MOGRE

1. MOGRE

2. Introduction • At the end of this lecture you will be able to: • Understand ways of using OGRE in languages other than C++ • Understand what MOGRE is • Understand the advantages and disadvantages of using MOGRE • Understand the process of how to install and setup MOGRE • Learn how to embed MOGRE into a Windows Form • Learn how to perform basic input processing in MOGRE

3. References • http://www.ogre3d.org/wiki/index.php/MOGRE

4. Using OGRE in Toolset Dev • Under Windows, OGRE and it’s plugins are written and built as a set of C++ static import and dynamic linked libraries • To use it natively, the client code needs to be also written in C++ • This is optimal for games programming where the power and speed of C++ is essential

5. Using OGRE in Toolset Dev • For toolset development, performance is not so much a high priority compared to fast development time • Development in C++ usually incurs longer development times (due to memory management, debugging, syntactical issues, etc.) • What would be ideal would be a means of using OGRE and accessing all it’s the functionality within another programming language which may better support RAD for the programming team • Reflective of industry game/graphics engines

6. OGRE for Other Languages • Axiom • C# port of OGRE • MOGRE • .NET wrapper for OGRE, with porting of some elements • OgreDotNet • Another .NET wrapper, though support and maintenance has lapsed since OGRE release 1.2 • PyOgre • Binding for Python • Ogre4j • Bindings for Java

7. What is MOGRE? • Stands for Managed OGRE • .NET 2.0 wrapper for the OGRE • Allows the OGRE rendering engine to be used by .NET programming languages • C#, VB.NET, Managed C++ etc. • Also wraps the Newton physics library with MogreNewt. • Currently supports OGRE Eihort 1.4.0 (Final)

8. Benefits of MOGRE • Application code can be developed in .NET languages • Can make use of all the in-built windows GUI forms and controls provided as part of the .NET framework • Garbage collection • Generally faster to time develop – aligned with Rapid Applications Development paradigm

9. Benefits of MOGRE • OGRE use with .NET languages, getting all associated benefits of the .NET framework. • Mogre releases are very responsive to OGRE code updates ( compared to a full .NET port of OGRE – like AXIOM ), as the majority of the Mogre wrapper classes can be auto-generated from the OGRE source • To date, most proven responsiveness to changes in OGRE

10. Benefits of MOGRE • Clients know that, under the hood, they are still mainly getting OGRE, rather than a rewrite ( with possible new bugs introduced, etc ) • Benefit and tradeoff profile is perfectly suited to game toolset development – where performance speed can be sacrificed for faster time to develop and responsiveness to change • .NET attractive to future direction of games industry

11. Disadvantages of MOGRE • Performance will not be optimal compared to developing in purely unmanaged languages like C/C++ • The wrapper objects introduces an extra layer of processing to delegate calls to OGRE – a performance hit • The OGRE source is modified, meaning that the OGRE code cannot be used as-is and all Mogre updates will also have it’s own special OGRE release ( with the appropriate source modifications ) coupled with it

12. Disadvantages of MOGRE • The original creator and maintainer will be leaving the project May 2007 ( however, other people have offered to step up and take over the role )

13. How MOGRE Works • Set of managed C++.NET wrapper classes • Wrapper classes are created for every underlying C++ OGRE class types • These wrapper classes attempt to expose the same C++ interface supported by the underlying classes, to encourage consistency • Additional .NET features are supported: • E.g. properties are used instead of get/set accessors • Under the hood, these wrapper objects delegate all calls to an internal, unmanaged OGRE C++ object

14. How MOGRE Works • MOGRE is built into a single .dll assembly which is included as a reference in all client .NET projects • All classes and types are contained within the MOGRE namespace • From a programming clients point of view, calls are simply made using a .NET interface. • The author of MOGRE uses a custom in-house tool to auto-generate the wrapper code from original OGRE source

15. How MOGRE Works • MOGRE actually modifies the OGRE source code, so it is not a pure “layered” wrapper as such • These code modifications efficiently deal with the management of the internal OGRE object, promoting faster access • External OGRE plugins will need to be recompiled with the modified Mogre interfaces in order to be used successfully within Mogre • For speed benefits, some elements of OGRE are totally rewritten in C++.NET rather than wrapped, mainly many of the maths classes

16. MOGRE vs OGRE • MOGRE methods use PascalCase rather than camelCase • OGRE’s get…(), set…(), and is…() methods are converted to properties under MOGRE • Properties with the first letter being in lower case indicates not an accessor, but a public exposure of the underlying class member

