fastsim::Particle Class Reference

Definition of a generic FastSim Particle which can be propagated through the detector (formerly ParticlePropagator) More...

#include <Particle.h>

Public Member Functions
double	charge () const
	Return charge of the particle. More...
bool	chargeIsSet () const
	Check if charge of particle was set. More...
double	gamma () const
	Return Lorentz' gamma factor. More...
int	genParticleIndex () const
	Return index of the particle in the genParticle vector. More...
double	getEnergyDeposit () const
	Return the energy the particle deposited in the tracker layer that was last hit (ionization). More...
double	getMotherDeltaR () const
	Get delta R to mother particle (only makes sense if mother and daughter charged). More...
int	getMotherPdgId () const
	Get pdgIdto mother particle (only makes sense if mother and daughter charged). More...
int	getMotherSimTrackIndex () const
	Get index of simTrack of mother particle (only makes sense if mother and daughter charged). More...
double	isLooper () const
	Check if this particle is about to do a loop in the tracker or the direction of the momentum is going inwards. More...
bool	isOnLayer (bool isForward, int index)
	Check if particle is on layer. More...
bool	isStable () const
	Returns true if particle is considered stable. More...
const math::XYZTLorentzVector &	momentum () const
	Return momentum of the particle. More...
math::XYZTLorentzVector &	momentum ()
	Return momentum of the particle. More...
	Particle (int pdgId, const math::XYZTLorentzVector &position, const math::XYZTLorentzVector &momentum)
	Constructor. More...
int	pdgId () const
	Return pdgId of the particle. More...
const math::XYZTLorentzVector &	position () const
	Return position of the particle. More...
math::XYZTLorentzVector &	position ()
	Return position of the particle. More...
double	remainingProperLifeTimeC () const
	Return the particle's remaining proper lifetime[in ct]. More...
bool	remainingProperLifeTimeIsSet () const
	Check if remaining proper lifetime of particle is set. More...
void	resetMother ()
	Reset all information stored about the mother particle. More...
void	resetOnLayer ()
	Reset layer this particle is currently on (i.e. particle is not on a layer anyomre) More...
void	setCharge (double charge)
	Set the charge of the particle. More...
void	setEnergyDeposit (double energyDeposit)
	Set the energy the particle deposited in the tracker layer that was last hit (ionization). More...
void	setGenParticleIndex (int index)
	Set index of the particle in the genParticle vector (if applies). More...
void	setLooper ()
	This particle is about to do a loop in the tracker or the direction of the momentum is going inwards. More...
void	setMotherDeltaR (const math::XYZTLorentzVector &motherMomentum)
	Set delta R to mother particle (only necessary if mother and daughter charged). More...
void	setMotherPdgId (int motherPpdId)
	Set pdgId of the mother particle (only necessary if mother and daughter charged). More...
void	setMotherSimTrackIndex (int id)
	Set the index of the SimTrack of the mother particle (only necessary if mother and daughter charged). More...
void	setOnLayer (bool isForward, int index)
	Set layer this particle is currently on. More...
void	setRemainingProperLifeTimeC (double remainingProperLifeTimeC)
	Set the particle's remaining proper lifetime if not stable [in ct]. More...
void	setSimTrackIndex (int index)
	Set the index of the SimTrack of this particle. More...
void	setSimVertexIndex (int index)
	Set the index of the origin SimVertex of this particle. More...
void	setStable ()
	Particle is stable. More...
int	simTrackIndex () const
	Return index of the SimTrack. More...
int	simVertexIndex () const
	Return index of the origin vertex. More...

Private Attributes
double	charge_
	charge of the particle in elemntary units More...
double	energyDeposit_
	energy deposit through ionization in the previous tracker layer More...
int	genParticleIndex_
	index of the particle in the vector of genParticles (if applies) More...
bool	isLooper_
	this particle is about to do a loop or momentum goes inwards More...
bool	isOnForwardLayer_
	the layer this particle is currently on: is it a ForwardLayer More...
int	isOnLayerIndex_
	the layer this particle is currently on: the index of the layer More...
math::XYZTLorentzVector	momentum_
	momentum of the particle More...
double	motherDeltaR_
	delta R to mother particle if both charged More...
int	motherPpdId_
	pdgId of mother particle if both charged More...
int	motherSimTrackIndex_
	simTrack index of mother particle if both charged More...
const int	pdgId_
	pdgId of the particle More...
math::XYZTLorentzVector	position_
	position of the particle More...
double	remainingProperLifeTimeC_
	remaining proper lifetime of the particle in units of t*c More...
int	simTrackIndex_
	index of the simTrack More...
int	simVertexIndex_
	index of the origin vertex More...

