在QT中搭建OSG开发环境_qt osg 集成

一、概述

        OpenSceneGraph（简称OSG）使用OpenGL技术开发，是一套基于C++平台的应用程序接口（API），它让程序员能够更加快速、便捷地创建高性能、跨平台的交互式图形程序。它作为中间件（middleware）为应用软件提供了各种高级渲染特性，IO，以及空间结构组织函数；而更低层次的OpenGL 硬件抽象层（HAL）实现了底层硬件显示的驱动。

        网上关于编译osg的资料太多，关于OSG的编译在此不过多赘述，本人使用的是vs2015+osg365，本篇将详细讲解一下如何在QT中搭建OSG开发环境。

        无论是集成到QT还是MFC还是其他开发环境，归根到底是显示方式的不同，就好比看视频，可以投屏、可以投影，只要找到显示的窗体类，借助窗体类完成显示即可，这是问题的思路。

        OSG集成到QT中有两种方式：

• osgQt。在较老版本的osg中自带osgQt源码包，主要适配的是QT4，网址：osgQt
• osgQOpenGL。需要自行编译适配的osg版本，主要适配QT5。

        本文采用的是第一种方式，采用osgQt的方式，源码集成。为什么采用源码集成而不采用原有的lib文件，是因为方便做二次开发，这在后面用到会逐渐讲到。

二、准备 GraphicsWindowQt

        首先是文件GraphicsWindowQt源码，这里拿到源码需要修改一下，修改项目如下：

• GraphicsWindowQt.h:
  • #include <QMutex>改为#include <QtCore/QMutex>；
  • 删除 #include <osgQt/Export>；
  • 删除 OSGQT_EXPORT 关键字。
•  GraphicsWindowQt.cpp:
  • #include <QMutex>改为#include <QtCore/QMutex>；
  • 删除 OSGQT_EXPORT 关键字;
  • 578行：

    getEventQueue()->syncWindowRectangleWithGraphicsContext();
    

    改为：

    getEventQueue()->getCurrentEventState()->getGraphicsContext();
    

         如果不想改，我改好的地址：osgQt修改版，提取码：0501。

三、代码集成

• 新建空白Qt Widgets  Application 项目，新建osgwidget QT设计师类，pro文件中引入opengl：

  QT       += core gui opengl
  

• 引入osg相关外部依赖： 

  win32:CONFIG(release, debug|release): LIBS += -L$$PWD/../../osg/denpendency/osg/lib/ -losg
  else:win32:CONFIG(debug, debug|release): LIBS += -L$$PWD/../../osg/denpendency/osg/lib/ -losgd
  else:unix: LIBS += -L$$PWD/../../osg/denpendency/osg/lib/ -losg
   
  INCLUDEPATH += $$PWD/../../osg/denpendency/osg/include
  DEPENDPATH += $$PWD/../../osg/denpendency/osg/include
   
  win32:CONFIG(release, debug|release): LIBS += -L$$PWD/../../osg/denpendency/osg/lib/ -lOpenThreads
  else:win32:CONFIG(debug, debug|release): LIBS += -L$$PWD/../../osg/denpendency/osg/lib/ -lOpenThreadsd
  else:unix: LIBS += -L$$PWD/../../osg/denpendency/osg/lib/ -lOpenThreads
   
  INCLUDEPATH += $$PWD/../../osg/denpendency/osg/include
  DEPENDPATH += $$PWD/../../osg/denpendency/osg/include
   
  win32:CONFIG(release, debug|release): LIBS += -L$$PWD/../../osg/denpendency/osg/lib/ -losgGA
  else:win32:CONFIG(debug, debug|release): LIBS += -L$$PWD/../../osg/denpendency/osg/lib/ -losgGAd
  else:unix: LIBS += -L$$PWD/../../osg/denpendency/osg/lib/ -losgGA
   
  INCLUDEPATH += $$PWD/../../osg/denpendency/osg/include
  DEPENDPATH += $$PWD/../../osg/denpendency/osg/include
   
  win32:CONFIG(release, debug|release): LIBS += -L$$PWD/../../osg/denpendency/osg/lib/ -losgViewer
  else:win32:CONFIG(debug, debug|release): LIBS += -L$$PWD/../../osg/denpendency/osg/lib/ -losgViewerd
  else:unix: LIBS += -L$$PWD/../../osg/denpendency/osg/lib/ -losgViewer
   
  INCLUDEPATH += $$PWD/../../osg/denpendency/osg/include
  DEPENDPATH += $$PWD/../../osg/denpendency/osg/include
   
   
  win32:CONFIG(release, debug|release): LIBS += -L$$PWD/../../osg/denpendency/osg/lib/ -losgDB
  else:win32:CONFIG(debug, debug|release): LIBS += -L$$PWD/../../osg/denpendency/osg/lib/ -losgDBd
  else:unix: LIBS += -L$$PWD/../../osg/denpendency/osg/lib/ -losgDB
   
