public static double DistanceBetweenPoints(this Surface surface, UV point1, UV point2)
        {
            Point A = surface.PointAtParameter(point1.U, point1.V);
            Point B = surface.PointAtParameter(point2.U, point2.V);

            return A.DistanceTo(B);
        }

        /// <summary>
        /// Determine the X intercept of a polygon edge 
        /// with a horizontal line at the Y value of the 
        /// test point.
        /// </summary>
        public static double GetXIntercept(UV p, UV q, double y)
        {
            Debug.Assert(0 != (p.V - q.V),
              "unexpected horizontal segment");

            return q.U
              - ((q.V - y)
                * ((p.U - q.U) / (p.V - q.V)));
        }

        public Autodesk.Revit.UI.Result Execute(ExternalCommandData commandData, ref string message, ElementSet elements)
        {
            ExternalCommandData cdata = commandData;
             Autodesk.Revit.ApplicationServices.Application app = commandData.Application.Application;
             Document doc = commandData.Application.ActiveUIDocument.Document;
             UIDocument uiDoc = commandData.Application.ActiveUIDocument;

             SpatialFieldManager sfm = SpatialFieldManager.GetSpatialFieldManager(doc.ActiveView);
             if (sfm == null) sfm = SpatialFieldManager.CreateSpatialFieldManager(doc.ActiveView, 1);

             IList<Reference> refList = new List<Reference>();
             refList = uiDoc.Selection.PickObjects(Autodesk.Revit.UI.Selection.ObjectType.Face);
                 foreach (Reference reference in refList)
                 {

                         IList<UV> uvPts = new List<UV>();

                         List<double> doubleList = new List<double>();
                         IList<ValueAtPoint> valList = new List<ValueAtPoint>();
                         Face face = doc.GetElement(reference).GetGeometryObjectFromReference(reference)as Face;
                         BoundingBoxUV bb = face.GetBoundingBox();
                         UV min = bb.Min;
                         UV max = bb.Max;

                         for (double u = min.U; u < max.U; u += (max.U - min.U) / 10)
                         {
                             for (double v = min.V; v < max.V; v += (max.V - min.V) / 10)
                             {
                                 UV uv = new UV(u, v);
                                 if (face.IsInside(uv))
                                 {
                                     uvPts.Add(uv);
                                     doubleList.Add(v + DateTime.Now.Second);
                                     valList.Add(new ValueAtPoint(doubleList));
                                     doubleList.Clear();
                                 }
                             }
                         }

                         FieldDomainPointsByUV pnts = new FieldDomainPointsByUV(uvPts);
                         FieldValues vals = new FieldValues(valList);
                         int idx = sfm.AddSpatialFieldPrimitive(reference);
                         AnalysisResultSchema resultSchema = new AnalysisResultSchema("Schema 1", "Schema 1 Description");
                         sfm.UpdateSpatialFieldPrimitive(idx, pnts, vals, sfm.RegisterResult(resultSchema));
                 }

             return Result.Succeeded;
        }

        public Result Execute(
            ExternalCommandData commandData,
            ref string message,
            ElementSet elements)
        {
            Result rc = Result.Failed;

              ViewPlan view = commandData.View as ViewPlan;

              if( null == view
            || view.ViewType != ViewType.AreaPlan )
              {
            message = "Please run this command in an area plan view.";
            return rc;
              }

              UIApplication app = commandData.Application;
              UIDocument uidoc = app.ActiveUIDocument;
              Document doc = uidoc.Document;

              Element room = Util.GetSingleSelectedElement( uidoc );

              if( null == room || !(room is Room) )
              {
            room = Util.SelectSingleElement( uidoc, "a room" );
              }

              if( null == room || !( room is Room ) )
              {
            message = "Please select a single room element.";
              }
              else
              {
            using ( Transaction t = new Transaction( doc ) )
            {
              t.Start( "Create New Area" );

              Location loc = room.Location;
              LocationPoint lp = loc as LocationPoint;
              XYZ p = lp.Point;
              UV q = new UV( p.X, p.Y );
              Area area = doc.Create.NewArea( view, q );
              rc = Result.Succeeded;
              t.Commit();
            }
              }
              return rc;
        }

        public IExternalCommand.Result Execute(ExternalCommandData commandData, ref string message, ElementSet elements)
        {
            Application revit = commandData.Application;
            Document curDoc = revit.ActiveDocument;

