main/src/georegression/geometry/UtilPolygons2D_I32.java
public static void flip( Polygon2D_I32 a ) {
		int N = a.size();
		int H = N/2;

		for (int i = 1; i <= H; i++) {
			int j = N-i;
			Point2D_I32 tmp = a.vertexes.data[i];
			a.vertexes.data[i] = a.vertexes.data[j];
			a.vertexes.data[j] = tmp;
		}
	}
public static void flip( Polygon2D_I32 a ) {
		int N = a.size();
		int H = N/2;

		for (int i = 1; i <= H; i++) {
			int j = N-i;
			Point2D_I32 tmp = a.vertexes.data[i];
			a.vertexes.data[i] = a.vertexes.data[j];
			a.vertexes.data[j] = tmp;
		}
	}
public static void flip ( Polygon2D_I32 a ) { int N = a . size ( ) ; int H = N / 2 ; for ( int i = 1 ; i <= H ; i ++ ) { int j = N - i ; Point2D_I32 tmp = a . vertexes . data [ i ] ; a . vertexes . data [ i ] = a . vertexes . data [ j ] ; a . vertexes . data [ j ] = tmp ; } }
Flips the order of points inside the polygon.  The first index will remain the same will otherwise be reversed

@param a Polygon of order 3 or more.
Flips the order of points inside the polygon . The first index will remain the same will otherwise be reversed