Intro to Box2D with Cocos2D 2.X Tutorial: Bouncing Balls

[rwenderlich]

This is the official thread to discuss the following blog post: Intro to Box2D with Cocos2D 2.X Tutorial: Bouncing Balls

[nicopasso]

Hi, i'm new to Box2D. This is a great tutorial!!!
But I found this problem:
the article uses the lines
[self setTouchEnabled:YES]; and [self setAccelerometerEnabled:YES]
and XCode tells me tha these methods are "not found".

At the begininng I didn't understand the warnings but then i found that the correct lines for me are:
[self setIsTouchEnabled:YES]; and [self setIsAccelerometerEnabled:YES];
Now the code work properly!

I just want to share this problem with all of you!
Bye
Nic

[ptc79]

Hi, I'm new to Objective-C, Xcode, Cocos2D and Box2D. My question is do we need to learn C++ in order to use Box2D. The tutorial doesn't make any mention of C++ but the Box2D part is written in C++, right? The files are .mm extension but the code just seems to be mixed into the usual Objective-C functions. So, if you want to use Box2D with an obj-c app do you have to learn C++ first?

[VitalRemains]

Hello,
I'm trying to add more balls with a button click.

I wrote this:

Code: Select all

[...]
CCMenuItem *addMenuItem = [CCMenuItemImage itemWithNormalImage:@"ButtonPlus.png" selectedImage:@"ButtonPlusSel.png" target:self selector:@selector(addNewBall)];
        addMenuItem.position = ccp(winSize.width - (addMenuItem.contentSize.width/2), winSize.height - (addMenuItem.contentSize.height/2));
        CCMenu *addMenu = [CCMenu menuWithItems:addMenuItem, nil];
        addMenu.position = CGPointZero;
        [self addChild:addMenu];
[...]

- (void)addNewBall {   
    CCSprite* newBall = [CCSprite spriteWithFile:@"ball.png" rect:CGRectMake(0, 0, 52, 52)];
    newBall.position = ccp(0, 300);
    [self addChild:newBall];
   
    b2Body* newBallBody;
   
    b2BodyDef ballBodyDef;
    ballBodyDef.type = b2_dynamicBody;
    ballBodyDef.position.Set(0/PTM_RATIO, 300/PTM_RATIO);
    ballBodyDef.userData = newBall;
    newBallBody = _world->CreateBody(&ballBodyDef);
   
    b2CircleShape circle;
    circle.m_radius = 26.0/PTM_RATIO;
   
    b2FixtureDef ballShapeDef;
    ballShapeDef.shape = &circle;
    ballShapeDef.density = 1.0f;
    ballShapeDef.friction = 0.2f;
    ballShapeDef.restitution = 0.8f;
    newBallBody->CreateFixture(&ballShapeDef);
}


But it won't add any new balls if I press on the button.
Do I have to tell the program that there's a new body it has to deal with or anything if it's not created in the init method?

~VitalRemains