WxOgreView         A minimalistic C++ class providing Ogre render windows within wxWidgets

WxOgreView v. 1.0

The following article presents a minimalistic C++ class, that provides an Ogre 3D
render window inside a wxWidgets application. It can be applied to different wxWidgets/Ogre
applications like 3D editors or model viewers.

Requirements

  • OGRE 1.6
  • wxWidgets 2.8

Advantages

  • Supports multiple Ogre render windows in one application (the class is not a Singleton)
  • great separation of Ogre and wxWidgets (for more flexible applications and a better source code clarity)
  • platform independent (Windows and Linux, Linux support not tested yet, direct3D support can be added easily )

Disadvantages

  • The main Ogre components like Root, Scenemanager, etc. need to be created manually in every application that is based on wxOgreView, because they are not created in the wxOgreView class automatically (because of the seperation of Ogre and wxWidgets)

Code

wxOgreView.h

/// The wxOgreView class
/** The wxOgreView class provides an Ogre render window
    and a function to get the window handle. You can create and assign a render 
    window with the setRenderWindow method.
*/
#ifndef __WXOGRE_H__
#define __WXOGRE_H__

#include <wx/wx.h>
#include <Ogre.h>
#include <OgrePrerequisites.h>

class wxOgreView : public wxControl
{
public:
    /** Constructor - A new wxOgreView must receive a parent window to which it can be attached
        @param parent pointer to a parent window.
        @param id pointer to a parent window.
        @param pos Window position. wxDefaultPosition indicates that wxWidgets should generate a default
               position for the window. If using the wxWindow class directly, supply an actual position.
        @param size Window size. wxDefaultSize indicates that wxWidgets should generate a default size
               for the window. If no suitable size can be found, the window will be sized to 20x20 pixels
               so that the window is visible but obviously not correctly sized.
        @param style Window style. For generic window styles, please see wxWindow.
        @param validator pointer to a pvalidator.
        @param name wxOgreView name. */
    wxOgreView (wxWindow* parent,
                wxWindowID id = -1,
                const wxPoint &pos=wxDefaultPosition,
                const wxSize &size=wxDefaultSize,
                long style=0,
                const wxValidator& validator = wxDefaultValidator,
                const wxString &name=wxPanelNameStr);
    wxOgreView();
    /** Standard Destructor*/
    ~wxOgreView();
    /** Create a new RenderWindow with the specified name and assign it to the 
     *  RenderWindow pointer. 
        @param name The name of the window. */
    void setRenderWindow(const Ogre::String &name);
    /** Return the RenderWindow pointer */
    Ogre::RenderWindow* getRenderWindow();
    /** Return the window handle that is used to create a RenderWindow */
    Ogre::String getWindowHandle();

private:
    /** Notify Ogre on a window resize event
        @param event the rezising event. */
    void OnSize(wxSizeEvent& event);

protected:
    ///RenderWindow pointer
      Ogre::RenderWindow* mpRenderWindow;
    ///Event table for resize events
    DECLARE_EVENT_TABLE()

};

#endif // __WXOGRE_H__


wxOgreView.cpp

#include "wxOgreView.h"

//================================================================================= BEGIN_EVENT_TABLE()//
BEGIN_EVENT_TABLE(wxOgreView, wxControl)
    EVT_SIZE(wxOgreView::OnSize)
    //EVT_PAINT(wxOgre::OnPaint) // Produces flickers and runs too fast!
    //EVT_ERASE_BACKGROUND( wxOgre::OnEraseBackground )
END_EVENT_TABLE()

//================================================================================= wxOgreView()//
wxOgreView::wxOgreView(wxWindow* parent,
                       wxWindowID id,
                       const wxPoint &pos,
                       const wxSize &size,
                       long style,
                       const wxValidator& validator,
                       const wxString &name) :   wxControl(parent, id, pos, size, style, validator, name),
                                                 mpRenderWindow(0)
{

}

wxOgreView::wxOgreView() : wxControl(),
                           mpRenderWindow(0)
{
}
//================================================================================= ~wxOgreView()//
wxOgreView::~wxOgreView()
{
}

//================================================================================= getWindowHandle()//
Ogre::String wxOgreView::getWindowHandle()
{
    Ogre::String handle;