Friends
std::ostream &	operator<< (std::ostream &os, const Particle &particle)
	Some basic output. More...

Detailed Description

Definition of a generic FastSim Particle which can be propagated through the detector (formerly ParticlePropagator)

Contains all information necessary for the propagation and tracking of a particle:

Definition at line 19 of file Particle.h.

Constructor & Destructor Documentation

fastsim::Particle::Particle ( int  pdgId, const math::XYZTLorentzVector &  position, const math::XYZTLorentzVector &  momentum  )

inline

Constructor.

Parameters

pdgId	The pdgId of the particle.
position	The position of the particle.
momentum	The momentum of the particle.

Definition at line 28 of file Particle.h.

            : pdgId_(pdgId)
            , charge_(-999.)
            , position_(position)
            , momentum_(momentum)
            , remainingProperLifeTimeC_(-999.) // lifetime in ct
            , simTrackIndex_(-1)
            , simVertexIndex_(-1)
            , genParticleIndex_(-1)
            , isOnForwardLayer_(false)
            , isOnLayerIndex_(-1)
            , energyDeposit_(0)
            , isLooper_(false)
            , motherDeltaR_(-1)
            , motherPpdId_(0)
            , motherSimTrackIndex_(-999)
    {;}

Member Function Documentation

double fastsim::Particle::charge ( void  ) const

inline

Return charge of the particle.

Definition at line 139 of file Particle.h.

References charge_.

Referenced by fastsim::ParticleFilter::acceptsEn(), FastSimProducer::createFSimTrack(), fastsim::Trajectory::createTrajectory(), fastsim::Decayer::decay(), fastsim::EnergyLoss::interact(), fastsim::MultipleScattering::interact(), fastsim::TrackerSimHitProducer::interact(), fastsim::NuclearInteraction::interact(), fastsim::NuclearInteractionFTF::interact(), and setCharge().

{return charge_;}

bool fastsim::Particle::chargeIsSet ( ) const

inline

Check if charge of particle was set.

Definition at line 178 of file Particle.h.

References charge_.

{return charge_!=-999.;}

double fastsim::Particle::gamma ( ) const

inline

Return Lorentz' gamma factor.

Definition at line 184 of file Particle.h.

References momentum().

Referenced by fastsim::LayerNavigator::moveParticleToNextLayer().

{ return momentum().Gamma();}

int fastsim::Particle::genParticleIndex ( ) const

inline

Return index of the particle in the genParticle vector.

Returns -1 if not a genParticle.

Definition at line 167 of file Particle.h.

References genParticleIndex_.

Referenced by fastsim::ParticleManager::addSimTrack(), and FastSimProducer::createFSimTrack().

{return genParticleIndex_;}

double fastsim::Particle::getEnergyDeposit ( ) const

inline

Return the energy the particle deposited in the tracker layer that was last hit (ionization).

This energy can then be assigned with a SimHit (if any).

See also

fastsim::EnergyLoss::interact(fastsim::Particle & particle, const SimplifiedGeometry & layer,std::vector<std::unique_ptr<fastsim::Particle> > & secondaries,const RandomEngineAndDistribution & random)

fastsim::TrackerSimHitProducer::interact(Particle & particle,const SimplifiedGeometry & layer,std::vector<std::unique_ptr<Particle> > & secondaries,const RandomEngineAndDistribution & random)

Definition at line 192 of file Particle.h.

References energyDeposit_.

Referenced by fastsim::TrackerSimHitProducer::interact().

{return energyDeposit_;}

double fastsim::Particle::getMotherDeltaR ( ) const

inline

Get delta R to mother particle (only makes sense if mother and daughter charged).

Needed for FastSim (cheat) tracking: daughter can continue the track of the mother.

See also

fastsim::ParticleManager::addSecondaries(const math::XYZTLorentzVector & vertexPosition, int parentSimTrackIndex, std::vector<std::unique_ptr<Particle> > & secondaries)

Definition at line 206 of file Particle.h.