            Level createlevel = curDoc.ActiveView.GenLevel;
            UV point = new UV(0, 0);
            // 利用标高，坐标创建房间对象
            Room createdRoom = curDoc.Create.NewRoom(createlevel, ref point);
            if (null == createdRoom)
            {
                message = "Create the wall failed.";
                return IExternalCommand.Result.Failed;
            }
            curDoc.Create.NewRoomTag(createdRoom, ref point);

            return IExternalCommand.Result.Succeeded;
        }

        /// <summary>
        /// Determine whether given 2D point lies within 
        /// the polygon.
        /// 
        /// Written by Jeremy Tammik, Autodesk, 2009-09-23, 
        /// based on code that I wrote back in 1996 in C++, 
        /// which in turn was based on C code from the 
        /// article "An Incremental Angle Point in Polygon 
        /// Test" by Kevin Weiler, Autodesk, in "Graphics 
        /// Gems IV", Academic Press, 1994.
        /// 
        /// Copyright (C) 2009 by Jeremy Tammik. All 
        /// rights reserved.
        /// 
        /// This code may be freely used. Please preserve 
        /// this comment.
        /// </summary>
        public static bool PolygonContains(List<UV> polygon, UV point)
        {
            // initialize
            Int32 quad = GetQuadrant(
              polygon[0], point);

            Int32 angle = 0;

            // loop on all vertices of polygon
            Int32 next_quad, delta;
            int n = polygon.Count;
            for (int i = 0; i < n; ++i)
            {
                UV vertex = polygon[i];

                UV next_vertex = polygon[(i + 1 < n) ? i + 1 : 0];

                // calculate quadrant and delta from last quadrant

                next_quad = GetQuadrant(next_vertex, point);
                delta = next_quad - quad;

                AdjustDelta(
                  ref delta, vertex, next_vertex, point);

                // add delta to total angle sum
                angle = angle + delta;

                // increment for next step
                quad = next_quad;
            }

            // complete 360 degrees (angle of + 4 or -4 ) 
            // means inside

            return (angle == +4) || (angle == -4);

            // odd number of windings rule:
            // if (angle & 4) return INSIDE; else return OUTSIDE;
            // non-zero winding rule:
            // if (angle != 0) return INSIDE; else return OUTSIDE;
        }

        /// <summary>
        /// Find all quadtree points (UVs) in the quadtree within a radius of the given UV location.
        /// </summary>
        /// <param name="center">The UV at the center of the search area.</param>
        /// <param name="radius">The radius of the search area.</param>
        /// <returns>A list of UVs.</returns>
        public List<UV> FindPointsWithinRadius(UV center, double radius)
        {
            if (center == null)
            {
                throw new ArgumentNullException(
                    "center",
                    Resources.FindPointsWithinRadiusNullPointMessage);
            }

            if (radius <= 0.0)
            {
                throw new ArgumentException(
                    "radius",
                    Resources.FindPointsWithinRadiusSearchRadiusMessage);
            }

            return Root.FindNodesWithinRadius(center, radius)
                .Where(n => n.Point != null)
                .Select(n => n.Point)
                .ToList();
        }

 public static void AdjustDelta(
   ref int delta,
   UV vertex,
   UV next_vertex,
   UV p)
 {
     switch (delta)
     {
         // make quadrant deltas wrap around:
         case 3: delta = -1; break;
         case -3: delta = 1; break;
         // check if went around point cw or ccw:
         case 2:
         case -2:
             if (GetXIntercept(vertex, next_vertex, p.V)
               > p.U)
             {
                 delta = -delta;
             }
             break;
     }
 }

        /// <summary>
        /// Generates the UV value of a point projected to a plane, given an extrusion direction.
        /// </summary>
        /// <param name="plane">The plane.</param>
        /// <param name="projDir">The projection direction.</param>
        /// <param name="point">The point.</param>
        /// <returns>The UV value.</returns>
        public static UV ProjectPointToPlane(Plane plane, XYZ projDir, XYZ point)
        {
            XYZ zDir = plane.Normal;

            double denom = projDir.DotProduct(zDir);
            if (MathUtil.IsAlmostZero(denom))
                return null;

            XYZ xDir = plane.XVec;
            XYZ yDir = plane.YVec;
            XYZ orig = plane.Origin;

            double distToPlane = ((orig - point).DotProduct(zDir)) / denom;
            XYZ pointProj = distToPlane * projDir + point;
            XYZ pointProjOffset = pointProj - orig;
            UV pointProjUV = new UV(pointProjOffset.DotProduct(xDir), pointProjOffset.DotProduct(yDir));
            return pointProjUV;
        }

        public override Value Evaluate(FSharpList<Value> args)
        {
            this.ClearPreviousResults();

