How to get collision between bat of player and ball and ignore player's body - cocos2d-x

Question

I have baseball player animation where player are hitting with bat, I have 90 frames in that animation and on sprite for ball. I added circle physic body to ball. How to make, what is a concept, to get collision only with ball and bat and not between player's body and ball ?
Bat is on every image together with player.
I am using Cocos2d-x and Chipmunk but I can switch to Box2d easily if this problem is solvable.

Answer 1

What you are looking for is a way to distinguish between collisions in your physics world. When using box2D you can set the user data for the physics body. When a collision happens you can get the two bodies that are colliding and get the user information set on it. Then handle your collision appropriately.
Pseudo-code below to create a body:
b2BodyDef ballBodyDef;
ballBodyDef.type = b2_dynamicBody;
ballBodyDef.position.Set(tileNode->getPositionX() / Pixel_To_Meter_Ratio,
tileNode->getPositionY()/ Pixel_To_Meter_Ratio);
auto b2CircleShape ballShape;
ballShape->m_radius = ballSize / PTM_RATIO; // Pixel to meter ration is 32.0 in my project
auto ballBody= physicsWorld->CreateBody(ballBodyDef);
// This will be used later on when you want to have different reactions for different collisions.
ballBody->SetUserData("BallBody");
Using similar code above create your bat body (will not put all the code below).
...
auto batBody = physicsWorld->CreateBody(batBodyDef);
batBody->setUserData("BatBody");
When doing your check in your contact listener you can ignore all collisions that has user data that does not match BallBody and BatBody. Something like below in your collision handler.
auto objectOne = contact->GetFixtureA()->GetBody();
auto objectTwo = contact->GetFixtureB()->GetBody();
auto objectOneUserData = (objectOne->GetUserData());
auto objectTwoUserData = (objectTwo->GetUserData());
Do your checks on the userData above and return out of the function. This should do the trick. It's what I use to handle or ignore specific types of collisions.
I hope this helps.