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Call a function from a other class/actor in InputComponent->BindAction

Development Discussion C++ Gameplay Programming
#1

Hey guys!

First of all: i’m pretty new to UE4.

I want the InputComponent->BindAction to call a function from a other class. How can i do that? I try to get this working for like 4 hours now and don’t get anything… So hopefully you guys can help me out!

When you need more Information, please let me know!

Sincerely Leroy :slight_smile:

#2

bump

Does no one have a clue?

#3

Bind your action to a function in your current class. From there call your function in another class.

#4

Thank you so much for your answer!

Ok, this was pretty basic… Anyways, how do i call this function out of another class?

I have this code in the header file of my player (AKeyPickUp is, of course, the class with the function i want to call):



protected:
	UPROPERTY(EditDefaultsOnly, Category = "MyCategory")
		class AKeyPickUp* Other;

Now i want to call this function through:



Other->PickKeyUp();

But i get this error: Access violation when writing to position 0x0000000000000330

Am i missing something?

#5

Ok, so i think i found the problem.

This was the entire function:



void AKeyPickUp::PickKeyUp()
{
	if (canPickUpKey)
	{
		GEngine->AddOnScreenDebugMessage(-1, 5.f, FColor::Cyan, TEXT("Called PickKeyUp() function"));
		HasKey = true;
		this->Destroy();
	}
}

I only get this error when i use any variable from the KeyPickUp class. Otherwise, when i only call ‘GEngine->AddOnScreenDebugMessage’, it works perfect.

For explanation: the bool ‘canPickUpKey’ is true, when the player overlaps with the sphere collider of this actor. Only in this sphere, the player can pick up the key. But, as i said, it’s irrelevant which variable i use in this function, i’m always getting “Access violation when writing to position 0x0000000000000330”…

#6

How are you setting the pointer Other? If you just declare it, it will just be NULL, and calling a function on it will crash. You’ll need to set it somehow (via a line trace, via an iteration over all AKeyPickUp instances etc).

#7

Thanks for your answer!

This could be the problem. I posted all the code i use for this, but why is ‘AddOnScreenDebugMessage’ working then?

Are there any tutorials for iteration or line trace?

Sorry, i’m new to Unreal Engine and C++ and my knowledge comes from Unity.

Sincerely Leroy

#8

I finally solved it!

The codeword was ‘iterator’.

I added/edited this code:



void AAbandonedPlayer::PickUpKey()
{
	for (TActorIterator<AKeyPickUp> ActorItr(GetWorld()); ActorItr; ++ActorItr)
	{
		ActorItr->PickKeyUp();
	}
}

Thank you both, that you have brought me on the right path! :smiley:

Sincerely Leroy

#9

Oops, i forgot to mention, that i made a #include at the top of the player.cpp.


#include "KeyPickUp.h"

Just in case someone comes on this thread ^^