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.


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).

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