  INCLUDEPATH += $$PWD/../../osg/denpendency/osg/include
  DEPENDPATH += $$PWD/../../osg/denpendency/osg/include
  

  这里文件路径替换成你自己的osg文件路径。

• main.h:

  #include "osgwidget.h"
  #include <QApplication>
   
  int main(int argc, char *argv[])
  {
      QApplication a(argc, argv);
      OSGWidget w;
      w.show();
   
      return a.exec();
  }
  

• osgwidget.h: 

  #ifndef OSGWIDGET_H
  #define OSGWIDGET_H
   
  #include <QWidget>
  #include <QTimer>
  #include <osgDB/ReadFile>
  #include <osg/Group>
  #include <osg/Node>
  #include <osg/Camera>
  #include <osgGA/TrackballManipulator>
  #include <osgGA/StateSetManipulator>
  #include <osgViewer/ViewerEventHandlers>
   
  #include "GraphicsWindowQt.h"	// 这个是本地自己建的。所以用双引号
  #include <QDebug>
  namespace Ui {
  class OSGWidget;
  }
   
  class OSGWidget : public QWidget
  {
      Q_OBJECT
   
  public:
      explicit OSGWidget(QWidget *parent = nullptr);
      ~OSGWidget();
   
  private:
      Ui::OSGWidget *ui;
   
   
  public:
      QTimer* m_timer;
      osgViewer::Viewer* viewer;
   
   
  public:
      void initEarth();
   
  public slots:
      void updateFrame();
   
  };
   
  #endif // OSGWIDGET_H
  

• osgwidget.cpp:

  #include "osgwidget.h"
  #include "ui_osgwidget.h"
   
  OSGWidget::OSGWidget(QWidget *parent) :
      QWidget(parent),
      ui(new Ui::OSGWidget)
  {
      ui->setupUi(this);
      m_timer = new QTimer;
      viewer = new osgViewer::Viewer;
      initEarth();
   
  }
   
  OSGWidget::~OSGWidget()
  {
      delete ui;
      //    delete m_timer;
  }
   
  void OSGWidget::initEarth(){
   
      // 设置模型
      osg::ref_ptr<osg::Group> root = new osg::Group;
      // 显示cow.osg 模型
      root->addChild(osgDB::readNodeFile("cow.osg"));
      // 显示 .earth 文件中的地球模型
  //    root->addChild(osgDB::readNodeFile("china-simple-3d.earth"));
   
   
      osg::ref_ptr<osg::GraphicsContext::Traits> traits = new osg::GraphicsContext::Traits;
      traits->windowDecoration = false;//声明是否显示窗口的描述
      traits->x = 50;
      traits->y = 50;
      traits->width = 800;
      traits->height = 600;
      traits->doubleBuffer = true;//创建图形窗口是否使用双缓存
   
      osg::ref_ptr<osg::Camera> camera = new osg::Camera;
      camera->setGraphicsContext(new osgQt::GraphicsWindowQt(traits.get()));
      camera->setClearColor(osg::Vec4(0.2f, 0.2f, 0.6f, 1.0));
      camera->setViewport(new osg::Viewport(0, 0, 800, 600));
      camera->setProjectionMatrixAsPerspective(30.0, 800.0/600.0, 1.0, 10000.0);
   
   
      //设置渲染器
      viewer->setCamera(camera);
      viewer->setSceneData(root);
      viewer->setCameraManipulator(new osgGA::TrackballManipulator);
      viewer->setThreadingModel(osgViewer::Viewer::SingleThreaded);//创建为单线程
      viewer->addEventHandler(new osgGA::StateSetManipulator(viewer->getCamera()->getOrCreateStateSet()));
      viewer->addEventHandler(new osgViewer::WindowSizeHandler);
      viewer->addEventHandler(new osgViewer::StatsHandler);
   
   
      osgQt::GraphicsWindowQt* gw = dynamic_cast<osgQt::GraphicsWindowQt*>(camera->getGraphicsContext());
   
      // 这里是直接在ui文件中添加了一个布局，重命名成了horizontalLayoutOSG
      ui->horizontalLayoutOSG->addWidget((QWidget*)(gw->getGLWidget()));
      QObject::connect(m_timer, SIGNAL(timeout()), this, SLOT(updateFrame()));
      m_timer->start(5);	// 每5ms触发一次帧的刷新
   
   
   
  }
  void OSGWidget::updateFrame(){
          viewer->frame();
  }
  

   
• 将之前修改好的GraphicsWindowQt.h，GraphicsWindowQt.cpp文件引入到项目中即可，如图：