lw_dist2d_distanceline()

LWGEOM* lw_dist2d_distanceline	(	const LWGEOM *	lw1,
		const LWGEOM *	lw2,
		int32_t	srid,
		int	mode
	)

Function initializing shortestline and longestline calculations.

Definition at line 96 of file measures.c.

{
        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;
}

References COLLECTIONTYPE, DIST_MIN, DISTPTS::distance, lw_dist2d_comp(), lwcollection_construct_empty(), LWDEBUG, lwerror(), lwline_from_ptarray(), lwpoint_make2d(), DISTPTS::mode, DISTPTS::p1, DISTPTS::p2, result, DISTPTS::tolerance, POINT2D::x, and POINT2D::y.

Referenced by lw_dist3d_distanceline(), lwgeom_closest_line(), and lwgeom_furthest_line().

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