Scripting with LuaBind in Ogre         This tutorial will teach the reader how to use Lua and LuaBind in a simple Ogre application
Print

Introduction: Compiler and Developement Environment

 
This tutorial will teach the reader how to use -Lua and LuaBind(external link) in a simple Ogre application created using the Code::Blocks' development environment.

If you use VC++7 (or more) and it's dev. env., you can directly use the project files provided in this tutorial(external link).

Note: To use this tutorial you'll need reasonable experience with C++ and Ogre. If you are not ready for this tutorial then find one that's appropriate. If you're an experienced LuaBind user then you won't benefit from this simple tutorial either.

 

Downloading and Installing the Required Libraries

 
Our project will be based on 3 free libraries :

  1. Boost 1.33.1(external link) - This library is required by LuaBind. Though some applications might require you to compile Boost the header files will be enough for this project.
  2. Lua 5.1.1(external link) - You'll probably need the Sources. Read below.
  3. LuaBind 0.7(external link) - You'll probably need the Sources too.

 

Problem with Luabind's support of boost

 
As written in the "Nuclex tutorial"(external link), "changes in the Boost library have not been reflected in LuaBind yet". So, in order to be able to compile these three libraries together, you should "set up and compile each library as well as possibly modify LuaBind". This is what we are going to do to use Luabind inside Code::Blocks.

Nevertheless, "this whole process can be somewhat troublesome", so :

  1. Download directly the ready-to-use pack provided on the Nuclex website(external link) - You can download it directly by following this link(external link).

 
As you can see, this pack already contains compiled -Lua and Luabind libraries (both static and dynamic), but unfortunately these libraries are meant to compile in an "VC8-friendly" developement environment, that means that for example you'd need the Windows SDK to add them to your project. It would be one more (heavy) SDK to download, this is why it's easier to recompile these libraries in a "pure Code::blocks" way (Code::Blocks with the MinGW compiler provide the minimum required files to compile Win32 applications without downloading the whole Windows SDK).

This is exactly what we are going to do. Read below.

 

Prerequisite : Creating an Ogre Project

 

  1. Run Code::Blocks, then use the wizard to create a new "Ogre3D project" that we will name myOgreProject. Run it.

 
If it doesn't run fine, then it means that you have a problem with your installation of Code::Blocks/the Ogre3D SDK/the DirectX SDK/whatever else. In this case, read the installation instructions again.

 

Add -Lua and Luabind projects to your Code::Blocks Solution

 
The goal of this step is to take advantage of Lua/Luabind/Boost's modified sources mentioned previously and to insert them in our solution as Code::Blocks projects instead of VC++8 projects.

Follow these instructions :

  1. Unpack the "Nuclex Pack" archive somewhere. It should be named luabind-binariesAndDemo if you kept the original name. We'll come back to this directory later.
  2. Unpack the library-sources.zip archive contained in the previous one. In the newly created folder, you should find a Visual Studio solution (.sln) and the three "modified" folders in which we find a so great interest : boost_1_33_1_lite, lua-5.1.1(external link) and luabind.
  3. Copy the library-sources folder to your myOgreProject folder.

 
Creating the -Lua project :

  1. In myOgreProject\library-sources\lua-5.1.1\Build, create a CodeBlocks folder, just next to the MSVC8 folder. The location of our Code::Blocks project is not important, but it's nicer to keep the original directories structure ;-)
  2. Inside Code::blocks, Create a new project. In the list, choose the "Static library" project type. Name it lua-5.1.1. Place it at the location myOgreProject\library-sources\lua-5.1.1\Build\CodeBlocks. This new project should appear in your solution, under your myOgreProject project.
  3. Right-click on the lua-5.1.1 project and select "Add files...". Select all ".c" and ".h" files from the myOgreProject\library-sources\lua-5.1.1\src folder.
  4. Set the lua-5.1.1 project as the active project and compile it. It should compile well.

 
Creating the Luabind project :

  1. (same as above) In myOgreProject\library-sources\luabind\Build, create a CodeBlocks folder, just next to the MSVC8 folder.
  2. (same as above) Inside Code::blocks, Create a new project. In the list, choose the "Static library" project type. Name it luabind. Place it at the location myOgreProject\library-sources\bind\Build\CodeBlocks. This new project should appear in your solution, under your lua-5.1.1 project.
  3. (same as above) Right-click on the luabind project and select "Add files...". Select all ".cpp" files from the myOgreProject\library-sources\luabind\src folder.
  4. Right-click on the luabind project and select "Build Options". In the left pane, click on "luabind", so that your actions have effect on both "Release" and "Debug" configurations. Click on "Directories" pane, then on "Compiler" subpane. Click on "add" three times, to add these 3 folders :
* luabind
     * lua-5.1.1\src
     * boost_1_33_1_lite

 
Everytime, keep them as relative paths. Now, your luabind project know where to find the headers of these 3 projects. Click OK.

  1. Right-click on the luabind project and select "Properties...". Then click on "Project's dependencies". Select "luabind" and check "depends on lua-5.1.1". Click OK. Note : luabind doesn't really depend on lua but later the order of compilation will be important when we'll use both projects in our Ogre3D project.
  2. Set the luabind project as the active project and compile it. It should compile well.

