PerParticleEtherDrag.h

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// Copyright Epic Games, Inc. All Rights Reserved.
#pragma once
 
#include "Chaos/PerParticleRule.h"
#include "Chaos/ParticleHandle.h"
#include "Chaos/Utilities.h"
 
namespace Chaos
{
    extern FRealSingle LinearEtherDragOverride;
    extern FRealSingle AngularEtherDragOverride;
 
    class FPerParticleEtherDrag : public FPerParticleRule
    {
    public:
        FPerParticleEtherDrag() {}
        virtual ~FPerParticleEtherDrag() {}
 
        inline void ApplyHelper(FVec3& V, FVec3& W, FReal LinearDamp, FReal AngularDamp, FReal LinearLimitSq, FReal AngularLimitSq, FReal Dt) const
        {
            const FReal LinearDrag = LinearEtherDragOverride >= 0 ? LinearEtherDragOverride : LinearDamp * Dt;
            const FReal LinearMultiplier = FMath::Max(FReal(0), FReal(1) - LinearDrag);
            V *= LinearMultiplier;
 
            const FReal AngularDrag = AngularEtherDragOverride >= 0 ? AngularEtherDragOverride : AngularDamp * Dt;
            const FReal AngularMultiplier = FMath::Max(FReal(0), FReal(1) - AngularDrag);
            W *= AngularMultiplier;
 
            const FReal LinearSpeedSq = V.SizeSquared();
            const FReal AngularSpeedSq = W.SizeSquared();
 
            if(LinearSpeedSq > LinearLimitSq)
            {
                V *= FMath::Sqrt(LinearLimitSq / LinearSpeedSq);
            }
 
            if(AngularSpeedSq > AngularLimitSq)
            {
                W *= FMath::Sqrt(AngularLimitSq / AngularSpeedSq);
            }
        }
 
        inline void Apply(FDynamicParticles& InParticles, const FReal Dt, const int32 Index) const override //-V762
        {
            ensure(false);
        }
 
        inline void Apply(TRigidParticles<FReal, 3>& InParticles, const FReal Dt, const int32 Index) const override //-V762
        {
            FVec3 V = InParticles.GetV(Index);
            FVec3 W = InParticles.GetW(Index);
            ApplyHelper(V, W, InParticles.LinearEtherDrag(Index), InParticles.AngularEtherDrag(Index), InParticles.MaxLinearSpeedSq(Index), InParticles.MaxAngularSpeedSq(Index), Dt);
            InParticles.SetV(Index, V);
            InParticles.SetW(Index, W);
        }
 
        inline void Apply(TTransientPBDRigidParticleHandle<FReal, 3>& Particle, const FReal Dt) const override //-V762
        {
            FVec3 V = Particle.GetV();
            FVec3 W = Particle.GetW();
            ApplyHelper(V, W, Particle.LinearEtherDrag(), Particle.AngularEtherDrag(), Particle.MaxLinearSpeedSq(), Particle.MaxAngularSpeedSq(), Dt);
            Particle.SetV(V);
            Particle.SetW(W);
        }
    };
 
    template<class T, int d>
    using TPerParticleEtherDrag UE_DEPRECATED(4.27, "Deprecated. this class is to be deleted, use FPerParticleEtherDrag instead") = FPerParticleEtherDrag;
}