lwpoly_covers_lwpoly()

int lwpoly_covers_lwpoly	(	const LWPOLY *	poly1,
		const LWPOLY *	poly2
	)

Given a polygon1 check if all points of polygon2 are inside polygon1 and no intersections of the polygon edges occur.

return LW_TRUE if polygon is inside or on edge of polygon.

Definition at line 2619 of file lwgeodetic.c.

{
        uint32_t i;
 
        /* Nulls and empties don't contain anything! */
        if ( ! poly1 || lwgeom_is_empty((LWGEOM*)poly1) )
        {
                LWDEBUG(4,"returning false, geometry1 is empty or null");
                return LW_FALSE;
        }
 
        /* Nulls and empties don't contain anything! */
        if ( ! poly2 || lwgeom_is_empty((LWGEOM*)poly2) )
        {
                LWDEBUG(4,"returning false, geometry2 is empty or null");
                return LW_FALSE;
        }
 
        /* check if all vertices of poly2 are inside poly1 */
        for (i = 0; i < poly2->nrings; i++)
        {
 
                /* every other ring is a hole, check if point is inside the actual polygon */
                if ( i % 2 == 0)
                {
                        if (LW_FALSE == lwpoly_covers_pointarray(poly1, poly2->rings[i]))
                        {
                                LWDEBUG(4,"returning false, geometry2 has point outside of geometry1");
                                return LW_FALSE;
                        }
                }
                else
                {
                        if (LW_TRUE == lwpoly_covers_pointarray(poly1, poly2->rings[i]))
                        {
                                LWDEBUG(4,"returning false, geometry2 has point inside a hole of geometry1");
                                return LW_FALSE;
                        }
                }
        }
 
        /* check for any edge intersections, so nothing is partially outside of poly1 */
        for (i = 0; i < poly2->nrings; i++)
        {
                if (LW_TRUE == lwpoly_intersects_line(poly1, poly2->rings[i]))
                {
                        LWDEBUG(4,"returning false, geometry2 is partially outside of geometry1");
                        return LW_FALSE;
                }
        }
 
        /* no abort condition found, so the poly2 should be completly inside poly1 */
        return LW_TRUE;
}

References LW_FALSE, LW_TRUE, LWDEBUG, lwgeom_is_empty(), lwpoly_covers_pointarray(), lwpoly_intersects_line(), LWPOLY::nrings, and LWPOLY::rings.

Referenced by lwgeom_covers_lwgeom_sphere().

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