 
If both compilations went well, you should now have two files :

* ''myOgreProject\library-sources\bind\Build\CodeBlocks\lua-5.1.1\obj\Debug\liblua-5.1.1.a''
     * ''myOgreProject\library-sources\bind\Build\CodeBlocks\luabind\obj\Debug\libluabind.a''

(replace Debug by Release if you compiled as Release)

Note that these libraries are named the Linux way. they are named "libxxxxxx.a" instead of "xxxxxx.lib", but they work anyway!

Reference lua and luabind static libraries in your Ogre3D project :

  1. Right-click on your myOgreProject and select "Build Options".
  2. In the left pane, select "Debug" (resp. "Release") and in the "link libraries" pane add the two files we mentioned above :
* ''myOgreProject\library-sources\bind\Build\CodeBlocks\lua-5.1.1\obj\Debug'''(resp. Release)'''\liblua-5.1.1.a''
     * ''myOgreProject\library-sources\bind\Build\CodeBlocks\luabind\obj\Debug'''(resp. Release)'''\libluabind.a''

Both libraries are now part of the project, but we don't use them yet, so in effect nothing has changed.

  1. Right-click on the myOgreProject project and select "Properties...". Then click on "Project's dependencies". Select "myOgreProject" and check "depends on luabind". Now, each project will be compiled in the right order for you to always have up-to-date libraries.

 
Enable Luabind in your project :

  1. In your myOgrePrject folder, create an Include folder.
  2. Now it's time to go back to your luabind-binariesAndDemo folder. Copy the contents of it's Include folder into your myOgreProject\Include folder. You now have the include files from lua, luabind and boost available in your project and they will travel with it if you move it. ;-)
  3. You may delete luabind-binariesAndDemo, you don't need it anymore.
  4. Inside Code::Blocks, right-click on the myOgreProject project and select "Build Options". In the left pane, click on "myOgreProject", so that your actions have effect on both "Release" and "Debug" configurations. Click on "Directories" pane, then on "Compiler" subpane. Click on "add" and add the myOgreProject\Include directory we created above, so that we didn't copy the include files for nothing ;-) Now, the compiler knows where to find them.
  5. Add this code at the top of your main.cpp file :
// Include the lua headers (the extern "C" is a requirement because we're
 // using C++ and lua has been compiled as C code)
 extern "C" {
   #include "lua/lua.h"
   #include "lua/lauxlib.h"
 }
 
 // This is the only header we need to include for LuaBind to work
 #include "luabind/luabind.hpp"

 

  1. In it's current state, compiling and running your program will run the Lua console, which is a bit intrusive! This happens if you are using the MigW compiler and linking to static libraries as described above, your workspace now contains multiple main() functions. Either explicitly comment out the WinMain() which gets generated by code::blocks's ogre3D wizard, or if you need to use windows.h, you can modify the code in main.cpp to look as follows (although I would also, alternatively, suggest you include windows.h in a common header file).:
// ----------------------------------------------------------------------------
 // Ogre Generated Main function, just boots the application object
 // ----------------------------------------------------------------------------
 #if OGRE_PLATFORM == OGRE_PLATFORM_WIN32
 #define WIN32_LEAN_AND_MEAN
 #include "windows.h"
 INT WINAPI WinMain( HINSTANCE hInst, HINSTANCE, LPSTR strCmdLine, INT );
 
 int main(int argc, char **argv)
 {
         return WinMain(GetModuleHandle(0),0,GetCommandLine(),0);
 }
 
 INT WINAPI WinMain( HINSTANCE hInst, HINSTANCE, LPSTR strCmdLine, INT )
 #else
 int main(int argc, char **argv)
 #endif

 
Note: If you just want to run your application as a console-style application, comment out the code related to OGRE_PLATFORM_WIN32 within your main.cpp file generated by code::blocks's ogre3D wizard.

Our project is now fully ready to welcome some luabind code!

Add a link to Lua's State:

  1. modify the following code block (created by default by code::blocks's ogre3D wizard) to add the luabind code :
try
    {
        lua_State *pMyLuaState = lua_open(); //Add this
        app.go();
        lua_close(pMyLuaState); //Add this too
    }

 
You can find explanations concerning this code in the next paragraph.

  1. Set the myOgreProject project as the active project and compile it. If it compiles well, then you're ready to code with lua and luabind !

 

How -Lua works

-Lua is used primarily through an object called a lua_State. This is Lua's virtual machine. It's somewhat like a seperate mini-program running within your application.

To use -Lua we need a pointer to our lua_State. It's pMyLuaState.

pMyLuaState= lua_open(); // initialize mLuaState for Lua

 
And now -Lua is initialized and ready to be given a .lua file to work with.

Shutting down -Lua is just as easy. Add this code to your deconstructor.

if( pMyLuaState)
 {
     lua_close(pMyLuaState);
     pMyLuaState= 0;
 }

 

Further coding in LUA

 
You should read these turorials:

  1. http://www.rasterbar.com/products/luabind/docs.html(external link)
  2. http://www.nuclex.org/articles/quick-introduction-to-luabind(external link)

 

See also

 

 


Alias: Scripting_with_LuaBind_in_Ogre


Contributors to this page: Beauty14435 points  , OgreWikiBot54 points  and jacmoe177744 points  .
Page last modified on Wednesday 09 of February, 2011 21:47:59 UTC by Beauty14435 points .


The content on this page is licensed under the terms of the Creative Commons Attribution-ShareAlike License.
As an exception, any source code contributed within the content is released into the Public Domain.