OSG-Win32窗口显示osg

深藏阁楼爱情的钟 2022-08-23 03:57 502阅读 0赞

上一节是入门：  
[OSG+VS2015+Win10配置][OSG_VS2015_Win10]

**win32控制台程序下使用osg**  
为了方便，在上一节中，我们使用VS创建了一个win32控制台程序，然后添加代码：

写法一

#include<osgViewer/Viewer>
    
    #include<osgDB/ReadFile>
    
    int main(int argc, char **argv)
    
    {
    
      osgViewer::Viewer viewer;
    
      viewer.setSceneData(osgDB::readNodeFile("cessna.osg"));
    
      return viewer.run();
    
    }

写法二  
更加优雅一点，使用了智能指针。

#include<osgViewer/Viewer>
    #include<osg/Node>
    #include<osg/Geode>
    #include<osg/Group>
    
    #include<osgDB/ReadFile>
    #include<osgDB/WriteFile>
    
    #include<osgUtil/Optimizer>
    
    int main(int argc, char **argv)
    {
      osg::ref_ptr<osgViewer::Viewer> viewer = new osgViewer::Viewer();
    
      osg::ref_ptr<osg::Group> root = new osg::Group();
    
      osg::ref_ptr<osg::Node> node =  osgDB::readNodeFile("cessna.osg");
    
      root->addChild(node.get());
    
      osgUtil::Optimizer optimizer;
      optimizer.optimize(root.get());
    
      viewer->setSceneData(root.get());
    
      viewer->realize();
    
      viewer->run();
    
      return 0;
    }

**Win32 Project下使用osg**  
首先回顾一下，一个win32窗口是如何创建的：  
1.1 入口函数WinMain

1.2 窗口处理函数  
当窗口处理消息事件时,系统调用该函数  
　　LRESULT CALLBACK WindowProc(  
HWND hwnd, // 窗口的句柄  
UINT uMsg, // 消息的ID号  
WPARAM wParam, // 消息所对应的参数  
LPARAM lParam // 消息所对应的参数  
);

1.3 注册窗口类型  
　　typedef struct \_WNDCLASS \{  
UINT style; //窗口类的风格：不是窗口类型的风格  
WNDPROC lpfnWndProc; //窗口处理函数  
int cbClsExtra; //窗口类附加数据大小  
int cbWndExtra; //窗口附加数据大小  
HANDLE hInstance; //当前应用程序的实例句柄  
HICON hIcon; //窗口图标  
HCURSOR hCursor; //窗口的鼠标  
HBRUSH hbrBackground; //窗口的背景画刷  
LPCTSTR lpszMenuName; //菜单  
LPCTSTR lpszClassName; //类型名称：不是窗口标题的名称，只是注册的名称  
\} WNDCLASS;

注册函数 RegisterClass

1.4 创建窗口  
　　HWND CreateWindow(  
LPCTSTR lpClassName, //窗口类型名称  
LPCTSTR lpWindowName, //窗口名称  
DWORD dwStyle, //窗口类型  
int x, //窗口的左上角X坐边  
int y, //窗口的左上角X坐边  
int nWidth, //窗口的宽度  
int nHeight, //窗口的高度  
HWND hWndParent, //父窗口句柄  
HMENU hMenu, //窗口菜单句柄  
HANDLE hInstance, //应用程序的实例句柄  
LPVOID lpParam //创建的参数，一般为NULL  
);

1.5 显示窗口  
ShowWindow 显示窗口  
　　BOOL ShowWindow(  
HWND hWnd, //显示的窗口句柄  
int nCmdShow //显示的方式  
);  
UpdateWindow 刷新窗口

1.6 消息处理  
GetMessage 获取消息  
DispatchMessage 派发消息

1.7 程序退出  
窗口销毁时，退出程序。在WndProc中实现。  
WM\_DESTROY: 当窗口销毁时，会调用WndProc  
传递给使用者。

**直接在窗口过程函数中使用，显示osg**

定义一些变量：

sg::ref_ptr<osgViewer::Viewer> viewer;
    osg::observer_ptr<osgViewer::GraphicsWindow> window;
    osg::ref_ptr<osg::Group> root;
    osg::ref_ptr<osg::Node> loadedModel;
    osgUtil::Optimizer optimizer;
    osg::ref_ptr<osg::GraphicsContext::Traits> traits;
    osg::ref_ptr<osg::Referenced> windata;
    osg::GraphicsContext* gc;
    osg::ref_ptr<osg::Camera> camera;
    bool renderok;

在WM\_CREATE消息中添加代码：

root = new osg::Group;
        loadedModel = osgDB::readNodeFile("cessna.osg");
        if (!loadedModel)
          return 1;
        optimizer.optimize(loadedModel.get());
        optimizer.reset();
        root->addChild(loadedModel.get());
        traits = new osg::GraphicsContext::Traits;
        windata = new osgViewer::GraphicsWindowWin32::WindowData(hwnd);
        traits->x = 0;
        traits->y = 0;
        traits->width = 800;
        traits->height = 600;
        traits->windowDecoration = false;
        traits->doubleBuffer = true;
        traits->sharedContext = 0;
        traits->inheritedWindowData = windata;
        traits->setInheritedWindowPixelFormat = true;
        gc = osg::GraphicsContext::createGraphicsContext(traits.get());
        camera = new osg::Camera;
        camera->setGraphicsContext(gc);
        camera->setViewport(new osg::Viewport(traits->x, traits->y, traits->width, traits->height));
        viewer = new osgViewer::Viewer;
        viewer->addSlave(camera.get());
        viewer->setSceneData(root.get());
        viewer->setCameraManipulator(new osgGA::TrackballManipulator);
        viewer->addEventHandler(new osgViewer::StatsHandler);
        viewer->setThreadingModel(osgViewer::Viewer::SingleThreaded);
        viewer->realize();
        renderok = false;
        _beginthread(render, 0, NULL);

