measures.c

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/**********************************************************************
 *
 * 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 2001-2006 Refractions Research Inc.
 * Copyright 2010 Nicklas Avén
 * Copyright 2012 Paul Ramsey
 *
 **********************************************************************/
 
 
#include <string.h>
#include <stdlib.h>
 
#include "measures.h"
#include "lwgeom_log.h"
 
 
 
/*------------------------------------------------------------------------------------------------------------
Initializing functions
The functions starting the distance-calculation processses
--------------------------------------------------------------------------------------------------------------*/
 
LWGEOM *
lwgeom_closest_line(const LWGEOM *lw1, const LWGEOM *lw2)
{
  return lw_dist2d_distanceline(lw1, lw2, lw1->srid, DIST_MIN);
}
 
LWGEOM *
lwgeom_furthest_line(const LWGEOM *lw1, const LWGEOM *lw2)
{
  return lw_dist2d_distanceline(lw1, lw2, lw1->srid, DIST_MAX);
}
 
LWGEOM *
lwgeom_closest_point(const LWGEOM *lw1, const LWGEOM *lw2)
{
  return lw_dist2d_distancepoint(lw1, lw2, lw1->srid, DIST_MIN);
}
 
LWGEOM *
lwgeom_furthest_point(const LWGEOM *lw1, const LWGEOM *lw2)
{
  return lw_dist2d_distancepoint(lw1, lw2, lw1->srid, DIST_MAX);
}
 
 
void
lw_dist2d_distpts_init(DISTPTS *dl, int mode)
{
        dl->twisted = -1;
        dl->p1.x = dl->p1.y = 0.0;
        dl->p2.x = dl->p2.y = 0.0;
        dl->mode = mode;
        dl->tolerance = 0.0;
        if ( mode == DIST_MIN )
                dl->distance = FLT_MAX;
        else
                dl->distance = -1 * FLT_MAX;
}
 
LWGEOM *
lw_dist2d_distanceline(const LWGEOM *lw1, const LWGEOM *lw2, int srid, int mode)
{
        double x1,x2,y1,y2;
 
        double initdistance = ( mode == DIST_MIN ? FLT_MAX : -1.0);
        DISTPTS thedl;
        LWPOINT *lwpoints[2];
        LWGEOM *result;
 
        thedl.mode = mode;
        thedl.distance = initdistance;
        thedl.tolerance = 0.0;
 
        LWDEBUG(2, "lw_dist2d_distanceline is called");
 
        if (!lw_dist2d_comp( lw1,lw2,&thedl))
        {
                /*should never get here. all cases ought to be error handled earlier*/
                lwerror("Some unspecified error.");
                result = (LWGEOM *)lwcollection_construct_empty(COLLECTIONTYPE, srid, 0, 0);
        }
 
        /*if thedl.distance is unchanged there where only empty geometries input*/
        if (thedl.distance == initdistance)
        {
                LWDEBUG(3, "didn't find geometries to measure between, returning null");
                result = (LWGEOM *)lwcollection_construct_empty(COLLECTIONTYPE, srid, 0, 0);
        }
        else
        {
                x1=thedl.p1.x;
                y1=thedl.p1.y;
                x2=thedl.p2.x;
                y2=thedl.p2.y;
 
                lwpoints[0] = lwpoint_make2d(srid, x1, y1);
                lwpoints[1] = lwpoint_make2d(srid, x2, y2);
 
                result = (LWGEOM *)lwline_from_ptarray(srid, 2, lwpoints);
        }
        return result;
}
 
LWGEOM *
lw_dist2d_distancepoint(const LWGEOM *lw1, const LWGEOM *lw2,int srid,int mode)
{
        double x,y;
        DISTPTS thedl;
        double initdistance = FLT_MAX;
        LWGEOM *result;
 
        thedl.mode = mode;
        thedl.distance= initdistance;
        thedl.tolerance = 0;
 
        LWDEBUG(2, "lw_dist2d_distancepoint is called");
 
        if (!lw_dist2d_comp( lw1,lw2,&thedl))
        {
                /*should never get here. all cases ought to be error handled earlier*/
                lwerror("Some unspecified error.");
                result = (LWGEOM *)lwcollection_construct_empty(COLLECTIONTYPE, srid, 0, 0);
        }
        if (thedl.distance == initdistance)
        {
                LWDEBUG(3, "didn't find geometries to measure between, returning null");
                result = (LWGEOM *)lwcollection_construct_empty(COLLECTIONTYPE, srid, 0, 0);
        }
        else
        {
                x=thedl.p1.x;
                y=thedl.p1.y;
                result = (LWGEOM *)lwpoint_make2d(srid, x, y);
        }
        return result;
}
 
 
double
lwgeom_maxdistance2d(const LWGEOM *lw1, const LWGEOM *lw2)
{
        LWDEBUG(2, "lwgeom_maxdistance2d is called");
 
        return lwgeom_maxdistance2d_tolerance( lw1, lw2, 0.0 );
}
 
double
lwgeom_maxdistance2d_tolerance(const LWGEOM *lw1, const LWGEOM *lw2, double tolerance)
{
        /*double thedist;*/
        DISTPTS thedl;
        LWDEBUG(2, "lwgeom_maxdistance2d_tolerance is called");
        thedl.mode = DIST_MAX;
        thedl.distance= -1;
        thedl.tolerance = tolerance;
        if (lw_dist2d_comp( lw1,lw2,&thedl))
        {
                return thedl.distance;
        }
        /*should never get here. all cases ought to be error handled earlier*/
        lwerror("Some unspecified error.");
        return -1;
}
 
double
lwgeom_mindistance2d(const LWGEOM *lw1, const LWGEOM *lw2)
{
        LWDEBUG(2, "lwgeom_mindistance2d is called");
        return lwgeom_mindistance2d_tolerance( lw1, lw2, 0.0 );
}
 
double
lwgeom_mindistance2d_tolerance(const LWGEOM *lw1, const LWGEOM *lw2, double tolerance)
{
        DISTPTS thedl;
        LWDEBUG(2, "lwgeom_mindistance2d_tolerance is called");
        thedl.mode = DIST_MIN;
        thedl.distance= FLT_MAX;
        thedl.tolerance = tolerance;
        if (lw_dist2d_comp( lw1,lw2,&thedl))
        {
                return thedl.distance;
        }
        /*should never get here. all cases ought to be error handled earlier*/
        lwerror("Some unspecified error.");
        return FLT_MAX;
}
 
 
/*------------------------------------------------------------------------------------------------------------
End of Initializing functions
--------------------------------------------------------------------------------------------------------------*/
 
/*------------------------------------------------------------------------------------------------------------
Preprocessing functions
Functions preparing geometries for distance-calculations
--------------------------------------------------------------------------------------------------------------*/
 
int
lw_dist2d_comp(const LWGEOM *lw1,const LWGEOM *lw2, DISTPTS *dl)
{
        LWDEBUG(2, "lw_dist2d_comp is called");
 
        return lw_dist2d_recursive(lw1, lw2, dl);
}
 
static int
lw_dist2d_is_collection(const LWGEOM *g)
{
 
        switch (g->type)
        {
        case MULTIPOINTTYPE:
        case MULTILINETYPE:
        case MULTIPOLYGONTYPE:
        case COLLECTIONTYPE:
        case MULTICURVETYPE:
        case MULTISURFACETYPE:
        case COMPOUNDTYPE:
        case POLYHEDRALSURFACETYPE:
                return LW_TRUE;
                break;
 
        default:
                return LW_FALSE;
        }
}
 
int lw_dist2d_recursive(const LWGEOM *lwg1, const LWGEOM *lwg2, DISTPTS *dl)
{
        int i, j;
        int n1=1;
        int n2=1;
        LWGEOM *g1 = NULL;
        LWGEOM *g2 = NULL;
        LWCOLLECTION *c1 = NULL;
        LWCOLLECTION *c2 = NULL;
 
        LWDEBUGF(2, "lw_dist2d_comp is called with type1=%d, type2=%d", lwg1->type, lwg2->type);
 
        if (lw_dist2d_is_collection(lwg1))
        {
                LWDEBUG(3, "First geometry is collection");
                c1 = lwgeom_as_lwcollection(lwg1);
                n1 = c1->ngeoms;
        }
        if (lw_dist2d_is_collection(lwg2))
        {
                LWDEBUG(3, "Second geometry is collection");
                c2 = lwgeom_as_lwcollection(lwg2);
                n2 = c2->ngeoms;
        }
 
        for ( i = 0; i < n1; i++ )
        {
 
                if (lw_dist2d_is_collection(lwg1))
                {
                        g1 = c1->geoms[i];
                }
                else
                {
                        g1 = (LWGEOM*)lwg1;
                }
 
                if (lwgeom_is_empty(g1)) return LW_TRUE;
 
                if (lw_dist2d_is_collection(g1))
                {
                        LWDEBUG(3, "Found collection inside first geometry collection, recursing");
                        if (!lw_dist2d_recursive(g1, lwg2, dl)) return LW_FALSE;
                        continue;
                }
                for ( j = 0; j < n2; j++ )
                {
                        if (lw_dist2d_is_collection(lwg2))
                        {
                                g2 = c2->geoms[j];
                        }
                        else
                        {
                                g2 = (LWGEOM*)lwg2;
                        }
                        if (lw_dist2d_is_collection(g2))
                        {
                                LWDEBUG(3, "Found collection inside second geometry collection, recursing");
                                if (!lw_dist2d_recursive(g1, g2, dl)) return LW_FALSE;
                                continue;
                        }
 
                        if ( ! g1->bbox )
                        {
                                lwgeom_add_bbox(g1);
                        }
                        if ( ! g2->bbox )
                        {
                                lwgeom_add_bbox(g2);
                        }
 
                        /*If one of geometries is empty, return. True here only means continue searching. False would have stopped the process*/
                        if (lwgeom_is_empty(g1)||lwgeom_is_empty(g2)) return LW_TRUE;
 
