QtOgre         Embedding Ogre into a qt application

Note: There is a recent QOgreWidget written by djbe that is tested on Mac and Linux: http://www.ogre3d.org/phpBB2/viewtopic.php?p=258064 Alanic
However the links pointing to this version are not valid anymore. A code snippet working on Mac OSX 10.6 with Cocoa, Qt 4.7.4 and Ogre 1.7.3 was inserted below.
For a similar thread specific to Mac see http://www.ogre3d.org/forums/viewtopic.php?f=2&t=62967.

I found this documentation: Lakin's Ogre-Qt.

It is for Linux.. I prefer to do my development on my Windows machine (it has more ram / better video) and when I develop on Windows I use Visual Studio. As such, these instructions are priceless.

Once you have Qt built and you've set up your environment variables, you can run qmake on Ogre-Qt to get a vcproj. Open that up in visual studio and the first thing you'll have to do is add the OGRE include directory to the C++ Additional Include Directories. If you try to build now you will see some errors like this:

1>c:\qt-4.2.3-msvc2005\include\qtcore\../../src/corelib/tools/qhash.h(175) : error C2872: 'uint' : ambiguous symbol
1>        could be 'c:\qt-4.2.3-msvc2005\include\qtcore\../../src/corelib/global/qglobal.h(632) : unsigned int uint'
1>        or 'c:\ogresdk\include\OgrePrerequisites.h(134) : Ogre::uint'


There's a whole bunch of these, you need to add :: to the front of any reference to uint in the Qt code. You shouldn't need to recompile Qt after you do this.

Then you need to add the OGRE lib directory to the Linker Additional Library Directories and add OgreMain.lib to Linker Inputs.

For the debug configuration you will want to do the same but use OgreMain_d.lib.

Of course, so far my success rate hasn't been too high.

An Example using QT4 and Ogre Eihort

This is a standard QT Widget with an Ogre instance in it. You can create one on QT's designer by elevating a regular widget to an "OgreWidget" and including ogrewidget.h in your project. You'll probably want to do something about the chooseRenderer() function, since it doesn't really do much right now. I generally derive another class from this one and reimplement chooseRenderer(), and build my world in that class. Good Luck with it!

project.pro:

QT += widgets
QT += opengl

SOURCES += \
    main.cpp \
    ogrewidget.cpp

HEADERS += \
    ogrewidget.h

INCLUDEPATH += "(OgreFolder)\\include"

LIBS += -L"(OgreFolder)\\lib\\Release" -lcg
LIBS += -L"(OgreFolder)\\lib\\Release" -lFreeImage
LIBS += -L"(OgreFolder)\\lib\\Release" -lfreetype
LIBS += -L"(OgreFolder)\\lib\\Release" -lOgreMain
LIBS += -L"(OgreFolder)\\lib\\Release" -lOgreOverlay
LIBS += -L"(OgreFolder)\\lib\\Release" -lOgrePaging
LIBS += -L"(OgreFolder)\\lib\\Release" -lOgreProperty
LIBS += -L"(OgreFolder)\\lib\\Release" -lOgreRTShaderSystem
LIBS += -L"(OgreFolder)\\lib\\Release" -lOgreTerrain
LIBS += -L"(OgreFolder)\\lib\\Release" -lOgreVolume
LIBS += -L"(OgreFolder)\\lib\\Release" -lOIS
LIBS += -L"(OgreFolder)\\lib\\Release" -lzlib
LIBS += -L"(OgreFolder)\\lib\\Release" -lzziplib
LIBS += -L"(OgreFolder)\\boost\\lib" -llibboost_thread-vc120-mt-gd-1_55
LIBS += -L"(OgreFolder)\\boost\\lib" -llibboost_system-vc120-mt-gd-1_55
LIBS += -L"(OgreFolder)\\boost\\lib" -llibboost_date_time-vc120-mt-gd-1_55
LIBS += -L"(OgreFolder)\\boost\\lib" -llibboost_chrono-vc120-mt-gd-1_55

Replace (OgreFolder) with the path of the folder in which you installed Ogre, for example C:\\Program Files (x86)\\Microsoft Visual Studio 14.0\\Libraries\\OgreSDK\\OgreSDK_vc11_v1-9-0. Use two backslashes, not one.

ogrewidget.h:

