diff --git a/Kiwano/2d/Action.h b/Kiwano/2d/Action.h
index beecd92a..fe3e6c28 100644
--- a/Kiwano/2d/Action.h
+++ b/Kiwano/2d/Action.h
@@ -28,7 +28,7 @@ namespace kiwano
 	class ActionManager;
 
 	class KGE_API Action
-		: public virtual Object
+		: public Object
 		, protected IntrusiveListItem<ActionPtr>
 	{
 		friend class ActionManager;
diff --git a/Kiwano/2d/Frames.h b/Kiwano/2d/Frames.h
index 0f13324f..11eabe32 100644
--- a/Kiwano/2d/Frames.h
+++ b/Kiwano/2d/Frames.h
@@ -25,7 +25,7 @@ namespace kiwano
 {
 	// 序列帧
 	class KGE_API Frames
-		: public virtual Object
+		: public Object
 	{
 	public:
 		Frames();
diff --git a/Kiwano/2d/Geometry.h b/Kiwano/2d/Geometry.h
index 249605b8..6f54a492 100644
--- a/Kiwano/2d/Geometry.h
+++ b/Kiwano/2d/Geometry.h
@@ -26,7 +26,7 @@ namespace kiwano
 {
 	// 几何抽象
 	class KGE_API Geometry
-		: public virtual Object
+		: public Object
 	{
 		friend class Canvas;
 		friend class GeometryNode;
diff --git a/Kiwano/2d/Image.h b/Kiwano/2d/Image.h
index d47c8dc8..3e6319d8 100644
--- a/Kiwano/2d/Image.h
+++ b/Kiwano/2d/Image.h
@@ -27,7 +27,7 @@ namespace kiwano
 {
 	// 图片
 	class KGE_API Image
-		: public virtual Object
+		: public Object
 	{
 	public:
 		Image();
diff --git a/Kiwano/2d/Node.h b/Kiwano/2d/Node.h
index 0794ec68..60ea6394 100644
--- a/Kiwano/2d/Node.h
+++ b/Kiwano/2d/Node.h
@@ -31,7 +31,7 @@ namespace kiwano
 
 	// 节点
 	class KGE_API Node
-		: public virtual Object
+		: public Object
 		, public TimerManager
 		, public ActionManager
 		, public EventDispatcher
diff --git a/Kiwano/2d/Transition.h b/Kiwano/2d/Transition.h
index 0d605cb7..20d1ab3c 100644
--- a/Kiwano/2d/Transition.h
+++ b/Kiwano/2d/Transition.h
@@ -28,7 +28,7 @@ namespace kiwano
 
 	// 场景过渡
 	class KGE_API Transition
-		: public virtual Object
+		: public Object
 	{
 		friend class Application;
 
diff --git a/Kiwano/audio/Sound.h b/Kiwano/audio/Sound.h
index f2c0dd97..a7ae2b1e 100644
--- a/Kiwano/audio/Sound.h
+++ b/Kiwano/audio/Sound.h
@@ -27,7 +27,7 @@ namespace kiwano
 
 	// 音乐对象
 	class KGE_API Sound
-		: public virtual Object
+		: public Object
 	{
 	public:
 		Sound();
diff --git a/Kiwano/base/EventListener.h b/Kiwano/base/EventListener.h
index 7af83d46..7edebffb 100644
--- a/Kiwano/base/EventListener.h
+++ b/Kiwano/base/EventListener.h
@@ -37,7 +37,7 @@ namespace kiwano
 
 	// 事件监听器
 	class KGE_API EventListener
-		: public virtual Object
+		: public Object
 		, protected IntrusiveListItem<EventListenerPtr>
 	{
 		friend class EventDispatcher;
diff --git a/Kiwano/base/Timer.h b/Kiwano/base/Timer.h
index abed8099..ed5512e4 100644
--- a/Kiwano/base/Timer.h
+++ b/Kiwano/base/Timer.h
@@ -34,7 +34,7 @@ namespace kiwano
 
