private SelVertex[] PickVertices(int x, int y, int w = 0, int h = 0)
        {
            List<SelVertex> result = new List<SelVertex>();
            if (this.allObjSel == null)
                return result.ToArray();
            IEnumerable<SelPolyShape> shapes = this.allObjSel.OfType<SelPolyShape>();

            foreach (SelPolyShape shape in shapes)
            {
                PolyShapeInfo polygon = shape.ActualObject as PolyShapeInfo;
                if (polygon == null)
                    continue;

                Transform transform = polygon.Parent.GameObj.Transform;
                if (polygon.Parent == null || polygon.Parent.GameObj == null || polygon.Parent.GameObj.Transform == null)
                    continue;

                Vector3 worldCoord = this.GetSpaceCoord(new Vector3(x, y, transform.Pos.Z));
                float scale = GetScaleAtZ(transform.Pos.Z);
                Rect selectionRect = new Rect(worldCoord.X, worldCoord.Y, w/scale, h/scale);

                float size = VertexSize/scale;

                for (int i = 0; i < polygon.Vertices.Length; i++)
                {

                    Vector2 vertexPosition = transform.GetWorldPoint(polygon.Vertices[i]);
                    Rect vertexRect = new Rect(vertexPosition.X - size/2, vertexPosition.Y - size/2, size, size);

                    if (selectionRect.Intersects(vertexRect))
                    {
                        result.Add(new SelVertex(polygon, i));
                    }
                }
            }
            return result.ToArray();
        }