CollectionMuscleActivationFacade.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
#pragma once
 
#include "CoreMinimal.h"
#include "GeometryCollection/GeometryCollection.h"
#include "GeometryCollection/ManagedArrayAccessor.h"
#include "GeometryCollection/ManagedArrayCollection.h"
#include "GeometryCollection/Facades/CollectionSelectionFacade.h"
 
namespace Chaos
{
    class FLinearCurve;
}
 
namespace GeometryCollection::Facades
{
    //Activation data for each muscle
    struct FMuscleActivationData
    {
        int32 GeometryGroupIndex; //Geometry group index of the muscle
        TArray<int32> MuscleActivationElement; //Contractible tetrahedra
        FIntVector2 OriginInsertionPair; //Muscle origin point and insertion point (to determine muscle length)
        float OriginInsertionRestLength; //Muscle origin-insertion rest length
        TArray<Chaos::PMatrix33d> FiberDirectionMatrix; //Per-element fiber direction orthogonal matrix: [v, w1, w2], v is the fiber direction
        TArray<float> ContractionVolumeScale; // Per-element volume scale for muscle contraction. Muscles gain volume during contraction if > 1. Volume-preserving if 1.
        float FiberLengthRatioAtMaxActivation = 0.5f; // How much muscle fibers shorten at max activation 1. A smaller value means more contraction in the fiber direction.
        float MuscleLengthRatioThresholdForMaxActivation = 0.75f; // Muscle length ratio (defined by origin-insertion distance) below this threshold is considered to reach max activation 1.
        float InflationVolumeScale = 1.f; // Increases muscle rest volume if > 1 and decreases muscle rest volume if < 1.
        TArray<TArray<FVector3f>> FiberStreamline; //Fiber streamline(s) for inverse dynamics
        TArray<float> FiberStreamlineRestLength; //Fiber streamline rest length(s)
    };
    
    class FMuscleActivationFacade
    {
    public:
 
        static CHAOS_API const FName GroupName;
        static CHAOS_API const FName GeometryGroupIndex;
        static CHAOS_API const FName MuscleActivationElement;
        static CHAOS_API const FName OriginInsertionPair;
        static CHAOS_API const FName OriginInsertionRestLength;
        static CHAOS_API const FName FiberDirectionMatrix;
        static CHAOS_API const FName ContractionVolumeScale;
        static CHAOS_API const FName FiberLengthRatioAtMaxActivation;
        static CHAOS_API const FName MuscleLengthRatioThresholdForMaxActivation;
        static CHAOS_API const FName InflationVolumeScale;
        static CHAOS_API const FName FiberStreamline;
        static CHAOS_API const FName FiberStreamlineRestLength;
        static CHAOS_API const FName MuscleActivationCurveName;
        static CHAOS_API const FName LengthActivationCurve;
 
        CHAOS_API FMuscleActivationFacade(FManagedArrayCollection& InCollection);
        CHAOS_API FMuscleActivationFacade(const FManagedArrayCollection& InCollection);
 
        CHAOS_API void DefineSchema();
 
        bool IsConst() const { return Collection == nullptr; }
 
        CHAOS_API bool IsValid() const;
 
        //
        //  Skeletal Mesh Bone Bindings
        //
        CHAOS_API int32 AddMuscleActivationData(const FMuscleActivationData& InputData);
        CHAOS_API bool UpdateMuscleActivationData(const int32 DataIndex, const FMuscleActivationData& InputData);
        CHAOS_API FMuscleActivationData GetMuscleActivationData(const int32 DataIndex) const;
        bool IsValidGeometryIndex(const int32 Index) const { return 0 <= Index && Index < ConstCollection.NumElements(FGeometryCollection::GeometryGroup); };
        bool IsValidElementIndex(const int32 Index) const { return 0 <= Index && Index < ConstCollection.NumElements("Tetrahedral"); };
        int32 NumMuscles() const { return MuscleActivationElementAttribute.Num(); }
        bool IsValidMuscleIndex(const int32 Index) const { return 0 <= Index && Index < NumMuscles(); };
        CHAOS_API int32 MuscleVertexOffset(const int32 MuscleIndex) const;
        CHAOS_API int32 NumMuscleVertices(const int32 MuscleIndex) const;
        CHAOS_API FString FindMuscleName(const int32 MuscleIndex) const;
        CHAOS_API int32 FindMuscleIndexByName(const FString MuscleName) const;
        CHAOS_API int32 FindMuscleGeometryIndex(const int32 MuscleIndex) const;
        CHAOS_API int32 RemoveInvalidMuscles();
        CHAOS_API bool SetUpMuscleActivation(const TArray<int32>& Origin, const TArray<int32>& Insertion, float ContractionVolumeScale = 1.f);
        CHAOS_API void UpdateGlobalMuscleActivationParameters(
            float InGlobalContractionVolumeScale,
            float InGlobalFiberLengthRatioAtMaxActivation,
            float InGlobalMuscleLengthRatioThresholdForMaxActivation,
            float InGlobalInflationVolumeScale);
        CHAOS_API bool UpdateMuscleActivationParameters(
            int32 MuscleIndex,
            float InContractionVolumeScale,
            float InFiberLengthRatioAtMaxActivation,
            float InMuscleLengthRatioThresholdForMaxActivation,
            float InInflationVolumeScale);
        CHAOS_API void UpdateGlobalLengthActivationCurve(const Chaos::FLinearCurve& InGlobalLengthActivationCurve);
        CHAOS_API void UpdateLengthActivationCurve(int32 MuscleIndex, const Chaos::FLinearCurve& InLengthActivationCurve);
        CHAOS_API Chaos::FLinearCurve GetLengthActivationCurve(int32 MuscleIndex) const;
        CHAOS_API TArray<TArray<TArray<FVector3f>>> BuildStreamlines(const TArray<int32>& Origin, const TArray<int32>& Insertion,
             int32 NumLinesMultiplier, int32 MaxStreamlineIterations, int32 MaxPointsPerLine);
        CHAOS_API int32 AssignCurveName(const FString& CurveName, const FString& MuscleName);
        CHAOS_API TArray<int32> FindMuscleIndexByCurveName(const FString& CurveName) const;
    private:
        const FManagedArrayCollection& ConstCollection;
        FManagedArrayCollection* Collection = nullptr;
        TManagedArrayAccessor<int32> GeometryGroupIndexAttribute;
        TManagedArrayAccessor<TArray<int32>> MuscleActivationElementAttribute;
        TManagedArrayAccessor<FIntVector2> OriginInsertionPairAttribute;
        TManagedArrayAccessor<float> OriginInsertionRestLengthAttribute;
        TManagedArrayAccessor<TArray<Chaos::PMatrix33d>> FiberDirectionMatrixAttribute;
        TManagedArrayAccessor<TArray<float>> ContractionVolumeScaleAttribute;
        TManagedArrayAccessor<float> FiberLengthRatioAtMaxActivationAttribute;
        TManagedArrayAccessor<float> MuscleLengthRatioThresholdForMaxActivationAttribute;
        TManagedArrayAccessor<float> InflationVolumeScaleAttribute;
        TManagedArrayAccessor<TArray<TArray<FVector3f>>> FiberStreamlineAttribute;
        TManagedArrayAccessor<TArray<float>> FiberStreamlineRestLengthAttribute;
        TManagedArrayAccessor<FString> MuscleActivationCurveNameAttribute;
        TManagedArrayAccessor<Chaos::FLinearCurve> LengthActivationCurveAttribute;
    };
}