MovePointAlongLine Method

Constructs a point the specified distance along a polyline or polygon.

Syntax

C#
Visual Basic (Declaration)

MapPoint MovePointAlongLine( 
   Multipart multipart,
   double distanceAlong,
   bool asRatio,
   double offset,
   SegmentExtension extension
)

Function MovePointAlongLine( _
   ByVal multipart As Multipart, _
   ByVal distanceAlong As Double, _
   ByVal asRatio As Boolean, _
   ByVal offset As Double, _
   ByVal extension As SegmentExtension _
) As MapPoint

Parameters

multipart: The multipart along which the point will be moved.
distanceAlong: The distance to move the point.
asRatio: Set the asRatio flag to be true if you want the distance to be a ratio of the curve length.
offset: The offset distance.
extension: Determines how and from where a segment is to be extended.

Exceptions

Exception	Description
System.ArgumentNullException	Multipart is null or empty.
GeometryObjectException	Occurs if asRatio is true and the geometry has a 2d and 3d distance of 0.

Remarks

A positive offset distance will create a point on the right side of the curve and a negative offset will create a point on the left side of the curve.

Example

LineSegment line = LineBuilder.CreateLineSegment(MapPointBuilder.CreateMapPoint(0, 3), MapPointBuilder.CreateMapPoint(5.0, 3.0));
Polyline polyline = PolylineBuilder.CreatePolyline(line);
bool simple = GeometryEngine.Instance.IsSimpleAsFeature(polyline);

// ratio = false
MapPoint pt = GeometryEngine.Instance.MovePointAlongLine(polyline, 1.0, false, 0.0, SegmentExtension.NoExtension);
// pt = 1.0, 3.0

pt = GeometryEngine.Instance.MovePointAlongLine(polyline, 1.0, false, -1.0, SegmentExtension.NoExtension);
// pt = 1.0, 4.0

pt = GeometryEngine.Instance.MovePointAlongLine(polyline, 1.0, false, 2.0, SegmentExtension.NoExtension);
// pt = 1.0, 1.0

// ratio = true
pt = GeometryEngine.Instance.MovePointAlongLine(polyline, 0.5, true, 0, SegmentExtension.NoExtension);
// pt = 2.5, 3.0

// move past the line
pt = GeometryEngine.Instance.MovePointAlongLine(polyline, 7, false, 0, SegmentExtension.NoExtension);
// pt = 5.0, 3.0

// move past the line with extension at "to" point
pt = GeometryEngine.Instance.MovePointAlongLine(polyline, 7, false, 0, SegmentExtension.ExtendEmbeddedAtTo);
// pt = 7.0, 3.0

// negative distance with extension at "from" point
pt = GeometryEngine.Instance.MovePointAlongLine(polyline, -2, false, 0, SegmentExtension.ExtendEmbeddedAtFrom);
// pt = -2.0, 3.0

// ratio = true
pt = GeometryEngine.Instance.MovePointAlongLine(polyline, 0.5, true, 0, SegmentExtension.NoExtension);
// pt = 2.5, 3.0

// line with Z
List<Coordinate3D> coords3D = new List<Coordinate3D> { new Coordinate3D(0, 0, 0), new Coordinate3D(1113195, 1118890, 5000) };
Polyline polylineZ = PolylineBuilder.CreatePolyline(coords3D, SpatialReferences.WebMercator);
// polylineZ.HasZ = true

// ratio = true, no offset
pt = GeometryEngine.Instance.MovePointAlongLine(polylineZ, 0.5, true, 0, SegmentExtension.NoExtension);
// pt.X = 556597.5
// pt.Y = 559445
// pt.Z = 2500

// ratio = true, past the line with "to" extension, no offset
pt = GeometryEngine.Instance.MovePointAlongLine(polylineZ, 1.5, true, 0, SegmentExtension.ExtendEmbeddedAtTo);
// pt.X = 1669792.5
// pt.Y = 1678335
// pt.Z = 7500

// ratio = true, negative distance past the line with no extension, no offset
pt = GeometryEngine.Instance.MovePointAlongLine(polylineZ, -1.5, true, 0, SegmentExtension.NoExtension);
// pt.X = 0
// pt.Y = 0
// pt.Z = -7500

// polyline with Z but 2d distance = 0
MapPoint pt3 = MapPointBuilder.CreateMapPoint(5, 5, 0);
MapPoint pt4 = MapPointBuilder.CreateMapPoint(5, 5, 10);
List<MapPoint> pts = new List<MapPoint>() { pt3, pt4 };

polyline = PolylineBuilder.CreatePolyline(pts);
// polyline.HasZ = true
// polyline.Length3D = 10
// polyline.Length = 0

MapPoint result = GeometryEngine.Instance.MovePointAlongLine(polyline, 2, false, 0, SegmentExtension.NoExtension);
// result = 5, 5, 2

// polyline with length2d = 0 and length3d = 0
MapPoint pt5 = MapPointBuilder.CreateMapPoint(5, 5, 10);
MapPoint pt6 = MapPointBuilder.CreateMapPoint(5, 5, 10);
pts.Clear();
pts.Add(pt5);
pts.Add(pt6);

polyline = PolylineBuilder.CreatePolyline(pts);
// polyline.HasZ = true
// polyline.Length3D = 0
// polyline.Length = 0

result = GeometryEngine.Instance.MovePointAlongLine(polyline, 3, true, 0, SegmentExtension.NoExtension);
// result = 5, 5, 10

result = GeometryEngine.Instance.MovePointAlongLine(polyline, 3, true, 0, SegmentExtension.ExtendEmbeddedAtFrom);
// result = 5, 5, 10

// polyline with Z and M
List<MapPoint> inputPoints = new List<MapPoint>()
{
    MapPointBuilder.CreateMapPoint(1, 2, 3, 4),
    MapPointBuilder.CreateMapPoint(1, 2, 33, 44),
};

Polyline polylineZM = PolylineBuilder.CreatePolyline(inputPoints, SpatialReferences.WGS84);
// polylineZM.HasZ = true
// polylineZM.HasM = true

// ratio = true, no offset
MapPoint pointAlong = GeometryEngine.Instance.MovePointAlongLine(polylineZM, 0.5, true, 0, SegmentExtension.NoExtension);
// pointAlong = 1, 2, 18, 24

// ratio = true with offset
pointAlong = GeometryEngine.Instance.MovePointAlongLine(polylineZM, 0.2, true, 2.23606797749979, SegmentExtension.NoExtension);
// pointAlong = 1, 2, 9, 12

Requirements

Target Platforms: Windows 10, Windows 8.1, Windows 7

Reference

IGeometryEngine Interface
IGeometryEngine Members