     // 定时任务
 	class KGE_API Timer
-		: public virtual Object
+		: public Object
 		, protected IntrusiveListItem<TimerPtr>
 	{
 		friend class TimerManager;
diff --git a/Kiwano/math/Rect.hpp b/Kiwano/math/Rect.hpp
index 9d502e95..c45480ae 100644
--- a/Kiwano/math/Rect.hpp
+++ b/Kiwano/math/Rect.hpp
@@ -49,8 +49,8 @@ namespace kiwano
 			{}
 
 			RectT(
-				const Vec2& pos,
-				const Vec2& size
+				const Vec2T<value_type>& pos,
+				const Vec2T<value_type>& size
 			)
 				: origin(pos.x, pos.y)
 				, size(size.x, size.y)
@@ -75,36 +75,38 @@ namespace kiwano
 				return (origin == rect.origin) && (size == rect.size);
 			}
 
-			inline void Set(value_type x, value_type y, value_type width, value_type height) { origin = Vec2{ x, y }; size = Vec2{ width, height }; }
+			inline void Set(value_type x, value_type y, value_type width, value_type height)
+			{
+				origin = Vec2T<value_type>{ x, y };
+				size = Vec2T<value_type>{ width, height };
+			}
 
-			inline Vec2 GetCenter() const { return Vec2{ origin.x + size.x / 2, origin.y + size.y / 2 }; }
+			inline Vec2T<value_type> GetCenter() const		{ return Vec2T<value_type>{ origin.x + size.x / 2, origin.y + size.y / 2 }; }
 
-			inline Vec2 GetLeftTop() const { return origin; }
+			inline Vec2T<value_type> GetLeftTop() const		{ return origin; }
 
-			inline Vec2 GetRightBottom() const { return Vec2{ GetRight(), GetBottom() }; }
+			inline Vec2T<value_type> GetRightBottom() const	{ return Vec2T<value_type>{ GetRight(), GetBottom() }; }
 
-			inline Vec2 GetRightTop() const { return Vec2{ GetRight(), GetTop() }; }
+			inline Vec2T<value_type> GetRightTop() const	{ return Vec2T<value_type>{ GetRight(), GetTop() }; }
 
-			inline Vec2 GetLeftBottom() const { return Vec2{ GetLeft(), GetBottom() }; }
+			inline Vec2T<value_type> GetLeftBottom() const	{ return Vec2T<value_type>{ GetLeft(), GetBottom() }; }
 
-			inline value_type GetLeft() const { return origin.x; }
+			inline value_type GetLeft() const				{ return origin.x; }
 
-			inline value_type GetTop() const { return origin.y; }
+			inline value_type GetTop() const				{ return origin.y; }
 
-			inline value_type GetRight() const { return origin.x + size.x; }
+			inline value_type GetRight() const				{ return origin.x + size.x; }
 
-			inline value_type GetBottom() const { return origin.y + size.y; }
+			inline value_type GetBottom() const				{ return origin.y + size.y; }
 
-			inline bool IsEmpty() const { return origin.IsOrigin() && size.IsOrigin(); }
+			inline bool IsEmpty() const						{ return origin.IsOrigin() && size.IsOrigin(); }
 
-			// 判断点是否在矩形内
-			inline bool ContainsPoint(const Vec2& point) const
+			inline bool ContainsPoint(const Vec2T<value_type>& point) const
 			{
 				return	point.x >= origin.x && point.x <= (origin.x + size.x) &&
 					point.y >= origin.y && point.y <= (origin.y + size.y);
 			}
 
-			// 判断两矩形是否相交
 			inline bool Intersects(const RectT& rect) const
 			{
 				return !((origin.x + size.x)			< rect.origin.x ||
diff --git a/Kiwano/math/Vec2.hpp b/Kiwano/math/Vec2.hpp
index ac2bf2ca..acdd8168 100644
--- a/Kiwano/math/Vec2.hpp
+++ b/Kiwano/math/Vec2.hpp
@@ -80,6 +80,34 @@ namespace kiwano
 				return Vec2T(-x, -y);
 			}
 
