RhinoCommon:Transform

注意以下Transform写法：

    public static Rhino.Commands.Result ConstrainedCopy(Rhino.RhinoDoc doc)
    {
        // Get a single planar closed curve
        var go = new Rhino.Input.Custom.GetObject();
        go.SetCommandPrompt("Select curve");
        go.GeometryFilter = Rhino.DocObjects.ObjectType.Curve;
        go.GeometryAttributeFilter = Rhino.Input.Custom.GeometryAttributeFilter.ClosedCurve;
        go.Get();
        if( go.CommandResult() != Rhino.Commands.Result.Success )
          return go.CommandResult();
        var objref = go.Object(0);
        var base_curve = objref.Curve();
        var first_point = objref.SelectionPoint();
        if( base_curve==null || !first_point.IsValid )
          return Rhino.Commands.Result.Cancel;

        Rhino.Geometry.Plane plane;
        if( !base_curve.TryGetPlane(out plane) )
          return Rhino.Commands.Result.Cancel;

        // Get a point constrained to a line passing through the initial selection
        // point and parallel to the plane's normal
        var gp = new Rhino.Input.Custom.GetPoint();
        gp.SetCommandPrompt("Offset point");
        gp.DrawLineFromPoint(first_point, true);
        var line = new Rhino.Geometry.Line(first_point, first_point+plane.Normal);
        gp.Constrain(line);
        gp.Get();
        if( gp.CommandResult() != Rhino.Commands.Result.Success )
          return gp.CommandResult();
        var second_point = gp.Point();
        Rhino.Geometry.Vector3d vec = second_point - first_point;
        if( vec.Length > 0.001 )
        {
          var xf = Rhino.Geometry.Transform.Translation(vec);
          Guid id = doc.Objects.Transform(objref, xf, false);
          if( id!=Guid.Empty )
          {
        doc.Views.Redraw();
        return Rhino.Commands.Result.Success;
          }
        }
        return Rhino.Commands.Result.Cancel;
    }