How to properly use a callback for eventlistener?

[patrikpatrik]

Hello, Im sorry for asking this but I'm confused on how to create this custom event listener? I've read the manual several times but still dont understand it.

If I have an object that's falling to hit a plane and want to determine if the collision occurred, how would I create a callback for that? It says to use const CollisionCallback::CallbackData& but how exactly do I instantiate this to my capsule object falling and hitting my plane:?

[DanielChappuis]

As described here in the manual, you need to create your own class that inherits from the rp3d::EventListener class. Then, you need to override the onContact() method to receive a callback when collision occurs. When this method is called, the callbackData parameter will contains the pairs of bodies that collided with information about the contacts. Take a look at the code example in the manual.

You can find more information about what is inside the CallbackData here in the API reference.

Let me know if something is not clear.

[patrikpatrik]

Thank you Daniel. I followed that template on the user manual. It does trigger a response, but it seems to output twice for each contact. Is there a way to only trigger once? For instance here is my code:

// test event listener class 
class YourEventListener : public rp3d::EventListener {

	// Override the onContact() method 
	virtual void onContact(const CollisionCallback::CallbackData& callbackData) override {

		//callbackData.getContactPair(0);
		//CollisionCallback::ContactPair madeContact = callbackData.getContactPair(0);
		printf("i made contact!\n"); // <-- always outputs twice on first contact hit
	}
};