BlendableTokenStack.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
#pragma once
 
#include "MovieSceneFwd.h"
#include "Evaluation/MovieSceneAnimTypeID.h"
#include "Evaluation/Blending/MovieSceneBlendingActuatorID.h"
#include "Misc/InlineValue.h"
#include "Evaluation/MovieSceneEvaluationScope.h"
#include "Evaluation/MovieSceneEvaluationOperand.h"
#include "Evaluation/Blending/BlendableToken.h"
#include "IMovieScenePlayer.h"
#include "Evaluation/PreAnimatedState/MovieScenePreAnimatedCaptureSource.h"
 
struct FMovieSceneInterrogationData;
struct FMovieSceneContext;
struct FMovieSceneBlendingAccumulator;
template<typename T> struct TMovieSceneBlendingActuator;
 
template<typename T> FMovieSceneAnimTypeID GetBlendingDataType()
{
    // Always assert on instantiation
    static_assert(std::is_same_v<T, void>, "GetBlendingDataType must be specialized for a type in order to use it with an accumulator.");
    return FMovieSceneAnimTypeID::Unique();
}
 
struct IBlendableTokenStack
{
protected:
 
    IBlendableTokenStack(FMovieSceneAnimTypeID InDataTypeID) : DataTypeID(InDataTypeID) {}
 
public:
 
    virtual ~IBlendableTokenStack() {}
 
    virtual void ComputeAndActuate(UObject* InObject, FMovieSceneBlendingAccumulator& Accumulator, FMovieSceneBlendingActuatorID ActuatorTypeID, const FMovieSceneContext& Context, FPersistentEvaluationData& PersistentData, IMovieScenePlayer& Player) = 0;
 
    virtual void Interrogate(UObject* AnimatedObject, FMovieSceneInterrogationData& InterrogationData, FMovieSceneBlendingAccumulator& Accumulator, FMovieSceneBlendingActuatorID ActuatorTypeID, const FMovieSceneContext& Context) = 0;
 
    FMovieSceneAnimTypeID DataTypeID;
};
 
template<typename DataType>
struct TBlendableTokenStack : IBlendableTokenStack
{
    TArray<const TBlendableToken<DataType>*> Tokens;
 
    int32 CurrentBias;
 
    TBlendableTokenStack() : IBlendableTokenStack(GetBlendingDataType<DataType>()), CurrentBias(TNumericLimits<int32>::Lowest()) {}
 
    void AddToken(const TBlendableToken<DataType>* TokenToAdd)
    {
        check(TokenToAdd);
 
        if (TokenToAdd->HierarchicalBias > CurrentBias)
        {
            Tokens.Reset();
            CurrentBias = TokenToAdd->HierarchicalBias;
        }
 
        if (TokenToAdd->HierarchicalBias == CurrentBias)
        {
            // Just add the token
            Tokens.Add(TokenToAdd);
        }
    }
 
public:
 
    virtual void ComputeAndActuate(UObject* InObject, FMovieSceneBlendingAccumulator& Accumulator, FMovieSceneBlendingActuatorID InActuatorType, const FMovieSceneContext& Context, FPersistentEvaluationData& PersistentData, IMovieScenePlayer& Player) override final;
 
    virtual void Interrogate(UObject* AnimatedObject, FMovieSceneInterrogationData& InterrogationData, FMovieSceneBlendingAccumulator& Accumulator, FMovieSceneBlendingActuatorID ActuatorTypeID, const FMovieSceneContext& Context) override final;
 
    template<typename...T>
    void SavePreAnimatedStateForAllEntities(IMovieScenePlayer& Player, T&&... Args) const
    {
        SavePreAnimatedStateImpl(Player, EMovieSceneCompletionMode::RestoreState, Args...);
    }
 
    template<typename...T>
    void SavePreAnimatedState(IMovieScenePlayer& Player, T&&... Args) const
    {
        SavePreAnimatedStateImpl(Player, TOptional<EMovieSceneCompletionMode>(), Args...);
    }
    
private:
 
    template<typename...T>
    void SavePreAnimatedStateImpl(IMovieScenePlayer& Player, TOptional<EMovieSceneCompletionMode> CompletionModeOverride, T&&... Args) const
    {
        bool bSavedState = false;
        for (const TBlendableToken<DataType>* Token : Tokens)
        {
            if (CompletionModeOverride.Get(Token->AnimatingScope.CompletionMode) == EMovieSceneCompletionMode::RestoreState)
            {
                FScopedPreAnimatedCaptureSource CaptureSource(&Player.PreAnimatedState, Token->AnimatingScope.Key, true);
                Player.SavePreAnimatedState(Forward<T>(Args)...);
                bSavedState = true;
            }
        }
 
        // Save global state if nothing else did
        if (!bSavedState)
        {
            Player.SavePreAnimatedState(Forward<T>(Args)...);
        }
    }
};