lw_dist2d_poly_poly()

int lw_dist2d_poly_poly	(	LWPOLY *	poly1,
		LWPOLY *	poly2,
		DISTPTS *	dl
	)

Function handling polygon to polygon calculation 1 if we are looking for maxdistance, just check the outer rings.

2 check if poly1 has first point outside poly2 and vice versa, if so, just check outer rings 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 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 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.

Definition at line 843 of file measures.c.

References DIST_MAX, DISTPTS::distance, getPoint2d_cp(), lw_dist2d_ptarray_ptarray(), LW_FALSE, LW_OUTSIDE, LW_TRUE, LWDEBUG, lwerror(), DISTPTS::mode, LWPOLY::nrings, DISTPTS::p1, DISTPTS::p2, ptarray_contains_point(), LWPOLY::rings, POINT2D::x, and POINT2D::y.

Referenced by lw_dist2d_distribute_bruteforce().

{

        const POINT2D *pt;
        int 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 wich one is inside wich 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;
}

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