                        if ( (dl->mode != DIST_MAX) &&
                                 (! lw_dist2d_check_overlap(g1, g2)) &&
                             (g1->type == LINETYPE || g1->type == POLYGONTYPE) &&
                             (g2->type == LINETYPE || g2->type == POLYGONTYPE) )
                        {
                                if (!lw_dist2d_distribute_fast(g1, g2, dl)) return LW_FALSE;
                        }
                        else
                        {
                                if (!lw_dist2d_distribute_bruteforce(g1, g2, dl)) return LW_FALSE;
                                if (dl->distance<=dl->tolerance && dl->mode == DIST_MIN) return LW_TRUE; /*just a check if  the answer is already given*/
                        }
                }
        }
        return LW_TRUE;
}
 
 
int
lw_dist2d_distribute_bruteforce(const LWGEOM *lwg1,const LWGEOM *lwg2, DISTPTS *dl)
{
 
        int     t1 = lwg1->type;
        int     t2 = lwg2->type;
 
        switch ( t1 )
        {
                case POINTTYPE:
                {
                        dl->twisted = 1;
                        switch ( t2 )
                        {
                                case POINTTYPE:
                                        return lw_dist2d_point_point((LWPOINT *)lwg1, (LWPOINT *)lwg2, dl);
                                case LINETYPE:
                                        return lw_dist2d_point_line((LWPOINT *)lwg1, (LWLINE *)lwg2, dl);
                                case POLYGONTYPE:
                                        return lw_dist2d_point_poly((LWPOINT *)lwg1, (LWPOLY *)lwg2, dl);
                                case CIRCSTRINGTYPE:
                                        return lw_dist2d_point_circstring((LWPOINT *)lwg1, (LWCIRCSTRING *)lwg2, dl);
                                case CURVEPOLYTYPE:
                                        return lw_dist2d_point_curvepoly((LWPOINT *)lwg1, (LWCURVEPOLY *)lwg2, dl);
                                default:
                                        lwerror("Unsupported geometry type: %s", lwtype_name(t2));
                                        return LW_FALSE;
                        }
                }
                case LINETYPE:
                {
                        dl->twisted = 1;
                        switch ( t2 )
                        {
                                case POINTTYPE:
                                        dl->twisted=(-1);
                                        return lw_dist2d_point_line((LWPOINT *)lwg2, (LWLINE *)lwg1, dl);
                                case LINETYPE:
                                        return lw_dist2d_line_line((LWLINE *)lwg1, (LWLINE *)lwg2, dl);
                                case POLYGONTYPE:
                                        return lw_dist2d_line_poly((LWLINE *)lwg1, (LWPOLY *)lwg2, dl);
                                case CIRCSTRINGTYPE:
                                        return lw_dist2d_line_circstring((LWLINE *)lwg1, (LWCIRCSTRING *)lwg2, dl);
                                case CURVEPOLYTYPE:
                                        return lw_dist2d_line_curvepoly((LWLINE *)lwg1, (LWCURVEPOLY *)lwg2, dl);
                                default:
                                        lwerror("Unsupported geometry type: %s", lwtype_name(t2));
                                        return LW_FALSE;
                        }
                }
                case CIRCSTRINGTYPE:
                {
                        dl->twisted = 1;
                        switch ( t2 )
                        {
                                case POINTTYPE:
                                        dl->twisted = -1;
                                        return lw_dist2d_point_circstring((LWPOINT *)lwg2, (LWCIRCSTRING *)lwg1, dl);
                                case LINETYPE:
                                        dl->twisted = -1;
                                        return lw_dist2d_line_circstring((LWLINE *)lwg2, (LWCIRCSTRING *)lwg1, dl);
                                case POLYGONTYPE:
                                        return lw_dist2d_circstring_poly((LWCIRCSTRING *)lwg1, (LWPOLY *)lwg2, dl);
                                case CIRCSTRINGTYPE:
                                        return lw_dist2d_circstring_circstring((LWCIRCSTRING *)lwg1, (LWCIRCSTRING *)lwg2, dl);
                                case CURVEPOLYTYPE:
                                        return lw_dist2d_circstring_curvepoly((LWCIRCSTRING *)lwg1, (LWCURVEPOLY *)lwg2, dl);
                                default:
                                        lwerror("Unsupported geometry type: %s", lwtype_name(t2));
                                        return LW_FALSE;
                        }
                }
                case POLYGONTYPE:
                {
                        dl->twisted = -1;
                        switch ( t2 )
                        {
                                case POINTTYPE:
                                        return lw_dist2d_point_poly((LWPOINT *)lwg2, (LWPOLY *)lwg1, dl);
                                case LINETYPE:
                                        return lw_dist2d_line_poly((LWLINE *)lwg2, (LWPOLY *)lwg1, dl);
                                case CIRCSTRINGTYPE:
                                        return lw_dist2d_circstring_poly((LWCIRCSTRING *)lwg2, (LWPOLY *)lwg1, dl);
                                case POLYGONTYPE:
                                        dl->twisted = 1;
                                        return lw_dist2d_poly_poly((LWPOLY *)lwg1, (LWPOLY *)lwg2, dl);
                                case CURVEPOLYTYPE:
                                        dl->twisted = 1;
                                        return lw_dist2d_poly_curvepoly((LWPOLY *)lwg1, (LWCURVEPOLY *)lwg2, dl);
                                default:
                                        lwerror("Unsupported geometry type: %s", lwtype_name(t2));
                                        return LW_FALSE;
                        }
                }
                case CURVEPOLYTYPE:
                {
                        dl->twisted = (-1);
                        switch ( t2 )
                        {
                                case POINTTYPE:
                                        return lw_dist2d_point_curvepoly((LWPOINT *)lwg2, (LWCURVEPOLY *)lwg1, dl);
                                case LINETYPE:
                                        return lw_dist2d_line_curvepoly((LWLINE *)lwg2, (LWCURVEPOLY *)lwg1, dl);
                                case POLYGONTYPE:
                                        return lw_dist2d_poly_curvepoly((LWPOLY *)lwg2, (LWCURVEPOLY *)lwg1, dl);
                                case CIRCSTRINGTYPE:
                                        return lw_dist2d_circstring_curvepoly((LWCIRCSTRING *)lwg2, (LWCURVEPOLY *)lwg1, dl);
                                case CURVEPOLYTYPE:
                                        dl->twisted = 1;
                                        return lw_dist2d_curvepoly_curvepoly((LWCURVEPOLY *)lwg1, (LWCURVEPOLY *)lwg2, dl);
                                default:
                                        lwerror("Unsupported geometry type: %s", lwtype_name(t2));
                                        return LW_FALSE;
                        }
                }
                default:
                {
                        lwerror("Unsupported geometry type: %s", lwtype_name(t1));
                        return LW_FALSE;
                }
        }
 
        return LW_FALSE;
}
 
 
 
 
int
lw_dist2d_check_overlap(LWGEOM *lwg1,LWGEOM *lwg2)
{
        LWDEBUG(2, "lw_dist2d_check_overlap is called");
        if ( ! lwg1->bbox )
                lwgeom_calculate_gbox(lwg1, lwg1->bbox);
        if ( ! lwg2->bbox )
                lwgeom_calculate_gbox(lwg2, lwg2->bbox);
 
        /*Check if the geometries intersect.
        */
        if ((lwg1->bbox->xmax<lwg2->bbox->xmin||lwg1->bbox->xmin>lwg2->bbox->xmax||lwg1->bbox->ymax<lwg2->bbox->ymin||lwg1->bbox->ymin>lwg2->bbox->ymax))
        {
                LWDEBUG(3, "geometries bboxes did not overlap");
                return LW_FALSE;
        }
        LWDEBUG(3, "geometries bboxes overlap");
        return LW_TRUE;
}
 
int
lw_dist2d_distribute_fast(LWGEOM *lwg1, LWGEOM *lwg2, DISTPTS *dl)
{
        POINTARRAY *pa1, *pa2;
        int     type1 = lwg1->type;
        int     type2 = lwg2->type;
 
        LWDEBUGF(2, "lw_dist2d_distribute_fast is called with typ1=%d, type2=%d", lwg1->type, lwg2->type);
 
        switch (type1)
        {
        case LINETYPE:
                pa1 = ((LWLINE *)lwg1)->points;
                break;
        case POLYGONTYPE:
                pa1 = ((LWPOLY *)lwg1)->rings[0];
                break;
        default:
                lwerror("Unsupported geometry1 type: %s", lwtype_name(type1));
                return LW_FALSE;
        }
        switch (type2)
        {
        case LINETYPE:
                pa2 = ((LWLINE *)lwg2)->points;
                break;
        case POLYGONTYPE:
                pa2 = ((LWPOLY *)lwg2)->rings[0];
                break;
        default:
                lwerror("Unsupported geometry2 type: %s", lwtype_name(type1));
                return LW_FALSE;
        }
        dl->twisted=1;
        return lw_dist2d_fast_ptarray_ptarray(pa1, pa2, dl, lwg1->bbox, lwg2->bbox);
}
 
/*------------------------------------------------------------------------------------------------------------
End of Preprocessing functions
--------------------------------------------------------------------------------------------------------------*/
 
 
/*------------------------------------------------------------------------------------------------------------
Brute force functions
The old way of calculating distances, now used for:
1)      distances to points (because there shouldn't be anything to gain by the new way of doing it)
2)      distances when subgeometries geometries bboxes overlaps
--------------------------------------------------------------------------------------------------------------*/
 
int
lw_dist2d_point_point(LWPOINT *point1, LWPOINT *point2, DISTPTS *dl)
{
        const POINT2D *p1, *p2;
 
        p1 = getPoint2d_cp(point1->point, 0);
        p2 = getPoint2d_cp(point2->point, 0);
 
        return lw_dist2d_pt_pt(p1, p2, dl);
}
int
lw_dist2d_point_line(LWPOINT *point, LWLINE *line, DISTPTS *dl)
{
        const POINT2D *p;
        LWDEBUG(2, "lw_dist2d_point_line is called");
        p = getPoint2d_cp(point->point, 0);
        return lw_dist2d_pt_ptarray(p, line->points, dl);
}
 
int
lw_dist2d_point_circstring(LWPOINT *point, LWCIRCSTRING *circ, DISTPTS *dl)
{
        const POINT2D *p;
        p = getPoint2d_cp(point->point, 0);
        return lw_dist2d_pt_ptarrayarc(p, circ->points, dl);
}
 
int
lw_dist2d_point_poly(LWPOINT *point, LWPOLY *poly, DISTPTS *dl)
{
        const POINT2D *p;
        uint32_t i;
 
        LWDEBUG(2, "lw_dist2d_point_poly called");
 
        p = getPoint2d_cp(point->point, 0);
 
        if (dl->mode == DIST_MAX)
        {
                LWDEBUG(3, "looking for maxdistance");
                return lw_dist2d_pt_ptarray(p, poly->rings[0], dl);
        }
        /* Return distance to outer ring if not inside it */
        if ( ptarray_contains_point(poly->rings[0], p) == LW_OUTSIDE )
        {
                LWDEBUG(3, "first point not inside outer-ring");
                return lw_dist2d_pt_ptarray(p, poly->rings[0], dl);
        }
 
        /*
         * Inside the outer ring.
         * Scan though each of the inner rings looking to
         * see if its inside.  If not, distance==0.
         * Otherwise, distance = pt to ring distance
         */
        for ( i = 1;  i < poly->nrings; i++)
        {
                /* Inside a hole. Distance = pt -> ring */
                if ( ptarray_contains_point(poly->rings[i], p) != LW_OUTSIDE )
                {
                        LWDEBUG(3, " inside an hole");
                        return lw_dist2d_pt_ptarray(p, poly->rings[i], dl);
                }
        }
 
        LWDEBUG(3, " inside the polygon");
        if (dl->mode == DIST_MIN)
        {
                dl->distance = 0.0;
                dl->p1.x = dl->p2.x = p->x;
                dl->p1.y = dl->p2.y = p->y;
        }
        return LW_TRUE; /* Is inside the polygon */
}
 
int
lw_dist2d_point_curvepoly(LWPOINT *point, LWCURVEPOLY *poly, DISTPTS *dl)
{
        const POINT2D *p;
        uint32_t i;
 
        p = getPoint2d_cp(point->point, 0);
 
        if (dl->mode == DIST_MAX)
                lwerror("lw_dist2d_point_curvepoly cannot calculate max distance");
 