References motherDeltaR_.

Referenced by fastsim::Decayer::decay(), and fastsim::NuclearInteractionFTF::interact().

{return motherDeltaR_;}

int fastsim::Particle::getMotherPdgId ( ) const

inline

Get pdgIdto mother particle (only makes sense if mother and daughter charged).

Needed for FastSim (cheat) tracking: daughter can continue the track of the mother.

See also

fastsim::ParticleManager::addSecondaries(const math::XYZTLorentzVector & vertexPosition, int parentSimTrackIndex, std::vector<std::unique_ptr<Particle> > & secondaries)

Definition at line 213 of file Particle.h.

References motherPpdId_.

Referenced by fastsim::Decayer::decay(), and fastsim::NuclearInteractionFTF::interact().

{return motherPpdId_;}

int fastsim::Particle::getMotherSimTrackIndex ( ) const

inline

Get index of simTrack of mother particle (only makes sense if mother and daughter charged).

Needed for FastSim (cheat) tracking: daughter can continue the track of the mother.

See also

fastsim::ParticleManager::addSecondaries(const math::XYZTLorentzVector & vertexPosition, int parentSimTrackIndex, std::vector<std::unique_ptr<Particle> > & secondaries)

Definition at line 220 of file Particle.h.

References motherSimTrackIndex_.

Referenced by fastsim::TrackerSimHitProducer::interact().

{return motherSimTrackIndex_;}

double fastsim::Particle::isLooper ( ) const

inline

Check if this particle is about to do a loop in the tracker or the direction of the momentum is going inwards.

The TrackerSimHitProducer has the option not to store SimHits in this case, since tracking not possible (just leads to fakes).

See also

fastsim::TrackerSimHitProducer::interact(Particle & particle,const SimplifiedGeometry & layer,std::vector<std::unique_ptr<Particle> > & secondaries,const RandomEngineAndDistribution & random)

Definition at line 199 of file Particle.h.

References isLooper_.

Referenced by fastsim::TrackerSimHitProducer::interact().

{return isLooper_;}

bool fastsim::Particle::isOnLayer ( bool  isForward, int  index  )

inline

Check if particle is on layer.

Definition at line 170 of file Particle.h.

References isOnForwardLayer_, and isOnLayerIndex_.

Referenced by fastsim::LayerNavigator::moveParticleToNextLayer().

                                             {
        return isOnForwardLayer_ == isForward && isOnLayerIndex_ == index;
    }

bool fastsim::Particle::isStable ( ) const

inline

Returns true if particle is considered stable.

Definition at line 175 of file Particle.h.

References remainingProperLifeTimeC_.

Referenced by FastSimProducer::createFSimTrack(), fastsim::LayerNavigator::moveParticleToNextLayer(), and fastsim::operator<<().

{return remainingProperLifeTimeC_ == -1.;}

const math::XYZTLorentzVector& fastsim::Particle::momentum ( ) const

inline

Return momentum of the particle.

Definition at line 145 of file Particle.h.

References momentum_.

Referenced by fastsim::ParticleFilter::accepts(), fastsim::ParticleFilter::acceptsEn(), fastsim::ParticleManager::addSimTrack(), fastsim::Bremsstrahlung::brem(), fastsim::MuonBremsstrahlung::brem(), FastSimProducer::createFSimTrack(), fastsim::Trajectory::createTrajectory(), fastsim::Decayer::decay(), gamma(), fastsim::PairProduction::interact(), fastsim::EnergyLoss::interact(), fastsim::Bremsstrahlung::interact(), fastsim::MultipleScattering::interact(), fastsim::MuonBremsstrahlung::interact(), fastsim::TrackerSimHitProducer::interact(), fastsim::NuclearInteraction::interact(), fastsim::NuclearInteractionFTF::interact(), fastsim::LayerNavigator::moveParticleToNextLayer(), and fastsim::Trajectory::Trajectory().

{return momentum_;}

math::XYZTLorentzVector& fastsim::Particle::momentum ( )

inline

Return momentum of the particle.

Definition at line 231 of file Particle.h.

References momentum_, and operator<<.

{return momentum_;}

int fastsim::Particle::pdgId ( ) const

inline

Return pdgId of the particle.

Definition at line 136 of file Particle.h.

References pdgId_.

