调用lua函数executeGlobalFunction

闲来无事，搞了搞cocos2dx的lua脚本，话说lua这东西几年前学过一段时间，也自己开发过c++接口，做过一些小东西，不过时间久远，记忆模糊。捡起来还是费了点功夫，下面就是我的一些体会。


cocos2dx使用的是tolua++来制作的lua接口，tolua++文档不多，网上的一些文章也是答非所问，所以自己看代码是最佳学习途径。


cocos2dx操作lua的类是CCLuaEngine，其中实现了加载与实行lua脚本，以及操作lua stack。


LuaCocos2d.cpp很主要，文件的开头注释也说明其是由tolua++自动生成的，我们想在lua中操作自己定义的类就是通过修改此文件实现的，两个重要函数是void tolua_reg_types (lua_State* tolua_S)与int tolua_Cocos2d_open (lua_State* tolua_S)，前者是注册自定义类型，后者是定义其接口，调用关系是tolua_Cocos2d_open调用tolua_reg_types，而tolua_Cocos2d_open是在CCLuaEngine的init中调用的。


假设我要向lua注册新类，那么首先我要在tolua_reg_types中添加一行注册代码，然后在tolua_Cocos2d_open添加其接口说明，我将这两个步骤定义成两个函数，单独在一个文件中实现，文件名为cwLuaReg.cpp，内容为：
#include "cwLuaReg.h"


#include "cwGameObject.h"
#include "cwCollisionObject.h"
#include "cwGravityObject.h"


#ifdef __cplusplus


static int tolua_collect_cwGameObject(lua_State* tolua_S)
{
    cwGameObject* self = (cwGameObject*) tolua_tousertype(tolua_S,1,0);
    delete self;
    return 0;
}


static int tolua_collect_cwGravityObject(lua_State* tolua_S)
{
    cwGravityObject* self = (cwGravityObject*) tolua_tousertype(tolua_S,1,0);
    delete self;
    return 0;
}


#ifndef TOLUA_DISABLE_tolua_cw_GameObject_create00
static int tolua_cw_GameObject_create00(lua_State* tolua_S)
{
    tolua_Error tolua_err;
    if(!tolua_isusertable(tolua_S,1,"cwGameObject",0,&tolua_err) ||
        !tolua_isnoobj(tolua_S,2,&tolua_err))
        goto tolua_lerror;
    else
    {
        {
            cwGameObject* tolua_ret = (cwGameObject*)  cwGameObject::create();
            int nID = (tolua_ret) ? (int)tolua_ret->m_uID : -1;
            int* pLuaID = (tolua_ret) ? &tolua_ret->m_nLuaID : NULL;
            toluafix_pushusertype_ccobject(tolua_S, nID, pLuaID, (void*)tolua_ret,"cwGameObject");
        }
    }
    return 1;
tolua_lerror:
    return 0;
}
#endif //#ifndef TOLUA_DISABLE


#ifndef TOLUA_DISABLE_tolua_cw_GameObject_getSpeed00
static int tolua_cw_GameObject_getSpeed00(lua_State* tolua_S)
{
#ifndef TOLUA_RELEASE
    tolua_Error tolua_err;
    if (!tolua_isusertype(tolua_S,1,"cwGameObject",0,&tolua_err) ||
        !tolua_isnoobj(tolua_S,2,&tolua_err))
        goto tolua_lerror;
    else
#endif
    {
        cwGameObject* self = (cwGameObject*)  tolua_tousertype(tolua_S,1,0);
#ifndef TOLUA_RELEASE
        if (!self) tolua_error(tolua_S,"invalid 'self' in function 'speed'", NULL);
#endif
        {
            float tolua_ret = (float)  self->speed();
            tolua_pushnumber(tolua_S,(lua_Number)tolua_ret);
        }
    }
    return 1;
#ifndef TOLUA_RELEASE
    tolua_lerror:
    tolua_error(tolua_S,"#ferror in function 'speed'.",&tolua_err);
    return 0;
#endif
}
#endif


