/// <summary>
/// Return elbow centre point.
/// Return null if the start and end points
/// and direction vectors are not all coplanar.
/// </summary>
XYZ GetElbowCentre(Element e)
{
XYZ pc = null;
List <Connector> cons = GetElbowConnectors(e);
if (null != cons)
{
// Get start and end point and direction
XYZ ps = cons[0].CoordinateSystem.Origin;
XYZ vs = cons[0].CoordinateSystem.BasisZ;
XYZ pe = cons[1].CoordinateSystem.Origin;
XYZ ve = cons[1].CoordinateSystem.BasisZ;
XYZ vd = pe - ps;
// For a regular elbow, Z vector is normal
// of the 2D plane spanned by the coplanar
// start and end points and direction vectors.
XYZ vz = vs.CrossProduct(vd);
if (!vz.IsZeroLength())
{
XYZ vxs = vs.CrossProduct(vz);
XYZ vxe = ve.CrossProduct(vz);
pc = Util.LineLineIntersection(
ps, vxs, pe, vxe);
}
}
return(pc);
}