Referenced by Particle.Particle::__str__(), fastsim::ParticleFilter::accepts(), fastsim::ParticleFilter::acceptsEn(), fastsim::ParticleManager::addSimTrack(), FastSimProducer::createFSimTrack(), fastsim::Decayer::decay(), fastsim::PairProduction::interact(), fastsim::Bremsstrahlung::interact(), fastsim::MuonBremsstrahlung::interact(), fastsim::TrackerSimHitProducer::interact(), fastsim::NuclearInteraction::interact(), and fastsim::NuclearInteractionFTF::interact().

{return pdgId_;}

const math::XYZTLorentzVector& fastsim::Particle::position ( ) const

inline

Return position of the particle.

Definition at line 142 of file Particle.h.

References position_.

Referenced by fastsim::ParticleFilter::accepts(), fastsim::ParticleManager::addEndVertex(), FastSimProducer::createFSimTrack(), fastsim::Decayer::decay(), fastsim::PairProduction::interact(), fastsim::EnergyLoss::interact(), fastsim::Bremsstrahlung::interact(), fastsim::MultipleScattering::interact(), fastsim::MuonBremsstrahlung::interact(), fastsim::TrackerSimHitProducer::interact(), fastsim::NuclearInteraction::interact(), fastsim::NuclearInteractionFTF::interact(), fastsim::LayerNavigator::moveParticleToNextLayer(), and fastsim::Trajectory::Trajectory().

{return position_;}

math::XYZTLorentzVector& fastsim::Particle::position ( )

inline

Return position of the particle.

Definition at line 228 of file Particle.h.

References position_.

{return position_;}

double fastsim::Particle::remainingProperLifeTimeC ( ) const

inline

Return the particle's remaining proper lifetime[in ct].

Returns -1 in case particle is stable.

Returns

Important: defined in units of c*t!

Definition at line 152 of file Particle.h.

References remainingProperLifeTimeC_.

Referenced by FastSimProducer::createFSimTrack(), fastsim::LayerNavigator::moveParticleToNextLayer(), and setRemainingProperLifeTimeC().

{return remainingProperLifeTimeC_;}

bool fastsim::Particle::remainingProperLifeTimeIsSet ( ) const

inline

Check if remaining proper lifetime of particle is set.

Definition at line 181 of file Particle.h.

References remainingProperLifeTimeC_.

{return remainingProperLifeTimeC_ != -999.;}

void fastsim::Particle::resetMother ( )

inline

Reset all information stored about the mother particle.

Definition at line 128 of file Particle.h.

References motherDeltaR_, motherPpdId_, and motherSimTrackIndex_.

{motherDeltaR_ = -1; motherPpdId_ = 0; motherSimTrackIndex_ = -999;}

void fastsim::Particle::resetOnLayer ( )

inline

Reset layer this particle is currently on (i.e. particle is not on a layer anyomre)

Definition at line 81 of file Particle.h.

References isOnLayerIndex_.

Referenced by fastsim::LayerNavigator::moveParticleToNextLayer().

                       {
        isOnLayerIndex_ = -1;
    }

void fastsim::Particle::setCharge ( double  charge )

inline

Set the charge of the particle.

Definition at line 72 of file Particle.h.

References charge(), and charge_.

{charge_ = charge;}

void fastsim::Particle::setEnergyDeposit ( double  energyDeposit )

inline

Set the energy the particle deposited in the tracker layer that was last hit (ionization).

This energy is then assigned with a SimHit (if any).

Parameters

energyDeposit

The energy loss of the particle in the tracker material layer.

See also

fastsim::EnergyLoss::interact(fastsim::Particle & particle, const SimplifiedGeometry & layer,std::vector<std::unique_ptr<fastsim::Particle> > & secondaries,const RandomEngineAndDistribution & random)

fastsim::TrackerSimHitProducer::interact(Particle & particle,const SimplifiedGeometry & layer,std::vector<std::unique_ptr<Particle> > & secondaries,const RandomEngineAndDistribution & random)

Definition at line 92 of file Particle.h.

References energyDeposit_.

Referenced by fastsim::EnergyLoss::interact(), and fastsim::TrackerSimHitProducer::interact().

{energyDeposit_ = energyDeposit;}

void fastsim::Particle::setGenParticleIndex ( int  index )

inline

Set index of the particle in the genParticle vector (if applies).

