edge_distance_to_point()

double edge_distance_to_point	(	const GEOGRAPHIC_EDGE *	e,
		const GEOGRAPHIC_POINT *	gp,
		GEOGRAPHIC_POINT *	closest
	)

Definition at line 1214 of file lwgeodetic.c.

References cart2geog(), dot_product(), edge_contains_point(), GEOGRAPHIC_EDGE::end, geog2cart(), geographic_point_equals(), normalize(), robust_cross_product(), sphere_distance(), GEOGRAPHIC_EDGE::start, vector_difference(), and vector_scale().

Referenced by circ_tree_contains_point(), circ_tree_distance_tree_internal(), edge_distance_to_edge(), ptarray_distance_spheroid(), and test_edge_distance_to_point().

{
        double d1 = 1000000000.0, d2, d3, d_nearest;
        POINT3D n, p, k;
        GEOGRAPHIC_POINT gk, g_nearest;

        /* Zero length edge, */
        if ( geographic_point_equals(&(e->start), &(e->end)) )
        {
                *closest = e->start;
                return sphere_distance(&(e->start), gp);
        }

        robust_cross_product(&(e->start), &(e->end), &n);
        normalize(&n);
        geog2cart(gp, &p);
        vector_scale(&n, dot_product(&p, &n));
        vector_difference(&p, &n, &k);
        normalize(&k);
        cart2geog(&k, &gk);
        if ( edge_contains_point(e, &gk) )
        {
                d1 = sphere_distance(gp, &gk);
        }
        d2 = sphere_distance(gp, &(e->start));
        d3 = sphere_distance(gp, &(e->end));

        d_nearest = d1;
        g_nearest = gk;

        if ( d2 < d_nearest )
        {
                d_nearest = d2;
                g_nearest = e->start;
        }
        if ( d3 < d_nearest )
        {
                d_nearest = d3;
                g_nearest = e->end;
        }
        if (closest)
                *closest = g_nearest;

        return d_nearest;
}

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