Rotating Sprite Objects on DirectDraw Wrapper for C#

		public System.Exception AI()
		{
			try
			{
				if (pHead!=null)
				{
					CUnit u=pHead;
					while (u!=null) 
					{
						u.AI(this.m_Engine.m_FrameRate.m_FPS);
						u=u.pNext;
					}
				}
				return null;
			}
			catch(Exception e)
			{
				this.m_Trace.T("CUnitManager::Update>"+e);
				return e;
			}
		}
		public System.Exception DrawLastPosition(Microsoft.DirectX.DirectDraw.Surface s, DDW.ENGINE.CWorld w)
		{
			try
			{
				if (pHead!=null)
				{
					CUnit u=pHead;
					while (u!=null) 
					{
						u.DrawLastPosition(s,w);
						u=u.pNext;
					}
				}
				return null;
			}
			catch(Exception e)
			{
				this.m_Trace.T("CUnitManager::Draw>"+e);
				return e;
			}
		}
		public System.Exception UpdateXYFromLastXY()
		{
			try
			{
				if (pHead!=null)
				{
					CUnit u=pHead;
					while (u!=null) 
					{
						u.UpdateXYFromLastXY();
						u=u.pNext;
					}
				}
				return null;
			}
			catch(Exception e)
			{
				this.m_Trace.T("CUnitManager::UpdateXYFromLastXY>"+e);
				return e;
			}
		}
		public CUnitManager WhoDoesUnitSee(CUnit u0)
		{
			try
			{
				CUnitManager uList=new CUnitManager("WhoDoesUnitSee_List",this.m_Engine);
				double d=0;
				if (pHead!=null)
				{
					CUnit u=pHead;
					while (u!=null) 
					{
						if (u!=u0)
						{
							DDW.ENGINE.CUtils.VECTOR v1 = new DDW.ENGINE.CUtils.VECTOR(u0.m_X,u0.m_Y,u0.m_Angle);
							DDW.ENGINE.CUtils.VECTOR v2 = new DDW.ENGINE.CUtils.VECTOR(u.m_X,u.m_Y,u.m_Angle);
							d=m_Utils.AngleBetweenTwoVectors(v1,v2);
							if (d>-u0.m_ViewingAngle && d<u0.m_ViewingAngle)
							{
								d=m_Utils.DistanceBetweenVectors(v1,v2);
								if (d<u0.m_ViewingDistance)
									uList.Add(u);
							}
						}
						u=u.pNext;
					}
				}
				if (uList.Count()==0)
					uList=null;
				return uList;
			}
			catch(Exception e)
			{
				this.m_Trace.T("CUnitManager::WhoDoesUnitSee>"+e);
				return null;
			}
		}
		public System.Exception MoveTo(double x, double y)
		{
			try
			{
				if (pHead!=null)
				{
					CUnit u=pHead;
					while (u!=null) 
					{
						u.MoveTo(x,y);
						u=u.pNext;
					}
				}
				return null;
			}
			catch(Exception e)
			{
				this.m_Trace.T("CUnitManager::MoveTo>"+e);
				return e;
			}
		}