PBDExtremeDeformationConstraints.h

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// Copyright Epic Games, Inc. All Rights Reserved.
#pragma once
 
#include "Chaos/CollectionPropertyFacade.h"
#include "Chaos/PBDSoftsSolverParticles.h"
#include "Chaos/SoftsSolverParticlesRange.h"
#include "Chaos/Utilities.h"
#include "Containers/Array.h"
 
namespace Chaos::Softs
{
 
class FPBDExtremeDeformationConstraints
{
public:
 
    static bool IsEnabled(const FCollectionPropertyConstFacade& PropertyCollection)
    {
        return IsExtremeDeformationVertexSelectionEnabled(PropertyCollection, false) && 
            IsExtremeDeformationEdgeRatioThresholdEnabled(PropertyCollection, false);
    }
 
    template<int32 Valence UE_REQUIRES(Valence >= 2 && Valence <= 4)>
    FPBDExtremeDeformationConstraints(
        const FSolverParticlesRange& Particles,
        const TArray<TVector<int32, Valence>>& InConstraints,
        const TMap<FString, TConstArrayView<FRealSingle>>& WeightMaps,
        const TMap<FString, const TSet<int32>*>& VertexSets,
        const FCollectionPropertyConstFacade& PropertyCollection,
        bool bTrimKinematicConstraints = false)
        : VertexSet(VertexSets.FindRef(GetExtremeDeformationVertexSelectionString(PropertyCollection, ExtremeDeformationVertexSelectionName.ToString()), nullptr))
        , Constraints(TrimConstraints(InConstraints,
            [&Particles, bTrimKinematicConstraints, this](int32 Index0, int32 Index1)
            {
                return (bTrimKinematicConstraints && Particles.InvM(Index0) == (FSolverReal)0. && Particles.InvM(Index1) == (FSolverReal)0.)
                    || (VertexSet && (!VertexSet->Contains(Index0) || !VertexSet->Contains(Index1)));
            }))
        , ParticleOffset(0)
        , ParticleCount(Particles.GetRangeSize())
        , ExtremeDeformationThreshold(GetExtremeDeformationEdgeRatioThreshold(PropertyCollection, FLT_MAX))
        , ExtremeDeformationEdgeRatioThresholdIndex(PropertyCollection)
    {
        // Update distances
        Dists.Reset(Constraints.Num());
        for (const TVec2<int32>& Constraint : Constraints)
        {
            const FSolverVec3& P0 = Particles.X(Constraint[0]);
            const FSolverVec3& P1 = Particles.X(Constraint[1]);
            Dists.Add((P1 - P0).Size());
        }
    }
 
    template<int32 Valence UE_REQUIRES(Valence >= 2 && Valence <= 4)>
    FPBDExtremeDeformationConstraints(
        const FSolverParticles& Particles,
        int32 InParticleOffset,
        int32 InParticleCount,
        const TArray<TVector<int32, Valence>>& InConstraints,
        const TMap<FString, TConstArrayView<FRealSingle>>& WeightMaps,
        const TMap<FString, const TSet<int32>*>& VertexSets,
        const FCollectionPropertyConstFacade& PropertyCollection,
        bool bTrimKinematicConstraints = false)
        : VertexSet(VertexSets.FindRef(GetExtremeDeformationVertexSelectionString(PropertyCollection, ExtremeDeformationVertexSelectionName.ToString()), nullptr))
        , Constraints(TrimConstraints(InConstraints,
            [&Particles, bTrimKinematicConstraints, this](int32 Index0, int32 Index1)
            {
                return (bTrimKinematicConstraints && Particles.InvM(Index0) == (FSolverReal)0. && Particles.InvM(Index1) == (FSolverReal)0.)
                    || (VertexSet && (!VertexSet->Contains(Index0) || !VertexSet->Contains(Index1)));
            }))
        , ParticleOffset(InParticleOffset)
        , ParticleCount(InParticleCount)
        , ExtremeDeformationThreshold(GetExtremeDeformationEdgeRatioThreshold(PropertyCollection, FLT_MAX))
        , ExtremeDeformationEdgeRatioThresholdIndex(PropertyCollection)
    {
        // Update distances
        Dists.Reset(Constraints.Num());
        for (const TVec2<int32>& Constraint : Constraints)
        {
            const FSolverVec3& P0 = Particles.GetX(Constraint[0]);
            const FSolverVec3& P1 = Particles.GetX(Constraint[1]);
            Dists.Add((P1 - P0).Size());
        }
    }
 
    virtual ~FPBDExtremeDeformationConstraints()
    {}
 
    void SetProperties(const FCollectionPropertyConstFacade& PropertyCollection,
        const TMap<FString, TConstArrayView<FRealSingle>>& WeightMaps)
    {
        if (IsExtremeDeformationEdgeRatioThresholdMutable(PropertyCollection))
        {
            ExtremeDeformationThreshold = GetExtremeDeformationEdgeRatioThreshold(PropertyCollection, FLT_MAX);
        }
    }
 
    const TArray<TVec2<int32>>& GetConstraints() const { return Constraints; }
 
    CHAOS_API FSolverReal GetThreshold() const;
    
    CHAOS_API bool IsExtremelyDeformed(TConstArrayView<Softs::FSolverVec3> Positions) const;
 
    CHAOS_API bool IsExtremelyDeformed(TConstArrayView<Softs::FSolverVec3> Positions, const Softs::FSolverVec3* const RefencePositions) const;
 
    CHAOS_API TArray<TVec2<int32>> GetExtremelyDeformedEdges(TConstArrayView<Softs::FSolverVec3> Positions) const;
 
    CHAOS_API TArray<TVec2<int32>> GetExtremelyDeformedEdges(TConstArrayView<Softs::FSolverVec3> Positions, const Softs::FSolverVec3* const RefencePositions) const;
 
private:
    template<int32 Valence, typename Predicate UE_REQUIRES(Valence >= 2 && Valence <= 4)>
    static TArray<TVector<int32, 2>> TrimConstraints(const TArray<TVector<int32, Valence>>& InConstraints, Predicate TrimPredicate)
    {
        TSet<TVec2<int32>> TrimmedConstraints;
        TrimmedConstraints.Reserve(Valence == 2 ? InConstraints.Num() : InConstraints.Num() * Chaos::Utilities::NChooseR(Valence, 2));
 
        for (const TVector<int32, Valence>& ConstraintV : InConstraints)
        {
            for (int32 i = 0; i < Valence - 1; ++i)
            {
                for (int32 j = i + 1; j < Valence; ++j)
                {
                    const int32 IndexI = ConstraintV[i];
                    const int32 IndexJ = ConstraintV[j];
 
                    if (!TrimPredicate(IndexI, IndexJ))
                    {
                        TrimmedConstraints.Add(IndexI <= IndexJ ? TVec2<int32>(IndexI, IndexJ) : TVec2<int32>(IndexJ, IndexI));
                    }
                }
            }
        }
        return TrimmedConstraints.Array();
    }
 
    const TSet<int32>* VertexSet;
    TArray<TVec2<int32>> Constraints;
    const int32 ParticleOffset;
    const int32 ParticleCount;
    FSolverReal ExtremeDeformationThreshold;
    TArray<FSolverReal> Dists;
 
    UE_CHAOS_DECLARE_INDEXLESS_PROPERTYCOLLECTION_NAME(ExtremeDeformationVertexSelection, bool);  // Selection set name string property, the bool value is not actually used
    UE_CHAOS_DECLARE_PROPERTYCOLLECTION_NAME(ExtremeDeformationEdgeRatioThreshold, float);
};
 
}  // End namespace Chaos::Softs