Definition at line 60 of file Particle.h.

References genParticleIndex_.

{genParticleIndex_ = index;}

void fastsim::Particle::setLooper ( )

inline

This particle is about to do a loop in the tracker or the direction of the momentum is going inwards.

The TrackerSimHitProducer has the option not to store SimHits in this case, since tracking not possible (just leads to fakes).

See also

fastsim::TrackerSimHitProducer::interact(Particle & particle,const SimplifiedGeometry & layer,std::vector<std::unique_ptr<Particle> > & secondaries,const RandomEngineAndDistribution & random)

Definition at line 99 of file Particle.h.

References isLooper_.

Referenced by fastsim::TrackerSimHitProducer::interact().

{isLooper_ = true;}

void fastsim::Particle::setMotherDeltaR ( const math::XYZTLorentzVector &  motherMomentum )

inline

Set delta R to mother particle (only necessary if mother and daughter charged).

Needed for FastSim (cheat) tracking: daughter can continue the track of the mother.

Parameters

motherMomentum

The momentum 4-vector of the mother particle.

See also

fastsim::ParticleManager::addSecondaries(const math::XYZTLorentzVector & vertexPosition, int parentSimTrackIndex, std::vector<std::unique_ptr<Particle> > & secondaries)

Definition at line 107 of file Particle.h.

References momentum_, and motherDeltaR_.

                                                                      {
        motherDeltaR_ = (momentum_.Vect().Unit().Cross(motherMomentum.Vect().Unit())).R();
    }

void fastsim::Particle::setMotherPdgId ( int  motherPpdId )

inline

Set pdgId of the mother particle (only necessary if mother and daughter charged).

Needed for FastSim (cheat) tracking: daughter can continue the track of the mother.

Parameters

motherPpdId

The pdgId of the mother particle.

See also

fastsim::ParticleManager::addSecondaries(const math::XYZTLorentzVector & vertexPosition, int parentSimTrackIndex, std::vector<std::unique_ptr<Particle> > & secondaries)

Definition at line 117 of file Particle.h.

References motherPpdId_.

{motherPpdId_ = motherPpdId;}

void fastsim::Particle::setMotherSimTrackIndex ( int  id )

inline

Set the index of the SimTrack of the mother particle (only necessary if mother and daughter charged).

Needed for FastSim (cheat) tracking: daughter can continue the track of the mother.

Parameters

id	The Id of the SimTrack of the mother particle.

See also

fastsim::ParticleManager::addSecondaries(const math::XYZTLorentzVector & vertexPosition, int parentSimTrackIndex, std::vector<std::unique_ptr<Particle> > & secondaries)

Definition at line 125 of file Particle.h.

References triggerObjects_cff::id, and motherSimTrackIndex_.

{motherSimTrackIndex_ = id;}

void fastsim::Particle::setOnLayer ( bool  isForward, int  index  )

inline

Set layer this particle is currently on.

Definition at line 75 of file Particle.h.

References ecaldqm::isForward(), isOnForwardLayer_, and isOnLayerIndex_.

Referenced by fastsim::LayerNavigator::moveParticleToNextLayer().

                                              {
        isOnForwardLayer_ = isForward;
        isOnLayerIndex_ = index;
    }

void fastsim::Particle::setRemainingProperLifeTimeC ( double  remainingProperLifeTimeC )

inline

Set the particle's remaining proper lifetime if not stable [in ct].

Parameters

remainingProperLifeTimeC

Important: defined in units of c*t!

Definition at line 69 of file Particle.h.

References remainingProperLifeTimeC(), and remainingProperLifeTimeC_.

Referenced by fastsim::LayerNavigator::moveParticleToNextLayer().

{remainingProperLifeTimeC_ = remainingProperLifeTimeC;}

void fastsim::Particle::setSimTrackIndex ( int  index )

inline

Set the index of the SimTrack of this particle.

Definition at line 54 of file Particle.h.

References simTrackIndex_.

{simTrackIndex_ = index;}

void fastsim::Particle::setSimVertexIndex ( int  index )

inline

Set the index of the origin SimVertex of this particle.

Definition at line 57 of file Particle.h.

References simVertexIndex_.

{simVertexIndex_ = index;}

void fastsim::Particle::setStable ( )

inline

Particle is stable.

