lw_dist2d_line_poly()

int lw_dist2d_line_poly	(	LWLINE *	line,
		LWPOLY *	poly,
		DISTPTS *	dl
	)

line to polygon calculation Brute force.

Test line-ring distance against each ring. If there's an intersection (distance==0) then return 0 (crosses boundary). Otherwise, test to see if any point is inside outer rings of polygon, but not in inner rings. If so, return 0 (line inside polygon), otherwise return min distance to a ring (could be outside polygon or inside a hole)

Definition at line 737 of file measures.c.

{
        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 */
}

References DIST_MIN, DISTPTS::distance, getPoint2d_cp(), lw_dist2d_ptarray_ptarray(), LW_FALSE, LW_OUTSIDE, LW_TRUE, LWDEBUGF, DISTPTS::mode, LWPOLY::nrings, DISTPTS::p1, DISTPTS::p2, LWLINE::points, ptarray_contains_point(), LWPOLY::rings, DISTPTS::tolerance, POINT2D::x, and POINT2D::y.

Referenced by lw_dist2d_distribute_bruteforce().

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