edge_calculate_gbox_slow()

int edge_calculate_gbox_slow	(	const GEOGRAPHIC_EDGE *	e,
		GBOX *	gbox
	)

Definition at line 1340 of file lwgeodetic.c.

References distance(), GEOGRAPHIC_EDGE::end, FP_EQUALS, FP_IS_ZERO, gbox_init_point3d(), gbox_merge_point3d(), geog2cart(), LW_SUCCESS, LWDEBUG, normalize(), sphere_distance(), GEOGRAPHIC_EDGE::start, POINT3D::x, GBOX::xmax, GBOX::xmin, POINT3D::y, GBOX::ymax, GBOX::ymin, POINT3D::z, GBOX::zmax, and GBOX::zmin.

{
        int steps = 1000000;
        int i;
        double dx, dy, dz;
        double distance = sphere_distance(&(e->start), &(e->end));
        POINT3D pn, p, start, end;

        /* Edge is zero length, just return the naive box */
        if ( FP_IS_ZERO(distance) )
        {
                LWDEBUG(4, "edge is zero length. returning");
                geog2cart(&(e->start), &start);
                geog2cart(&(e->end), &end);
                gbox_init_point3d(&start, gbox);
                gbox_merge_point3d(&end, gbox);
                return LW_SUCCESS;
        }

        /* Edge is antipodal (one point on each side of the globe),
           set the box to contain the whole world and return */
        if ( FP_EQUALS(distance, M_PI) )
        {
                LWDEBUG(4, "edge is antipodal. setting to maximum size box, and returning");
                gbox->xmin = gbox->ymin = gbox->zmin = -1.0;
                gbox->xmax = gbox->ymax = gbox->zmax = 1.0;
                return LW_SUCCESS;
        }

        /* Walk along the chord between start and end incrementally,
           normalizing at each step. */
        geog2cart(&(e->start), &start);
        geog2cart(&(e->end), &end);
        dx = (end.x - start.x)/steps;
        dy = (end.y - start.y)/steps;
        dz = (end.z - start.z)/steps;
        p = start;
        gbox->xmin = gbox->xmax = p.x;
        gbox->ymin = gbox->ymax = p.y;
        gbox->zmin = gbox->zmax = p.z;
        for ( i = 0; i < steps; i++ )
        {
                p.x += dx;
                p.y += dy;
                p.z += dz;
                pn = p;
                normalize(&pn);
                gbox_merge_point3d(&pn, gbox);
        }
        return LW_SUCCESS;
}

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