#ifndef __OGREWIDGET_H__
#define __OGREWIDGET_H__

#include <OGRE/Ogre.h>
#include <QGLWidget>
#include <QX11Info>

class OgreWidget : public QGLWidget
{
  //Q_OBJECT;
  
 public:
  OgreWidget( QWidget *parent=0 ):
    QGLWidget( parent ),
    mOgreWindow(NULL)
    {
      init( "../bin/plugins.cfg", "../bin/ogre.cfg", "../bin/ogre.log" );
    }
  
  virtual ~OgreWidget()
    {
      mOgreRoot->shutdown();
      delete mOgreRoot;
      destroy();
    }
  
 protected:
  virtual void initializeGL();
  virtual void resizeGL( int, int );
  virtual void paintGL();

  void init( std::string, std::string, std::string );

  virtual Ogre::RenderSystem* chooseRenderer( Ogre::RenderSystemList* );

  Ogre::Root *mOgreRoot;
  Ogre::RenderWindow *mOgreWindow;
  Ogre::Camera *mCamera;
  Ogre::Viewport *mViewport;
  Ogre::SceneManager *mSceneMgr;
};

#endif

ogrewidget.cpp:

#include "ogrewidget.h"

#define THIS OgreWidget

/**
 * @brief init the object
 * @author kito berg-taylor
 */
void THIS::init( std::string plugins_file,
         std::string ogre_cfg_file,
         std::string ogre_log )
{
  // create the main ogre object
  mOgreRoot = new Ogre::Root( plugins_file, ogre_cfg_file, ogre_log );

  // setup a renderer
  Ogre::RenderSystemList *renderers = mOgreRoot->getAvailableRenderers();
  assert( !renderers->empty() ); // we need at least one renderer to do anything useful

  Ogre::RenderSystem *renderSystem;
  renderSystem = chooseRenderer( renderers );

  assert( renderSystem ); // user might pass back a null renderer, which would be bad!

  mOgreRoot->setRenderSystem( renderSystem );
  QString dimensions = QString( "%1x%2" )
                    .arg(this->width())
                    .arg(this->height());

  renderSystem->setConfigOption( "Video Mode", dimensions.toStdString() );

  // initialize without creating window
  mOgreRoot->getRenderSystem()->setConfigOption( "Full Screen", "No" );
  mOgreRoot->saveConfig();
  mOgreRoot->initialise(false); // don't create a window
}

/**
 * @brief setup the rendering context
 * @author Kito Berg-Taylor
 */
void THIS::initializeGL()
{
  //== Creating and Acquiring Ogre Window ==//

  // Get the parameters of the window QT created
  Ogre::String winHandle;
#ifdef WIN32
  // Windows code
  winHandle += Ogre::StringConverter::toString((unsigned long)(this->parentWidget()->winId()));
#elif MACOS
  // Mac code, tested on Mac OSX 10.6 using Qt 4.7.4 and Ogre 1.7.3
  Ogre::String winHandle  = Ogre::StringConverter::toString(winId());
#else
  // Unix code
  QX11Info info = x11Info();
  winHandle  = Ogre::StringConverter::toString((unsigned long)(info.display()));
  winHandle += ":";
  winHandle += Ogre::StringConverter::toString((unsigned int)(info.screen()));
  winHandle += ":";
  winHandle += Ogre::StringConverter::toString((unsigned long)(this->parentWidget()->winId()));
#endif
  

  Ogre::NameValuePairList params;
#ifndef MACOS
  // code for Windows and Linux
  params["parentWindowHandle"] = winHandle;
  mOgreWindow = mOgreRoot->createRenderWindow( "QOgreWidget_RenderWindow",
                           this->width(),
                           this->height(),
                           false,
                           &params );

  mOgreWindow->setActive(true);
  WId ogreWinId = 0x0;
  mOgreWindow->getCustomAttribute( "WINDOW", &ogreWinId );
  
  assert( ogreWinId );
  
  // bug fix, extract geometry
  QRect geo = this->frameGeometry ( );

  // create new window
  this->create( ogreWinId );

  // set geometrie infos to new window
  this->setGeometry (geo);

#else
  // code for Mac
  params["externalWindowHandle"] = winHandle;
  params["macAPI"] = "cocoa";
  params["macAPICocoaUseNSView"] = "true";
  mOgreWindow = mOgreRoot->createRenderWindow("QOgreWidget_RenderWindow",
      width(), height(), false, &params);
  mOgreWindow->setActive(true);
  makeCurrent();
#endif

  setAttribute( Qt::WA_PaintOnScreen, true );
  setAttribute( Qt::WA_NoBackground );

  //== Ogre Initialization ==//
  Ogre::SceneType scene_manager_type = Ogre::ST_EXTERIOR_CLOSE;

  mSceneMgr = mOgreRoot->createSceneManager( scene_manager_type );
  mSceneMgr->setAmbientLight( Ogre::ColourValue(1,1,1) );

  mCamera = mSceneMgr->createCamera( "QOgreWidget_Cam" );
  mCamera->setPosition( Ogre::Vector3(0,1,0) );
  mCamera->lookAt( Ogre::Vector3(0,0,0) );
  mCamera->setNearClipDistance( 1.0 );

