ArcGIS Pro 3.4 API Reference Guide
ArcGIS.Core.Geometry Namespace / IGeometryEngine Interface / ReverseOrientation Method
The polygon or polyline whose orientation will be reversed.
Example Version

ReverseOrientation Method (IGeometryEngine)
Reverse the orientation of the geometry.
Syntax
Multipart ReverseOrientation( 
   Multipart multipart
)

Parameters

multipart
The polygon or polyline whose orientation will be reversed.

Return Value

A geometry whose directionality has been reversed. If the input multipart is empty, then it is returned unchanged.
Exceptions
ExceptionDescription
Multipart is null.
Remarks
ReverseOrientation changes the direction of the curve without changing the spatial position of the curve. The From Point and To Point of each Segment are interchanged.
Caution should be taken in using ReverseOrientation on Polygons. Since ReverseOrientation changes the direction of each Ring within the Polygon, all Exterior Rings become Interior Rings and vice versa.

GeometryEngine Reverse Orientation

Example
Reverse the order of points in a Polygon
List<Coordinate2D> list2D = new List<Coordinate2D>();
list2D.Add(new Coordinate2D(1.0, 1.0));
list2D.Add(new Coordinate2D(1.0, 2.0));
list2D.Add(new Coordinate2D(2.0, 2.0));
list2D.Add(new Coordinate2D(2.0, 1.0));

Polygon polygon = PolygonBuilderEx.CreatePolygon(list2D);

Geometry g = GeometryEngine.Instance.ReverseOrientation(polygon);
Polygon gPolygon = g as Polygon;

// gPolygon.Points[0] = 1.0, 1.0
// gPolygon.Points[1] = 2.0, 1.0
// gPolygon.Points[2] = 2.0, 2.0
// gPolygon.Points[3] = 1.0, 2.0
// gPolygon.Points[4] = 1.0, 1.0
// gPolygon.Area = -1 * polygon.Area
Requirements

Target Platforms: Windows 11, Windows 10

ArcGIS Pro version: 3 or higher.
See Also