        /* Return distance to outer ring if not inside it */
        if ( lwgeom_contains_point(poly->rings[0], p) == LW_OUTSIDE )
        {
                return lw_dist2d_recursive((LWGEOM*)point, poly->rings[0], dl);
        }
 
        /*
         * Inside the outer ring.
         * Scan though each of the inner rings looking to
         * see if its inside.  If not, distance==0.
         * Otherwise, distance = pt to ring distance
         */
        for ( i = 1;  i < poly->nrings; i++)
        {
                /* Inside a hole. Distance = pt -> ring */
                if ( lwgeom_contains_point(poly->rings[i], p) != LW_OUTSIDE )
                {
                        LWDEBUG(3, " inside a hole");
                        return lw_dist2d_recursive((LWGEOM*)point, poly->rings[i], dl);
                }
        }
 
        LWDEBUG(3, " inside the polygon");
        if (dl->mode == DIST_MIN)
        {
                dl->distance = 0.0;
                dl->p1.x = dl->p2.x = p->x;
                dl->p1.y = dl->p2.y = p->y;
        }
 
        return LW_TRUE; /* Is inside the polygon */
}
 
int
lw_dist2d_line_line(LWLINE *line1, LWLINE *line2, DISTPTS *dl)
{
        POINTARRAY *pa1 = line1->points;
        POINTARRAY *pa2 = line2->points;
        LWDEBUG(2, "lw_dist2d_line_line is called");
        return lw_dist2d_ptarray_ptarray(pa1, pa2, dl);
}
 
int
lw_dist2d_line_circstring(LWLINE *line1, LWCIRCSTRING *line2, DISTPTS *dl)
{
        return lw_dist2d_ptarray_ptarrayarc(line1->points, line2->points, dl);
}
 
int
lw_dist2d_line_poly(LWLINE *line, LWPOLY *poly, DISTPTS *dl)
{
        const POINT2D *pt;
        uint32_t i;
 
        LWDEBUGF(2, "lw_dist2d_line_poly called (%d rings)", poly->nrings);
 
        pt = getPoint2d_cp(line->points, 0);
        if ( ptarray_contains_point(poly->rings[0], pt) == LW_OUTSIDE )
        {
                return lw_dist2d_ptarray_ptarray(line->points, poly->rings[0], dl);
        }
 
        for (i=1; i<poly->nrings; i++)
        {
                if (!lw_dist2d_ptarray_ptarray(line->points, poly->rings[i], dl)) return LW_FALSE;
 
                LWDEBUGF(3, " distance from ring %d: %f, mindist: %f",
                         i, dl->distance, dl->tolerance);
                /* just a check if  the answer is already given */
                if (dl->distance<=dl->tolerance && dl->mode == DIST_MIN) return LW_TRUE;
        }
 
        /*
         * No intersection, have to check if a point is
         * inside polygon
         */
        pt = getPoint2d_cp(line->points, 0);
 
        /*
         * Outside outer ring, so min distance to a ring
         * is the actual min distance
 
        if ( ! pt_in_ring_2d(&pt, poly->rings[0]) )
        {
                return ;
        } */
 
        /*
         * Its in the outer ring.
         * Have to check if its inside a hole
         */
        for (i=1; i<poly->nrings; i++)
        {
                if ( ptarray_contains_point(poly->rings[i], pt) != LW_OUTSIDE )
                {
                        /*
                         * Its inside a hole, then the actual
                         * distance is the min ring distance
                         */
                        return LW_TRUE;
                }
        }
        if (dl->mode == DIST_MIN)
        {
                dl->distance = 0.0;
                dl->p1.x = dl->p2.x = pt->x;
                dl->p1.y = dl->p2.y = pt->y;
        }
        return LW_TRUE; /* Not in hole, so inside polygon */
}
 
int
lw_dist2d_line_curvepoly(LWLINE *line, LWCURVEPOLY *poly, DISTPTS *dl)
{
        const POINT2D *pt = getPoint2d_cp(line->points, 0);
        uint32_t i;
 
        if ( lwgeom_contains_point(poly->rings[0], pt) == LW_OUTSIDE )
        {
                return lw_dist2d_recursive((LWGEOM*)line, poly->rings[0], dl);
        }
 
        for ( i = 1; i < poly->nrings; i++ )
        {
                if ( ! lw_dist2d_recursive((LWGEOM*)line, poly->rings[i], dl) )
                        return LW_FALSE;
 
                if ( dl->distance<=dl->tolerance && dl->mode == DIST_MIN )
                        return LW_TRUE;
        }
 
        for ( i=1; i < poly->nrings; i++ )
        {
                if ( lwgeom_contains_point(poly->rings[i],pt) != LW_OUTSIDE )
                {
                        /* Its inside a hole, then the actual */
                        return LW_TRUE;
                }
        }
 
        if (dl->mode == DIST_MIN)
        {
                dl->distance = 0.0;
                dl->p1.x = dl->p2.x = pt->x;
                dl->p1.y = dl->p2.y = pt->y;
        }
 
        return LW_TRUE; /* Not in hole, so inside polygon */
}
 
int
lw_dist2d_poly_poly(LWPOLY *poly1, LWPOLY *poly2, DISTPTS *dl)
{
 
        const POINT2D *pt;
        uint32_t i;
 
        LWDEBUG(2, "lw_dist2d_poly_poly called");
 
        /*1     if we are looking for maxdistance, just check the outer rings.*/
        if (dl->mode == DIST_MAX)
        {
                return lw_dist2d_ptarray_ptarray(poly1->rings[0], poly2->rings[0], dl);
        }
 
 
        /* 2    check if poly1 has first point outside poly2 and vice versa, if so, just check outer rings
        here it would be possible to handle the information about which one is inside which one and only search for the smaller ones in the bigger ones holes.*/
        pt = getPoint2d_cp(poly1->rings[0], 0);
        if ( ptarray_contains_point(poly2->rings[0], pt) == LW_OUTSIDE )
        {
                pt = getPoint2d_cp(poly2->rings[0], 0);
                if ( ptarray_contains_point(poly1->rings[0], pt) == LW_OUTSIDE )
                {
                        return lw_dist2d_ptarray_ptarray(poly1->rings[0], poly2->rings[0], dl);
                }
        }
 
        /*3     check if first point of poly2 is in a hole of poly1. If so check outer ring of poly2 against that hole of poly1*/
        pt = getPoint2d_cp(poly2->rings[0], 0);
        for (i=1; i<poly1->nrings; i++)
        {
                /* Inside a hole */
                if ( ptarray_contains_point(poly1->rings[i], pt) != LW_OUTSIDE )
                {
                        return lw_dist2d_ptarray_ptarray(poly1->rings[i], poly2->rings[0], dl);
                }
        }
 
        /*4     check if first point of poly1 is in a hole of poly2. If so check outer ring of poly1 against that hole of poly2*/
        pt = getPoint2d_cp(poly1->rings[0], 0);
        for (i=1; i<poly2->nrings; i++)
        {
                /* Inside a hole */
                if ( ptarray_contains_point(poly2->rings[i], pt) != LW_OUTSIDE )
                {
                        return lw_dist2d_ptarray_ptarray(poly1->rings[0], poly2->rings[i], dl);
                }
        }
 
 
        /*5     If we have come all the way here we know that the first point of one of them is inside the other ones outer ring and not in holes so we check wich one is inside.*/
        pt = getPoint2d_cp(poly1->rings[0], 0);
        if ( ptarray_contains_point(poly2->rings[0], pt) != LW_OUTSIDE )
        {
                dl->distance = 0.0;
                dl->p1.x = dl->p2.x = pt->x;
                dl->p1.y = dl->p2.y = pt->y;
                return LW_TRUE;
        }
 
        pt = getPoint2d_cp(poly2->rings[0], 0);
        if ( ptarray_contains_point(poly1->rings[0], pt) != LW_OUTSIDE )
        {
                dl->distance = 0.0;
                dl->p1.x = dl->p2.x = pt->x;
                dl->p1.y = dl->p2.y = pt->y;
                return LW_TRUE;
        }
 
 
        lwerror("Unspecified error in function lw_dist2d_poly_poly");
        return LW_FALSE;
}
 
int
lw_dist2d_poly_curvepoly(LWPOLY *poly1, LWCURVEPOLY *curvepoly2, DISTPTS *dl)
{
        LWCURVEPOLY *curvepoly1 = lwcurvepoly_construct_from_lwpoly(poly1);
        int rv = lw_dist2d_curvepoly_curvepoly(curvepoly1, curvepoly2, dl);
        lwgeom_free((LWGEOM*)curvepoly1);
        return rv;
}
 
int
lw_dist2d_circstring_poly(LWCIRCSTRING *circ, LWPOLY *poly, DISTPTS *dl)
{
        LWCURVEPOLY *curvepoly = lwcurvepoly_construct_from_lwpoly(poly);
        int rv = lw_dist2d_line_curvepoly((LWLINE*)circ, curvepoly, dl);
        lwgeom_free((LWGEOM*)curvepoly);
        return rv;
}
 
 
int
lw_dist2d_circstring_curvepoly(LWCIRCSTRING *circ, LWCURVEPOLY *poly, DISTPTS *dl)
{
        return lw_dist2d_line_curvepoly((LWLINE*)circ, poly, dl);
}
 
int
lw_dist2d_circstring_circstring(LWCIRCSTRING *line1, LWCIRCSTRING *line2, DISTPTS *dl)
{
        return lw_dist2d_ptarrayarc_ptarrayarc(line1->points, line2->points, dl);
}
 
static const POINT2D *
lw_curvering_getfirstpoint2d_cp(LWGEOM *geom)
{
        switch( geom->type )
        {
                case LINETYPE:
                        return getPoint2d_cp(((LWLINE*)geom)->points, 0);
                case CIRCSTRINGTYPE:
                        return getPoint2d_cp(((LWCIRCSTRING*)geom)->points, 0);
                case COMPOUNDTYPE:
                {
                        LWCOMPOUND *comp = (LWCOMPOUND*)geom;
                        LWLINE *line = (LWLINE*)(comp->geoms[0]);
                        return getPoint2d_cp(line->points, 0);
                }
                default:
                        lwerror("lw_curvering_getfirstpoint2d_cp: unknown type");
        }
        return NULL;
}
 
int
lw_dist2d_curvepoly_curvepoly(LWCURVEPOLY *poly1, LWCURVEPOLY *poly2, DISTPTS *dl)
{
        const POINT2D *pt;
        uint32_t i;
 
        LWDEBUG(2, "lw_dist2d_curvepoly_curvepoly called");
 
        /*1     if we are looking for maxdistance, just check the outer rings.*/
        if (dl->mode == DIST_MAX)
        {
                return lw_dist2d_recursive(poly1->rings[0],     poly2->rings[0], dl);
        }
 
