PickCurveAndCreateDirectShape.cs

using Autodesk.Revit.Attributes;
using Autodesk.Revit.DB;
using Autodesk.Revit.UI;
using Autodesk.Revit.UI.Selection;
using Autodesk.Revit.DB.Analysis;

[Transaction(TransactionMode.Manual)]
public class PickCurveAndCreateDirectShape : IExternalCommand
{
    public Result Execute(
      ExternalCommandData commandData,
      ref string message,
      ElementSet elements)
    {
        UIApplication uiapp = commandData.Application;
        UIDocument uidoc = uiapp.ActiveUIDocument;
        Document doc = uidoc.Document;

        try
        {
            // Pick a curve
            Reference pickedRef = uidoc.Selection.PickObject(ObjectType.Element, new CurveSelectionFilter(), "Select a curve");
            Element element = doc.GetElement(pickedRef);
            PathOfTravel curveElement = element as PathOfTravel;
            IList<Curve> pickedCurves = curveElement.GetCurves();

            // Define the height of the extrusion
            double extrusionHeight = 100.0;
            double width = 5.0; // Define the width of the rectangle

            List<Solid> solids = new List<Solid>();

            foreach (Curve pickedCurve in pickedCurves)
            {
                // Create the offset profile for each curve
                List<Curve> profile = CreateOffsetProfile(pickedCurve, width);
                CurveLoop profileLoop = CurveLoop.Create(profile);
                List<CurveLoop> curveLoops = new List<CurveLoop> { profileLoop };

                // Create the solid geometry
                SolidOptions options = new SolidOptions(ElementId.InvalidElementId, ElementId.InvalidElementId);
                Solid solid = GeometryCreationUtilities.CreateExtrusionGeometry(curveLoops, XYZ.BasisZ, extrusionHeight);
                solids.Add(solid);
            }

            using Transaction tx = new Transaction(doc);
            tx.Start("Create DirectShape");

            // Create the DirectShape
            DirectShape ds = DirectShape.CreateElement(doc, new ElementId(BuiltInCategory.OST_GenericModel));
            ds.SetShape(solids.Cast<GeometryObject>().ToArray());
            ds.Name = "MyDirectShape";

            // Commit the transaction
            tx.Commit();
            // MessageBox.Show("DirectShape created successfully.");

            return Result.Succeeded;
        }
        catch (Exception ex)
        {
            message = ex.ToString();
            return Result.Failed;
        }
    }

    private List<Curve> CreateOffsetProfile(Curve curve, double width)
    {
        XYZ startPoint = curve.GetEndPoint(0);
        XYZ endPoint = curve.GetEndPoint(1);
        XYZ direction = (endPoint - startPoint).Normalize();
        XYZ perpendicular = XYZ.BasisZ.CrossProduct(direction).Normalize();
        XYZ offset = perpendicular * (width / 2.0);

        // Create the offset points
        XYZ offsetStart1 = startPoint - offset;
        XYZ offsetEnd1 = endPoint - offset;
        XYZ offsetStart2 = startPoint + offset;
        XYZ offsetEnd2 = endPoint + offset;

        List<Curve> profile = new List<Curve>
        {
            Line.CreateBound(offsetStart1, offsetEnd1),
            Line.CreateBound(offsetEnd1, offsetEnd2),
            Line.CreateBound(offsetEnd2, offsetStart2),
            Line.CreateBound(offsetStart2, offsetStart1)
        };

        return profile;
    }
}

public class CurveSelectionFilter : ISelectionFilter
{
    public bool AllowElement(Element elem)
    {
        return elem is PathOfTravel;
    }

    public bool AllowReference(Reference reference, XYZ position)
    {
        return false;
    }
}