Getting contact points on bodies in Cocos2d & Box2d

I'm very new to Cocos2d and Box2d, I have been following tutorials and generally hacking. However, I have one problem I cannot solve.

I create 2 bodies and fixtures (in the Box2d world) and create a "Contact Listener" object. This object stores a list of contacts along with the "contact point".

When the two bodies collide a contact point is reported but this (I think) is in the world co-ordinate system.

My problem is I can't seem to convert the contact point to a usable co-ordinate on both of the bodies.

I want to add a crack graphic to the sprite (connected to the body) at the开发者_如何学Python point of contact on both bodies/fixtures.

Has anyone solved this? I may be storing the "contact point" relative to the "world" is completely the wrong way to go.

Here is how to get the world-point (or points, max of 2 points are returned) where the collision took place. Within your B2ContactListener object, in BeginContact or EndContact functions:

b2WorldManifold worldManifold;
contact->GetWorldManifold(&worldManifold);
std::cout << "Contact point X: " << worldManifold.points[0].x * Ascengine::Physics::PIXEL_TO_METER_RATIO << " Contact point Y: " << worldManifold.points[0].y  * Ascengine::Physics::PIXEL_TO_METER_RATIO << std::endl;

From here, as Jason F mentioned, you can then use b2Body::GetLocalPoint(const b2Vec2 &worldPoint) to convert this world point to local object space. I just wanted to add my own answer to include the whole part about getting the world contact points, since this seems to be omitted altogether in the accepted answer.

check out this. Take a look at b2Body::GetLocalPoint(const b2Vec2 &worldPoint)