 
        /* 2    check if poly1 has first point outside poly2 and vice versa, if so, just check outer rings
        here it would be possible to handle the information about which one is inside which one and only search for the smaller ones in the bigger ones holes.*/
        pt = lw_curvering_getfirstpoint2d_cp(poly1->rings[0]);
        if ( lwgeom_contains_point(poly2->rings[0], pt) == LW_OUTSIDE )
        {
                pt = lw_curvering_getfirstpoint2d_cp(poly2->rings[0]);
                if ( lwgeom_contains_point(poly1->rings[0], pt) == LW_OUTSIDE )
                {
                        return lw_dist2d_recursive(poly1->rings[0], poly2->rings[0], dl);
                }
        }
 
        /*3     check if first point of poly2 is in a hole of poly1. If so check outer ring of poly2 against that hole of poly1*/
        pt = lw_curvering_getfirstpoint2d_cp(poly2->rings[0]);
        for (i = 1; i < poly1->nrings; i++)
        {
                /* Inside a hole */
                if ( lwgeom_contains_point(poly1->rings[i], pt) != LW_OUTSIDE )
                {
                        return lw_dist2d_recursive(poly1->rings[i], poly2->rings[0], dl);
                }
        }
 
        /*4     check if first point of poly1 is in a hole of poly2. If so check outer ring of poly1 against that hole of poly2*/
        pt = lw_curvering_getfirstpoint2d_cp(poly1->rings[0]);
        for (i = 1; i < poly2->nrings; i++)
        {
                /* Inside a hole */
                if ( lwgeom_contains_point(poly2->rings[i], pt) != LW_OUTSIDE )
                {
                        return lw_dist2d_recursive(poly1->rings[0],     poly2->rings[i], dl);
                }
        }
 
 
        /*5     If we have come all the way here we know that the first point of one of them is inside the other ones outer ring and not in holes so we check which one is inside.*/
        pt = lw_curvering_getfirstpoint2d_cp(poly1->rings[0]);
        if ( lwgeom_contains_point(poly2->rings[0], pt) != LW_OUTSIDE )
        {
                dl->distance = 0.0;
                dl->p1.x = dl->p2.x = pt->x;
                dl->p1.y = dl->p2.y = pt->y;
                return LW_TRUE;
        }
 
        pt = lw_curvering_getfirstpoint2d_cp(poly2->rings[0]);
        if ( lwgeom_contains_point(poly1->rings[0], pt) != LW_OUTSIDE )
        {
                dl->distance = 0.0;
                dl->p1.x = dl->p2.x = pt->x;
                dl->p1.y = dl->p2.y = pt->y;
                return LW_TRUE;
        }
 
        lwerror("Unspecified error in function lw_dist2d_curvepoly_curvepoly");
        return LW_FALSE;
}
 
 
 
int
lw_dist2d_pt_ptarray(const POINT2D *p, POINTARRAY *pa,DISTPTS *dl)
{
        uint32_t t;
        const POINT2D *start, *end;
        int twist = dl->twisted;
 
        LWDEBUG(2, "lw_dist2d_pt_ptarray is called");
 
        start = getPoint2d_cp(pa, 0);
 
        if ( !lw_dist2d_pt_pt(p, start, dl) ) return LW_FALSE;
 
        for (t=1; t<pa->npoints; t++)
        {
                dl->twisted=twist;
                end = getPoint2d_cp(pa, t);
                if (!lw_dist2d_pt_seg(p, start, end, dl)) return LW_FALSE;
 
                if (dl->distance<=dl->tolerance && dl->mode == DIST_MIN) return LW_TRUE; /*just a check if  the answer is already given*/
                start = end;
        }
 
        return LW_TRUE;
}
 
int
lw_dist2d_pt_ptarrayarc(const POINT2D *p, const POINTARRAY *pa, DISTPTS *dl)
{
        uint32_t t;
        const POINT2D *A1;
        const POINT2D *A2;
        const POINT2D *A3;
        int twist = dl->twisted;
 
        LWDEBUG(2, "lw_dist2d_pt_ptarrayarc is called");
 
        if ( pa->npoints % 2 == 0 || pa->npoints < 3 )
        {
                lwerror("lw_dist2d_pt_ptarrayarc called with non-arc input");
                return LW_FALSE;
        }
 
        if (dl->mode == DIST_MAX)
        {
                lwerror("lw_dist2d_pt_ptarrayarc does not currently support DIST_MAX mode");
                return LW_FALSE;
        }
 
        A1 = getPoint2d_cp(pa, 0);
 
        if ( ! lw_dist2d_pt_pt(p, A1, dl) )
                return LW_FALSE;
 
        for ( t=1; t<pa->npoints; t += 2 )
        {
                dl->twisted = twist;
                A2 = getPoint2d_cp(pa, t);
                A3 = getPoint2d_cp(pa, t+1);
 
                if ( lw_dist2d_pt_arc(p, A1, A2, A3, dl) == LW_FALSE )
                        return LW_FALSE;
 
                if ( dl->distance <= dl->tolerance && dl->mode == DIST_MIN )
                        return LW_TRUE; /*just a check if  the answer is already given*/
 
                A1 = A3;
        }
 
        return LW_TRUE;
}
 
 
 
 
int
lw_dist2d_ptarray_ptarray(POINTARRAY *l1, POINTARRAY *l2,DISTPTS *dl)
{
        uint32_t t,u;
        const POINT2D   *start, *end;
        const POINT2D   *start2, *end2;
        int twist = dl->twisted;
 
        LWDEBUGF(2, "lw_dist2d_ptarray_ptarray called (points: %d-%d)",l1->npoints, l2->npoints);
 
        if (dl->mode == DIST_MAX)/*If we are searching for maxdistance we go straight to point-point calculation since the maxdistance have to be between two vertexes*/
        {
                for (t=0; t<l1->npoints; t++) /*for each segment in L1 */
                {
                        start = getPoint2d_cp(l1, t);
                        for (u=0; u<l2->npoints; u++) /*for each segment in L2 */
                        {
                                start2 = getPoint2d_cp(l2, u);
                                lw_dist2d_pt_pt(start, start2, dl);
                                LWDEBUGF(4, "maxdist_ptarray_ptarray; seg %i * seg %i, dist = %g\n",t,u,dl->distance);
                                LWDEBUGF(3, " seg%d-seg%d dist: %f, mindist: %f",
                                         t, u, dl->distance, dl->tolerance);
                        }
                }
        }
        else
        {
                start = getPoint2d_cp(l1, 0);
                for (t=1; t<l1->npoints; t++) /*for each segment in L1 */
                {
                        end = getPoint2d_cp(l1, t);
                        start2 = getPoint2d_cp(l2, 0);
                        for (u=1; u<l2->npoints; u++) /*for each segment in L2 */
                        {
                                end2 = getPoint2d_cp(l2, u);
                                dl->twisted=twist;
                                lw_dist2d_seg_seg(start, end, start2, end2, dl);
                                LWDEBUGF(4, "mindist_ptarray_ptarray; seg %i * seg %i, dist = %g\n",t,u,dl->distance);
                                LWDEBUGF(3, " seg%d-seg%d dist: %f, mindist: %f",
                                         t, u, dl->distance, dl->tolerance);
                                if (dl->distance<=dl->tolerance && dl->mode == DIST_MIN) return LW_TRUE; /*just a check if  the answer is already given*/
                                start2 = end2;
                        }
                        start = end;
                }
        }
        return LW_TRUE;
}
 
int
lw_dist2d_ptarray_ptarrayarc(const POINTARRAY *pa, const POINTARRAY *pb, DISTPTS *dl)
{
        uint32_t t, u;
        const POINT2D *A1;
        const POINT2D *A2;
        const POINT2D *B1;
        const POINT2D *B2;
        const POINT2D *B3;
        int twist = dl->twisted;
 
        LWDEBUGF(2, "lw_dist2d_ptarray_ptarrayarc called (points: %d-%d)",pa->npoints, pb->npoints);
 
        if ( pb->npoints % 2 == 0 || pb->npoints < 3 )
        {
                lwerror("lw_dist2d_ptarray_ptarrayarc called with non-arc input");
                return LW_FALSE;
        }
 
        if ( dl->mode == DIST_MAX )
        {
                lwerror("lw_dist2d_ptarray_ptarrayarc does not currently support DIST_MAX mode");
                return LW_FALSE;
        }
        else
        {
                A1 = getPoint2d_cp(pa, 0);
                for ( t=1; t < pa->npoints; t++ ) /* For each segment in pa */
                {
                        A2 = getPoint2d_cp(pa, t);
                        B1 = getPoint2d_cp(pb, 0);
                        for ( u=1; u < pb->npoints; u += 2 ) /* For each arc in pb */
                        {
                                B2 = getPoint2d_cp(pb, u);
                                B3 = getPoint2d_cp(pb, u+1);
                                dl->twisted = twist;
 
                                lw_dist2d_seg_arc(A1, A2, B1, B2, B3, dl);
 
                                /* If we've found a distance within tolerance, we're done */
                                if ( dl->distance <= dl->tolerance && dl->mode == DIST_MIN )
                                        return LW_TRUE;
 
                                B1 = B3;
                        }
                        A1 = A2;
                }
        }
        return LW_TRUE;
}
 
int
lw_dist2d_ptarrayarc_ptarrayarc(const POINTARRAY *pa, const POINTARRAY *pb, DISTPTS *dl)
{
        uint32_t t, u;
        const POINT2D *A1;
        const POINT2D *A2;
        const POINT2D *A3;
        const POINT2D *B1;
        const POINT2D *B2;
        const POINT2D *B3;
        int twist = dl->twisted;
 
        LWDEBUGF(2, "lw_dist2d_ptarrayarc_ptarrayarc called (points: %d-%d)",pa->npoints, pb->npoints);
 
        if (dl->mode == DIST_MAX)
        {
                lwerror("lw_dist2d_ptarrayarc_ptarrayarc does not currently support DIST_MAX mode");
                return LW_FALSE;
        }
        else
        {
                A1 = getPoint2d_cp(pa, 0);
                for ( t=1; t < pa->npoints; t += 2 ) /* For each segment in pa */
                {
                        A2 = getPoint2d_cp(pa, t);
                        A3 = getPoint2d_cp(pa, t+1);
                        B1 = getPoint2d_cp(pb, 0);
                        for ( u=1; u < pb->npoints; u += 2 ) /* For each arc in pb */
                        {
                                B2 = getPoint2d_cp(pb, u);
                                B3 = getPoint2d_cp(pb, u+1);
                                dl->twisted = twist;
 
                                lw_dist2d_arc_arc(A1, A2, A3, B1, B2, B3, dl);
 
                                /* If we've found a distance within tolerance, we're done */
                                if ( dl->distance <= dl->tolerance && dl->mode == DIST_MIN )
                                        return LW_TRUE;
 
                                B1 = B3;
                        }
                        A1 = A3;
                }
        }
        return LW_TRUE;
}
 
int
lw_dist2d_seg_arc(const POINT2D *A1, const POINT2D *A2, const POINT2D *B1, const POINT2D *B2, const POINT2D *B3, DISTPTS *dl)
{
        POINT2D C; /* center of arc circle */
        double radius_C; /* radius of arc circle */
        POINT2D D; /* point on A closest to C */
        double dist_C_D; /* distance from C to D */
        int pt_in_arc, pt_in_seg;
        DISTPTS dltmp;
 
