PerParticleDampVelocity.h

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// Copyright Epic Games, Inc. All Rights Reserved.
#pragma once
 
#include "Chaos/PBDSoftsEvolutionFwd.h"
#include "Chaos/CollectionPropertyFacade.h"
#include "Chaos/SoftsSimulationSpace.h"
#include "Chaos/Vector.h"
#include "Chaos/PBDSoftsSolverParticles.h"
 
namespace Chaos::Softs
{
 
class FPerParticleDampVelocity final
{
public:
 
    FPerParticleDampVelocity(const FSolverReal InCoefficient = (FSolverReal)0.01)
        : LinearCoefficient(InCoefficient)
        , AngularCoefficient(InCoefficient)
        , LocalDampingCoefficientIndex(ForceInit)
        , LocalDampingLinearCoefficientIndex(ForceInit)
        , LocalDampingAngularCoefficientIndex(ForceInit)
        , LocalDampingSpaceIndex(ForceInit)
    {
    }
 
    ~FPerParticleDampVelocity() {}
 
    void UpdatePositionBasedState(const FSolverParticles& Particles, const int32 Offset, const int32 Range);
    void UpdatePositionBasedState(const FSolverParticlesRange& Particles);
 
    // Apply damping without first checking for kinematic particles
    void ApplyFast(FSolverParticles& Particles, const FSolverReal /*Dt*/, const int32 Index) const
    {
        Apply(Particles.GetX(Index), Particles.V(Index));
    }
 
    void Apply(const FSolverVec3& X, FSolverVec3& V) const
    {
        const FSolverVec3 R = X - Xcm;
        const FSolverVec3 Dv = LinearCoefficient * (Vcm - V) + AngularCoefficient * FSolverVec3::CrossProduct(R, Omega);
        V += Dv;
    }
 
    bool IsEnabled() const
    {
        return LinearCoefficient > 0.f || AngularCoefficient > 0.f;
    }
 
    bool RequiresUpdatePositionBasedState() const
    {
        return LocalDampingSpace == EChaosSoftsLocalDampingSpace::CenterOfMass;
    }
 
    void SetProperties(
        const FCollectionPropertyConstFacade& PropertyCollection,
        const FSolverVec3& ReferenceLocation,
        const FSolverVec3& ReferenceVelocity,
        const FSolverVec3& ReferenceAngularVelocity);
 
private:
    EChaosSoftsLocalDampingSpace LocalDampingSpace = EChaosSoftsLocalDampingSpace::CenterOfMass;
    bool bPropertyIndicesInitialized = false;
    FSolverReal LinearCoefficient;
    FSolverReal AngularCoefficient;
    FSolverVec3 Xcm, Vcm, Omega;
 
    UE_CHAOS_DECLARE_PROPERTYCOLLECTION_NAME(LocalDampingCoefficient, float);
    UE_CHAOS_DECLARE_PROPERTYCOLLECTION_NAME(LocalDampingLinearCoefficient, float);
    UE_CHAOS_DECLARE_PROPERTYCOLLECTION_NAME(LocalDampingAngularCoefficient, float);
    UE_CHAOS_DECLARE_PROPERTYCOLLECTION_NAME(LocalDampingSpace, int32);
};
 
}  // End namespace Chaos::Softs
 
#if !defined(CHAOS_DAMP_VELOCITY_ISPC_ENABLED_DEFAULT)
#define CHAOS_DAMP_VELOCITY_ISPC_ENABLED_DEFAULT 1
#endif
 
#if !defined(USE_ISPC_KERNEL_CONSOLE_VARIABLES_IN_SHIPPING)
#define USE_ISPC_KERNEL_CONSOLE_VARIABLES_IN_SHIPPING 0
#endif
 
// Support run-time toggling on supported platforms in non-shipping configurations
#if INTEL_ISPC
#if UE_BUILD_SHIPPING && !USE_ISPC_KERNEL_CONSOLE_VARIABLES_IN_SHIPPING
static constexpr bool bChaos_DampVelocity_ISPC_Enabled = CHAOS_DAMP_VELOCITY_ISPC_ENABLED_DEFAULT;
#else
extern CHAOS_API bool bChaos_DampVelocity_ISPC_Enabled;
#endif // UE_BUILD_SHIPPING && !USE_ISPC_KERNEL_CONSOLE_VARIABLES_IN_SHIPPING
#endif