            //unwrap the values
            IEnumerable<double> nvals = ((Value.List)args[0]).Item.Select(q => (double)((Value.Number)q).Item);

            var curve = (Curve)((Value.Container)args[1]).Item;
            SpatialFieldManager = (Autodesk.Revit.DB.Analysis.SpatialFieldManager)((Value.Container)args[2]).Item;

            if (!SpatialFieldManager.IsResultSchemaNameUnique(DYNAMO_TEMP_CURVES_SCHEMA, -1))
            {
                IList<int> arses = SpatialFieldManager.GetRegisteredResults();
                foreach (int i in arses)
                {
                    AnalysisResultSchema arsTest = SpatialFieldManager.GetResultSchema(i);
                    if (arsTest.Name == DYNAMO_TEMP_CURVES_SCHEMA)
                    {
                        schemaId = i;
                        break;
                    }
                }
            }
            else
            {
                var ars = new AnalysisResultSchema(DYNAMO_TEMP_CURVES_SCHEMA, "Temporary curves from Dynamo.");
                schemaId = SpatialFieldManager.RegisterResult(ars);
            }

            Transform trf = Transform.Identity;

            //http://thebuildingcoder.typepad.com/blog/2012/09/sphere-creation-for-avf-and-filtering.html#3

            var create = dynRevitSettings.Doc.Application.Application.Create;

            Transform t = curve.ComputeDerivatives(0, true);

            XYZ x = t.BasisX.Normalize();
            XYZ y = t.BasisX.IsAlmostEqualTo(XYZ.BasisZ) ?
                t.BasisX.CrossProduct(XYZ.BasisY).Normalize() :
                t.BasisX.CrossProduct(XYZ.BasisZ).Normalize();
            XYZ z = x.CrossProduct(y);

            Autodesk.Revit.DB.Ellipse arc1 = dynRevitSettings.Revit.Application.Create.NewEllipse(t.Origin, .1, .1, y,z,-Math.PI, 0);
            Autodesk.Revit.DB.Ellipse arc2 = dynRevitSettings.Revit.Application.Create.NewEllipse(t.Origin, .1, .1, y, z, 0, Math.PI);

            var pathLoop = new Autodesk.Revit.DB.CurveLoop();
            pathLoop.Append(curve);
            var profileLoop = new Autodesk.Revit.DB.CurveLoop();
            profileLoop.Append(arc1);
            profileLoop.Append(arc2);

            double curveDomain = curve.get_EndParameter(1) - curve.get_EndParameter(0);

            int idx = -1;
            var s = GeometryCreationUtilities.CreateSweptGeometry(pathLoop, 0, 0, new List<Autodesk.Revit.DB.CurveLoop>{profileLoop});
            foreach (Face face in s.Faces)
            {
                //divide the V domain by the number of incoming
                BoundingBoxUV domain = face.GetBoundingBox();
                double vSpan = domain.Max.V - domain.Min.V;

                //analysis values
                idx = SpatialFieldManager.AddSpatialFieldPrimitive(face, trf);

                //a list to hold the analysis points
                IList<UV> uvPts = new List<UV>();

                //a list to hold the analysis values
                IList<ValueAtPoint> valList = new List<ValueAtPoint>();

                //int count = nvals.Count();

                //this is creating a lot of sample points, but if we used less
                //sampling points, AVF would draw the two surfaces as if there was a hard
                //edge between them. this provides a better blend.
                int count = 10;
                for (int i = 0; i < count; i ++)
                {
                    //get a UV point on the face
                    //find its XYZ location and project to
                    //the underlying curve. find the value which corresponds
                    //to the location on the curve
                    var uv = new UV(domain.Min.U, domain.Min.V + vSpan / count*(double) i);
                    var uv1 = new UV(domain.Max.U, domain.Min.V + vSpan / count * (double)i);
                    uvPts.Add(uv);
                    uvPts.Add(uv1);

                    XYZ facePt = face.Evaluate(uv);
                    IntersectionResult ir = curve.Project(facePt);
                    double curveParam = curve.ComputeNormalizedParameter(ir.Parameter);

                    if (curveParam < 0)
                        curveParam = 0;

                    if (curveParam > 1)
                        curveParam = 1;

                    var valueIndex = (int)Math.Floor(curveParam * (double)nvals.Count());
                    if (valueIndex >= nvals.Count())
//.........这里部分代码省略.........

