OSG-Win32窗口显示osg

深藏阁楼爱情的钟 2022-08-23 03:57 598阅读 0赞

上一节是入门：
OSG+VS2015+Win10配置

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

  1. #include<osgViewer/Viewer>
  3. #include<osgDB/ReadFile>
  5. int main(int argc, char **argv)
  7. {
  9.   osgViewer::Viewer viewer;
  11.   viewer.setSceneData(osgDB::readNodeFile("cessna.osg"));
  13.   return viewer.run();
  15. }

写法二
更加优雅一点，使用了智能指针。

  1. #include<osgViewer/Viewer>
  2. #include<osg/Node>
  3. #include<osg/Geode>
  4. #include<osg/Group>
  6. #include<osgDB/ReadFile>
  7. #include<osgDB/WriteFile>
  9. #include<osgUtil/Optimizer>
  11. int main(int argc, char **argv)
  12. {
  13.   osg::ref_ptr<osgViewer::Viewer> viewer = new osgViewer::Viewer();
  15.   osg::ref_ptr<osg::Group> root = new osg::Group();
  17.   osg::ref_ptr<osg::Node> node =  osgDB::readNodeFile("cessna.osg");
  19.   root->addChild(node.get());
  21.   osgUtil::Optimizer optimizer;
  22.   optimizer.optimize(root.get());
  24.   viewer->setSceneData(root.get());
  26.   viewer->realize();
  28.   viewer->run();
  30.   return 0;
  31. }

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;

  1. 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：

  1. sg::ref_ptr<osgViewer::Viewer> viewer;
  2. osg::observer_ptr<osgViewer::GraphicsWindow> window;
  3. osg::ref_ptr<osg::Group> root;
  4. osg::ref_ptr<osg::Node> loadedModel;
  5. osgUtil::Optimizer optimizer;
  6. osg::ref_ptr<osg::GraphicsContext::Traits> traits;
  7. osg::ref_ptr<osg::Referenced> windata;
  8. osg::GraphicsContext* gc;
  9. osg::ref_ptr<osg::Camera> camera;
  10. bool renderok;

在WM_CREATE消息中添加代码：

  1. root = new osg::Group;
  2.     loadedModel = osgDB::readNodeFile("cessna.osg");
  3.     if (!loadedModel)
  4.       return 1;
  5.     optimizer.optimize(loadedModel.get());
  6.     optimizer.reset();
  7.     root->addChild(loadedModel.get());
  8.     traits = new osg::GraphicsContext::Traits;
  9.     windata = new osgViewer::GraphicsWindowWin32::WindowData(hwnd);
  10.     traits->x = 0;
  11.     traits->y = 0;
  12.     traits->width = 800;
  13.     traits->height = 600;
  14.     traits->windowDecoration = false;
  15.     traits->doubleBuffer = true;
  16.     traits->sharedContext = 0;
  17.     traits->inheritedWindowData = windata;
  18.     traits->setInheritedWindowPixelFormat = true;
  19.     gc = osg::GraphicsContext::createGraphicsContext(traits.get());
  20.     camera = new osg::Camera;
  21.     camera->setGraphicsContext(gc);
  22.     camera->setViewport(new osg::Viewport(traits->x, traits->y, traits->width, traits->height));
  23.     viewer = new osgViewer::Viewer;
  24.     viewer->addSlave(camera.get());
  25.     viewer->setSceneData(root.get());
  26.     viewer->setCameraManipulator(new osgGA::TrackballManipulator);
  27.     viewer->addEventHandler(new osgViewer::StatsHandler);
  28.     viewer->setThreadingModel(osgViewer::Viewer::SingleThreaded);
  29.     viewer->realize();
  30.     renderok = false;
  31.     _beginthread(render, 0, NULL);

