How to pass FOnAkPostEventCallback struct in UE4 Wwise

Question

I have recently updated to the latest Wwise and Unreal Engine versions. What I noticed is that my "PostEvent" functions were now throwing errors, because they no longer require two parameters. One of the new parameters is a reference to a struct of type "FOnAkPostEventCallback", for which visual studio says that the declaration is undefined. So what exactly am I supposed to pass into this function? Would highly appreciate a descriptive response!

Comments

Ditto. Please advise. In addition, please implement a deprecation/change strategy for the Ak UE4 plugin code.

PostAkEvent() is a UFunction, and deprecation metadata can be added to the UFUNCTION attribute. Perhaps with a deprecation message like, 'PostAkEventDEPRECATED() will be removed in Wwise [major.minor]. Please convert caller to use the updated PostAkEvent().', etc.

Due to limitations with UHT, we can't have UFUNCTION overloads, so perhaps AkComponent::PostAkEvent(...) could have been copied to a PostAkEventDEPRECATED(...), so that callers would at least have a way to unblock in the short term.

UFunctions
https://docs.unrealengine.com/en-us/Programming/UnrealArchitecture/Reference/Functions


FWIW: On the Unity side, they respect System.ObsoleteAttribute.


- thanks

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I would also like to know this. Please could we get an official response for how to do this in C++.

Answer 1

Marc B., look at AkComponent.cpp for a workaround...

if you need to call a Blueprint function, you can use PostAkEventByName(), which calls PostAkEventByNameWithCallback() with the appropriate default/null args...
int32 UAkComponent::PostAkEventByName(const FString& in_EventName)

From cpp, you can call PostAkEventByNameWithCallback directly with the default/null args specified here in comments, if you want...
AkPlayingID UAkComponent::PostAkEventByNameWithCallback(const FString& in_EventName, AkUInt32 in_uFlags /*= 0*/, AkCallbackFunc in_pfnUserCallback /*= NULL*/, void * in_pUserCookie /*= NULL*/)

Whatever works for you. All roads eventually lead to AudioDevice->PostEvent().

- cheers

Answer 2

Though this question is asked at years ago, but for anyone in the future who steps into this QA.

Got me confused today too, but finally I noticed that the "FOnAkPostEventCallback" is a delegation's name, and it is defined in AkGameplayTypes.h (my Wwise SDK version is 2019.1.9.7221). The UE4 Delegate could be used like a class or struct, but the compiler won't find its reference or implement when it's used in another .h file... Here's the definition copied from AkGameplayTypes.h:

DECLARE_DYNAMIC_DELEGATE_TwoParams(FOnAkPostEventCallback, EAkCallbackType, CallbackType, UAkCallbackInfo*, CallbackInfo);

Answer 3

Let me give u an example. It just cost me lots of time to find a way to make my c++ callback work just like BP:

(Be careful about the event mask, u should set it to the event type u want to listen, set to 0 will miss all events. And also have a notice on the UFUNCTION macro of the callback, it's for dynamic delegate.)

class ATest : public AActor
{
public:
    FOnAkPostEventCallback OnAkPostEventDelegate;

    virtual void BeginPlay() override;
    virtual void EndPlay(const EEndPlayReason::Type EndPlayReason) override;
    
    UFUNCTION()
    void OnAkPostEventCallback(EAkCallbackType CallbackType, UAkCallbackInfo* CallbackInfo);

    void LetWwiseSpeakSomething(AActor* Actor, UAkAudioEvent* AkEvent);
};

void ATest::BeginPlay()
{
    OnAkPostEventDelegate.BindDynamic(this, &ATest::OnAkPostEventCallback);
    
    // other codes;
}

void ATest::EndPlay(const EEndPlayReason::Type EndPlayReason)
{
    OnAkPostEventDelegate.Clear();
    // other codes;
}


inline void ATest::LetWwiseSpeakSomething(AActor* Actor, UAkAudioEvent* AkEvent)
{
    UAkGameplayStatics::PostEvent(AkEvent, Actor, AK_EndOfEvent, OnAkPostEventDelegate);
}