        /// <summary>
        /// Attempts to create a clipping, recess, or opening from a collection of faces.
        /// </summary>
        /// <param name="exporterIFC">The exporter.</param>
        /// <param name="cuttingElement">The cutting element.  This will help determine whether to use a clipping or opening in boundary cases.</param>
        /// <param name="extrusionBasePlane">The plane of the extrusion base.</param>
        /// <param name="extrusionDirection">The extrusion direction.</param>
        /// <param name="faces">The collection of faces.</param>
        /// <param name="range">The valid range of the extrusion.</param>
        /// <param name="origBodyRepHnd">The original body representation.</param>
        /// <returns>The new body representation.  If the clipping completely clips the extrusion, this will be null.  Otherwise, this
        /// will be the clipped representation if a clipping was done, or the original representation if not.</returns>
        public static IFCAnyHandle CreateClippingFromFaces(ExporterIFC exporterIFC, Element cuttingElement, Plane extrusionBasePlane,
            XYZ extrusionDirection, ICollection<Face> faces, IFCRange range, IFCAnyHandle origBodyRepHnd)
        {
            if (IFCAnyHandleUtil.IsNullOrHasNoValue(origBodyRepHnd))
                return null;

            bool polygonalOnly = ExporterCacheManager.ExportOptionsCache.ExportAs2x2;

            IList<CurveLoop> outerCurveLoops = new List<CurveLoop>();
            IList<Plane> outerCurveLoopPlanes = new List<Plane>();
            IList<bool> boundaryIsPolygonal = new List<bool>();

            bool allPlanes = true;
            UV faceOriginUV = new UV(0, 0);
            foreach (Face face in faces)
            {
                FaceBoundaryType faceBoundaryType;
                CurveLoop curveLoop = GetOuterFaceBoundary(face, null, polygonalOnly, out faceBoundaryType);
                outerCurveLoops.Add(curveLoop);
                boundaryIsPolygonal.Add(faceBoundaryType == FaceBoundaryType.Polygonal);

                if (face is PlanarFace)
                {
                    PlanarFace planarFace = face as PlanarFace;
                    XYZ faceOrigin = planarFace.Origin;
                    XYZ faceNormal = planarFace.ComputeNormal(faceOriginUV);

                    Plane plane = new Plane(faceNormal, faceOrigin);
                    outerCurveLoopPlanes.Add(plane);

                    if (!curveLoop.IsCounterclockwise(faceNormal))
                        curveLoop.Flip();
                }
                else
                {
                    outerCurveLoopPlanes.Add(null);
                    allPlanes = false;
                }
            }

            if (allPlanes)
            {
                int numFaces = faces.Count;
                    
                // Special case: one face is a clip plane.
                if (numFaces == 1)
                {
                    return ProcessClippingFace(exporterIFC, outerCurveLoops[0], outerCurveLoopPlanes[0], extrusionBasePlane,
                        extrusionDirection, range, false, origBodyRepHnd);
                }

                KeyValuePair<bool, bool> clipsExtrusionEnds = CollectionClipsExtrusionEnds(outerCurveLoops, extrusionDirection, range);
                if (clipsExtrusionEnds.Key == true || clipsExtrusionEnds.Value == true)
                {
                    // Don't clip for a door, window or opening.
                    if (CreateOpeningForCategory(cuttingElement))
                        throw new Exception("Unhandled opening.");

                    ICollection<int> facesToSkip = new HashSet<int>();
                    bool clipStart = (clipsExtrusionEnds.Key == true);
                    bool clipBoth = (clipsExtrusionEnds.Key == true && clipsExtrusionEnds.Value == true);
                    if (!clipBoth)
                    {
                        for (int ii = 0; ii < numFaces; ii++)
                        {
                            double slant = outerCurveLoopPlanes[ii].Normal.DotProduct(extrusionDirection);
                            if (!MathUtil.IsAlmostZero(slant))
                            {
                                if (clipStart && (slant > 0.0))
                                    throw new Exception("Unhandled clip plane direction.");
                                if (!clipStart && (slant < 0.0))
                                    throw new Exception("Unhandled clip plane direction.");
                            }
                            else
                            {
                                facesToSkip.Add(ii);
                            }
                        }
                    }
                    else       
                    {
                        // If we are clipping both the start and end of the extrusion, we have to make sure all of the clipping
                        // planes have the same a non-negative dot product relative to one another.
                        int clipOrientation = 0;
                        for (int ii = 0; ii < numFaces; ii++)
                        {
                            double slant = outerCurveLoopPlanes[ii].Normal.DotProduct(extrusionDirection);
                            if (!MathUtil.IsAlmostZero(slant))
//.........这里部分代码省略.........