        /* Bail out on crazy modes */
        if ( dl->mode < 0 )
                lwerror("lw_dist2d_seg_arc does not support maxdistance mode");
 
        /* What if the "arc" is a point? */
        if ( lw_arc_is_pt(B1, B2, B3) )
                return lw_dist2d_pt_seg(B1, A1, A2, dl);
 
        /* Calculate center and radius of the circle. */
        radius_C = lw_arc_center(B1, B2, B3, &C);
 
        /* This "arc" is actually a line (B2 is collinear with B1,B3) */
        if ( radius_C < 0.0 )
                return lw_dist2d_seg_seg(A1, A2, B1, B3, dl);
 
        /* Calculate distance between the line and circle center */
        lw_dist2d_distpts_init(&dltmp, DIST_MIN);
        if ( lw_dist2d_pt_seg(&C, A1, A2, &dltmp) == LW_FALSE )
                lwerror("lw_dist2d_pt_seg failed in lw_dist2d_seg_arc");
 
        D = dltmp.p1;
        dist_C_D = dltmp.distance;
 
        /* Line intersects circle, maybe arc intersects edge? */
        /* If so, that's the closest point. */
        /* If not, the closest point is one of the end points of A */
        if ( dist_C_D < radius_C )
        {
                double length_A; /* length of the segment A */
                POINT2D E, F; /* points of intersection of edge A and circle(B) */
                double dist_D_EF; /* distance from D to E or F (same distance both ways) */
 
                dist_D_EF = sqrt(radius_C*radius_C - dist_C_D*dist_C_D);
                length_A = sqrt((A2->x-A1->x)*(A2->x-A1->x)+(A2->y-A1->y)*(A2->y-A1->y));
 
                /* Point of intersection E */
                E.x = D.x - (A2->x-A1->x) * dist_D_EF / length_A;
                E.y = D.y - (A2->y-A1->y) * dist_D_EF / length_A;
                /* Point of intersection F */
                F.x = D.x + (A2->x-A1->x) * dist_D_EF / length_A;
                F.y = D.y + (A2->y-A1->y) * dist_D_EF / length_A;
 
 
                /* If E is within A and within B then it's an intersection point */
                pt_in_arc = lw_pt_in_arc(&E, B1, B2, B3);
                pt_in_seg = lw_pt_in_seg(&E, A1, A2);
 
                if ( pt_in_arc && pt_in_seg )
                {
                        dl->distance = 0.0;
                        dl->p1 = E;
                        dl->p2 = E;
                        return LW_TRUE;
                }
 
                /* If F is within A and within B then it's an intersection point */
                pt_in_arc = lw_pt_in_arc(&F, B1, B2, B3);
                pt_in_seg = lw_pt_in_seg(&F, A1, A2);
 
                if ( pt_in_arc && pt_in_seg )
                {
                        dl->distance = 0.0;
                        dl->p1 = F;
                        dl->p2 = F;
                        return LW_TRUE;
                }
        }
 
        /* Line grazes circle, maybe arc intersects edge? */
        /* If so, grazing point is the closest point. */
        /* If not, the closest point is one of the end points of A */
        else if ( dist_C_D == radius_C )
        {
                /* Closest point D is also the point of grazing */
                pt_in_arc = lw_pt_in_arc(&D, B1, B2, B3);
                pt_in_seg = lw_pt_in_seg(&D, A1, A2);
 
                /* Is D contained in both A and B? */
                if ( pt_in_arc && pt_in_seg )
                {
                        dl->distance = 0.0;
                        dl->p1 = D;
                        dl->p2 = D;
                        return LW_TRUE;
                }
        }
        /* Line misses circle. */
        /* If closest point to A on circle is within B, then that's the closest */
        /* Otherwise, the closest point will be an end point of A */
        else
        {
                POINT2D G; /* Point on circle closest to A */
                G.x = C.x + (D.x-C.x) * radius_C / dist_C_D;
                G.y = C.y + (D.y-C.y) * radius_C / dist_C_D;
 
                pt_in_arc = lw_pt_in_arc(&G, B1, B2, B3);
                pt_in_seg = lw_pt_in_seg(&D, A1, A2);
 
                /* Closest point is on the interior of A and B */
                if ( pt_in_arc && pt_in_seg )
                        return lw_dist2d_pt_pt(&D, &G, dl);
 
        }
 
        /* Now we test the many combinations of end points with either */
        /* arcs or edges. Each previous check determined if the closest */
        /* potential point was within the arc/segment inscribed on the */
        /* line/circle holding the arc/segment. */
 
        /* Closest point is in the arc, but not in the segment, so */
        /* one of the segment end points must be the closest. */
        if (pt_in_arc && !pt_in_seg)
        {
                lw_dist2d_pt_arc(A1, B1, B2, B3, dl);
                lw_dist2d_pt_arc(A2, B1, B2, B3, dl);
                return LW_TRUE;
        }
        /* or, one of the arc end points is the closest */
        else if (pt_in_seg && !pt_in_arc)
        {
                lw_dist2d_pt_seg(B1, A1, A2, dl);
                lw_dist2d_pt_seg(B3, A1, A2, dl);
                return LW_TRUE;
        }
        /* Finally, one of the end-point to end-point combos is the closest. */
        else
        {
                lw_dist2d_pt_pt(A1, B1, dl);
                lw_dist2d_pt_pt(A1, B3, dl);
                lw_dist2d_pt_pt(A2, B1, dl);
                lw_dist2d_pt_pt(A2, B3, dl);
                return LW_TRUE;
        }
 
        return LW_FALSE;
}
 
int
lw_dist2d_pt_arc(const POINT2D* P, const POINT2D* A1, const POINT2D* A2, const POINT2D* A3, DISTPTS* dl)
{
        double radius_A, d;
        POINT2D C; /* center of circle defined by arc A */
        POINT2D X; /* point circle(A) where line from C to P crosses */
 
        if ( dl->mode < 0 )
                lwerror("lw_dist2d_pt_arc does not support maxdistance mode");
 
        /* What if the arc is a point? */
        if ( lw_arc_is_pt(A1, A2, A3) )
                return lw_dist2d_pt_pt(P, A1, dl);
 
        /* Calculate centers and radii of circles. */
        radius_A = lw_arc_center(A1, A2, A3, &C);
 
        /* This "arc" is actually a line (A2 is colinear with A1,A3) */
        if ( radius_A < 0.0 )
                return lw_dist2d_pt_seg(P, A1, A3, dl);
 
        /* Distance from point to center */
        d = distance2d_pt_pt(&C, P);
 
        /* P is the center of the circle */
        if ( FP_EQUALS(d, 0.0) )
        {
                dl->distance = radius_A;
                dl->p1 = *A1;
                dl->p2 = *P;
                return LW_TRUE;
        }
 
        /* X is the point on the circle where the line from P to C crosses */
        X.x = C.x + (P->x - C.x) * radius_A / d;
        X.y = C.y + (P->y - C.y) * radius_A / d;
 
        /* Is crossing point inside the arc? Or arc is actually circle? */
        if ( p2d_same(A1, A3) || lw_pt_in_arc(&X, A1, A2, A3) )
        {
                lw_dist2d_pt_pt(P, &X, dl);
        }
        else
        {
                /* Distance is the minimum of the distances to the arc end points */
                lw_dist2d_pt_pt(A1, P, dl);
                lw_dist2d_pt_pt(A3, P, dl);
        }
        return LW_TRUE;
}
 
/* Auxiliary function to calculate the distance between 2 concentric arcs*/
int lw_dist2d_arc_arc_concentric(       const POINT2D *A1, const POINT2D *A2,
                                        const POINT2D *A3, double radius_A,
                                        const POINT2D *B1, const POINT2D *B2,
                                        const POINT2D *B3, double radius_B,
                                        const POINT2D *CENTER, DISTPTS *dl);
 
int
lw_dist2d_arc_arc(const POINT2D *A1, const POINT2D *A2, const POINT2D *A3,
                  const POINT2D *B1, const POINT2D *B2, const POINT2D *B3,
                  DISTPTS *dl)
{
        POINT2D CA, CB; /* Center points of arcs A and B */
        double radius_A, radius_B, d; /* Radii of arcs A and B */
        POINT2D D; /* Mid-point between the centers CA and CB */
        int pt_in_arc_A, pt_in_arc_B; /* Test whether potential intersection point is within the arc */
 
        if ( dl->mode != DIST_MIN )
                lwerror("lw_dist2d_arc_arc only supports mindistance");
 
        /* TODO: Handle case where arc is closed circle (A1 = A3) */
 
        /* What if one or both of our "arcs" is actually a point? */
        if ( lw_arc_is_pt(B1, B2, B3) && lw_arc_is_pt(A1, A2, A3) )
                return lw_dist2d_pt_pt(B1, A1, dl);
        else if ( lw_arc_is_pt(B1, B2, B3) )
                return lw_dist2d_pt_arc(B1, A1, A2, A3, dl);
        else if ( lw_arc_is_pt(A1, A2, A3) )
                return lw_dist2d_pt_arc(A1, B1, B2, B3, dl);
 
        /* Calculate centers and radii of circles. */
        radius_A = lw_arc_center(A1, A2, A3, &CA);
        radius_B = lw_arc_center(B1, B2, B3, &CB);
 
        /* Two co-linear arcs?!? That's two segments. */
        if ( radius_A < 0 && radius_B < 0 )
                return lw_dist2d_seg_seg(A1, A3, B1, B3, dl);
 
        /* A is co-linear, delegate to lw_dist_seg_arc here. */
        if ( radius_A < 0 )
                return lw_dist2d_seg_arc(A1, A3, B1, B2, B3, dl);
 
        /* B is co-linear, delegate to lw_dist_seg_arc here. */
        if ( radius_B < 0 )
                return lw_dist2d_seg_arc(B1, B3, A1, A2, A3, dl);
 
        /* Center-center distance */
        d = distance2d_pt_pt(&CA, &CB);
 
        /* Concentric arcs */
        if ( FP_EQUALS(d, 0.0) )
                return lw_dist2d_arc_arc_concentric(A1, A2, A3, radius_A,
                                                    B1, B2, B3, radius_B,
                                                    &CA, dl);
 
        /* Make sure that arc "A" has the bigger radius */
        if ( radius_B > radius_A )
        {
                const POINT2D *tmp;
                POINT2D TP; /* Temporary point P */
                double td;
                tmp = B1; B1 = A1; A1 = tmp;
                tmp = B2; B2 = A2; A2 = tmp;
                tmp = B3; B3 = A3; A3 = tmp;
                TP = CB; CB = CA; CA = TP;
                td = radius_B; radius_B = radius_A; radius_A = td;
        }
 
        /* Circles touch at a point. Is that point within the arcs? */
        if ( d == (radius_A + radius_B) )
        {
                D.x = CA.x + (CB.x - CA.x) * radius_A / d;
                D.y = CA.y + (CB.y - CA.y) * radius_A / d;
 
                pt_in_arc_A = lw_pt_in_arc(&D, A1, A2, A3);
                pt_in_arc_B = lw_pt_in_arc(&D, B1, B2, B3);
 