+			inline Vec2T& operator += (const Vec2T& other)
+			{
+				x += other.x;
+				y += other.y;
+				return (*this);
+			}
+
+			inline Vec2T& operator -= (const Vec2T& other)
+			{
+				x -= other.x;
+				y -= other.y;
+				return (*this);
+			}
+
+			inline Vec2T& operator *= (value_type val)
+			{
+				x *= val;
+				y *= val;
+				return (*this);
+			}
+
+			inline Vec2T& operator /= (value_type val)
+			{
+				x /= val;
+				y /= val;
+				return (*this);
+			}
+
 			inline bool operator== (const Vec2T& other) const
 			{
 				return (x == other.x) && (y == other.y);
diff --git a/Kiwano/renderer/D2DDeviceResources.h b/Kiwano/renderer/D2DDeviceResources.h
index 817a1e23..a67e0515 100644
--- a/Kiwano/renderer/D2DDeviceResources.h
+++ b/Kiwano/renderer/D2DDeviceResources.h
@@ -69,12 +69,12 @@ namespace kiwano
 			_In_ ComPtr<ID2D1Bitmap1> const& target
 		);
 
-		inline ID2D1Factory1*			GetD2DFactory() const			{ return d2d_factory_.Get(); }
-		inline IWICImagingFactory*		GetWICImagingFactory() const	{ return imaging_factory_.Get(); }
-		inline IDWriteFactory*			GetDWriteFactory() const		{ return dwrite_factory_.Get(); }
-		inline ID2D1Device*				GetD2DDevice() const			{ return d2d_device_.Get(); }
-		inline ID2D1DeviceContext*		GetD2DDeviceContext() const		{ return d2d_device_context_.Get(); }
-		inline ID2D1Bitmap1*			GetD2DTargetBitmap() const		{ return d2d_target_bitmap_.Get(); }
+		inline ID2D1Factory1*			GetD2DFactory() const			{ KGE_ASSERT(d2d_factory_); return d2d_factory_.Get(); }
+		inline IWICImagingFactory*		GetWICImagingFactory() const	{ KGE_ASSERT(imaging_factory_); return imaging_factory_.Get(); }
+		inline IDWriteFactory*			GetDWriteFactory() const		{ KGE_ASSERT(dwrite_factory_); return dwrite_factory_.Get(); }
+		inline ID2D1Device*				GetD2DDevice() const			{ KGE_ASSERT(d2d_device_); return d2d_device_.Get(); }
+		inline ID2D1DeviceContext*		GetD2DDeviceContext() const		{ KGE_ASSERT(d2d_device_context_); return d2d_device_context_.Get(); }
+		inline ID2D1Bitmap1*			GetD2DTargetBitmap() const		{ KGE_ASSERT(d2d_target_bitmap_); return d2d_target_bitmap_.Get(); }
 
 		ID2D1StrokeStyle*				GetStrokeStyle(StrokeStyle stroke) const;
 
diff --git a/Kiwano/renderer/D3D10DeviceResources.h b/Kiwano/renderer/D3D10DeviceResources.h
index e8540dde..35a5176d 100644
--- a/Kiwano/renderer/D3D10DeviceResources.h
+++ b/Kiwano/renderer/D3D10DeviceResources.h
@@ -50,12 +50,12 @@ namespace kiwano
 
 		void DiscardResources();
 
-		inline ID3D10Device*			GetD3DDevice() const			{ return d3d_device_.Get(); }
-		inline ID3D10Device*			GetD3DDeviceContext() const		{ return d3d_device_.Get(); }
-		inline ID3D10RenderTargetView*	GetD3DRenderTargetView() const	{ return d3d_rt_view_.Get(); }
-		inline ID3D10DepthStencilView*	GetD3DDepthStencilView() const	{ return d3d_ds_view_.Get(); }
-		inline IDXGIFactory*			GetDXGIFactory() const			{ return dxgi_factory_.Get(); }
-		inline IDXGISwapChain*			GetDXGISwapChain() const		{ return dxgi_swap_chain_.Get(); }
+		inline ID3D10Device*			GetD3DDevice() const			{ KGE_ASSERT(d3d_device_); return d3d_device_.Get(); }
+		inline ID3D10Device*			GetD3DDeviceContext() const		{ KGE_ASSERT(d3d_device_); return d3d_device_.Get(); }
+		inline ID3D10RenderTargetView*	GetD3DRenderTargetView() const	{ KGE_ASSERT(d3d_rt_view_); return d3d_rt_view_.Get(); }
+		inline ID3D10DepthStencilView*	GetD3DDepthStencilView() const	{ KGE_ASSERT(d3d_ds_view_); return d3d_ds_view_.Get(); }
+		inline IDXGIFactory*			GetDXGIFactory() const			{ KGE_ASSERT(dxgi_factory_); return dxgi_factory_.Get(); }
+		inline IDXGISwapChain*			GetDXGISwapChain() const		{ KGE_ASSERT(dxgi_swap_chain_); return dxgi_swap_chain_.Get(); }
 
