三维引擎设计-图形窗口封装

一：概述：

每个操作系统都有自己的图形系统，三维引擎会抽象出一个窗口，然后通过继承的方式，子类分别封装不同平台下面的窗口，另外，三维图形API也支持将内容渲染到其他表面上，比如纹理中，所以三维引擎也会抽象出一个纹理，再通过继承的方式，由子类分别封装不同图形API的纹理。

窗口和纹理，都可以看成一个抽象的画布，接收三维引擎的结果渲染到这个画布上，总体来说，一个抽象的画布，代表抽象的窗口或纹理，不同平台和图形API下的窗口和纹理又子类实现。这是三维引擎封装窗口系统的一种方法。

二：OSG的设计：

1：继承关系：

osg::GraphicsContext(图形系统抽象)

   |-osg::GraphicsWindow（窗口及渲染环境抽象）

|-osg::GraphicsWindowFOX（）

|-osg::GraphicsWindowWX（WX窗口）

|-osg::GraphicsWindowQt（QT窗口）

|-osg::GraphicsWindowCarbon（MacOS窗口）

|-osg::GraphicsWindowCocoa（Mac OS X窗口）

|-osg::GraphicsWindowIOS（IOS窗口）

|-osg::GraphicsWindowWin32（Win32窗口）

|-osg::GraphicsWindowX11(X11窗口)

|-osg::PixelBufferCarbon(MacOS像素缓存)

|-osg::PixelBufferCocoa(Mac OS X像素缓存)

|-osg::PixelBufferWin32(W32像素缓存)

|-osg::PixelBufferX11(X11像素缓存)

3. 三：OGRE的设计：

1：继承关系：

OgreRenderTarget（抽象画布，接收引擎绘制结果）

|-OgreRenderWindow（抽象窗口）

|-OgreWin32Window

|-OgreGLXWindow

|-OgreAndroidWindow

|-OgreD3D9RenderWindow

|-OgreD3D11RenderWindow

|-OgreEAGL2Window

|-OgreOSXCocoaWindow

|-OgreOSXWindow

|-OgreSDLWindow

|-OgreNaClWindow

|-OgreRenderTexture

|-D3D11RenderTexture

|-D3D9RenderTexture

|-GLESRenderTexture

|-GLES2RenderTexture

四： 窗口封装例子：

        

#ifndef CANVAS_H#define CANVAS_H#include <iostream>#include <string>#define CALLBACK#define ES_WINDOW_RGB           0#define ES_WINDOW_ALPHA         1#define ES_WINDOW_DEPTH         2#define ES_WINDOW_STENCIL       4#define ES_WINDOW_MULTISAMPLE   8namespace TDEngine {typedef void (CALLBACK *TDEngineKeyFunc)(unsigned char, int, int);typedef void (CALLBACK *TDEngineMouseFunc)(int, int, int, int);typedef void (CALLBACK *TDEngineDrawFunc)();class Canvas {private:virtual bool initDisplay(void)         {return false;}virtual bool initWindow(void)         {return false;}virtual bool initContext(void)         {return false;}virtual bool userInterrupt(void)         {return false;}public:Canvas()         {_width = 0;_height = 0;_flags = 0;_keyFunc = 0;_mouseFunc = 0;_drawFunc = 0;_currFps = 0;_frames = 0;_totalTime = 0;_wndType = 0;_eglDisplay = 0;_eglContext = 0;_eglSurface = 0;_eglConfig = 0;_clientWidth = 0;_clientHeight = 0;_handler = NULL;disableRootEvents = 0;}virtual ~Canvas()         {}virtual bool createWindow(int winWidth, int winHeight, int winOptions,std::string winTitle = "") =0;virtual void mainLoop(void) {}virtual void registerKeyboardFunc(TDEngineKeyFunc keyFunc) {}virtual void registerMouseFunc(TDEngineMouseFunc mouseFunc) {}virtual void registerDrawFunc(TDEngineDrawFunc drawFunc) {}virtual void addEventListener(std::string name, ScreenActionHandler action,bool bubble) = 0;virtual void removeEventListener(std::string name,ScreenActionHandler action, bool bubble) = 0;virtual void removeEventALLListener() = 0;virtual void fireEvents(const std::string& name,EventOption& eventOption) = 0;public:int _width;int _height;int _flags;std::string _title;TDEngineKeyFunc _keyFunc;TDEngineMouseFunc _mouseFunc;TDEngineDrawFunc _drawFunc;float _currFps;int _frames;float _totalTime;unsigned long _wndType;void* _eglDisplay;void* _eglContext;void* _eglSurface;void* _eglConfig;int _clientWidth;int _clientHeight;ScreenSpaceEventHandler* _handler;std::map<std::string, ScreenActionHandler> _callbackActionList;bool disableRootEvents;};}#endif // CANVAS_H

#ifndef CANVASX11_H#define CANVASX11_H#include  <X11/Xlib.h>#include  <X11/Xatom.h>#include  <X11/Xutil.h>#include "Canvas.h"#include "ScreenSpaceEventHandler.h"namespace <span><span>TDEngine</span></span> {class CanvasX11: public Canvas {public:Window _win;private:virtual bool initDisplay(void);virtual bool initWindow(void);virtual bool initContext(void);virtual bool userInterrupt(void);public:CanvasX11();virtual ~CanvasX11();virtual bool createWindow(int winWidth, int winHeight, int winOptions,std::string winTitle = "");virtual void mainLoop(void);virtual void registerKeyboardFunc(<span><span>TDEngine</span></span>KeyFunc keyFun);virtual void registerMouseFunc(<span><span>TDEngine</span></span>MouseFunc mouseFunc);virtual void registerDrawFunc(<span><span>TDEngine</span></span>DrawFunc drawFunc);virtual void fireEvents(const std::string& name, EventOption& eventOption);virtual void addEventListener(std::string name, ScreenActionHandler action,bool bubble);virtual void removeEventALLListener(){}void removeEventListener(std::string name, ScreenActionHandler callback,bool bubble);static void moveMouse(Canvas& canvas, MouseButtons button,const Cartesian2& startPosition, const Cartesian2& endPosition,bool shiftKey = false);Display* get_xDisplay();private:Display* _xDisplay;Window _rootWin;private:typedef ScreenActionHandler CallFunc;typedef std::vector<CallFunc> CallFuncList;typedef std::map<std::string, CallFuncList> CallBacks;CallBacks _callbacks;std::vector<CallFunc> _keydown;std::vector<CallFunc> _mousemove;std::vector<CallFunc> _mouseup;std::vector<CallFunc> _mousedown;std::vector<CallFunc> _dblclick;std::vector<CallFunc> _mousewheel;std::vector<CallFunc> _touchstart;std::vector<CallFunc> _touchmove;std::vector<CallFunc> _touchend;S32 _numRegistered;bool _disableRootEvents;};}#endif // CANVASX11_H