Script cutscenes, quests... with Lua or JS

cocos2d-x C++
#1

Hi,

Hi,

I’m working on a game using cocos2d-x. All the code is written in c++ but now we would like to use lua or javascript only in certain parts of the code. For example in a cutscene system.

I know that cocos2dx support these two languages, and there are tons of tutorials that explains how to write a game using only one of these languages for the whole game. But in my case I want to run some scripts when a trigger is activated and then continue with the c++ code.

I don’t know where start. Anybody knows a good tutorial which covers this?

Thanks in advance

#2

Based on what your described. lua is better integrated with cocos2d-x c++, we’ll slowly moving js support back.

You’ll need the binding generator to generate the binding you need. And modify the binding templates

#3

Thanks!

I’m trying to initializing all the stuff in order to support lua. After include the cocos2d_lua_bindings project, I added these two lines of code:

bool AppDelegate::applicationDidFinishLaunching()
{
…

auto engine = LuaEngine::getInstance();

ScriptEngineManager::getInstance()->setScriptEngine(engine);

but the app crashs since _state is null after execute this code

bool LuaStack::init(void)
{
_state = lua_open();
…

What is wrong?

Thanks

#4

How do you get LuaStack

#5

When I call

auto engine = LuaEngine::getInstance();

the static create method is called:

LuaEngine* LuaEngine::getInstance(void)
{
if (!_defaultEngine)
{
_defaultEngine = new LuaEngine();
_defaultEngine->init();
}
return _defaultEngine;
}

and the init method calls LuaStack::create()

bool LuaEngine::init(void)
{
_stack = LuaStack::create();
_stack->retain();
executeScriptFile(“DeprecatedEnum.lua”);
executeScriptFile(“DeprecatedClass.lua”);
executeScriptFile(“Deprecated.lua”);
return true;
}

and finally, this ,method calls LuaStack::init() where the app crashes.

LuaStack *LuaStack::create(void)
{
LuaStack *stack = new LuaStack();
stack->init();
stack->autorelease();
return stack;
}

I’m compiling in mac and I found this post:

Should I compile only for 32 bits?

Thanks

#6

What version of cocos2d-x are you using?

Also can you create a lua project with command cocos new -l lua, and see what’s the difference between default lua project and your project?

#7

Fixed!

For 64 bits its necessary additional linker flags

Thanks

1 Like
#8

Hi,

OK, lua is working and I can execute a script from a file… but I have more questions.

In c++ I have some classes that inherit from a GameObject class and use components. My idea is manage the scripts encapsulating them into components. In this way a GameObject could have one or more scripts, these scripts could inherit from a super script with methods like update, onEnter, onExit… so the GameObject could call from the c++ code the proper lua functions when an event occurs.

But I need more information about these topics:

How to create lua classes in .lua files and how to create different lua object instances from the same class.

how to link these instances to the c++ parent object. So the c++ code would call the member methods of its scripts and this lua code would update the attributes of its own lua instances and the lua code would call the c++ methods of its GameObject parent.

How to call the different methods of these instances. By now I only know how to run a whole .lua script

Sorry for all of these questions. I know that this sounds very complex and I’m a newby with lua.

Thanks

#9

Your idea is really good, actually that’s how a lot of AAA game work, use lua as scripting/AI layer

invoke lua from c++ is actually not that hard

Here is some good read about binding c++ instance to lua using the self

Basically as long as a lua object have the pointer to the c++ instance, you can call all the functions on the c++ instance, vise-versa, if a c++ instance have access to the lua object, it can always invoke lua functions.

I’m not an export on lua, but you can always ask the folks knows lua here.
http://discuss.cocos2d-x.org/category/cocos2d-x/lua