePIP returning FALSE");
                        return LW_FALSE;
                }
                /* The candidate point is in the box, so it *might* be inside the tree */
                else
                {
                        POINT2D pt2d_outside; /* latlon */
                        POINT2D pt2d_inside;
                        pt2d_inside.x = in_point->x;
                        pt2d_inside.y = in_point->y;
                        /* Calculate a definitive outside point */
                        if (gbox_pt_outside(&gbox1, &pt2d_outside) == LW_FAILURE)
                                if (circ_tree_get_point_outside(tree1, &pt2d_outside) == LW_FAILURE)
                                        lwpgerror("%s: Unable to generate outside point!", __func__);
 
                        POSTGIS_DEBUGF(3, "p2d_inside=POINT(%g %g) p2d_outside=POINT(%g %g)", pt2d_inside.x, pt2d_inside.y, pt2d_outside.x, pt2d_outside.y);
                        /* Test the candidate point for strict containment */
                        POSTGIS_DEBUG(3, "calling circ_tree_contains_point for PiP test");
                        return circ_tree_contains_point(tree1, &pt2d_inside, &pt2d_outside, 0, NULL);
                }
        }
        else
        {
                POSTGIS_DEBUG(3, "tree1 not polygonal, so CircTreePIP returning FALSE");
                return LW_FALSE;
        }
}
 
static int
geography_distance_cache_tolerance(FunctionCallInfo fcinfo,
                                   const GSERIALIZED *g1,
                                   const GSERIALIZED *g2,
                                   const SPHEROID *s,
                                   double tolerance,
                                   double *distance)
{
        CircTreeGeomCache* tree_cache = NULL;
 
        int type1 = gserialized_get_type(g1);
        int type2 = gserialized_get_type(g2);
 
        Assert(distance);
 
        /* Two points? Get outa here... */
        if ( type1 == POINTTYPE && type2 == POINTTYPE )
                return LW_FAILURE;
 
        /* Fetch/build our cache, if appropriate, etc... */
        tree_cache = GetCircTreeGeomCache(fcinfo, g1, g2);
 
        /* OK, we have an index at the ready! Use it for the one tree argument and */
        /* fill in the other tree argument */
        if ( tree_cache && tree_cache->gcache.argnum && tree_cache->index )
        {
                CIRC_NODE* circtree_cached = tree_cache->index;
                CIRC_NODE* circtree = NULL;
                const GSERIALIZED* g_cached;
                const GSERIALIZED* g;
                LWGEOM* lwgeom = NULL;
                int geomtype_cached;
                int geomtype;
                POINT4D p4d;
 
                /* We need to dynamically build a tree for the uncached side of the function call */
                if ( tree_cache->gcache.argnum == 1 )
                {
                        g_cached = g1;
                        g = g2;
                        geomtype_cached = type1;
                        geomtype = type2;
                }
                else if ( tree_cache->gcache.argnum == 2 )
                {
                        g_cached = g2;
                        g = g1;
                        geomtype_cached = type2;
                        geomtype = type1;
                }
                else
                {
                        lwpgerror("geography_distance_cache this cannot happen!");
                        return LW_FAILURE;
                }
 
                lwgeom = lwgeom_from_gserialized(g);
                if ( geomtype_cached == POLYGONTYPE || geomtype_cached == MULTIPOLYGONTYPE )
                {
                        lwgeom_startpoint(lwgeom, &p4d);
                        if ( CircTreePIP(circtree_cached, g_cached, &p4d) )
                        {
                                *distance = 0.0;
                                lwgeom_free(lwgeom);
                                return LW_SUCCESS;
                        }
                }
 
                circtree = lwgeom_calculate_circ_tree(lwgeom);
                if ( geomtype == POLYGONTYPE || geomtype == MULTIPOLYGONTYPE )
                {
                        POINT2D p2d;
                        circ_tree_get_point(circtree_cached, &p2d);
                        p4d.x = p2d.x;
                        p4d.y = p2d.y;
                        if ( CircTreePIP(circtree, g, &p4d) )
                        {
                                *distance = 0.0;
                                circ_tree_free(circtree);
                                lwgeom_free(lwgeom);
                                return LW_SUCCESS;
                        }
                }
 
                *distance = circ_tree_distance_tree(circtree_cached, circtree, s, tolerance);
                circ_tree_free(circtree);
                lwgeom_free(lwgeom);
                return LW_SUCCESS;
        }
        else
        {
                return LW_FAILURE;
        }
}
 
int
geography_distance_cache(FunctionCallInfo fcinfo,
                         const GSERIALIZED *g1,
                         const GSERIALIZED *g2,
                         const SPHEROID *s,
                         double *distance)
{
        return geography_distance_cache_tolerance(fcinfo, g1, g2, s, FP_TOLERANCE, distance);
}
 
int
geography_dwithin_cache(FunctionCallInfo fcinfo,
                        const GSERIALIZED *g1,
                        const GSERIALIZED *g2,
                        const SPHEROID *s,
                        double tolerance,
                        int *dwithin)
{
        double distance;
        /* Ticket #2422, difference between sphere and spheroid distance can trip up the */
        /* threshold shortcircuit (stopping a calculation before the spheroid distance is actually */
        /* below the threshold. Lower in the code line, we actually reduce the threshold a little to */
        /* avoid this. */
        /* Correct fix: propogate the spheroid information all the way to the bottom of the calculation */
        /* so the "right thing" can be done in all cases. */
        if ( LW_SUCCESS == geography_distance_cache_tolerance(fcinfo, g1, g2, s, tolerance, &distance) )
        {
                *dwithin = (distance <= (tolerance + FP_TOLERANCE) ? LW_TRUE : LW_FALSE);
                return LW_SUCCESS;
        }
        return LW_FAILURE;
}
 
int
geography_tree_distance(const GSERIALIZED* g1, const GSERIALIZED* g2, const SPHEROID* s, double tolerance, double* distance)
{
        CIRC_NODE* circ_tree1 = NULL;
        CIRC_NODE* circ_tree2 = NULL;
        LWGEOM* lwgeom1 = NULL;
        LWGEOM* lwgeom2 = NULL;
        POINT4D pt1, pt2;
 
        lwgeom1 = lwgeom_from_gserialized(g1);
        lwgeom2 = lwgeom_from_gserialized(g2);
        circ_tree1 = lwgeom_calculate_circ_tree(lwgeom1);
        circ_tree2 = lwgeom_calculate_circ_tree(lwgeom2);
        lwgeom_startpoint(lwgeom1, &pt1);
        lwgeom_startpoint(lwgeom2, &pt2);
 
        if ( CircTreePIP(circ_tree1, g1, &pt2) || CircTreePIP(circ_tree2, g2, &pt1) )
        {
                *distance = 0.0;
        }
        else
        {
                /* Calculate tree/tree distance */
                *distance = circ_tree_distance_tree(circ_tree1, circ_tree2, s, tolerance);
        }
 
        circ_tree_free(circ_tree1);
        circ_tree_free(circ_tree2);
        lwgeom_free(lwgeom1);
        lwgeom_free(lwgeom2);
        return LW_SUCCESS;
}