Creating a mass from Toposurface geometry

Following up this suggestion from Julien, here’s a look at how to create a massing family with geometry built from the mesh of a toposurface.

public void topoToMass()
{
    Document doc = this.ActiveUIDocument.Document;
    UIDocument uidoc = this.ActiveUIDocument;
    Application app = this.Application;

    TopographySurface topo = doc.GetElement(uidoc.Selection.PickObject(ObjectType.Element)) as TopographySurface;

    Mesh mesh = topo.get_Geometry(new Options()).First(q => q is Mesh) as Mesh;

    Document famDoc = app.NewFamilyDocument(@"C:\ProgramData\Autodesk\RAC 2014\Family Templates\English_I\Conceptual Mass\Mass.rft");

    using (Transaction t = new Transaction(famDoc,"Create massing surfaces"))
    {
        t.Start();

        for (int i = 0; i < mesh.NumTriangles; i++)
        {
            MeshTriangle mt = mesh.get_Triangle(i);
            makeForm(famDoc, mt.get_Vertex(0), mt.get_Vertex(1), mt.get_Vertex(2));

            if (i > 0 && i % 100 == 0)
            {
                TaskDialog td = new TaskDialog("Form Counter");
                td.CommonButtons = TaskDialogCommonButtons.Yes|TaskDialogCommonButtons.No;
                td.MainInstruction = i + " out of " + mesh.NumTriangles + " triangles processed. Do you want to continue?";
                if (td.Show() == TaskDialogResult.No)
                    break;
            }
        }
        t.Commit();
    }
    famDoc.LoadFamily(doc);
}

private Form makeForm(Document doc, XYZ pt1, XYZ pt2, XYZ pt3)
{
    Form form = null;

    XYZ u = pt2.Subtract(pt1);
    XYZ v = pt3.Subtract(pt1);
    double area = u.CrossProduct(v).GetLength()/2;
    if (area < 10)
        return null;

    ReferenceArray ra = new ReferenceArray();
    ra.Append(MakeCuveByPoints(doc, pt1, pt2).GeometryCurve.Reference);
    ra.Append(MakeCuveByPoints(doc, pt2, pt3).GeometryCurve.Reference);
    ra.Append(MakeCuveByPoints(doc, pt3, pt1).GeometryCurve.Reference);

    form = doc.FamilyCreate.NewFormByCap(true, ra);

    return form;
}

private CurveByPoints MakeCuveByPoints(Document doc, XYZ ptA, XYZ ptB)
{
    ReferencePointArray rpa = new ReferencePointArray();
    rpa.Append(doc.FamilyCreate.NewReferencePoint(ptA));
    rpa.Append(doc.FamilyCreate.NewReferencePoint(ptB));
    return doc.FamilyCreate.NewCurveByPoints(rpa);
}