 		inline Size const&				GetLogicalSize() const			{ return logical_size_; }
 		inline Size const&				GetOutputSize() const			{ return output_size_; }
diff --git a/Kiwano/renderer/D3D11DeviceResources.h b/Kiwano/renderer/D3D11DeviceResources.h
index 1ffe41e9..8d62f24d 100644
--- a/Kiwano/renderer/D3D11DeviceResources.h
+++ b/Kiwano/renderer/D3D11DeviceResources.h
@@ -50,12 +50,12 @@ namespace kiwano
 
 		void DiscardResources();
 
-		inline ID3D11Device*			GetD3DDevice() const			{ return d3d_device_.Get(); }
-		inline ID3D11DeviceContext*		GetD3DDeviceContext() const		{ return d3d_device_context_.Get(); }
-		inline ID3D11RenderTargetView*	GetD3DRenderTargetView() const	{ return d3d_rt_view_.Get(); }
-		inline ID3D11DepthStencilView*	GetD3DDepthStencilView() const	{ return d3d_ds_view_.Get(); }
-		inline IDXGIFactory*			GetDXGIFactory() const			{ return dxgi_factory_.Get(); }
-		inline IDXGISwapChain*			GetDXGISwapChain() const		{ return dxgi_swap_chain_.Get(); }
+		inline ID3D11Device*			GetD3DDevice() const			{ KGE_ASSERT(d3d_device_); return d3d_device_.Get(); }
+		inline ID3D11DeviceContext*		GetD3DDeviceContext() const		{ KGE_ASSERT(d3d_device_context_); return d3d_device_context_.Get(); }
+		inline ID3D11RenderTargetView*	GetD3DRenderTargetView() const	{ KGE_ASSERT(d3d_rt_view_); return d3d_rt_view_.Get(); }
+		inline ID3D11DepthStencilView*	GetD3DDepthStencilView() const	{ KGE_ASSERT(d3d_ds_view_); return d3d_ds_view_.Get(); }
+		inline IDXGIFactory*			GetDXGIFactory() const			{ KGE_ASSERT(dxgi_factory_); return dxgi_factory_.Get(); }
+		inline IDXGISwapChain*			GetDXGISwapChain() const		{ KGE_ASSERT(dxgi_swap_chain_); return dxgi_swap_chain_.Get(); }
 
 		inline D3D_FEATURE_LEVEL		GetDeviceFeatureLevel() const	{ return d3d_feature_level_; }
 		inline Size const&				GetLogicalSize() const			{ return logical_size_; }
diff --git a/Kiwano/renderer/render.h b/Kiwano/renderer/render.h
index 1b3f5f71..47bb45d6 100644
--- a/Kiwano/renderer/render.h
+++ b/Kiwano/renderer/render.h
@@ -151,11 +151,11 @@ namespace kiwano
 
 		inline Size const&				GetOutputSize() const		{ return output_size_; }
 
-		inline DeviceResources*			GetDeviceResources() const	{ return device_resources_.Get(); }
+		inline DeviceResources*			GetDeviceResources() const	{ KGE_ASSERT(device_resources_); return device_resources_.Get(); }
 
-		inline ITextRenderer*			GetTextRenderer() const		{ return text_renderer_.Get(); }
+		inline ITextRenderer*			GetTextRenderer() const		{ KGE_ASSERT(text_renderer_); return text_renderer_.Get(); }
 
-		inline ID2D1SolidColorBrush*	GetSolidColorBrush() const	{ return solid_color_brush_.Get(); }
+		inline ID2D1SolidColorBrush*	GetSolidColorBrush() const	{ KGE_ASSERT(solid_color_brush_); return solid_color_brush_.Get(); }
 
 	private:
 		Renderer();