=============================================================  
全部代码：

#include <windows.h>
    #include <osgViewer/Viewer>
    #include <osgViewer/ViewerEventHandlers>
    #include <osgViewer/api/win32/GraphicsWindowWin32>
    #include <osgUtil/Optimizer>
    #include <osgGA/TrackballManipulator>
    #include <osgDB/ReadFile>
    #include <process.h>
    
    osg::ref_ptr<osgViewer::Viewer> viewer;
    osg::observer_ptr<osgViewer::GraphicsWindow> window;
    osg::ref_ptr<osg::Group> root;
    osg::ref_ptr<osg::Node> loadedModel;
    osgUtil::Optimizer optimizer;
    osg::ref_ptr<osg::GraphicsContext::Traits> traits;
    osg::ref_ptr<osg::Referenced> windata;
    osg::GraphicsContext* gc;
    osg::ref_ptr<osg::Camera> camera;
    bool renderok;
    
    LRESULT CALLBACK WndProc(HWND, UINT, WPARAM, LPARAM);
    
    int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, PSTR szCmdLine, int iCmdShow)
    {
      static TCHAR szAppName[] = TEXT("HelloOSG Win32 Project");
      HWND hwnd;
      MSG msg;
      WNDCLASS wndclass;
      wndclass.style = CS_HREDRAW | CS_VREDRAW;
      wndclass.lpfnWndProc = WndProc;
      wndclass.cbClsExtra = 0;
      wndclass.cbWndExtra = 0;
      wndclass.hInstance = hInstance;
      wndclass.hIcon = LoadIcon(NULL, IDI_APPLICATION);
      wndclass.hCursor = LoadCursor(NULL, IDC_ARROW);
      wndclass.hbrBackground = (HBRUSH)GetStockObject(WHITE_BRUSH);
      wndclass.lpszMenuName = NULL;
      wndclass.lpszClassName = szAppName;
      if (!RegisterClass(&wndclass))
      {
        MessageBox(NULL, TEXT("This program requires Windows NT!"), szAppName, MB_ICONERROR);
        return 0;
      }
      hwnd = CreateWindow(szAppName, // window class name
        TEXT("The Hello Program"), // window caption
        WS_OVERLAPPEDWINDOW, // window style
        100, // initial x position
        100, // initial y position
        800, // initial x size
        600, // initial y size
        NULL, // parent window handle
        NULL, // window menu handle
        hInstance, // program instance handle
        NULL); // creation parameters
      ShowWindow(hwnd, iCmdShow);
      UpdateWindow(hwnd);
      while (GetMessage(&msg, NULL, 0, 0))
      {
        TranslateMessage(&msg);
        DispatchMessage(&msg);
      }
      return (int)msg.wParam;
    }
    void render(void* ptr)
    {
      while (!viewer->done())
      {
        viewer->frame();
      }
      renderok = true;
    }
    LRESULT CALLBACK WndProc(HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
    {
      switch (message)
      {
      case WM_CREATE:
        root = new osg::Group;
        loadedModel = osgDB::readNodeFile("cessna.osg");
        if (!loadedModel)
          return 1;
        optimizer.optimize(loadedModel.get());
        optimizer.reset();
        root->addChild(loadedModel.get());
        traits = new osg::GraphicsContext::Traits;
        windata = new osgViewer::GraphicsWindowWin32::WindowData(hwnd);
        traits->x = 0;
        traits->y = 0;
        traits->width = 800;
        traits->height = 600;
        traits->windowDecoration = false;
        traits->doubleBuffer = true;
        traits->sharedContext = 0;
        traits->inheritedWindowData = windata;
        traits->setInheritedWindowPixelFormat = true;
        gc = osg::GraphicsContext::createGraphicsContext(traits.get());
        camera = new osg::Camera;
        camera->setGraphicsContext(gc);
        camera->setViewport(new osg::Viewport(traits->x, traits->y, traits->width, traits->height));
        viewer = new osgViewer::Viewer;
        viewer->addSlave(camera.get());
        viewer->setSceneData(root.get());
        viewer->setCameraManipulator(new osgGA::TrackballManipulator);
        viewer->addEventHandler(new osgViewer::StatsHandler);
        viewer->setThreadingModel(osgViewer::Viewer::SingleThreaded);
        viewer->realize();
        renderok = false;
        _beginthread(render, 0, NULL);
        return 0;
      case WM_PAINT:
        return 0;
      case WM_DESTROY:
        viewer->setDone(true);
        while (!renderok)
        {
          Sleep(10);
        }
        PostQuitMessage(0);
        return 0;
      }
      return DefWindowProc(hwnd, message, wParam, lParam);
    }

运行：  
![这里写图片描述][20160606234306849]

[OSG_VS2015_Win10]: http://blog.csdn.net/wangshubo1989/article/details/51591802
[20160606234306849]: /images/20220722/c9d25d1ccf344e3ab9edcb44ddfbdb14.png