        private void Stream(ArrayList data, UV UV)
        {
            data.Add(new Snoop.Data.ClassSeparator(typeof(UV)));

            data.Add(new Snoop.Data.Uv("Basis U", UV.BasisU));
            data.Add(new Snoop.Data.Uv("Basis V", UV.BasisV));
            //data.Add(new Snoop.Data.Bool("Is normalized", UV.IsNormalized));
            //data.Add(new Snoop.Data.Bool("Is zero", UV.IsZero));
            //data.Add(new Snoop.Data.Double("Length", UV.));
            data.Add(new Snoop.Data.Uv("Normalized", UV.Normalize()));
            data.Add(new Snoop.Data.Double("U", UV.U));
            data.Add(new Snoop.Data.Double("V", UV.V));
            data.Add(new Snoop.Data.Uv("Zero", UV.Zero));
        }

//.........这里部分代码省略.........
                                {
                                    found = true;
                                    break;
                                }
                            }
                            if (!(geobSym is Solid))
                                continue;

                            FaceArray solidFaces = ((Solid)geobSym).Faces;
                            int numFaces = solidFaces.Size;
                            for (int index = 0; index < numFaces && !found; index++)
                            {
                                Autodesk.Revit.DB.Face faceAt = solidFaces.get_Item(index);
                                if ((thisObject is Autodesk.Revit.DB.Face) && (thisObject == faceAt))
                                {
                                    found = true;
                                    break;
                                }
                                if (thisObject is Edge)
                                {
                                    var edge = thisObject as Edge;
                                    //use GetFace after r2013 support is dropped
                                    if (faceAt == edge.get_Face(0) || faceAt == edge.get_Face(1))
                                    {
                                        found = true;
                                        break;
                                    }
                                }
                            }
                        }
                    }

                    if (found)
                    {
                        thisTrf = ginsta.Transform;
                        break;
                    }
                }
                if (thisObject == null)
                    throw new Exception("could not resolve reference for XYZ on Element");
            }

            XYZ thisXYZ;

            if (_reference.ElementReferenceType == ElementReferenceType.REFERENCE_TYPE_SURFACE
                && thisObject is Autodesk.Revit.DB.Face)
            {
                var face = thisObject as Autodesk.Revit.DB.Face;
                if (!_init)
                {
                    _param0 = _reference.UVPoint[0];
                    _param1 = _reference.UVPoint[1];
                    _init = true;
                }
                var uv = new UV(_param0, _param1);
                thisXYZ = face.Evaluate(uv);
                if (thisTrf != null)
                    thisXYZ = thisTrf.OfPoint(thisXYZ);
            }
            else if (_reference.ElementReferenceType == ElementReferenceType.REFERENCE_TYPE_LINEAR)
            {
                Curve curve;
                if (thisObject is Edge)
                {
                    var edge = (Edge)SelectedElement.GetGeometryObjectFromReference(_reference);
                    curve = edge.AsCurve();
                }
                else
                    curve = (Curve)SelectedElement.GetGeometryObjectFromReference(_reference);
                if (curve != null)
                {
                    if (_init)
                        thisXYZ = curve.Evaluate(_param0, true);
                    else
                    {
                        XYZ curPoint = _reference.GlobalPoint;
                        if (thisTrf != null)
                        {
                            Autodesk.Revit.DB.Transform inverseTrf = thisTrf.Inverse;
                            curPoint = inverseTrf.OfPoint(_reference.GlobalPoint);
                        }
                        IntersectionResult thisResult = curve.Project(curPoint);
                        _param0 = curve.ComputeNormalizedParameter(thisResult.Parameter);
                        _init = true;
                    }
                    thisXYZ = curve.Evaluate(_param0, true);
                    _param1 = -1.0;
                }
                else
                    throw new Exception("could not evaluate point on face or edge of the element");
                if (thisTrf != null)
                    thisXYZ = thisTrf.OfPoint(thisXYZ);
            }
            else
                throw new Exception("could not evaluate point on face or edge of the element");

            old_refXyz = _reference;

            return Value.NewContainer(thisXYZ);
        }

    FrameWall( Autodesk.Revit.ApplicationServices.Application rvtApp, Autodesk.Revit.DB.Wall wall, double spacing, FamilySymbol columnType )
    {
      Document rvtDoc = wall.Document;