#ifndef TOLUA_DISABLE_tolua_cw_GameObject_setSpeed00
static int tolua_cw_GameObject_setSpeed00(lua_State* tolua_S)
{
#ifndef TOLUA_RELEASE
    tolua_Error tolua_err;
    if (!tolua_isusertype(tolua_S,1,"cwGameObject",0,&tolua_err) ||
        !tolua_isnumber(tolua_S,2,0,&tolua_err) ||
        !tolua_isnoobj(tolua_S,3,&tolua_err))
        goto tolua_lerror;
    else
#endif
    {
        cwGameObject* self = (cwGameObject*)  tolua_tousertype(tolua_S,1,0);
        float speed = ((float)  tolua_tonumber(tolua_S,2,0));
#ifndef TOLUA_RELEASE
        if (!self) tolua_error(tolua_S,"invalid 'self' in function 'setSpeed'", NULL);
#endif
        {
            self->setSpeed(speed);
        }
    }
    return 0;
#ifndef TOLUA_RELEASE
    tolua_lerror:
    tolua_error(tolua_S,"#ferror in function 'setSpeed'.",&tolua_err);
    return 0;
#endif
}
#endif


#ifndef TOLUA_DISABLE_tolua_cw_GameObject_getMoveDir00
static int tolua_cw_GameObject_getMoveDir00(lua_State* tolua_S)
{
#ifndef TOLUA_RELEASE
    tolua_Error tolua_err;
    if (!tolua_isusertype(tolua_S,1,"cwGameObject",0,&tolua_err) ||
        !tolua_isnoobj(tolua_S,2,&tolua_err))
        goto tolua_lerror;
    else
#endif
    {
        cwGameObject* self = (cwGameObject*)  tolua_tousertype(tolua_S,1,0);
#ifndef TOLUA_RELEASE
        if (!self) tolua_error(tolua_S,"invalid 'self' in function 'getMoveDir'", NULL);
#endif
        cwVector2D& dir = self->moveDir();
        tolua_pushnumber(tolua_S,(lua_Number)dir.x);
        tolua_pushnumber(tolua_S,(lua_Number)dir.y);
    }
    return 2;
#ifndef TOLUA_RELEASE
    tolua_lerror:
    tolua_error(tolua_S,"#ferror in function 'getMoveDir'.",&tolua_err);
    return 0;
#endif
}
#endif


#ifndef TOLUA_DISABLE_tolua_cw_GameObject_setMoveDir00
static int tolua_cw_GameObject_setMoveDir00(lua_State* tolua_S)
{
#ifndef TOLUA_RELEASE
    tolua_Error tolua_err;
    if (!tolua_isusertype(tolua_S,1,"cwGameObject",0,&tolua_err) ||
        !tolua_isnumber(tolua_S,2,0,&tolua_err) ||
        !tolua_isnumber(tolua_S,3,0,&tolua_err) ||
        !tolua_isnoobj(tolua_S,4,&tolua_err))
        goto tolua_lerror;
    else
#endif
    {
        cwGameObject* self = (cwGameObject*)  tolua_tousertype(tolua_S,1,0);
        float dirX = ((float)  tolua_tonumber(tolua_S,2,0));
        float dirY = ((float)  tolua_tonumber(tolua_S,3,0));
#ifndef TOLUA_RELEASE
        if (!self) tolua_error(tolua_S,"invalid 'self' in function 'setMoveDir'", NULL);
#endif
        self->setMoveDir(dirX, dirY);
    }
    return 0;
#ifndef TOLUA_RELEASE
    tolua_lerror:
    tolua_error(tolua_S,"#ferror in function 'getMoveDir'.",&tolua_err);
    return 0;
#endif
}
#endif


#endif


TOLUA_API int tolua_cwLua_reg_types(lua_State* tolua_S)
{
    //add by sunny
    tolua_usertype(tolua_S,"cwGameObject");
    tolua_usertype(tolua_S,"cwGravityObject");
    //end sunny


    return 1;
}


TOLUA_API int tolua_cwLua_reg(lua_State* tolua_S)
{
#ifdef __cplusplus
    tolua_cclass(tolua_S,"cwGameObject","cwGameObject","CCSprite",tolua_collect_cwGameObject);
#else
    tolua_cclass(tolua_S,"cwGameObject","cwGameObject","CCSprite",NULL);
#endif


    tolua_beginmodule(tolua_S,"cwGameObject");
    tolua_function(tolua_S,"create",tolua_cw_GameObject_create00);
    tolua_function(tolua_S,"speed",tolua_cw_GameObject_getSpeed00);
    tolua_function(tolua_S,"setSpeed",tolua_cw_GameObject_setSpeed00);
    tolua_function(tolua_S,"moveDir",tolua_cw_GameObject_getMoveDir00);
    tolua_function(tolua_S,"setMoveDir",tolua_cw_GameObject_setMoveDir00);
    tolua_endmodule(tolua_S);