                /* Arcs do touch at D, return it */
                if ( pt_in_arc_A && pt_in_arc_B )
                {
                        dl->distance = 0.0;
                        dl->p1 = D;
                        dl->p2 = D;
                        return LW_TRUE;
                }
        }
        /* Disjoint or contained circles don't intersect. Closest point may be on */
        /* the line joining CA to CB. */
        else if ( d > (radius_A + radius_B) /* Disjoint */ || d < (radius_A - radius_B) /* Contained */ )
        {
                POINT2D XA, XB; /* Points where the line from CA to CB cross their circle bounds */
 
                /* Calculate hypothetical nearest points, the places on the */
                /* two circles where the center-center line crosses. If both */
                /* arcs contain their hypothetical points, that's the crossing distance */
                XA.x = CA.x + (CB.x - CA.x) * radius_A / d;
                XA.y = CA.y + (CB.y - CA.y) * radius_A / d;
                XB.x = CB.x + (CA.x - CB.x) * radius_B / d;
                XB.y = CB.y + (CA.y - CB.y) * radius_B / d;
 
                pt_in_arc_A = lw_pt_in_arc(&XA, A1, A2, A3);
                pt_in_arc_B = lw_pt_in_arc(&XB, B1, B2, B3);
 
                /* If the nearest points are both within the arcs, that's our answer */
                /* the shortest distance is at the nearest points */
                if ( pt_in_arc_A && pt_in_arc_B )
                {
                        return lw_dist2d_pt_pt(&XA, &XB, dl);
                }
        }
        /* Circles cross at two points, are either of those points in both arcs? */
        /* http://paulbourke.net/geometry/2circle/ */
        else if ( d < (radius_A + radius_B) )
        {
                POINT2D E, F; /* Points where circle(A) and circle(B) cross */
                /* Distance from CA to D */
                double a = (radius_A*radius_A - radius_B*radius_B + d*d) / (2*d);
                /* Distance from D to E or F */
                double h = sqrt(radius_A*radius_A - a*a);
 
                /* Location of D */
                D.x = CA.x + (CB.x - CA.x) * a / d;
                D.y = CA.y + (CB.y - CA.y) * a / d;
 
                /* Start from D and project h units perpendicular to CA-D to get E */
                E.x = D.x + (D.y - CA.y) * h / a;
                E.y = D.y + (D.x - CA.x) * h / a;
 
                /* Crossing point E contained in arcs? */
                pt_in_arc_A = lw_pt_in_arc(&E, A1, A2, A3);
                pt_in_arc_B = lw_pt_in_arc(&E, B1, B2, B3);
 
                if ( pt_in_arc_A && pt_in_arc_B )
                {
                        dl->p1 = dl->p2 = E;
                        dl->distance = 0.0;
                        return LW_TRUE;
                }
 
                /* Start from D and project h units perpendicular to CA-D to get F */
                F.x = D.x - (D.y - CA.y) * h / a;
                F.y = D.y - (D.x - CA.x) * h / a;
 
                /* Crossing point F contained in arcs? */
                pt_in_arc_A = lw_pt_in_arc(&F, A1, A2, A3);
                pt_in_arc_B = lw_pt_in_arc(&F, B1, B2, B3);
 
                if ( pt_in_arc_A && pt_in_arc_B )
                {
                        dl->p1 = dl->p2 = F;
                        dl->distance = 0.0;
                        return LW_TRUE;
                }
        }
        else
        {
                lwerror("lw_dist2d_arc_arc: arcs neither touch, intersect nor are disjoint! INCONCEIVABLE!");
                return LW_FALSE;
        }
 
        /* Closest point is in the arc A, but not in the arc B, so */
        /* one of the B end points must be the closest. */
        if (pt_in_arc_A && !pt_in_arc_B)
        {
                lw_dist2d_pt_arc(B1, A1, A2, A3, dl);
                lw_dist2d_pt_arc(B3, A1, A2, A3, dl);
                return LW_TRUE;
        }
        /* Closest point is in the arc B, but not in the arc A, so */
        /* one of the A end points must be the closest. */
        else if  ( pt_in_arc_B && ! pt_in_arc_A )
        {
                lw_dist2d_pt_arc(A1, B1, B2, B3, dl);
                lw_dist2d_pt_arc(A3, B1, B2, B3, dl);
                return LW_TRUE;
        }
        /* Finally, one of the end-point to end-point combos is the closest. */
        else
        {
                lw_dist2d_pt_pt(A1, B1, dl);
                lw_dist2d_pt_pt(A1, B3, dl);
                lw_dist2d_pt_pt(A3, B1, dl);
                lw_dist2d_pt_pt(A3, B3, dl);
                return LW_TRUE;
        }
 
        return LW_TRUE;
}
 
int
lw_dist2d_arc_arc_concentric(   const POINT2D *A1, const POINT2D *A2,
                                const POINT2D *A3, double radius_A,
                                const POINT2D *B1, const POINT2D *B2,
                                const POINT2D *B3, double radius_B,
                                const POINT2D *CENTER, DISTPTS *dl)
{
        int seg_size;
        double dist_sqr, shortest_sqr;
        const POINT2D *P1;
        const POINT2D *P2;
        POINT2D proj;
 
        if (radius_A == radius_B)
        {
                /* Check if B1 or B3 are in the same side as A2 in the A1-A3 arc */
                seg_size = lw_segment_side(A1, A3, A2);
                if (seg_size == lw_segment_side(A1, A3, B1))
                {
                        dl->p1 = *B1;
                        dl->p2 = *B1;
                        dl->distance = 0;
                        return LW_TRUE;
                }
                if (seg_size == lw_segment_side(A1, A3, B3))
                {
                        dl->p1 = *B3;
                        dl->p2 = *B3;
                        dl->distance = 0;
                        return LW_TRUE;
                }
                /* Check if A1 or A3 are in the same side as B2 in the B1-B3 arc */
                seg_size = lw_segment_side(B1, B3, B2);
                if (seg_size == lw_segment_side(B1, B3, A1))
                {
                        dl->p1 = *A1;
                        dl->p2 = *A1;
                        dl->distance = 0;
                        return LW_TRUE;
                }
                if (seg_size == lw_segment_side(B1, B3, A3))
                {
                        dl->p1 = *A3;
                        dl->p2 = *A3;
                        dl->distance = 0;
                        return LW_TRUE;
                }
        }
        else
        {
                /* Check if any projection of B ends are in A*/
                seg_size = lw_segment_side(A1, A3, A2);
 
                /* B1 */
                proj.x = CENTER->x + (B1->x - CENTER->x) * radius_A / radius_B;
                proj.y = CENTER->y + (B1->y - CENTER->y) * radius_A / radius_B;
 
                if (seg_size == lw_segment_side(A1, A3, &proj))
                {
                        dl->p1 = proj;
                        dl->p2 = *B1;
                        dl->distance = fabs(radius_A - radius_B);
                        return LW_TRUE;
                }
                /* B3 */
                proj.x = CENTER->x + (B3->x - CENTER->x) * radius_A / radius_B;
                proj.y = CENTER->y + (B3->y - CENTER->y) * radius_A / radius_B;
                if (seg_size == lw_segment_side(A1, A3, &proj))
                {
                        dl->p1 = proj;
                        dl->p2 = *B3;
                        dl->distance = fabs(radius_A - radius_B);
                        return LW_TRUE;
                }
 
                /* Now check projections of A in B */
                seg_size = lw_segment_side(B1, B3, B2);
 
                /* A1 */
                proj.x = CENTER->x + (A1->x - CENTER->x) * radius_B / radius_A;
                proj.y = CENTER->y + (A1->y - CENTER->y) * radius_B / radius_A;
                if (seg_size == lw_segment_side(B1, B3, &proj))
                {
                        dl->p1 = proj;
                        dl->p2 = *A1;
                        dl->distance = fabs(radius_A - radius_B);
                        return LW_TRUE;
                }
 
                /* A3 */
                proj.x = CENTER->x + (A3->x - CENTER->x) * radius_B / radius_A;
                proj.y = CENTER->y + (A3->y - CENTER->y) * radius_B / radius_A;
                if (seg_size == lw_segment_side(B1, B3, &proj))
                {
                        dl->p1 = proj;
                        dl->p2 = *A3;
                        dl->distance = fabs(radius_A - radius_B);
                        return LW_TRUE;
                }
        }
 
        /* Check the shortest between the distances of the 4 ends */
        shortest_sqr = dist_sqr = distance2d_sqr_pt_pt(A1, B1);
        P1 = A1;
        P2 = B1;
 
        dist_sqr = distance2d_sqr_pt_pt(A1, B3);
        if (dist_sqr < shortest_sqr)
        {
                shortest_sqr = dist_sqr;
                P1 = A1;
                P2 = B3;
        }
 
        dist_sqr = distance2d_sqr_pt_pt(A3, B1);
        if (dist_sqr < shortest_sqr)
        {
                shortest_sqr = dist_sqr;
                P1 = A3;
                P2 = B1;
        }
 
        dist_sqr = distance2d_sqr_pt_pt(A3, B3);
        if (dist_sqr < shortest_sqr)
        {
                shortest_sqr = dist_sqr;
                P1 = A3;
                P2 = B3;
        }
 
        dl->p1 = *P1;
        dl->p2 = *P2;
        dl->distance = sqrt(shortest_sqr);
 
        return LW_TRUE;
}
 
int
lw_dist2d_seg_seg(const POINT2D *A, const POINT2D *B, const POINT2D *C, const POINT2D *D, DISTPTS *dl)
{
        double  s_top, s_bot,s;
        double  r_top, r_bot,r;
 
        LWDEBUGF(2, "lw_dist2d_seg_seg [%g,%g]->[%g,%g] by [%g,%g]->[%g,%g]",
                 A->x,A->y,B->x,B->y, C->x,C->y, D->x, D->y);
 
        /*A and B are the same point */
        if (  ( A->x == B->x) && (A->y == B->y) )
        {
                return lw_dist2d_pt_seg(A,C,D,dl);
        }
        /*U and V are the same point */
 
        if (  ( C->x == D->x) && (C->y == D->y) )
        {
                dl->twisted= ((dl->twisted) * (-1));
                return lw_dist2d_pt_seg(D,A,B,dl);
        }
        /* AB and CD are line segments */
        /* from comp.graphics.algo
 
        Solving the above for r and s yields
                                (Ay-Cy)(Dx-Cx)-(Ax-Cx)(Dy-Cy)
                   r = ----------------------------- (eqn 1)
                                (Bx-Ax)(Dy-Cy)-(By-Ay)(Dx-Cx)
 
                        (Ay-Cy)(Bx-Ax)-(Ax-Cx)(By-Ay)
                s = ----------------------------- (eqn 2)
                        (Bx-Ax)(Dy-Cy)-(By-Ay)(Dx-Cx)
        Let P be the position vector of the intersection point, then
                P=A+r(B-A) or
                Px=Ax+r(Bx-Ax)
                Py=Ay+r(By-Ay)
        By examining the values of r & s, you can also determine some other limiting conditions:
                If 0<=r<=1 & 0<=s<=1, intersection exists
                r<0 or r>1 or s<0 or s>1 line segments do not intersect
                If the denominator in eqn 1 is zero, AB & CD are parallel
                If the numerator in eqn 1 is also zero, AB & CD are collinear.
 
