PerParticleEulerStepVelocity.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 FPerParticleEulerStepVelocity : public FPerParticleRule
{
  public:
    FPerParticleEulerStepVelocity() {}
    virtual ~FPerParticleEulerStepVelocity() {}
 
    template<class T_PARTICLES>
    inline void ApplyHelper(T_PARTICLES& InParticles, const FReal Dt, const int32 Index) const
    {
        InParticles.SetV(Index, InParticles.GetV(Index) + InParticles.Acceleration(Index) * Dt);
    }
 
    inline void Apply(FDynamicParticles& InParticles, const FReal Dt, const int32 Index) const override //-V762
    {
        if (InParticles.InvM(Index) == 0)
            return;
        ApplyHelper(InParticles, Dt, Index);
    }
 
    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.AngularAcceleration(Index) * Dt);
    }
    
    inline void Apply(TTransientPBDRigidParticleHandle<FReal, 3>& Particle, const FReal Dt) const override //-V762
    {
        Particle.SetV(Particle.GetV() + Particle.Acceleration() * Dt);
        Particle.SetW(Particle.GetW() + Particle.AngularAcceleration() * Dt);
    }
};
 
template<class T, int d>
using TPerParticleEulerStepVelocity UE_DEPRECATED(4.27, "Deprecated. this class is to be deleted, use FPerParticleEulerStepVelocity instead") = FPerParticleEulerStepVelocity;
 
}