  Ogre::Viewport *mViewport = mOgreWindow->addViewport( mCamera );
  mViewport->setBackgroundColour( Ogre::ColourValue( 0.8,0.8,1 ) );
}

/**
 * @brief render a frame
 * @author Kito Berg-Taylor
 */
void THIS::paintGL()
{
  // Be sure to call "OgreWidget->repaint();" to call paintGL
  assert( mOgreWindow );
  mOgreRoot->renderOneFrame();
}

/**
 * @brief resize the GL window
 * @author Kito Berg-Taylor
 */
void THIS::resizeGL( int width, int height )
{
  assert( mOgreWindow );
  mOgreWindow->windowMovedOrResized();
}

/**
 * @brief choose the right renderer
 * @author Kito Berg-Taylor
 */
Ogre::RenderSystem* THIS::chooseRenderer( Ogre::RenderSystemList *renderers )
{
  // It would probably be wise to do something more friendly 
  // that just use the first available renderer
  return *renderers->begin();
}


For OGRE Cthugha (v1.7.3)

In ogrewidget.cpp just replace....

// setup a renderer
  Ogre::RenderSystemList *renderers = mOgreRoot->getAvailableRenderers();
  assert( !renderers->empty() ); // we need at least one renderer to do anything useful

  Ogre::RenderSystem *renderSystem;
  renderSystem = chooseRenderer( renderers );

  assert( renderSystem ); // user might pass back a null renderer, which would be bad!


with

// setup a renderer
  Ogre::RenderSystemList::const_iterator renderers = mOgreRoot->getAvailableRenderers().begin();
  while(renderers != mOgreRoot->getAvailableRenderers().end())
  {
      Ogre::String rName = (*renderers)->getName();
        if (rName == "OpenGL Rendering Subsystem")
            break;
        renderers++;
  }

  Ogre::RenderSystem *renderSystem = *renderers;

For Qt 5.x.x

In Qt 5.x.x something is wrong with the resizing. The viewport ist positioned outside the visible area, so that
you only see a black widget. To solve this problem you have to replace the following code in ogrewidget.cpp:

void THIS::resizeGL( int width, int height )
{
   assert( mOgreWindow );
   mOgreWindow->windowMovedOrResized();
}


with

void THIS::resizeGL( int width, int height )
{
   assert( mOgreWindow );
   mOgreWindow->reposition( this->pos().x(), 
                            this->pos().y() );    
   mOgreWindow->resize( width, height );
   paintGL();
}


this

void THIS::paintGL()
{
  // Be sure to call "OgreWidget->repaint();" to call paintGL
  assert( mOgreWindow );
  mOgreRoot->renderOneFrame();
}


with

void THIS::paintGL()
{
  // Be sure to call "OgreWidget->repaint();" to call paintGL
  swapBuffers();
  assert( mOgreWindow );
  mOgreRoot->renderOneFrame();
}


and this

{
  ...
  setAttribute( Qt::WA_PaintOnScreen, true );
  setAttribute( Qt::WA_NoBackground );
  ...
}


with

{
  ...
  setAutoBufferSwap(false);
  setAttribute( Qt::WA_PaintOnScreen, true );
  setAttribute( Qt::WA_NoBackground );
  ...
}


To use...

#include <QApplication>
#include <QWidget>
#include "ogrewidget.h"
#include <QVBoxLayout>

int main(int argc, char *argv[])
{
    QApplication app(argc, argv);

    QWidget window;

    window.resize(800, 600);
    window.setWindowTitle("Simple example");
    
    OgreWidget* ogreWidget = new OgreWidget;

    QVBoxLayout *layout = new QVBoxLayout;
    layout->addWidget(ogreWidget);
         
    window.setLayout(layout);
    window.show();

    return app.exec();
}


Possible errors

The above code may produce compiling errors. If that's the case, try to replace:

In ogrewidget.cpp:

replace:

Ogre::RenderSystemList *renderers = mOgreRoot->getAvailableRenderers();


with:

const Ogre::RenderSystemList *renderers = &(mOgreRoot->getAvailableRenderers());



replace:

Ogre::RenderSystem* THIS::chooseRenderer( Ogre::RenderSystemList *renderers )


with:

Ogre::RenderSystem* THIS::chooseRenderer(const Ogre::RenderSystemList *renderers )



In ogrewidget.h:

replace:

virtual Ogre::RenderSystem* chooseRenderer( Ogre::RenderSystemList* );


with:

virtual Ogre::RenderSystem* chooseRenderer(const Ogre::RenderSystemList* );

For Windows

On Windows, you will have to remove
#include <QX11Info>