Anim Instance Chooser with Struct Output C++

Development Programming & Scripting
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Hey Unreal Devs!

Just wanted to contibute some helpful knowledge I wasn’t able to find on the net myself.

If you need to Evaluate Choosers with a struct parameter output in C++ look no further than below! (As of current 5.5.4 Unreal Version).

// Very important to ensure the struct output matches the chooser output!
	template<class T>
	static UAnimationAsset* EvaluateAnimInstanceChooser(UAnimInstance* AnimInstance, UChooserTable* ChooserTable,
		T& StructOutput)
	{
		if (!IsValid(AnimInstance) || !IsValid(ChooserTable))
		{
			UE_LOG(LogTemp, Error, TEXT("[YourClassName]::EvaluateAnimChooser - Invalid chooser evaluation data"));
			return nullptr;
		}

		const FInstancedStruct ChooserInstance = UChooserFunctionLibrary::MakeEvaluateChooser(ChooserTable);
		FChooserEvaluationContext ChooserEvaluationContext = UChooserFunctionLibrary::MakeChooserEvaluationContext();
		ChooserEvaluationContext.AddObjectParam(AnimInstance);
		ChooserEvaluationContext.AddStructParam(StructOutput);

		UAnimationAsset* ChooserAnimation {
			Cast<UAnimationAsset>(UChooserFunctionLibrary::EvaluateObjectChooserBase(ChooserEvaluationContext, ChooserInstance,
				UAnimationAsset::StaticClass()))
		};

		return ChooserAnimation;
	}

// Very important to ensure the struct output matches the chooser output!
template<class T>
	static TArray<UAnimationAsset*> EvaluateAnimInstanceChooserMulti(UAnimInstance* AnimInstance, UChooserTable* ChooserTable,
		T& StructOutput)
	{
		TArray<UAnimationAsset*> ResultAnimations;
		
		if (!IsValid(AnimInstance) || !IsValid(ChooserTable))
		{
			UE_LOG(LogTemp, Error, TEXT("[YourClassName]::EvaluateAnimChooser - Invalid chooser evaluation data"));
			return ResultAnimations;
		}

		const FInstancedStruct ChooserInstance = UChooserFunctionLibrary::MakeEvaluateChooser(ChooserTable);
		FChooserEvaluationContext ChooserEvaluationContext = UChooserFunctionLibrary::MakeChooserEvaluationContext();
		ChooserEvaluationContext.AddObjectParam(AnimInstance);
		ChooserEvaluationContext.AddStructParam(StructOutput);

		const TArray<UObject*> ChooserObjects {
			UChooserFunctionLibrary::EvaluateObjectChooserBaseMulti(ChooserEvaluationContext, ChooserInstance,
				UAnimationAsset::StaticClass())
		};

		for (UObject* ChooserObject : ChooserObjects)
		{
			if (UAnimationAsset* ChooserAnimation = Cast<UAnimationAsset>(ChooserObject))
			{
				ResultAnimations.Add(ChooserAnimation);
			}
		}

		return ResultAnimations;
	}

If you don’t need a struct output just create another function without the StructOutput parameter and remove the “ChooserEvaluationContext.AddStructParam(StructOutput);” line.

Hope this can help some peeps.

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