17. MOGRE vs OGRE • In place of OGRE’s listener functions, MOGRE uses .NET events and delegate functions mRoot.FrameStarted += new FrameListener.FrameStartedHandler(Skeletal_FrameStarted); • FrameStarted: the event • FrameListener.FrameStartedHandler: the delegate( for naming clarification ) • Skeletal_FrameStarted: the function

18. MOGRE Installation • Download the MOGRE 0.2.0 + OGRE 1.4.0 SDK installer from the MOGRE Wiki page • http://www.ogre3d.org/wiki/index.php/MOGRE • Run the Installer • Can specify a different install directory if desired (OGRE_HOME environment variable will be appropriately set) • Ensure the we have Visual Studio 8 SP1 installed • New Dlls for MOGRE: • Mogre.dll • MogreNewt.dll • These need to be copied to the project’s output/working directory where all the existing OGRE dlls are

19. Setting Up MOGRE Project • Add Reference to Mogre.dll • Two alternatives for setting the output location • Use the Mogre SDKs output path • Add the following to Properties->Build Events->post build event: copy "$(TargetPath)" "%OGRE_HOME%\bin\$(ConfigurationName)“ • Create our own output directory: • Ensure that all the required .dll files are copied • Ensure all the paths in the .cfg files are correct

20. Executing MOGRE Projects • Two alternatives for how to execute MOGRE Projects: • Directly navigate to the output directory and run the compiled .exe file • To run ( and debug) within Visual Studio’s IDE: • Point Properties->Debug->Start external programto the output .exe ( where the assocated .dlls and .cfg files are ) • Point Properties->Debug- >Working directoryto the path where the output .exe and .dlls and .cfg files are located

21. MogreFramework • Similar to the ExampleApplication framework provided and used for the OGRE samples • Written in C# and supports MOGRE • Usage is very similar • Creates its own window so not suitable out-of-the box for Win Forms integration

22. MOGRE and Win Forms • Create a C# Windows Form in Visual Studio • During Form intialisation, perform the usual OGRE setup sequence, up to the creation of the render window, i.e. • Create root • Load config file • Add resource locations • Set render system

23. MOGRE and Win Forms • We need to create a render window manually to get MOGRE to embed itself into the form rather than create it’s own separate window – as in the MogreFramework mRoot.Initialise(false, "Main Ogre Window"); NameValuePairList misc = new NameValuePairList(); misc["externalWindowHandle"] = Handle.ToString(); RenderWindow window = mRoot.CreateRenderWindow("Main RenderWindow", 800, 600, false, misc);

24. MOGRE and Win Forms • MOGRE can be embedded to controls as well as forms • Multiple render windows can be created and attached to independent controls / forms • The rest of the setup process can then proceed, ie: • Initialise resource groups • Create scenemanager • Create camera • Create viewport • Create scene • Position camera • Etc…

25. MOGRE and Win Forms • Other considerations: • Disposing of the MOGRE root object when the form disposes • Create an event handler and attach to .Disposed event of the form • Call m_Root.Dispose(); • Resizing MOGRE window when the form is resized • Create an event handler and attach to .Resize event of form • Call m_Window.WindowMovedOrResized();

26. MOGRE and Win Forms • The render loop: Show(); while (mRoot != null && mRoot.RenderOneFrame()) { Application.DoEvents(); }

27. MOGRE and Win Froms • Refer to: http://www.ogre3d.org/tikiwiki/Mogre+Basic+Tutorial+6 for full code listing

28. Keyboard and Mouse Input • For basic, buffered keyboard and mouse input, the .NET Framework’s input system can be used • Use the appropriate Key and Mouse events and attach corresponding Key and Mouse Input Handlers this.KeyDown += new KeyEventHandler(KeyDownHandler); void KeyDownHandler(object sender, KeyEventArgs e) { switch (e.KeyCode) { case Keys.I: etc..

29. Keyboard and Mouse Input this.MouseDown += new MouseEventHandler(MouseDownHandler); void MouseDownHandler(object sender, MouseEventArgs e) { if (e.Button == MouseButtons.Middle) etc..

30. Keyboard and Mouse Input • Another advantage of using MOGRE and .NET is that individual forms and controls can be given individual input handlers • This allows easier implementation of the multiple viewport type presentation typical of scene editors • e.g. when the mouse is dragged whilst in the perspective viewport, only the scene in that viewport is rotated, panned, zoomed etc.

31. Lecture Review • Understand ways of using OGRE in languages other than C++ • Understand what MOGRE is • Understand the advantages and disadvantages of using MOGRE • Understand the process of how to install and setup MOGRE • Learn how to embed MOGRE into a Windows Form • Learn how to perform basic input processing in MOGRE