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

  1. #include <windows.h>
  2. #include <osgViewer/Viewer>
  3. #include <osgViewer/ViewerEventHandlers>
  4. #include <osgViewer/api/win32/GraphicsWindowWin32>
  5. #include <osgUtil/Optimizer>
  6. #include <osgGA/TrackballManipulator>
  7. #include <osgDB/ReadFile>
  8. #include <process.h>
  10. osg::ref_ptr<osgViewer::Viewer> viewer;
  11. osg::observer_ptr<osgViewer::GraphicsWindow> window;
  12. osg::ref_ptr<osg::Group> root;
  13. osg::ref_ptr<osg::Node> loadedModel;
  14. osgUtil::Optimizer optimizer;
  15. osg::ref_ptr<osg::GraphicsContext::Traits> traits;
  16. osg::ref_ptr<osg::Referenced> windata;
  17. osg::GraphicsContext* gc;
  18. osg::ref_ptr<osg::Camera> camera;
  19. bool renderok;
  21. LRESULT CALLBACK WndProc(HWND, UINT, WPARAM, LPARAM);
  23. int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, PSTR szCmdLine, int iCmdShow)
  24. {
  25.   static TCHAR szAppName[] = TEXT("HelloOSG Win32 Project");
  26.   HWND hwnd;
  27.   MSG msg;
  28.   WNDCLASS wndclass;
  29.   wndclass.style = CS_HREDRAW | CS_VREDRAW;
  30.   wndclass.lpfnWndProc = WndProc;
  31.   wndclass.cbClsExtra = 0;
  32.   wndclass.cbWndExtra = 0;
  33.   wndclass.hInstance = hInstance;
  34.   wndclass.hIcon = LoadIcon(NULL, IDI_APPLICATION);
  35.   wndclass.hCursor = LoadCursor(NULL, IDC_ARROW);
  36.   wndclass.hbrBackground = (HBRUSH)GetStockObject(WHITE_BRUSH);
  37.   wndclass.lpszMenuName = NULL;
  38.   wndclass.lpszClassName = szAppName;
  39.   if (!RegisterClass(&wndclass))
  40.   {
  41.     MessageBox(NULL, TEXT("This program requires Windows NT!"), szAppName, MB_ICONERROR);
  42.     return 0;
  43.   }
  44.   hwnd = CreateWindow(szAppName, // window class name
  45.     TEXT("The Hello Program"), // window caption
  46.     WS_OVERLAPPEDWINDOW, // window style
  47.     100, // initial x position
  48.     100, // initial y position
  49.     800, // initial x size
  50.     600, // initial y size
  51.     NULL, // parent window handle
  52.     NULL, // window menu handle
  53.     hInstance, // program instance handle
  54.     NULL); // creation parameters
  55.   ShowWindow(hwnd, iCmdShow);
  56.   UpdateWindow(hwnd);
  57.   while (GetMessage(&msg, NULL, 0, 0))
  58.   {
  59.     TranslateMessage(&msg);
  60.     DispatchMessage(&msg);
  61.   }
  62.   return (int)msg.wParam;
  63. }
  64. void render(void* ptr)
  65. {
  66.   while (!viewer->done())
  67.   {
  68.     viewer->frame();
  69.   }
  70.   renderok = true;
  71. }
  72. LRESULT CALLBACK WndProc(HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
  73. {
  74.   switch (message)
  75.   {
  76.   case WM_CREATE:
  77.     root = new osg::Group;
  78.     loadedModel = osgDB::readNodeFile("cessna.osg");
  79.     if (!loadedModel)
  80.       return 1;
  81.     optimizer.optimize(loadedModel.get());
  82.     optimizer.reset();
  83.     root->addChild(loadedModel.get());
  84.     traits = new osg::GraphicsContext::Traits;
  85.     windata = new osgViewer::GraphicsWindowWin32::WindowData(hwnd);
  86.     traits->x = 0;
  87.     traits->y = 0;
  88.     traits->width = 800;
  89.     traits->height = 600;
  90.     traits->windowDecoration = false;
  91.     traits->doubleBuffer = true;
  92.     traits->sharedContext = 0;
  93.     traits->inheritedWindowData = windata;
  94.     traits->setInheritedWindowPixelFormat = true;
  95.     gc = osg::GraphicsContext::createGraphicsContext(traits.get());
  96.     camera = new osg::Camera;
  97.     camera->setGraphicsContext(gc);
  98.     camera->setViewport(new osg::Viewport(traits->x, traits->y, traits->width, traits->height));
  99.     viewer = new osgViewer::Viewer;
  100.     viewer->addSlave(camera.get());
  101.     viewer->setSceneData(root.get());
  102.     viewer->setCameraManipulator(new osgGA::TrackballManipulator);
  103.     viewer->addEventHandler(new osgViewer::StatsHandler);
  104.     viewer->setThreadingModel(osgViewer::Viewer::SingleThreaded);
  105.     viewer->realize();
  106.     renderok = false;
  107.     _beginthread(render, 0, NULL);
  108.     return 0;
  109.   case WM_PAINT:
  110.     return 0;
  111.   case WM_DESTROY:
  112.     viewer->setDone(true);
  113.     while (!renderok)
  114.     {
  115.       Sleep(10);
  116.     }
  117.     PostQuitMessage(0);
  118.     return 0;
  119.   }
  120.   return DefWindowProc(hwnd, message, wParam, lParam);
  121. }

运行：
这里写图片描述

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