      LocationCurve loc = (LocationCurve) wall.Location;
      XYZ startPt = loc.Curve.GetEndPoint( 0 );
      XYZ endPt = loc.Curve.GetEndPoint( 1 );

      UV wallVec = new UV( endPt.X - startPt.X, endPt.Y - startPt.Y );

      UV axis = new UV( 1.0, 0.0 );


      ElementId baseLevelId = wall.get_Parameter( BuiltInParameter.WALL_BASE_CONSTRAINT ).AsElementId();
      ElementId topLevelId = wall.get_Parameter( BuiltInParameter.WALL_HEIGHT_TYPE ).AsElementId();

      double wallLength = VecLength( wallVec );
      wallVec = VecNormalise( wallVec );

      int nmax = (int) ( wallLength / spacing );

      MessageBox.Show( "Wall Length = " + wallLength + "\nSpacing = " + spacing + "\nMax Number = " + nmax, "Structural Sample", MessageBoxButtons.OK, MessageBoxIcon.Information );

      double angle = VecAngle( wallVec, axis );

      XYZ loc2 = startPt;

      double dx = wallVec.U * spacing;
      double dy = wallVec.V * spacing;

      for( int i = 0; i < nmax; i++ )
      {
        PlaceColumn( rvtApp, rvtDoc, loc2, angle, columnType, baseLevelId, topLevelId );
        loc2 = new XYZ( startPt.X + dx, startPt.Y + dy, startPt.Z );
      }

      PlaceColumn( rvtApp, rvtDoc, endPt, angle, columnType, baseLevelId, topLevelId );
    }

        /// <summary>
        /// Returns the color in this color range at the specified parameter.
        /// </summary>
        /// <param name="parameter">A UV between (0.0,0.0) and (1.0,1.0).</param>
        /// <returns>A Color.</returns>
        public Color GetColorAtParameter(UV parameter)
        {
            var color = Color.ByARGB(255, 255, 255, 255);

            var weightedColors = indexedColors.ToList()
                .OrderBy(ic => ic.Parameter.Area(parameter)).Take(4).ToList();

            color = Color.Blerp(weightedColors, parameter);

            return color;
        }

        PlaceViews(ViewSet views, ViewSheet sheet)
        {
            double xDistance = 0;
            double yDistance = 0;
            CalculateDistance(sheet.Outline, views.Size, ref xDistance, ref yDistance);

            UV origin = GetOffset(sheet.Outline, xDistance, yDistance);
            UV temp = new UV(origin.U, origin.V);

            int n = 1;
            foreach (Autodesk.Revit.DB.View v in views) {
                UV location = new UV(temp.U, temp.V);
                Autodesk.Revit.DB.View view = v;
                Rescale(view, xDistance, yDistance);
                Viewport.Create(view.Document, sheet.Id, view.Id, new XYZ(location.U, location.V, 0));

                if (0 != n++ % m_rows) {
                    temp = new UV( temp.U + xDistance * (1 - TITLEBAR), temp.V );                    
                }
                else {
                    temp = new UV( origin.U,temp.V + yDistance);
                }
            }
        }

 private static double Area(UV min, UV max)
 {
     var u = System.Math.Sqrt(System.Math.Pow(max.U - min.U, 2));
     var v = System.Math.Sqrt(System.Math.Pow(max.V - min.V, 2));
     return u * v;
 }

 public MultithreadedCalculationContainer(string _docName, UV _min, UV _max)
 {
     m_docName = _docName;
     m_min = _min;
     m_max = _max;
 }

        /// <summary>
        /// Creates IfcCartesianPoint object from a 2D point.
        /// </summary>
        /// <param name="file">The file.</param>
        /// <param name="point">The point</param>
        /// <returns>The IfcCartesianPoint handle.</returns>
        public static IFCAnyHandle CreateCartesianPoint(IFCFile file, UV point)
        {
            if (point == null)
                throw new ArgumentNullException("point");

            List<double> points = new List<double>();
            points.Add(point.U);
            points.Add(point.V);

            return CreateCartesianPoint(file, points);
        }

 VecDot( UV va, UV vb )
 {
   return ( ( va.U * vb.U ) + ( va.V * vb.V ) );
 }