3D equivalent of a 2d curve on a surface

The Inventor 2013 API has several new methods for SurfaceEvaluator. One of these new methods allows you to get the equivalent 3D curve for a 2D curve defined in the parametric space of the surface.

New 2013 method: 

• SurfaceEvaluator.Get3dCurveFrom2dCurve()

VBA Example:

Keep in mind that we only recommend using VBA for prototyping and learning the API but do not recommend using VBA in production.

To use this example have a part file open and run the code. First it will prompt you to select a face. (The second time the code is run it will prompt to find out if you want to keep the existing client graphics).

It will then create several curves in the 2d parametric space. Then it gets the equivalent 3D curves, and creates those as client graphics to allow you to view the results. You can see the curves lie on the surface now, but they were originally defined as circle and five lines, but they came back as curves, because the surface is curved.

VBA Code:

' Demonstrates the conversion of a 2d parameteric
' space curve into the ' equivalent 3d model space
' curve.  To use this sample you must have a part
' open.  You can select any face and 3D curves
' will be drawn on the face using client graphics
Public Sub ParamCurveto3D()
   ' Have the user select a face whose parametric
    ' space will be used
    Dim testFace As Face
    Set testFace = ThisApplication. _
             CommandManager.Pick _
           (kPartFaceFilter, "Select a face")
   
    ' Get the surface evaluator from the face
    Dim surfEval As SurfaceEvaluator
    Set surfEval = testFace.Evaluator
   
    ' Get the parametric range of the face
    Dim paramRange As Box2d
    Set paramRange = surfEval.ParamRangeRect
   
   ' Get the transient geometry object
    Dim tg As TransientGeometry
    Set tg = ThisApplication.TransientGeometry
   
   ' Get the active document.  This assumes
    ' a part is active
    Dim partDoc As PartDocument
    Set partDoc = ThisApplication.ActiveDocument
   
   ' Create a client graphics object.  If one
    ' already exists, give the user
    ' the option of re-using it, or creating
    ' a new one.
    Dim graphics As ClientGraphics
    On Error Resume Next
    Set graphics = partDoc.ComponentDefinition. _
             ClientGraphicsCollection.Item("Test")
    If Err Then
     Set graphics = partDoc.ComponentDefinition. _
          ClientGraphicsCollection.Add("Test")
    Else
        If MsgBox("Yes add to existing graphics No = new", _
        vbYesNo + vbQuestion) = vbNo Then
            graphics.Delete
           
            Set graphics = partDoc.ComponentDefinition. _
            ClientGraphicsCollection.Add("Test")
        End If
    End If
   
    ' Create a new graphics node.
    Dim node As GraphicsNode
    Set node = graphics.AddNode(1)

    ' Do a loop that creates 5 lines that go
    ' from the minimum range point to
    ' five points along the maximum u parameter.
    Dim startPnt As Point2d
    Set startPnt = paramRange.MinPoint
    Dim endPnt As Point2d
    Dim i As Integer
    For i = 1 To 5
       ' Create the 2d line in parametric space
        Set endPnt = tg.CreatePoint2d _
          (paramRange.MaxPoint.X, (((paramRange. _
                MaxPoint.y – paramRange.MinPoint.y) _
             / 4) * (i – 1)) + paramRange.MinPoint.y)
       
        Dim surfCurve As LineSegment2d
        Set surfCurve = tg.CreateLineSegment2d _
                                    (startPnt, endPnt)
       
        ' Get the equivalent 3d curve in model space
        Dim resultCurve As Object
        Set resultCurve = surfEval. _
                       Get3dCurveFrom2dCurve(surfCurve)
       
        ' Create client graphics for this curve
        Dim crvGraphics As CurveGraphics
        Set crvGraphics = node.AddCurveGraphics _
                                          (resultCurve)
        crvGraphics.DepthPriority = 2
    Next
   
   ' Create a 2d circle in parametric space
    Dim center As Point2d
    Set center = tg.CreatePoint2d _
      ((paramRange.MaxPoint.X + paramRange.MinPoint.X) _
                         / 2, (paramRange.MaxPoint.y + _
                              paramRange.MinPoint.y) / 2)
   
    Dim radius As Double
    radius = (paramRange.MaxPoint.X – _
                           paramRange.MinPoint.X) * 0.25
    Dim paramCircle As Circle2d
    Set paramCircle = tg.CreateCircle2d(center, radius)
   
    ' Get the equivalent 3d curve in model space
    Set resultCurve = surfEval. _
                       Get3dCurveFrom2dCurve(paramCircle)
   
   ' Create client graphics for this curve
    Set crvGraphics = node.AddCurveGraphics(resultCurve)
    crvGraphics.DepthPriority = 2
       
    ThisApplication.ActiveView.Update
    ThisApplication.ActiveView.Fit
End Sub

-Wayne