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 744 of file measures.c.

{
        POINTARRAY *pa = line->points;
        const POINT2D *pt = getPoint2d_cp(pa, 0);
 
        /* Line has a point outside poly. Check distance to outer ring only. */
        if (ptarray_contains_point(poly->rings[0], pt) == LW_OUTSIDE || dl->mode == DIST_MAX)
                return lw_dist2d_ptarray_ptarray(pa, poly->rings[0], dl);
 
        for (uint32_t i = 1; i < poly->nrings; i++)
        {
                if (!lw_dist2d_ptarray_ptarray(pa, poly->rings[i], dl))
                        return LW_FALSE;
 
                /* just a check if the answer is already given */
                if (dl->distance <= dl->tolerance && dl->mode == DIST_MIN)
                        return LW_TRUE;
        }
 
        /* It's inside a hole, then the actual distance is the min ring distance */
        for (uint32_t i = 1; i < poly->nrings; i++)
                if (ptarray_contains_point(poly->rings[i], pt) != LW_OUTSIDE)
                        return LW_TRUE;
 
        /* Not in hole, so inside polygon */
        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;
}

References DIST_MAX, DIST_MIN, DISTPTS::distance, getPoint2d_cp(), lw_dist2d_ptarray_ptarray(), LW_FALSE, LW_OUTSIDE, LW_TRUE, 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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