SubPath.GetTangentAt

Function GetTangentAt([Offset As Double = 0.5], [OffsetType As cdrSegmentOffsetType = cdrRelativeSegmentOffset]) As Double

Member of SubPath

The GetTangentAt method returns the tangent to a point on a curve’s subpath.


Parameters	Description
Offset	Specifies the offset, in document units, of the tangent This parameter is optional, and its default value is 0.5.
OffsetType	Specifies the type of offset. This parameter returns cdrSegmentOffsetType. This parameter is optional, and its default value is cdrRelativeSegmentOffset (1).

The following code example draws perpendicular and tangent vectors for several points uniformly distributed along the subpaths of the selected curve:

Sub Test() 
 Dim sp As SubPath 
 Dim t As Double 
 For Each sp In ActiveShape.Curve.Subpaths 
  For t = 0 To 0.9 Step 0.1 
   MarkPoint sp, t 
  Next t 
 Next sp 
End Sub 
Private Sub MarkPoint(sp As SubPath, t As Double) 
 Dim x As Double, y As Double 
 Dim dx As Double, dy As Double 
 Dim a1 As Double, a2 As Double 
 sp.GetPointPositionAt x, y, t, cdrRelativeSegmentOffset 
 a1 = sp.GetTangentAt(t, cdrRelativeSegmentOffset) * 3.1415926 / 180 
 a2 = sp.GetPerpendicularAt(t, cdrRelativeSegmentOffset) * 3.1415926 
/ 180 
 dx = 0.5 * Cos(a1) 
 dy = 0.5 * Sin(a1) 
 With ActiveLayer.CreateLineSegment(x, y, x + dx, y + dy) 
  .Outline.EndArrow = ArrowHeads(1) 
 End With 
 dx = 0.5 * Cos(a2) 
 dy = 0.5 * Sin(a2) 
 With ActiveLayer.CreateLineSegment(x, y, x + dx, y + dy) 
  .Outline.EndArrow = ArrowHeads(1) 
 End With 
End Sub