        */
        r_top = (A->y-C->y)*(D->x-C->x) - (A->x-C->x)*(D->y-C->y);
        r_bot = (B->x-A->x)*(D->y-C->y) - (B->y-A->y)*(D->x-C->x);
 
        s_top = (A->y-C->y)*(B->x-A->x) - (A->x-C->x)*(B->y-A->y);
        s_bot = (B->x-A->x)*(D->y-C->y) - (B->y-A->y)*(D->x-C->x);
 
        if  ( (r_bot==0) || (s_bot == 0) )
        {
                if ((lw_dist2d_pt_seg(A,C,D,dl)) && (lw_dist2d_pt_seg(B,C,D,dl)))
                {
                        dl->twisted= ((dl->twisted) * (-1));  /*here we change the order of inputted geometries and that we  notice by changing sign on dl->twisted*/
                        return ((lw_dist2d_pt_seg(C,A,B,dl)) && (lw_dist2d_pt_seg(D,A,B,dl))); /*if all is successful we return true*/
                }
                else
                {
                        return LW_FALSE; /* if any of the calls to lw_dist2d_pt_seg goes wrong we return false*/
                }
        }
 
        s = s_top/s_bot;
        r=  r_top/r_bot;
 
        if (((r<0) || (r>1) || (s<0) || (s>1)) || (dl->mode == DIST_MAX))
        {
                if ((lw_dist2d_pt_seg(A,C,D,dl)) && (lw_dist2d_pt_seg(B,C,D,dl)))
                {
                        dl->twisted= ((dl->twisted) * (-1));  /*here we change the order of inputted geometries and that we  notice by changing sign on dl->twisted*/
                        return ((lw_dist2d_pt_seg(C,A,B,dl)) && (lw_dist2d_pt_seg(D,A,B,dl))); /*if all is successful we return true*/
                }
                else
                {
                        return LW_FALSE; /* if any of the calls to lw_dist2d_pt_seg goes wrong we return false*/
                }
        }
        else
        {
                if (dl->mode == DIST_MIN)       /*If there is intersection we identify the intersection point and return it but only if we are looking for mindistance*/
                {
                        POINT2D theP;
 
                        if (((A->x==C->x)&&(A->y==C->y))||((A->x==D->x)&&(A->y==D->y)))
                        {
                                theP.x = A->x;
                                theP.y = A->y;
                        }
                        else if (((B->x==C->x)&&(B->y==C->y))||((B->x==D->x)&&(B->y==D->y)))
                        {
                                theP.x = B->x;
                                theP.y = B->y;
                        }
                        else
                        {
                                theP.x = A->x+r*(B->x-A->x);
                                theP.y = A->y+r*(B->y-A->y);
                        }
                        dl->distance=0.0;
                        dl->p1=theP;
                        dl->p2=theP;
                }
                return LW_TRUE;
        }
}
 
 
/*------------------------------------------------------------------------------------------------------------
End of Brute force functions
--------------------------------------------------------------------------------------------------------------*/
 
 
/*------------------------------------------------------------------------------------------------------------
New faster distance calculations
--------------------------------------------------------------------------------------------------------------*/
 
int
lw_dist2d_fast_ptarray_ptarray(POINTARRAY *l1, POINTARRAY *l2,DISTPTS *dl, GBOX *box1, GBOX *box2)
{
        /*here we define two lists to hold our calculated "z"-values and the order number in the geometry*/
 
        double k, thevalue;
        float   deltaX, deltaY, c1m, c2m;
        POINT2D c1, c2;
        const POINT2D *theP;
        float min1X, max1X, max1Y, min1Y,min2X, max2X, max2Y, min2Y;
        int t;
        int n1 = l1->npoints;
        int n2 = l2->npoints;
 
        LISTSTRUCT *list1, *list2;
        list1 = (LISTSTRUCT*)lwalloc(sizeof(LISTSTRUCT)*n1);
        list2 = (LISTSTRUCT*)lwalloc(sizeof(LISTSTRUCT)*n2);
 
        LWDEBUG(2, "lw_dist2d_fast_ptarray_ptarray is called");
 
        max1X = box1->xmax;
        min1X = box1->xmin;
        max1Y = box1->ymax;
        min1Y = box1->ymin;
        max2X = box2->xmax;
        min2X = box2->xmin;
        max2Y = box2->ymax;
        min2Y = box2->ymin;
        /*we want the center of the bboxes, and calculate the slope between the centerpoints*/
        c1.x = min1X + (max1X-min1X)/2;
        c1.y = min1Y + (max1Y-min1Y)/2;
        c2.x = min2X + (max2X-min2X)/2;
        c2.y = min2Y + (max2Y-min2Y)/2;
 
        deltaX=(c2.x-c1.x);
        deltaY=(c2.y-c1.y);
 
 
        /*Here we calculate where the line perpendicular to the center-center line crosses the axes for each vertex
        if the center-center line is vertical the perpendicular line will be horizontal and we find it's crossing the Y-axes with z = y-kx */
        if ((deltaX*deltaX)<(deltaY*deltaY))        /*North or South*/
        {
                k = -deltaX/deltaY;
                for (t=0; t<n1; t++) /*for each segment in L1 */
                {
                        theP = getPoint2d_cp(l1, t);
                        thevalue = theP->y - (k * theP->x);
                        list1[t].themeasure=thevalue;
                        list1[t].pnr=t;
 
                }
                for (t=0; t<n2; t++) /*for each segment in L2*/
                {
                        theP = getPoint2d_cp(l2, t);
                        thevalue = theP->y - (k * theP->x);
                        list2[t].themeasure=thevalue;
                        list2[t].pnr=t;
 
                }
                c1m = c1.y-(k*c1.x);
                c2m = c2.y-(k*c2.x);
        }
 
 
        /*if the center-center line is horizontal the perpendicular line will be vertical. To eliminate problems with dividing by zero we are here mirroring the coordinate-system
         and we find it's crossing the X-axes with z = x-(1/k)y */
        else        /*West or East*/
        {
                k = -deltaY/deltaX;
                for (t=0; t<n1; t++) /*for each segment in L1 */
                {
                        theP = getPoint2d_cp(l1, t);
                        thevalue = theP->x - (k * theP->y);
                        list1[t].themeasure=thevalue;
                        list1[t].pnr=t;
                        /* lwnotice("l1 %d, measure=%f",t,thevalue ); */
                }
                for (t=0; t<n2; t++) /*for each segment in L2*/
                {
                        theP = getPoint2d_cp(l2, t);
                        thevalue = theP->x - (k * theP->y);
                        list2[t].themeasure=thevalue;
                        list2[t].pnr=t;
                        /* lwnotice("l2 %d, measure=%f",t,thevalue ); */
                }
                c1m = c1.x-(k*c1.y);
                c2m = c2.x-(k*c2.y);
        }
 
        /*we sort our lists by the calculated values*/
        qsort(list1, n1, sizeof(LISTSTRUCT), struct_cmp_by_measure);
        qsort(list2, n2, sizeof(LISTSTRUCT), struct_cmp_by_measure);
 
        if (c1m < c2m)
        {
                if (!lw_dist2d_pre_seg_seg(l1,l2,list1,list2,k,dl))
                {
                        lwfree(list1);
                        lwfree(list2);
                        return LW_FALSE;
                }
        }
        else
        {
                dl->twisted= ((dl->twisted) * (-1));
                if (!lw_dist2d_pre_seg_seg(l2,l1,list2,list1,k,dl))
                {
                        lwfree(list1);
                        lwfree(list2);
                        return LW_FALSE;
                }
        }
        lwfree(list1);
        lwfree(list2);
        return LW_TRUE;
}
 
int
struct_cmp_by_measure(const void *a, const void *b)
{
        LISTSTRUCT *ia = (LISTSTRUCT*)a;
        LISTSTRUCT *ib = (LISTSTRUCT*)b;
        return
                (ia->themeasure > ib->themeasure) ? 1 : ((ia->themeasure < ib->themeasure) ? -1 : 0);
}
 
int
lw_dist2d_pre_seg_seg(POINTARRAY *l1, POINTARRAY *l2,LISTSTRUCT *list1, LISTSTRUCT *list2,double k, DISTPTS *dl)
{
        const POINT2D *p1, *p2, *p3, *p4, *p01, *p02;
        int pnr1,pnr2,pnr3,pnr4, n1, n2, i, u, r, twist;
        double maxmeasure;
        n1=     l1->npoints;
        n2 = l2->npoints;
 
        LWDEBUG(2, "lw_dist2d_pre_seg_seg is called");
 
        p1 = getPoint2d_cp(l1, list1[0].pnr);
        p3 = getPoint2d_cp(l2, list2[0].pnr);
        lw_dist2d_pt_pt(p1, p3, dl);
        maxmeasure = sqrt(dl->distance*dl->distance + (dl->distance*dl->distance*k*k));
        twist = dl->twisted; /*to keep the incoming order between iterations*/
        for (i =(n1-1); i>=0; --i)
        {
                /*we break this iteration when we have checked every
                point closer to our perpendicular "checkline" than
                our shortest found distance*/
                if (((list2[0].themeasure-list1[i].themeasure)) > maxmeasure) break;
                for (r=-1; r<=1; r +=2) /*because we are not iterating in the original point order we have to check the segment before and after every point*/
                {
                        pnr1 = list1[i].pnr;
                        p1 = getPoint2d_cp(l1, pnr1);
                        if (pnr1+r<0)
                        {
                                p01 = getPoint2d_cp(l1, (n1-1));
                                if (( p1->x == p01->x) && (p1->y == p01->y)) pnr2 = (n1-1);
                                else pnr2 = pnr1; /* if it is a line and the last and first point is not the same we avoid the edge between start and end this way*/
                        }
 
                        else if (pnr1+r>(n1-1))
                        {
                                p01 = getPoint2d_cp(l1, 0);
                                if (( p1->x == p01->x) && (p1->y == p01->y)) pnr2 = 0;
                                else pnr2 = pnr1; /* if it is a line and the last and first point is not the same we avoid the edge between start and end this way*/
                        }
                        else pnr2 = pnr1+r;
 
 
                        p2 = getPoint2d_cp(l1, pnr2);
                        for (u=0; u<n2; ++u)
                        {
                                if (((list2[u].themeasure-list1[i].themeasure)) >= maxmeasure) break;
                                pnr3 = list2[u].pnr;
                                p3 = getPoint2d_cp(l2, pnr3);
                                if (pnr3==0)
                                {
                                        p02 = getPoint2d_cp(l2, (n2-1));
                                        if (( p3->x == p02->x) && (p3->y == p02->y)) pnr4 = (n2-1);
                                        else pnr4 = pnr3; /* if it is a line and the last and first point is not the same we avoid the edge between start and end this way*/
                                }
                                else pnr4 = pnr3-1;
 
