lwpoly_intersects_line()

int lwpoly_intersects_line	(	const LWPOLY *	lwpoly,
		const POINTARRAY *	line
	)

Checks if any edges of lwpoly intersect with the line formed by the pointarray return LW_TRUE if any intersection beetween the given polygon and the line.

Definition at line 2698 of file lwgeodetic.c.

References edge_intersects(), getPoint2d_cp(), ll2cart(), LW_FALSE, LW_TRUE, POINTARRAY::npoints, LWPOLY::nrings, PIR_B_TOUCH_RIGHT, PIR_COLINEAR, PIR_INTERSECTS, and LWPOLY::rings.

Referenced by lwpoly_covers_lwline(), and lwpoly_covers_lwpoly().

{
        int i, j, k;
        POINT3D pa1, pa2, pb1, pb2;
        for (i = 0; i < lwpoly->nrings; i++)
        {
                for (j = 0; j < lwpoly->rings[i]->npoints - 1; j++)
                {
                        const POINT2D* a1 = getPoint2d_cp(lwpoly->rings[i], j);
                        const POINT2D* a2 = getPoint2d_cp(lwpoly->rings[i], j+1);

                        /* Set up our stab line */
                        ll2cart(a1, &pa1);
                        ll2cart(a2, &pa2);

                        for (k = 0; k < line->npoints - 1; k++)
                        {
                                const POINT2D* b1 = getPoint2d_cp(line, k);
                                const POINT2D* b2 = getPoint2d_cp(line, k+1);

                                /* Set up our stab line */
                                ll2cart(b1, &pb1);
                                ll2cart(b2, &pb2);

                                int inter = edge_intersects(&pa1, &pa2, &pb1, &pb2);

                                /* ignore same edges */
                                if (inter & PIR_INTERSECTS
                                        && !(inter & PIR_B_TOUCH_RIGHT || inter & PIR_COLINEAR) )
                                {
                                        return LW_TRUE;
                                }
                        }
                }
        }

        return LW_FALSE;
}

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