Sweep with the same path/profile produce different results when different path sketch planes are used

By Mikako Harada

Issue

I created a very simple sweep solid with a simple rectangular profile on a xy-plane, sweeping along z-axis.  However, depending on the sketch plane I used (e.g., xz-plane or yz-plane), the results are different. Why is that?  

The following code demonstrates my problem. 

public void CreateSweep()
        {
            Transaction trans = new Transaction(m_rvtDoc, "Sweep");
            trans.Start();
 
            SweepProfile profile = CreateSweepProfile();
 
            // (1) the path plane is xz-plane 
            //     Plane(normal, origin) 
 
            Plane plane1 = 
              new Plane(new XYZ(0, 1, 0), new XYZ(0, 0, 0));
            SketchPlane sketchPlane1 = 
              m_rvtDoc.FamilyCreate.NewSketchPlane(plane1);
 
            Lineline1 = m_rvtApp.Create.NewLineBound(
              new XYZ(0, 0, 0), new XYZ(0, 0, 1));
            ModelCurve mLine1 = m_rvtDoc.FamilyCreate.NewModelCurve(
              line1, sketchPlane1);
            CurveArray pathArray1 = new CurveArray();
            pathArray1.Append(line1);
            m_rvtDoc.FamilyCreate.NewSweep(
              true, pathArray1, sketchPlane1, 
              profile, 0, ProfilePlaneLocation.Start);
             
            // (2) the path plane is yz-plane 
 
            Plane plane2 = new Plane(
              new XYZ(1, 0, 0), new XYZ(0, 0, 0));
            SketchPlane sketchPlane2 = 
               m_rvtDoc.FamilyCreate.NewSketchPlane(plane2);
 
            Line line2 = m_rvtApp.Create.NewLineBound(
              new XYZ(0, 0, 0), new XYZ(0, 0, 2));
            ModelCurve mLine2 = m_rvtDoc.FamilyCreate.NewModelCurve(
              line2, sketchPlane2);
            CurveArray pathArray2 = new CurveArray();
            pathArray2.Append(line2);
            m_rvtDoc.FamilyCreate.NewSweep(
              true, pathArray2, sketchPlane2, 
              profile, 0, ProfilePlaneLocation.Start);
             
            trans.Commit();
        }

private SweepProfile CreateSweepProfile()
        {
            XYZ pt1 = new XYZ(0, 0, 0);
            XYZ pt2 = new XYZ(10, 0, 0);
            XYZ pt3 = new XYZ(10, 20, 0);
            XYZ pt4 = new XYZ(0, 20, 0);
 
            Line line1 = m_rvtApp.Create.NewLineBound(pt1, pt2);
            Line line2 = m_rvtApp.Create.NewLineBound(pt2, pt3);
            Line line3 = m_rvtApp.Create.NewLineBound(pt3, pt4);
            Line line4 = m_rvtApp.Create.NewLineBound(pt4, pt1);
 
            CurveArray curArray = new CurveArray();
            curArray.Append(line1);
            curArray.Append(line2);
            curArray.Append(line3);
            curArray.Append(line4);
 
            CurveArrArray curArrArray = new CurveArrArray();
            curArrArray.Append(curArray);
 
            SweepProfile result = 
              m_rvtApp.Create.NewCurveLoopsProfile(curArrArray);
 
            return result;
        }

 
Solution
 
This is actually "as designed" behavior. Even though mathematically it does look like both should produce the same result, the behavior of this function is analogous to the UI's; i.e., the profile's coordinate system is defined at the starting point of path, where the direction of the path is the z-axis, and sketch plane's normal is y-direction. 
In the above example, the first one uses the same coordinate for both profile and sweep, while the second one will take z-direction as z-axis (the direction of path), and x-direction as y-axis of sweep (as defined as a normal of the sketch plane), resulting that the profile will be rotated.