PerParticleAddImpulses.h

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// Copyright Epic Games, Inc. All Rights Reserved.
#pragma once
 
#include "Chaos/PerParticleRule.h"
#include "Chaos/Particle/ParticleUtilities.h"
#include "Chaos/Utilities.h"
 
namespace Chaos
{
    class FPerParticleAddImpulses : public FPerParticleRule
    {
    public:
        FPerParticleAddImpulses() {}
        virtual ~FPerParticleAddImpulses() {}
 
        template<class T_PARTICLES>
        inline void ApplyHelper(T_PARTICLES& InParticles, const FReal Dt, const int32 Index) const
        {
            InParticles.SetV(Index, InParticles.GetV(Index) + InParticles.LinearImpulseVelocity(Index));
        }
 
        inline void Apply(FDynamicParticles& InParticles, const FReal Dt, const int32 Index) const override //-V762
        {
            // @todo(mlentine): Is this something we want to support?
            ensure(false);
        }
 
        inline void Apply(TRigidParticles<FReal, 3>& InParticles, const FReal Dt, const int32 Index) const override //-V762
        {
            if (InParticles.InvM(Index) == 0 || InParticles.Disabled(Index) || InParticles.Sleeping(Index))
                return;
            ApplyHelper(InParticles, Dt, Index);
 
            //
            // TODO: This is the first-order approximation.
            //       If needed, we might eventually want to do a second order Euler's Equation,
            //       but if we do that we'll need to do a transform into a rotating reference frame.
            //       Just using W += InvI * (Torque - W x (I * W)) * dt is not correct, since Torque
            //       and W are in an inertial frame.
            //
 
            InParticles.SetW(Index, InParticles.GetW(Index) + InParticles.AngularImpulseVelocity(Index));
            InParticles.LinearImpulseVelocity(Index) = FVec3(0);
            InParticles.AngularImpulseVelocity(Index) = FVec3(0);
        }
 
        inline void Apply(TTransientPBDRigidParticleHandle<FReal, 3>& Particle, const FReal Dt) const override //-V762
        {
            Particle.SetV(Particle.GetV() + Particle.LinearImpulseVelocity());
            Particle.SetW(Particle.GetW() + Particle.AngularImpulseVelocity());
            Particle.LinearImpulseVelocity() = FVec3(0);
            Particle.AngularImpulseVelocity() = FVec3(0);
        }
    };
 
    template<class T, int d>
    using TPerParticleAddImpulses UE_DEPRECATED(4.27, "Deprecated. this class is to be deleted, use FPerParticleAddImpulses instead") = FPerParticleAddImpulses;
}