#ifdef __cplusplus
    tolua_cclass(tolua_S,"cwGravityObject","cwGravityObject","cwGameObject",tolua_collect_cwGravityObject);
#else
    tolua_cclass(tolua_S,"cwGravityObject","cwGravityObject","cwGameObject",NULL);
#endif


    tolua_beginmodule(tolua_S,"cwGravityObject");
    tolua_endmodule(tolua_S);


    return 1;
}


将tolua_cwLua_reg_types和tolua_cwLua_reg分别加到LuaCocos2d.cpp对应函数末尾，这样两个类cwGameObject与cwGravityObject就可以在lua中使用了。


做到这还不能达到我的期望，原因是cocos2d的lua工程里，在AppDelegate::applicationDidFinishLaunching函数中只是加载并执行了hello.lua脚本文件，然后一切就都交给lua了，而我只是想使用lua实现一些AI方面的功能，即cwGameObject在需要执行AI时，调用lua中的一个函数。所以我需要的是一个可以调用lua函数的功能，查看了一下CCLuaEngine类，貌似没有我想要的，只能自己添了个函数：
virtual int executeGlobalFunction(const char* functionName, float dt, CCObject* pObject, const char* typeName);
functionName：被调lua函数名；dt：帧时间间隔；pObject：调用lua的对象；typeName：pObject对象类型
实现如下：
int CCLuaEngine::executeGlobalFunction(const char* functionName, float dt, CCObject* pObject, const char* typeName)
{
    lua_getglobal(m_state, functionName);      


    if (!lua_isfunction(m_state, -1))
    {
        CCLOG("[LUA ERROR] name '%s' does not represent a Lua function", functionName);
        lua_pop(m_state, 1);
        return 0;
    }


    pushFloat(dt);
    pushCCObject(pObject, typeName);


    int error = lua_pcall(m_state, 2, 1, 0);            


    if (error)
    {
        CCLOG("[LUA ERROR] %s", lua_tostring(m_state, - 1));
        lua_pop(m_state, 1); // clean error message
        return 0;
    }


    // get return value
    if (!lua_isnumber(m_state, -1))
    {
        lua_pop(m_state, 1);
        return 0;
    }


    int ret = lua_tointeger(m_state, -1);
    lua_pop(m_state, 1);                                               
    return ret;
}
基本上是照着其他函数扒下来的，不同之处就是加了两个push。
函数写的比较死，可以写一个接受可变参数的函数，做的通用些。


假设我要在cwGameObject的upadte函数中调用“do_obj_update”lua函数，写法如下：
void cwGameObject::update(float dt)
{
    CCLuaEngine::defaultEngine()->executeGlobalFunction("do_obj_update", dt, this,"cwGameObject");
}
这样在创建cwGameObject时scheduleUpdate一下就可以了。


lua脚本：
-- for CCLuaEngine traceback
function __G__TRACKBACK__(msg)
    print("----------------------------------------")
    print("LUA ERROR: " .. tostring(msg) .. "\n")
    print(debug.traceback())
    print("----------------------------------------")
end


winSize = CCDirector:sharedDirector():getWinSize()


-- avoid memory leak
collectgarbage("setpause", 100)
collectgarbage("setstepmul", 5000)


function do_obj_update(dt, obj)
    local x, y = obj:getPosition()
    local vx, vy = obj:moveDir()


    x = x + vx*dt*obj:speed()
    y = y + vy*dt*obj:speed()


    if x < 0 then
        x = 0
        obj:setMoveDir(-vx, vy)
    end


    if x > winSize.width then
        x = winSize.width
        obj:setMoveDir(-vx, vy)
    end
   
    if y < 0 then
        y = 0
        obj:setMoveDir(vx, -vy)
    end


    if y > winSize.height then
        y = winSize.height
        obj:setMoveDir(vx, -vy)
    end


    obj:setPosition(x, y)
end


print("test.lua loaded.")


脚本很简单，do_obj_update函数只是做了一些边框判断。
别忘了修改AppDelegate::applicationDidFinishLaunching中加载的脚本文件名～～

cocos2dx版本：cocos2d-2.0-x-2.0.3

http://blog.csdn.net/honghaier/article/details/8700574