AnimSubsystem_NodeRelevancy.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
#pragma once
 
#include "AnimSubsystemInstance.h"
#include "Animation/AnimTypes.h"
#include "AnimSubsystem_NodeRelevancy.generated.h"
 
struct FAnimationUpdateContext;
struct FAnimNode_Base;
class UAnimInstance;
 
// Relevancy status of a animation node tracked by this subsystem
struct FAnimNodeRelevancyStatus
{
public:
    // Get the current weight
    ENGINE_API float GetCurrentWeight() const;
 
    // Get the previous weight
    ENGINE_API float GetPreviousWeight() const;
    
    // Node has zero weight
    ENGINE_API bool HasFullyBlendedOut() const;
 
    // Node has just become relevant
    bool HasJustBecomeRelevant() const { return IsStartingBlendingIn(); }
    
    // Node has weight and had zero weight last update
    ENGINE_API bool IsStartingBlendingIn() const;
 
    // Node has full weight and had non-full weight last update
    ENGINE_API bool IsFinishingBlendingIn() const;
 
    // Node has full weight and had full weight last update
    ENGINE_API bool HasFullyBlendedIn() const;
 
    // Node has non-full weight and had full weight last update
    ENGINE_API bool IsStartingBlendingOut() const;
 
    // Node has zero weight and had non-zero weight last update
    ENGINE_API bool IsFinishingBlendingOut() const;
 
private:
    friend struct FAnimSubsystemInstance_NodeRelevancy;
    
    // Previous weight 
    float PreviousWeight = 0.0f;
 
    // Current weight
    float CurrentWeight = 0.0f;
};
 
// Initialization status of a node
enum class EAnimNodeInitializationStatus
{
    NotUpdated = 0,
    
    InitialUpdate,
 
    Updated,
};
 
USTRUCT()
struct FAnimSubsystemInstance_NodeRelevancy : public FAnimSubsystemInstance
{
    GENERATED_BODY()
 
    // FAnimSubsystemInstance interface
    ENGINE_API virtual void Initialize_WorkerThread() override;
    
    // Update the relevancy of the passed-in node using the supplied context
    ENGINE_API FAnimNodeRelevancyStatus UpdateNodeRelevancy(const FAnimationUpdateContext& InContext, const FAnimNode_Base& InNode);
 
    // Get the tracked relevancy of the passed-in node. If the node is not tracked the relevancy will be default (zero weighted).
    ENGINE_API FAnimNodeRelevancyStatus GetNodeRelevancy(const FAnimNode_Base& InNode) const;
 
    // Update the initialization state of the passed-in node using the supplied context
    ENGINE_API EAnimNodeInitializationStatus UpdateNodeInitializationStatus(const FAnimationUpdateContext& InContext, const FAnimNode_Base& InNode);
 
    // Get the tracked initialization state of the passed-in node. If the node is not tracked the initialization state will be default (NotUpdated)
    ENGINE_API EAnimNodeInitializationStatus GetNodeInitializationStatus(const FAnimNode_Base& InNode) const;
    
private:
    // Tracks the relevancy of a node
    struct FTracker
    {
        // Counter used to determine relevancy
        FGraphTraversalCounter Counter;
 
        // Status of the node's relevancy
        FAnimNodeRelevancyStatus Status;
    };
 
private:
    // Map of tracked anim nodes
    TMap<const FAnimNode_Base*, FTracker> NodeTrackers;
 
    // Map of tracked anim nodes initialization
    TMap<const FAnimNode_Base*, EAnimNodeInitializationStatus> NodeInitTrackers;
};