Add sketch3d circle by three sketch3d points

By Xiaodong Liang

UI has not the ability to create 3d circle by 3 points while API can AddByThreePoints. But the problem are:

1) AddByThreePoints failed if the arguments are sketch3d points. In the help document, AddByThreePoints does not indicate if the argument should be Point only, but it does not either obviously show the argument could be SketchPoint3d. While other method such as SketchLines3D.AddByTwoPoints indicates SketchPoint3d is also acceptable. So, the workaround is to get the geometry of each sketchpoint3d and create the circle.

2) Even though the circle is created, those sketchpoint3d are not constrained with the circle. To solve it, we need to add Coincident constraint for each point. Finally, the circle can be updated if the points update.

Sub create3DCircleBy3Points()
 
        ' get active Inventor process
        Dim InvApp As Inventor.Application = _
             Runtime.InteropServices.Marshal. _
             GetActiveObject("Inventor.Application")
 
        ' get TransientGeometry
        Dim oTG As TransientGeometry
        oTG = InvApp.TransientGeometry
 
        ' create three points
        Dim oStrP As Point
        oStrP = oTG.CreatePoint(1, 0, 3)
 
        Dim oMidP As Point
        oMidP = oTG.CreatePoint(0, 1, 3)
 
        Dim oEndP As Point
        oEndP = oTG.CreatePoint(-1, 0, 3)
 
 
        ' get current document
        Dim oDoc As PartDocument
        oDoc = InvApp.ActiveDocument
 
        Dim pdef As PartComponentDefinition
        pdef = oDoc.ComponentDefinition
 
        ' add the sketch3d
        Dim oSketch3d As Sketch3D
        oSketch3d = pdef.Sketches3D.Add()
 
        ' add p1, p2, p3 as sketch 3d point 
        Dim oP1_sketch As SketchPoint3D
        oP1_sketch = oSketch3d.SketchPoints3D.Add(oStrP)
 
        Dim oP2_sketch As SketchPoint3D
        oP2_sketch = oSketch3d.SketchPoints3D.Add(oMidP)
 
        Dim oP3_sketch As SketchPoint3D
        oP3_sketch = oSketch3d.SketchPoints3D.Add(oEndP)
 
        Dim oSketch3DCircle As SketchCircle3D
 
        ' this failed because AddByThreePoints does not accept
        ' SketchPoint3D
 
        'oSketch3d.SketchCircles3D.AddByThreePoints(oP1_sketch, _
        '                                           oP2_sketch, _
        '                                           oP3_sketch)
 
 
        ' we intensionlly get the geometry (point) again
        ' this mimic if we have had some SketchPoint3D
 
        Dim oP1_Geometry As Point
        oP1_Geometry = oP1_sketch.Geometry
 
        Dim oP2_Geometry As Point
        oP2_Geometry = oP2_sketch.Geometry
 
        Dim oP3_Geometry As Point
        oP3_Geometry = oP3_sketch.Geometry
 
 
        oSketch3DCircle = oSketch3d.SketchCircles3D. _
                        AddByThreePoints(oP1_Geometry, _
                                         oP2_Geometry, _
                                         oP3_Geometry)
 
        ' add GeometricConstraint
        Dim oCC3D1 As CoincidentConstraint3D
        oCC3D1 = oSketch3d.GeometricConstraints3D. _
                AddCoincident(oSketch3DCircle, oP1_sketch)
 
 
        Dim oCC3D2 As CoincidentConstraint3D
        oCC3D2 = oSketch3d.GeometricConstraints3D. _
                AddCoincident(oSketch3DCircle, oP2_sketch)
 
        Dim oCC3D3 As CoincidentConstraint3D
        oCC3D3 = oSketch3d.GeometricConstraints3D. _
                AddCoincident(oSketch3DCircle, oP3_sketch)
 
 
 
 
    End Sub