# Connect Two Curves

This Rhino script allows the user to select two curves to be connected, closing them into a single polyline, using either a rough equivalent of blend curve or straight connections… or not, it’s your call, give it a try you’ll see what I mean. Its a great time saver for closing offset curves.

### Rhino Script

```Option Explicit
'Script written by <David Mans>
'Script copyrighted by <Neoarchaic Design>
'Script version Monday, September 01, 2008 6:39:25 AM

Call Main()
Sub Main()
Call connectTwoCurves()
End Sub
Function connectTwoCurves()
connectTwoCurves = Null
Dim curve(1)
curve(0) = Rhino.GetObject("Select Curve 1", 4)
If isNull(curve(0)) Then Exit Function
curve(1) = Rhino.GetObject("Select Curve 2", 4)
If isNull(curve(1)) Then Exit Function
Call Rhino.EnableRedraw(False)
Dim dir
Dim ptA(1),ptB(1),dist(1),cap(1)
ptA(0) = Rhino.CurveStartPoint(curve(0))
ptA(1) = Rhino.CurveEndPoint(curve(0))
ptB(0) = Rhino.CurveStartPoint(curve(1))
ptB(1) = Rhino.CurveEndPoint(curve(1))
dist(0) = Rhino.Distance(ptA(0), ptB(0))
dist(1) = Rhino.Distance(ptA(0), ptB(1))

If dist(0) = dist(1) Then
dir = True
cap(0) = Rhino.AddLine(ptA(0), ptB(0))
cap(1) = Rhino.AddLine(ptA(1), ptB(1))
Else
If dist(0) < dist(1) Then
dir = True
cap(0) = Rhino.AddLine(ptA(0), ptB(0))
cap(1) = Rhino.AddLine(ptA(1), ptB(1))
Else
dir = False
cap(0) = Rhino.AddLine(ptA(0), ptB(1))
cap(1) = Rhino.AddLine(ptA(1), ptB(0))
End If
End If
Call Rhino.EnableRedraw(True)
Dim arrResults,arrInputs,arrValues
arrInputs = array("Flip", "Yes", "No", "Type", "Smooth", "Straight", "Join", "Yes", "No")
arrValues = array(True, True, False)
arrResults = Rhino.GetBoolean("Connection Options", arrInputs, arrValues)

Call Rhino.EnableRedraw(False)
Dim tan(3),blend, ptC(3)
If arrResults(1) = False Then
Call Rhino.DeleteObjects(cap)
blend = 0.25
tan(0) = Rhino.VectorScale(Rhino.VectorUnitize(Rhino.VectorReverse(Rhino.CurveTangent(curve(0), Rhino.CurveDomain(curve(0))(0)))), Rhino.Distance(ptA(0), ptA(1)) * blend)
tan(1) = Rhino.VectorScale(Rhino.VectorUnitize(Rhino.CurveTangent(curve(0), Rhino.CurveDomain(curve(0))(1))), Rhino.Distance(ptA(0), ptA(1)) * blend)
tan(2) = Rhino.VectorScale(Rhino.VectorUnitize(Rhino.VectorReverse(Rhino.CurveTangent(curve(1), Rhino.CurveDomain(curve(1))(0)))), Rhino.Distance(ptB(0), ptB(1)) * blend)
tan(3) = Rhino.VectorScale(Rhino.VectorUnitize(Rhino.CurveTangent(curve(1), Rhino.CurveDomain(curve(1))(1))), Rhino.Distance(ptB(0), ptB(1)) * blend)

ptC(0) = Rhino.PointAdd(Rhino.CurveStartPoint(curve(0)), tan(0))
ptC(1) = Rhino.PointAdd(Rhino.CurveEndPoint(curve(0)), tan(1))
ptC(2) = Rhino.PointAdd(Rhino.CurveStartPoint(curve(1)), tan(2))
ptC(3) = Rhino.PointAdd(Rhino.CurveEndPoint(curve(1)), tan(3))
If arrResults(0) = True Then
If dir = False Then
cap(0) = Rhino.AddCurve(array(ptA(0), ptC(0), ptC(3), ptB(1)), 3)
cap(0) = Rhino.AddCurve(array(ptA(1), ptC(1), ptC(2), ptB(0)), 3)
Else
cap(0) = Rhino.AddCurve(array(ptA(0), ptC(0), ptC(2), ptB(0)), 3)
cap(0) = Rhino.AddCurve(array(ptA(1), ptC(1), ptC(3), ptB(1)), 3)
End If
Else
If dir = False Then
cap(0) = Rhino.AddCurve(array(ptA(0), ptC(0), ptC(2), ptB(0)), 3)
cap(0) = Rhino.AddCurve(array(ptA(1), ptC(1), ptC(3), ptB(1)), 3)
Else
cap(0) = Rhino.AddCurve(array(ptA(0), ptC(0), ptC(3), ptB(1)), 3)
cap(0) = Rhino.AddCurve(array(ptA(1), ptC(1), ptC(2), ptB(0)), 3)
End If

End If
Else
If arrResults(0) = False Then
Call Rhino.DeleteObjects(cap)
If dir = False Then
cap(0) = Rhino.AddLine(ptA(0), ptB(0))
cap(1) = Rhino.AddLine(ptA(1), ptB(1))
Else
cap(0) = Rhino.AddLine(ptA(0), ptB(1))
cap(1) = Rhino.AddLine(ptA(1), ptB(0))
End If
Else

End If
End If
If arrResults(2) = False Then
Call Rhino.JoinCurves(array(curve(0), cap(0), curve(1), cap(1)), True)
End If
Call Rhino.EnableRedraw(True)

connectTwoCurves = array()
End Function
```