The line:
curvePiece = curvePiece.MakeBound(paraIntersection1, cv1.GetEndParameter(1))
Effectively creates a 0 length curve because you have changed the variable cv1 already to make the EndParameter(1) match the parameter of your intersection result.
You should instead create two new curves from the unchanged original as below.
Note also the parameters returned by GetEndPointParameter can really only be used as you are doing for straight lines. Other types of curves have a different parameter relationship to the curve length e.g. arc parameters are given in terms of an angle which you would have to multiply by the radius to get the arc segment length. Elliptical arcs are more complicated to get segment lengths from to test for short curves. Probably for such cases it is easier to catch the exception. Although perhaps someone else is aware of a more convenient method for getting curve lengths without first creating the curve.
C#
public object SplitCurve(Autodesk.Revit.UI.ExternalCommandData commandData, ref string message, Autodesk.Revit.DB.ElementSet elements)
{
if (commandData.Application.ActiveUIDocument == null)
return Result.Succeeded;
UIDocument IntUIDoc = commandData.Application.ActiveUIDocument;
Document IntDoc = IntUIDoc.Document;
Reference R = null;
try
{
R = IntUIDoc.Selection.PickObject(ObjectType.Element);
}
catch (Exception)
{
}
if (R == null)
return Result.Cancelled;
XYZ Pt = R.GlobalPoint;
Element El = IntDoc.GetElement(R);
CurveElement CE = El as CurveElement;
if (CE == null)
return Result.Failed;
Curve Crv0 = CE.GeometryCurve;
IntersectionResult IR = Crv0.Project(Pt);
Curve Crv_Pt1 = Crv0.Clone();
Curve Crv_Pt2 = Crv0.Clone();
double SCT = commandData.Application.Application.ShortCurveTolerance;
if (Crv0.GetType() == typeof(Line))
{
double L1 = Math.Abs(IR.Parameter - Crv0.GetEndParameter(0));
double L2 = Math.Abs(Crv0.GetEndParameter(1) - IR.Parameter);
if (L1 < SCT || L2 < SCT)
{
TaskDialog.Show("Error", "Resulting curve parts too small.");
return Result.Failed;
}
else
{
Crv_Pt1.MakeBound(Crv0.GetEndParameter(0), IR.Parameter);
Crv_Pt2.MakeBound(IR.Parameter, Crv0.GetEndParameter(1));
}
}
else
{
try
{
Crv_Pt1.MakeBound(Crv0.GetEndParameter(0), IR.Parameter);
Crv_Pt2.MakeBound(IR.Parameter, Crv0.GetEndParameter(1));
}
catch (Exception ex)
{
TaskDialog.Show("Error", ex.Message);
return Result.Failed;
}
}
using (Transaction Tx = new Transaction(IntDoc, "Curve split"))
{
if (Tx.Start() == TransactionStatus.Started)
{
IntDoc.Create.NewDetailCurve(IntDoc.ActiveView, Crv_Pt1);
IntDoc.Create.NewDetailCurve(IntDoc.ActiveView, Crv_Pt2);
IntDoc.Delete(El.Id);
Tx.Commit();
}
}
return Result.Succeeded;
}
VB:
Public Function SplitCurve(ByVal commandData As Autodesk.Revit.UI.ExternalCommandData, _
ByRef message As String, ByVal elements As Autodesk.Revit.DB.ElementSet)
If commandData.Application.ActiveUIDocument Is Nothing Then Return Result.Succeeded Else
Dim IntUIDoc As UIDocument = commandData.Application.ActiveUIDocument
Dim IntDoc As Document = IntUIDoc.Document
Dim R As Reference = Nothing
Try
R = IntUIDoc.Selection.PickObject(Selection.ObjectType.Element)
Catch ex As Exception
End Try
If R Is Nothing Then Return Result.Cancelled Else
Dim Pt As XYZ = R.GlobalPoint
Dim El As Element = IntDoc.GetElement(R)
Dim CE As CurveElement = TryCast(El, CurveElement)
If CE Is Nothing Then Return Result.Failed Else
Dim Crv0 As Curve = CE.GeometryCurve
Dim IR As IntersectionResult = Crv0.Project(Pt)
Dim Crv_Pt1 As Curve = Crv0.Clone
Dim Crv_Pt2 As Curve = Crv0.Clone
Dim SCT As Double = commandData.Application.Application.ShortCurveTolerance
If Crv0.GetType = GetType(Line) Then
Dim L1 As Double = Math.Abs(IR.Parameter - Crv0.GetEndParameter(0))
Dim L2 As Double = Math.Abs(Crv0.GetEndParameter(1) - IR.Parameter)
If L1 < SCT OrElse L2 < SCT Then
TaskDialog.Show("Error", "Resulting curve parts too small.")
Return Result.Failed
Else
Crv_Pt1.MakeBound(Crv0.GetEndParameter(0), IR.Parameter)
Crv_Pt2.MakeBound(IR.Parameter, Crv0.GetEndParameter(1))
End If
Else
Try
Crv_Pt1.MakeBound(Crv0.GetEndParameter(0), IR.Parameter)
Crv_Pt2.MakeBound(IR.Parameter, Crv0.GetEndParameter(1))
Catch ex As Exception
TaskDialog.Show("Error", ex.Message)
Return Result.Failed
End Try
End If
Using Tx As New Transaction(IntDoc, "Curve split")
If Tx.Start = TransactionStatus.Started Then
IntDoc.Create.NewDetailCurve(IntDoc.ActiveView, Crv_Pt1)
IntDoc.Create.NewDetailCurve(IntDoc.ActiveView, Crv_Pt2)
IntDoc.Delete(El.Id)
Tx.Commit()
End If
End Using
Return Result.Succeeded
End Function
