Error using Arc as sweepPath CreateSweptGeometry

[dirk.neethling]

Hello,

I am trying to draw a sweep Profile in a Project document using

GeometryCreationUtilities.CreateSweptGeometry 
and
DirectShape.CreateElement

When I use a straight line for the sweepPath, all goes well. However, when I use an Arc, I get the following error:

exc = {"The Curve Loop does not lie in the plane orthogonal to the projPlaneNorm.\r\nParameter name: profileLoops"}

I suspect that the error comes from creating the SweepProfile on a plane which is not perpendicular to the Initial Gradient of the Arc.

In the method, I tesselate() the Arc, which somes in as a Curve, and then use the first line Segment as a Normal to determine the plane on which the SweepProfile is created.

So the question is, how do I obtain the Initial Gradient of an Arc, without using the line segments from the Tesselate() function?

Dirk

Here is the call wo the method:

ModelArc upperArc = CreateModelCurve(doc, planeTop, arc_top);
CurveLoop sweepes = new CurveLoop();
sweepes.Append(upperArc.GeometryCurve);
Solid seal = sealProfile(doc, fi, sweepes);

Below are the methods:

    Solid sealProfile(Document doc, FamilyInstance fi, CurveLoop sweeps)
    {
        CurveLoop profileLoop = null;
        Solid solid = null;
        Line initV = null;
        ElementId categoryId = new ElementId(BuiltInCategory.OST_GenericModel);
        DirectShape ds = null;
        List<GeometryObject> solids = null;

        try
        {
            //get the sweep, get plane per to first sweep vector, 
            //then you instantiate the cross-section in that plane to get it normal to the first sweep vector
            double param = sweeps.First().GetEndParameter(0);
            Curve firstCurve = sweeps.First();
            XYZ xyz = firstCurve.GetEndPoint(0);
            Transform tr = firstCurve.ComputeDerivatives(0, true);
            var v = XYZ.BasisZ;
            var v_normaltostartofarc = tr.OfVector(v);

            //tilt this profile into the sweep path
            XYZ endPoint1 = (sweeps.First() as Curve).Tessellate().ElementAt(0);
            XYZ endPoint2 = (sweeps.First() as Curve).Tessellate().ElementAt(1);
            initV = Line.CreateBound(endPoint1, endPoint2);
            var tangent = initV.Direction.CrossProduct(XYZ.BasisZ);
            Plane plane = new Plane(initV.Direction, endPoint1);

            var _profilepoints = new List<XYZ>() { 
                MmToFootPlanePoint(plane,new UV(-10,0)), 
                MmToFootPlanePoint(plane,new UV(-11.36,-7.7)), 
                MmToFootPlanePoint(plane,new UV(-14.15,-10.49)), 
                MmToFootPlanePoint(plane,new UV(-13,-16.5)), 
                MmToFootPlanePoint(plane,new UV(-11,-16.5)), 
                MmToFootPlanePoint(plane,new UV(-10.27,-13.78)), 
                MmToFootPlanePoint(plane,new UV(-9.41,-12.5)), 
                MmToFootPlanePoint(plane,new UV(-7.95,-12)), 
                MmToFootPlanePoint(plane,new UV(-6.49,-12.5)), 
                MmToFootPlanePoint(plane,new UV(-5.63,-13.78)), 
                MmToFootPlanePoint(plane,new UV(-4.91,-16.5)), 
                MmToFootPlanePoint(plane,new UV(-2.91,-16.5)), 
                MmToFootPlanePoint(plane,new UV(-2.18,-13.78)), 
                MmToFootPlanePoint(plane,new UV(-1.4,-12.5)), 
                MmToFootPlanePoint(plane,new UV(0,-12)), 
                MmToFootPlanePoint(plane,new UV(1.4,-12.5 )), 
                MmToFootPlanePoint(plane,new UV(2.18,-13.78)), 
                MmToFootPlanePoint(plane,new UV(2.91,-16.5)), 
                MmToFootPlanePoint(plane,new UV(4.91,-16.5)), 
                MmToFootPlanePoint(plane,new UV(5.63,-13.78)), 
                MmToFootPlanePoint(plane,new UV(6.49,-12.5)), 
                MmToFootPlanePoint(plane,new UV(7.95,-12)), 
                MmToFootPlanePoint(plane,new UV(9.41,-12.5)), 
                MmToFootPlanePoint(plane,new UV(10.27,-13.78)), 
                MmToFootPlanePoint(plane,new UV(11,-16.5)), 
                MmToFootPlanePoint(plane,new UV(13,-16.5)), 
                MmToFootPlanePoint(plane,new UV(14.15,-10.49)), 
                MmToFootPlanePoint(plane,new UV(11.36,-7.7)), 
                MmToFootPlanePoint(plane,new UV(10,0)), 
                MmToFootPlanePoint(plane,new UV(-10,0))
            };

            profileLoop = new CurveLoop();

            for (int i = 0; i < (_profilepoints.Count - 1); i++)
            {
                Line line = Line.CreateBound(_profilepoints[i], _profilepoints[i + 1]);
                profileLoop.Append(line);
            }
            //rotate profileLoop on plane into position
            var angle = Math.PI / 2 + Angle.DegreeToRadiant(33.75);
            var transform = Transform.CreateRotationAtPoint(plane.Normal, angle, endPoint1);
            profileLoop.Transform(transform);
            IList<CurveLoop> profileLoops = new List<CurveLoop>();
            profileLoops.Add(profileLoop);

            SolidOptions solOptions = new SolidOptions(ElementId.InvalidElementId, ElementId.InvalidElementId);
            solid = GeometryCreationUtilities.CreateSweptGeometry(sweeps /*sweepPath*/, 0, param, profileLoops, solOptions);

            categoryId = new ElementId(BuiltInCategory.OST_GenericModel);
            ds = DirectShape.CreateElement(doc, categoryId, Guid.NewGuid().ToString(), Guid.NewGuid().ToString());
            solids = new List<GeometryObject>() { solid };
            ds.SetShape(solids);
            ds.Name = "ExtrusionTest3";
            //SolidSolidCutUtils 
        }
        catch (Exception exc)
        {
            Debug.WriteLine(exc);
        }

        return solid;
    }

    public ModelArc CreateModelCurve(Document document, Plane geomPlane, Arc geomArc)
    {
        // get handle to application from document
        Autodesk.Revit.ApplicationServices.Application application = document.Application;

        // Create a sketch plane in current document
        SketchPlane sketch = SketchPlane.Create(document, geomPlane);

        // Create a ModelArc element using the created geometry arc and sketch plane
        ModelArc arc = document.Create.NewModelCurve(geomArc, sketch) as ModelArc;

        return arc;
    }

   public static XYZ MmToFootPlanePoint(Plane plane, UV pt)
    {
        return plane.Origin + plane.XVec.Multiply(pt.U / 304.8) + plane.YVec.Multiply(pt.V / 304.8);
    }

[FAIR59 · Accepted solution]

the direction of a curve is the BasisX vector of ComputeDerivatives( ).

the point on the curve is the Origin of ComputeDerivatives( ).

so your plane is:

Plane plane = new Plane(tr.BasisX.Normalize(), tr.Origin);

[dirk.neethling]

Thanks FAIR59, that solved the issue. I have another question: I am creating a sweepPath, composed of 2 Arcs on planes directly above each other, which are connected by their endpoints. In which direction are Arcs drawn? Does the sweepPath need to be a closed loop?