                                p4 = getPoint2d_cp(l2, pnr4);
                                dl->twisted=twist;
                                if (!lw_dist2d_selected_seg_seg(p1, p2, p3, p4, dl)) return LW_FALSE;
 
                                if (pnr3>=(n2-1))
                                {
                                        p02 = getPoint2d_cp(l2, 0);
                                        if (( p3->x == p02->x) && (p3->y == p02->y)) pnr4 = 0;
                                        else pnr4 = pnr3; /* if it is a line and the last and first point is not the same we avoid the edge between start and end this way*/
                                }
 
                                else pnr4 = pnr3+1;
 
                                p4 = getPoint2d_cp(l2, pnr4);
                                dl->twisted=twist; /*we reset the "twist" for each iteration*/
                                if (!lw_dist2d_selected_seg_seg(p1, p2, p3, p4, dl)) return LW_FALSE;
 
                                maxmeasure = sqrt(dl->distance*dl->distance + (dl->distance*dl->distance*k*k));/*here we "translate" the found mindistance so it can be compared to our "z"-values*/
                        }
                }
        }
 
        return LW_TRUE;
}
 
 
int
lw_dist2d_selected_seg_seg(const POINT2D *A, const POINT2D *B, const POINT2D *C, const POINT2D *D, DISTPTS *dl)
{
        LWDEBUGF(2, "lw_dist2d_selected_seg_seg [%g,%g]->[%g,%g] by [%g,%g]->[%g,%g]",
                 A->x,A->y,B->x,B->y, C->x,C->y, D->x, D->y);
 
        /*A and B are the same point */
        if (  ( A->x == B->x) && (A->y == B->y) )
        {
                return lw_dist2d_pt_seg(A,C,D,dl);
        }
        /*U and V are the same point */
 
        if (  ( C->x == D->x) && (C->y == D->y) )
        {
                dl->twisted= ((dl->twisted) * (-1));
                return lw_dist2d_pt_seg(D,A,B,dl);
        }
 
        if ((lw_dist2d_pt_seg(A,C,D,dl)) && (lw_dist2d_pt_seg(B,C,D,dl)))
        {
                dl->twisted= ((dl->twisted) * (-1));  /*here we change the order of inputted geometrys and that we  notice by changing sign on dl->twisted*/
                return ((lw_dist2d_pt_seg(C,A,B,dl)) && (lw_dist2d_pt_seg(D,A,B,dl))); /*if all is successful we return true*/
        }
        else
        {
                return LW_FALSE; /* if any of the calls to lw_dist2d_pt_seg goes wrong we return false*/
        }
}
 
/*------------------------------------------------------------------------------------------------------------
End of New faster distance calculations
--------------------------------------------------------------------------------------------------------------*/
 
 
/*------------------------------------------------------------------------------------------------------------
Functions in common for Brute force and new calculation
--------------------------------------------------------------------------------------------------------------*/
 
int
lw_dist2d_pt_seg(const POINT2D *p, const POINT2D *A, const POINT2D *B, DISTPTS *dl)
{
        POINT2D c;
        double  r;
        /*if start==end, then use pt distance */
        if (  ( A->x == B->x) && (A->y == B->y) )
        {
                return lw_dist2d_pt_pt(p,A,dl);
        }
        /*
         * otherwise, we use comp.graphics.algorithms
         * Frequently Asked Questions method
         *
         *  (1)        AC dot AB
         *         r = ---------
         *              ||AB||^2
         *      r has the following meaning:
         *      r=0 P = A
         *      r=1 P = B
         *      r<0 P is on the backward extension of AB
         *      r>1 P is on the forward extension of AB
         *      0<r<1 P is interior to AB
         */
 
        r = ( (p->x-A->x) * (B->x-A->x) + (p->y-A->y) * (B->y-A->y) )/( (B->x-A->x)*(B->x-A->x) +(B->y-A->y)*(B->y-A->y) );
 
        /*This is for finding the maxdistance.
        the maxdistance have to be between two vertexes,
        compared to mindistance which can be between
        two vertexes vertex.*/
        if (dl->mode == DIST_MAX)
        {
                if (r>=0.5)
                {
                        return lw_dist2d_pt_pt(p,A,dl);
                }
                if (r<0.5)
                {
                        return lw_dist2d_pt_pt(p,B,dl);
                }
        }
 
        if (r<0)        /*If p projected on the line is outside point A*/
        {
                return lw_dist2d_pt_pt(p,A,dl);
        }
        if (r>=1)       /*If p projected on the line is outside point B or on point B*/
        {
                return lw_dist2d_pt_pt(p,B,dl);
        }
 
        /*If the point p is on the segment this is a more robust way to find out that*/
        if (( ((A->y-p->y)*(B->x-A->x)==(A->x-p->x)*(B->y-A->y) ) ) && (dl->mode ==  DIST_MIN))
        {
                dl->distance = 0.0;
                dl->p1 = *p;
                dl->p2 = *p;
        }
 
        /*If the projection of point p on the segment is between A and B
        then we find that "point on segment" and send it to lw_dist2d_pt_pt*/
        c.x=A->x + r * (B->x-A->x);
        c.y=A->y + r * (B->y-A->y);
 
        return lw_dist2d_pt_pt(p,&c,dl);
}
 
 
int
lw_dist2d_pt_pt(const POINT2D *thep1, const POINT2D *thep2, DISTPTS *dl)
{
        double hside = thep2->x - thep1->x;
        double vside = thep2->y - thep1->y;
        double dist = sqrt ( hside*hside + vside*vside );
 
        if (((dl->distance - dist)*(dl->mode))>0) /*multiplication with mode to handle mindistance (mode=1)  and maxdistance (mode = (-1)*/
        {
                dl->distance = dist;
 
                if (dl->twisted>0)      /*To get the points in right order. twisted is updated between 1 and (-1) every time the order is changed earlier in the chain*/
                {
                        dl->p1 = *thep1;
                        dl->p2 = *thep2;
                }
                else
                {
                        dl->p1 = *thep2;
                        dl->p2 = *thep1;
                }
        }
        return LW_TRUE;
}
 
 
 
 
/*------------------------------------------------------------------------------------------------------------
End of Functions in common for Brute force and new calculation
--------------------------------------------------------------------------------------------------------------*/
 
inline double
distance2d_pt_pt(const POINT2D *p1, const POINT2D *p2)
{
        double hside = p2->x - p1->x;
        double vside = p2->y - p1->y;
 
        return hypot(hside, vside);
}
 
inline double
distance2d_sqr_pt_pt(const POINT2D *p1, const POINT2D *p2)
{
        double hside = p2->x - p1->x;
        double vside = p2->y - p1->y;
 
        return hside * hside + vside * vside;
}
 
double
distance2d_pt_seg(const POINT2D *p, const POINT2D *A, const POINT2D *B)
{
        double  r,s;
 
        /*if start==end, then use pt distance */
        if (  ( A->x == B->x) && (A->y == B->y) )
                return distance2d_pt_pt(p,A);
 
        /*
         * otherwise, we use comp.graphics.algorithms
         * Frequently Asked Questions method
         *
         *  (1)               AC dot AB
                *         r = ---------
                *               ||AB||^2
         *      r has the following meaning:
         *      r=0 P = A
         *      r=1 P = B
         *      r<0 P is on the backward extension of AB
         *      r>1 P is on the forward extension of AB
         *      0<r<1 P is interior to AB
         */
 
        r = ( (p->x-A->x) * (B->x-A->x) + (p->y-A->y) * (B->y-A->y) )/( (B->x-A->x)*(B->x-A->x) +(B->y-A->y)*(B->y-A->y) );
 
        if (r<0) return distance2d_pt_pt(p,A);
        if (r>1) return distance2d_pt_pt(p,B);
 
 
        /*
         * (2)
         *           (Ay-Cy)(Bx-Ax)-(Ax-Cx)(By-Ay)
         *      s = -----------------------------
         *                      L^2
         *
         *      Then the distance from C to P = |s|*L.
         *
         */
 
        s = ( (A->y-p->y)*(B->x-A->x)- (A->x-p->x)*(B->y-A->y) ) /
            ( (B->x-A->x)*(B->x-A->x) +(B->y-A->y)*(B->y-A->y) );
 
        return FP_ABS(s) * sqrt(
                   (B->x-A->x)*(B->x-A->x) + (B->y-A->y)*(B->y-A->y)
               );
}
 
/* return distance squared, useful to avoid sqrt calculations */
double
distance2d_sqr_pt_seg(const POINT2D *p, const POINT2D *A, const POINT2D *B)
{
        double  r,s;
 
        if (  ( A->x == B->x) && (A->y == B->y) )
                return distance2d_sqr_pt_pt(p,A);
 
        r = ( (p->x-A->x) * (B->x-A->x) + (p->y-A->y) * (B->y-A->y) )/( (B->x-A->x)*(B->x-A->x) +(B->y-A->y)*(B->y-A->y) );
 
        if (r<0) return distance2d_sqr_pt_pt(p,A);
        if (r>1) return distance2d_sqr_pt_pt(p,B);
 
 
        /*
         * (2)
         *           (Ay-Cy)(Bx-Ax)-(Ax-Cx)(By-Ay)
         *      s = -----------------------------
         *                      L^2
         *
         *      Then the distance from C to P = |s|*L.
         *
         */
 
        s = ( (A->y-p->y)*(B->x-A->x)- (A->x-p->x)*(B->y-A->y) ) /
            ( (B->x-A->x)*(B->x-A->x) +(B->y-A->y)*(B->y-A->y) );
 
        return s * s * ( (B->x-A->x)*(B->x-A->x) + (B->y-A->y)*(B->y-A->y) );
}
 
 
 
int
azimuth_pt_pt(const POINT2D *A, const POINT2D *B, double *d)
{
        if ( A->x == B->x )
        {
                if ( A->y < B->y ) *d=0.0;
                else if ( A->y > B->y ) *d=M_PI;
                else return 0;
                return 1;
        }
 
        if ( A->y == B->y )
        {
                if ( A->x < B->x ) *d=M_PI/2;
                else if ( A->x > B->x ) *d=M_PI+(M_PI/2);
                else return 0;
                return 1;
        }
 
        if ( A->x < B->x )
        {
                if ( A->y < B->y )
                {
                        *d=atan(fabs(A->x - B->x) / fabs(A->y - B->y) );
                }
                else /* ( A->y > B->y )  - equality case handled above */
                {
                        *d=atan(fabs(A->y - B->y) / fabs(A->x - B->x) )
                           + (M_PI/2);
                }
        }
 
        else /* ( A->x > B->x ) - equality case handled above */
        {
                if ( A->y > B->y )
                {
                        *d=atan(fabs(A->x - B->x) / fabs(A->y - B->y) )
                           + M_PI;
                }
                else /* ( A->y < B->y )  - equality case handled above */
                {
                        *d=atan(fabs(A->y - B->y) / fabs(A->x - B->x) )
                           + (M_PI+(M_PI/2));
                }
        }
 
        return 1;
}