Cocos2d-x: Using your own C ++ class in Lua

Good day to all.

It so happened that about the use of cocos2d-x Lua in nature there are quite a few informational materials, even taking into account English-language sources. Therefore, in many respects you have to understand yourself, digging into someone else's code and reading (often not very informative) documentation.

In this article I want to at least partially correct this injustice and talk about the extension of the standard functionality available in cocos2d-x Lua with the help of native classes.
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I faced this task, one might say, face to face after realizing my own poor knowledge of Lua. At the same time, the solution of a part of the game logic was written to write on the good old C ++.

So, who is interested in this process, please under the cat.

As a starting point, we take what your CocosCode IDE is installed and configured. If not, then this is a good article in Russian right here .

1. Create our C ++ class

Let's start by creating a class that we will connect to Lua.


Here you should pay attention to the fact that our class must be a descendant from Ref, which is caused by the peculiarities of memory management in cocos2d-x.


We place the files with our class in the “myclass” directory, which we create in / framework / cocos2d-x / cocos / (inside the project). If you do not have a framework folder, then in CocosCode you need to do the following:
Right-click on a project -> Cocos Tools -> Add Native Code Support

2. Create a Lua wrapper for our class.

To do this, in the / frameworks / cocos2d-x / tools / tolua folder, create the following file:

I will not go into the details of the contents of this file, you can read about it here .

Now we need to add the newly created ini file to the Lua wrapper generation script. To do this, open genbindings.py and add the following line before the closing brace:

 cmd_args = {'cocos2dx.ini' : ('cocos2d-x', 'lua_cocos2dx_auto'), \ 'cocos2dx_extension.ini' : ('cocos2dx_extension', 'lua_cocos2dx_extension_auto'), \ 'cocos2dx_ui.ini' : ('cocos2dx_ui', 'lua_cocos2dx_ui_auto'), \ 'cocos2dx_studio.ini' : ('cocos2dx_studio', 'lua_cocos2dx_studio_auto'), \ 'cocos2dx_spine.ini' : ('cocos2dx_spine', 'lua_cocos2dx_spine_auto'), \ 'cocos2dx_physics.ini' : ('cocos2dx_physics', 'lua_cocos2dx_physics_auto'), \ 'cocos2dx_experimental_video.ini' : ('cocos2dx_experimental_video', 'lua_cocos2dx_experimental_video_auto'), \ 'cocos2dx_experimental.ini' : ('cocos2dx_experimental', 'lua_cocos2dx_experimental_auto'), \ 'cocos2dx_controller.ini' : ('cocos2dx_controller', 'lua_cocos2dx_controller_auto'), \ 'cocos2dx_myclass.ini' : ('cocos2dx_myclass', 'lua_cocos2dx_myclass_auto') \ } 

Run genbindings.py. In case of successful completion of all the above manipulations, we should have the following files (in the directory / frameworks / cocos2d-x / cocos / scripting / lua-binding):

• lua_cocos2dx_myclass_auto.hpp
• lua_cocos2dx_myclass_auto.cpp
• ./api/MyClass.lua

Now we have everything we need to connect our class to Lua. This process consists of two similar procedures: one for iOS, the other for Android.

3.1. Connect files to iOS

Open the application project. First of all, add the C ++ source to cocos2d_libs:



Now add the generated files to cocos2d_lua_bindings:



Do not forget to also set the path to the header files in cocos2d_lua_bindings -> Build Settings -> User Header Search Paths



Using the opportunity, register our class in AppDelegate.cpp:

 ... #include "ConfigParser.h" //      #include "lua_cocos2dx_myclass_auto.hpp" using namespace CocosDenshion; bool AppDelegate::applicationDidFinishLaunching() { ... // set FPS. the default value is 1.0/60 if you don't call this director->setAnimationInterval(1.0 / 60); auto engine = LuaEngine::getInstance(); ScriptEngineManager::getInstance()->setScriptEngine(engine); LuaStack* stack = engine->getLuaStack(); stack->setXXTEAKeyAndSign("2dxLua", strlen("2dxLua"), "XXTEA", strlen("XXTEA")); //       register_all_cocos2dx_myclass(stack->getLuaState()); #if (COCOS2D_DEBUG>0) if (startRuntime()) return true; #endif engine->executeScriptFile(ConfigParser::getInstance()->getEntryFile().c_str()); return true; } ... 

This is where our iOS adventure ends.

3.2. Connect files to Android

Here, in essence, everything is similar to the previous section. You need to connect the source of the class to the cocos2d-x project and the generated files to the cocos2dx_lua project. The only difference is that you will have to deal with text files of Android.mk.

We add files of our class to the coconut project. To do this, we make several additions to the file /frameworks/cocos2d-x/cocos/Android.mk

Here (specify * .cpp files):



And here (specify the path to the header files):



Now it remains to connect the generated files to cocos2d_lua. To do this, edit the file /frameworks/cocos2d-x/cocos/scripting/lua-bindings/Android.mk

Here (specify * .cpp file):



And here it is (specify the path to the header file):

4. Update the runtime environment

In principle, everything will work if you run a project in XCode or Eclipse. For everything to work in CocosCode IDE, you need to rebuild the runtime environment. To do this, right-click on the project -> Cocos Tools -> Build Custom Runtimes. That's all.

5. Run, rejoice

I do not see much point in showing the results in the form of screenshots of a single line in the console. However, the output will be:

 [Lua Debug]: Hello, Habrahabr! 

Similarly, with the help of the binding-generator-a, you can add your classes to cocos2d-js. It should however be warned that I had to spend a good couple of hours on the normal launch of the generator itself. Fiddling with the mismatch of the various libraries required. If everything is done as it is written, then there should be no problems (instructions for setting up the generator can be found here ).

PS

In my opinion, the “garter” of the engine for scripting languages ​​in some cases can greatly simplify life. I don’t know if she ultimately simplified my life, but I gained an interesting experience.