PBDUnilateralTetConstraints.h

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// Copyright Epic Games, Inc. All Rights Reserved.
#pragma once
 
#include "Chaos/CollectionEmbeddedSpringConstraintFacade.h"
#include "Chaos/CollectionPropertyFacade.h"
#include "Chaos/Core.h"
#include "Chaos/PBDFlatWeightMap.h"
#include "Chaos/PBDSoftsEvolutionFwd.h"
#include "Chaos/PBDSoftsSolverParticles.h"
#include "Chaos/SoftsSolverParticlesRange.h"
#include "Containers/Array.h"
 
namespace Chaos::Softs
{
 
    class FPBDUnilateralTetConstraints
    {
    public:
        static constexpr FSolverReal MinStiffness = (FSolverReal)0;
        static constexpr FSolverReal MaxStiffness = (FSolverReal)1.f;
        static constexpr FSolverReal DefaultStiffness = (FSolverReal)0.5f;
 
        CHAOS_API FPBDUnilateralTetConstraints(
            const FSolverParticlesRange& Particles,
            TArray<TVector<int32, 4>>&& InConstraints,
            TArray<FSolverReal>&& InVolumes,
            FSolverReal InStiffness,
            int32 InMaxNumIters);
 
        ~FPBDUnilateralTetConstraints() = default;
 
        void ApplyProperties(const FSolverReal /*Dt*/, const int32 /*NumIterations*/)
        {
        }
 
        CHAOS_API void Apply(FSolverParticlesRange& Particles, const FSolverReal Dt) const;
        
        const TArray<TVector<int32, 4>>& GetConstraints() const { return Constraints; }
 
#if CHAOS_DEBUG_DRAW
        const TArray<bool>& GetConstraintIsActive() const { return ConstraintIsActive; }
#endif
 
    private:
 
        void TrimKinematicConstraints(const FSolverParticlesRange& Particles);
        void InitColor(const FSolverParticlesRange& Particles);
 
        void ApplyVolumeConstraint(FSolverParticlesRange& Particles, const FSolverReal Dt) const;
#if INTEL_ISPC
        void ApplyVolumeConstraint_ISPC(FSolverParticlesRange& Particles, const FSolverReal Dt) const {}
#endif
 
        TArray<TVector<int32, 4>> Constraints;
        TArray<FSolverReal> Volumes;
 
        TArray<int32> ConstraintsPerColorStartIndex; // Constraints are ordered so each batch is contiguous. This is ColorNum + 1 length so it can be used as start and end.
 
#if CHAOS_DEBUG_DRAW
        // Used for debug draw to show which constraints were active last apply
        mutable TArray<bool> ConstraintIsActive;
#endif
 
    protected:
        FSolverReal Stiffness;
        int32 MaxNumIters;
    };
 
    class FPBDVertexFaceRepulsionConstraints final : public FPBDUnilateralTetConstraints
    {
    public:
 
        static bool IsEnabled(const FCollectionPropertyConstFacade& PropertyCollection)
        {
            return IsVertexFaceRepulsionStiffnessEnabled(PropertyCollection, false);
        }
 
        CHAOS_API FPBDVertexFaceRepulsionConstraints(
            const FSolverParticlesRange& Particles,
            const FCollectionPropertyConstFacade& PropertyCollection,
            const FEmbeddedSpringConstraintFacade& SpringConstraintFacade);
 
        CHAOS_API void SetProperties(const FCollectionPropertyConstFacade& PropertyCollection);
 
    private:
        static TArray<TVector<int32, 4>> ExtractConstraintIndices(const FEmbeddedSpringConstraintFacade& SpringConstraintFacade);
        static TArray<FSolverReal> ExtractVolumes(const FSolverParticlesRange& Particles, const FEmbeddedSpringConstraintFacade& SpringConstraintFacade);
 
        UE_CHAOS_DECLARE_PROPERTYCOLLECTION_NAME(VertexFaceRepulsionStiffness, float);
        UE_CHAOS_DECLARE_PROPERTYCOLLECTION_NAME(VertexFaceMaxRepulsionIters, int32);
    };
 
}  // End namespace Chaos::Softs