use box2d in lua

cocos2d-x Lua
#1

as we know,using cocos2d-x in lua,we must register cocos2d-x’s class to lua,the job cocos2d-x did.But ,if we want to use box2d in lua ,wo should register box2d to lua ourself?

#2

So sorry that we haven’t finish the binding of box2d library to lua. You can refer to this pull request https://github.com/cocos2d/cocos2d-x/pull/471, which exports SimpleAudioEngine to lua layer.
The community will deeply appreciate if you would like to contribute the box2d binding :slight_smile:

#3

Hi, I just made one.

#4

@ local PTM_RATIO = 32.0

local gravity = b2Vec2(0.0, –10.0)
local *world = b2World:new_local

— Create edges around the entire screen
local groundBodyDef = b2BodyDef:new_local
groundBodyDef.position = b2Vec2
local groundBody =*world:CreateBody(groundBodyDef)

local groundEdge = b2EdgeShape:new_local()
local boxShapeDef = b2FixtureDef:new_local()
boxShapeDef.shape = groundEdge

groundEdge:Set(b2Vec2(0,0), b2Vec2(winSize.width/PTM_RATIO, 0))
groundBody:CreateFixture(boxShapeDef)
groundEdge:Set(b2Vec2(0,0), b2Vec2(0, winSize.height/PTM_RATIO))
groundBody:CreateFixture(boxShapeDef)
groundEdge:Set(b2Vec2(0, winSize.height/PTM_RATIO), b2Vec2(winSize.width/PTM_RATIO, winSize.height/PTM_RATIO))
groundBody:CreateFixture(boxShapeDef)
groundEdge:Set(b2Vec2(winSize.width/PTM_RATIO, winSize.height/PTM_RATIO), b2Vec2(winSize.width/PTM_RATIO, 0))
groundBody:CreateFixture(boxShapeDef)

— Create body and shape
local bodyDef = b2BodyDef:new_local()
bodyDef.type = b2_dynamicBody
bodyDef.position:Set(x/PTM_RATIO, y/PTM_RATIO)
bodyDef.userData = bodySprite
local *body =*world:CreateBody(bodyDef)

local circle = b2CircleShape:new_local()
circle.m_radius = 26.0/PTM_RATIO

shapeDef = b2FixtureDef:new_local()
shapeDef.shape = circle
shapeDef.density = 1.0
shapeDef.friction = 0.2
shapeDef.restitution = 0.8
*body:CreateFixture
table.insert

— tick
local function tick
*world:Step(dt, 10, 10)
if body_list ~= nil then
for i, body in ipairs(body_list) do
local sprite = sprite_list[i]
sprite:setPosition(b2Vec2(body:GetPosition().x * PTM_RATIO, body:GetPosition().y * PTM_RATIO))
sprite:setRotation(–1 * CC_RADIANS_TO_DEGREES(body:GetAngle()))
end
end
end

CCDirector:sharedDirector():getScheduler():scheduleScriptFunc(tick, 0, false)

reference: http://www.cnblogs.com/zhongzf/archive/2012/06/10/2544002.html

#5

Thanks zhong zhaofeng, the bindings you provided work perfectly in cocos2d-2.0-x-2.0.3! :slight_smile: For those that need more help:

  • Include LuaBox2D.cpp and LuaBox2D.h in your project. LuaBox2D.h is missing an include, be sure to #include "tolua++.h" there.

  • Register the lua box2D extension by editing your Appdelegate.cpp file.

    • Add the include: #include "LuaBox2D.h"
    • Add the following to the bottom of the AppDelegate::applicationDidFinishLaunching() function: tolua_LuaBox2D_open(pEngine->getLuaState());

That’s it! You should be able to use the sample lua code provided by zhong above. There is a couple of variables missing, but it’s easy to figure out.

I’m working an a ContactListener implementation that allows you to listen for contact events from lua, will hopefully post this in a few days.

#6

As promised, a LuaContactListener implementation is attached.

LUA sample code:

    local listener = CContactListener:new_local()
    listener:registerScriptContactHandler(function (type, contact)
        print("LUA: Contact")
        if type == BEGIN_CONTACT then 
            print('begin') 
        else 
            print('end')
        end

        -- copy out contact data
        local function printPos(fixture)
            local pos = fixture:GetBody():GetPosition();
            print(pos.x, pos.y)
        end
        printPos(contact:GetFixtureA())
        printPos(contact:GetFixtureB())
    end)
    self.world:SetContactListener(listener)
#7

Simon - wrote:

Thanks zhong zhaofeng, the bindings you provided work perfectly in cocos2d-2.0-x-2.0.3! :slight_smile: For those that need more help:
>
* Include LuaBox2D.cpp and LuaBox2D.h in your project. LuaBox2D.h is missing an include, be sure to #include "tolua++.h" there.
>
* Register the lua box2D extension by editing your Appdelegate.cpp file.
* Add the include: #include "LuaBox2D.h"
>* Add the following to the bottom of the AppDelegate::applicationDidFinishLaunching() function: tolua_LuaBox2D_open(pEngine->getLuaState());
>
That’s it! You should be able to use the sample lua code provided by zhong above. There is a couple of variables missing, but it’s easy to figure out.
>
I’m working an a ContactListener implementation that allows you to listen for contact events from lua, will hopefully post this in a few days.

This not works for me. My cocos2dx version is 2.1.4,I think that’s the problem. Is there any way for me to generate the API for lua myself.