Definition at line 63 of file Particle.h.

References remainingProperLifeTimeC_.

{remainingProperLifeTimeC_ = -1.;}

int fastsim::Particle::simTrackIndex ( ) const

inline

Return index of the SimTrack.

Definition at line 155 of file Particle.h.

References simTrackIndex_.

Referenced by fastsim::ParticleManager::addEndVertex(), FastSimProducer::createFSimTrack(), fastsim::Decayer::decay(), fastsim::TrackerSimHitProducer::interact(), fastsim::NuclearInteraction::interact(), and fastsim::NuclearInteractionFTF::interact().

{return simTrackIndex_;}

int fastsim::Particle::simVertexIndex ( ) const

inline

Return index of the origin vertex.

Returns -1 for primary vertex.

Definition at line 161 of file Particle.h.

References simVertexIndex_.

Referenced by fastsim::ParticleManager::addSimTrack(), and FastSimProducer::createFSimTrack().

{return simVertexIndex_;}

Friends And Related Function Documentation

std::ostream& operator<< ( std::ostream &  os, const Particle &  particle  )

friend

Some basic output.

Referenced by momentum().

Member Data Documentation

double fastsim::Particle::charge_

private

charge of the particle in elemntary units

Definition at line 237 of file Particle.h.

Referenced by charge(), chargeIsSet(), and setCharge().

double fastsim::Particle::energyDeposit_

private

energy deposit through ionization in the previous tracker layer

Definition at line 246 of file Particle.h.

Referenced by getEnergyDeposit(), and setEnergyDeposit().

int fastsim::Particle::genParticleIndex_

private

index of the particle in the vector of genParticles (if applies)

Definition at line 243 of file Particle.h.

Referenced by genParticleIndex(), and setGenParticleIndex().

bool fastsim::Particle::isLooper_

private

this particle is about to do a loop or momentum goes inwards

Definition at line 247 of file Particle.h.

Referenced by isLooper(), and setLooper().

bool fastsim::Particle::isOnForwardLayer_

private

the layer this particle is currently on: is it a ForwardLayer

Definition at line 244 of file Particle.h.

Referenced by isOnLayer(), and setOnLayer().

int fastsim::Particle::isOnLayerIndex_

private

the layer this particle is currently on: the index of the layer

Definition at line 245 of file Particle.h.

Referenced by isOnLayer(), resetOnLayer(), and setOnLayer().

math::XYZTLorentzVector fastsim::Particle::momentum_

private

momentum of the particle

Definition at line 239 of file Particle.h.

Referenced by momentum(), fastsim::operator<<(), and setMotherDeltaR().

double fastsim::Particle::motherDeltaR_

private

delta R to mother particle if both charged

Definition at line 248 of file Particle.h.

Referenced by getMotherDeltaR(), resetMother(), and setMotherDeltaR().

int fastsim::Particle::motherPpdId_

private

pdgId of mother particle if both charged

Definition at line 249 of file Particle.h.

Referenced by getMotherPdgId(), resetMother(), and setMotherPdgId().

int fastsim::Particle::motherSimTrackIndex_

private

simTrack index of mother particle if both charged

Definition at line 250 of file Particle.h.

Referenced by getMotherSimTrackIndex(), resetMother(), and setMotherSimTrackIndex().

const int fastsim::Particle::pdgId_

private

pdgId of the particle

Definition at line 236 of file Particle.h.

Referenced by fastsim::operator<<(), and pdgId().

math::XYZTLorentzVector fastsim::Particle::position_

private

position of the particle

Definition at line 238 of file Particle.h.

Referenced by fastsim::operator<<(), and position().

double fastsim::Particle::remainingProperLifeTimeC_

private

remaining proper lifetime of the particle in units of t*c

Definition at line 240 of file Particle.h.

Referenced by isStable(), fastsim::operator<<(), remainingProperLifeTimeC(), remainingProperLifeTimeIsSet(), setRemainingProperLifeTimeC(), and setStable().

int fastsim::Particle::simTrackIndex_

private

index of the simTrack

Definition at line 241 of file Particle.h.

Referenced by setSimTrackIndex(), and simTrackIndex().

int fastsim::Particle::simVertexIndex_

private

index of the origin vertex

Definition at line 242 of file Particle.h.

Referenced by setSimVertexIndex(), and simVertexIndex().