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Object Model Reference : Classes : S : SubPath : Methods : SubPath.GetTangentAt


SubPath.GetTangentAt

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

Description

Member of SubPath

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

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

VBA example

The following VBA 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

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