#ifdef __WXMSW__
    handle = Ogre::StringConverter::toString((size_t)((HWND)GetHandle()));
#elif defined(__WXGTK__)NameValuePairList
    // TODO: Someone test this. you might to use "parentWindowHandle" if this
    // does not work.  Ogre 1.2 + Linux + GLX platform wants a string of the
    // format display:screen:window, which has variable types ulong:uint:ulong.
    GtkWidget* widget = GetHandle();
    gtk_widget_realize( widget );    // Mandatory. Otherwise, a segfault happens.
    std::stringstream handleStream;
    Display* display = GDK_WINDOW_XDISPLAY( widget->window );
    Window wid = GDK_WINDOW_XWINDOW( widget->window );    // Window is a typedef for XID, which is a typedef for unsigned int
    /* Get the right display (DisplayString() returns ":display.screen") */
    std::string displayStr = DisplayString( display );
    displayStr = displayStr.substr( 1, ( displayStr.find( ".", 0 ) - 1 ) );
    /* Put all together */
    handleStream << displayStr << ':' << DefaultScreen( display ) << ':' << wid;
    handle = handleStream.str();
#else
    #error Not supported on this platform.
#endif

    return handle;
}

//================================================================================= getRenderWindow()
Ogre::RenderWindow* wxOgreView::getRenderWindow()
{
    return mpRenderWindow;
}

//================================================================================= setRenderWindow()
void wxOgreView::setRenderWindow(const Ogre::String &name)
{
    static int width, height;
    GetSize(&width,&height);
    Ogre::NameValuePairList params;
    params["externalWindowHandle"] = getWindowHandle();
    mpRenderWindow = Ogre::Root::getSingleton().createRenderWindow(name, width, height, false, &params);
}

//================================================================================= OnSize()//
void wxOgreView::OnSize(wxSizeEvent& event)
{
    if(mpRenderWindow)
    {
        static int width;
        static int height;
        GetSize(&width, &height);
        mpRenderWindow->resize( width, height );
        // Letting Ogre know the window has been resized;
        mpRenderWindow->windowMovedOrResized();
    }
}

Description

wxOgreView extends wxControl. It containes a pointer to a render window which is
used to render an Ogre scene inside the view. To create a new wxOgreView object you
need to pass a wxWindow (or a subclass) pointer to the constructor. The setRenderWindow method creates
a render window with the size of the wxOgreView using the handle that is returnd by
the platform independent getWindowHandle method. The getRenderWindow method simply
returns the render window pointer. Finally there is the OnSize method to notify
Ogre on a window resize event.

Usage Information

To attach a wxOgreView to a wxWidgets window (or frame) you need to pass the window
to the wxOgreView constructor (see also mainFrame.cpp):

wxOgreView* MainOgreView = new wxOgreView( this );

Within the application this pointer is used to get access to the related render window
(see also wxOgreScene.cpp):

MainOgreView->setRenderWindow( "OgreRenderWindow" );
Ogre::RenderWindow* MainWindow = MainOgreView->getRenderWindow();

The desired scene can be created by the class wxOgreScene. This class is also used to
select the rendering system and to create the main Ogre components. For access to the
render window you only need to pass the wxOgreView pointer to the wxOgreScene class as
a constructor parameter (see also mainFrame.cpp):

wxOgreScene* OgreScene = new wxOgreScene (OgreView);

The window handle is returned by the getWindowHandle method and is used to create
the render window at the setRenderWindow method. Beacause of this you don't need
to take care of the handle by yourself.

You also have the possibility to derive a subclass of wxOgreView (see wxOgreViewEventHandler)
and declare some event methods for mouse or keyboard interaction to get the
appropriate bahaviour for yout own application. Using the wxOgreView class you are
able to create a lot of different GUI-Applications with several render windows.

Example

To see the wxOgreView class in action you can take a look at the example application which you can download below.
This application creates a wxWidgets frame including a wxOgreView and a wxOgreViewEventHandler class (subclass of wxOgreView). The wxOgreViews provide two independent render windows that show a test scene from differen perspectives. The wxOgreViews are created within the constructor of the mainFrame class (mainFrame.cpp):

mpOgreViewLeft = new wxOgreView( this ) ;
mpOgreViewRight = new wxOgreViewEventHandler( this ) ;

The wxOgreViews are added to a BoxSizer to get a better optical seperation of the render windows.

MainBoxSizer->Add(mpMainOgreView,0, wxSHAPED|wxALL|wxALIGN_CENTER,5);
MainBoxSizer->Add(mpSecOgreView,0, wxSHAPED|wxALL|wxALIGN_CENTER,5);

The two render windows are created within the constructor of the wxOgreScene class (wxOgreScene.cpp):

MainOgreView->setRenderWindow( "OgreRenderWindow1" ) ;
SecOgreView->setRenderWindow( "OgreRenderWindow2" ) ;

The wxOgreScene object is created within the constructor of the mainFrame class (mainFrame.cpp):

mpMainScene = new wxOgreScene(mpMainOgreView, mpSecOgreView);


The wxOgreViewEventHandler class extends wxOgreView and implements two methods for mouse interaction with the corresponding render window. This allows you to rotate the camera and zoom into or out of the scene within the right render window.

You can download the source code of the example program and the related doxygen
documentation from the following links:

wxOgreView Example (Code::Blocks project)
(Don't forget to change the paths of the global variables, if you use Code::Blocks)

wxOgreView documentation (Doxygen)

or from GitHub:

wxOgreView example and documentation