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Gyoto::Photon Class Reference

A null geodesic transporting light. More...

#include <GyotoPhoton.h>

Inheritance diagram for Gyoto::Photon:
Gyoto::Worldline Gyoto::SmartPointee Gyoto::Photon::Refined

Classes

class  Refined
 Refine last step of integration in a Photon. More...

Public Member Functions

virtual std::string className () const
 "Photon"
virtual std::string className_l () const
 "photon"
 Photon ()
 Default constructor.
 Photon (const Photon &)
 Copy constructor.
Photonclone () const
 Photon (SmartPointer< Metric::Generic > gg, SmartPointer< Astrobj::Generic > obj, double *coord)
 same as Photon() followed by setInitialCondition()
 Photon (SmartPointer< Metric::Generic > gg, SmartPointer< Astrobj::Generic > obj, SmartPointer< Screen > screen, double d_alpha, double d_delta)
 same as Photon() followed by setInitialCondition()
virtual ~Photon ()
 Destructor.
virtual double getMass () const
 Return 0.
void setAstrobj (SmartPointer< Astrobj::Generic >)
 Set Astrobj.
SmartPointer< Astrobj::GenericgetAstrobj () const
 Get Astrobj.
void setSpectrometer (SmartPointer< Spectrometer > spr)
SmartPointer< SpectrometergetSpectrometer () const
double getFreqObs () const
void operator= (const Photon &)
 Assignment to another Photon.
void setInitialCondition (SmartPointer< Metric::Generic > gg, SmartPointer< Astrobj::Generic > obj, const double coord[8])
 Set or re-set the initial condition prior to integration.
void setInitialCondition (SmartPointer< Metric::Generic > gg, SmartPointer< Astrobj::Generic > obj, SmartPointer< Screen > screen, double d_alpha, double d_delta)
 Set or re-set the initial condition prior to integration.
int hit (Astrobj::Properties *data=NULL)
 Integrate the geodesic and tell whether this photon hits the object.
double findMin (Functor::Double_constDoubleArray *object, double t1, double t2, double &tmin, double threshold=DBL_MIN)
 Find minimum of photon–object distance.
void findValue (Functor::Double_constDoubleArray *object, double value, double tinside, double &toutside)
 Find date for which the photon is at a given distance from the object.
void fillElement (FactoryMessenger *fmp)
 called from Factory
void resetTransmission ()
double getTransmission (size_t i) const
 get transmission for freqobs
double const * getTransmission () const
 get pointer to transmission array
virtual void transmit (size_t i, double t)
int getImin () const
int getImax () const
int getI0 () const
void setMetric (SmartPointer< Metric::Generic >)
 Set metric Smartpointer.
SmartPointer< Metric::GenericgetMetric () const
 Get metric.
void setInitCoord (const double coord[8], int dir=0)
 Set Initial coordinate.
void reset ()
 Forget integration, keeping initial contition.
void setDelta (const double delta)
 Set delta.
double getTlim () const
 Get tlim value.
void setTlim (double tlim)
 Set tlim to a given value.
double const * getCst () const
 Returns the worldline's cst of motion (if any)
void setCst (double const *cst, size_t const ncsts)
void setInitialCondition (SmartPointer< Metric::Generic > gg, const double coord[8], const int dir)
 Set or re-set the initial condition prior to integration.
void getInitialCoord (double dest[8]) const
 get initial coordinate
void getCoord (size_t index, double dest[8]) const
 get coordinates corresponding to index
void getCoord (double const *const dates, size_t const n_dates, double *const x1dest, double *const x2dest, double *const x3dest, double *const x0dot=NULL, double *const x1dot=NULL, double *const x2dot=NULL, double *const x3dot=NULL)
void getCoord (double *x0, double *x1, double *x2, double *x3) const
void getCartesianPos (size_t index, double dest[4]) const
 get Cartesian expression of 4-position at index.
void xFill (double tlim)
 Fill x0, x1... by integrating the Worldline from previously set inittial condition to time tlim.
int get_nelements () const
void get_t (double *dest) const
void getCartesian (double const *const dates, size_t const n_dates, double *const x, double *const y, double *const z, double *const xprime=NULL, double *const yprime=NULL, double *const zprime=NULL)
void get_xyz (double *x, double *y, double *z) const
void getSkyPos (SmartPointer< Screen > screen, double *dalpha, double *ddellta, double *dD) const
void get_dot (double *x0dot, double *x1dot, double *x2dot, double *x3dot) const
void get_prime (double *x1prime, double *x2prime, double *x3prime) const
void save_txyz (char *fichierxyz) const
 Save in a file.
void save_txyz (char *const filename, double const t1, double const mass_sun, double const distance_kpc, std::string const unit, SmartPointer< Screen > sc=NULL)
 Save, converted.

Protected Types

typedef Gyoto::SmartPointer
< Gyoto::SmartPointee
Subcontractor_t (Gyoto::FactoryMessenger *)
 A subcontractor builds an object upon order from the Factory.

Protected Member Functions

 Photon (Photon *orig, size_t i0, int dir, double step_max)
 Used by Photon::Refined::Refined.
void xAllocate ()
 Allocate x0, x1 etc. with default size.
void xAllocate (size_t size)
 Allocate x0, x1 etc. with a specified size.
size_t xExpand (int dir)
 Expand x0, x1 etc... to hold more elements.
void incRefCount ()
 Increment the reference counter. Warning: Don't mess with the counter.
int decRefCount ()
 Decrement the reference counter and return current value. Warning: Don't mess with the counter.
int getRefCount ()
 Get the current number of references.

Protected Attributes

SmartPointer
< Gyoto::Astrobj::Generic
object_
 The astronomical target.
double freq_obs_
 Photon's frequency in observer's frame.
double transmission_freqobs_
 integrated optical transmission
SmartPointer< Spectrometerspectro_
double * transmission_
SmartPointer
< Gyoto::Metric::Generic
metric_
 The Gyoto::Metric in this part of the universe.
double * x0_
 t or T
double * x1_
 r or x
double * x2_
 theta or y
double * x3_
 phi or z
double * x0dot_
 tdot or Tdot
double * x1dot_
 rdot or xdot
double * x2dot_
 thetadot or ydot
double * x3dot_
 phidot or zdot
size_t x_size_
 Size of x0, x1... arrays.
size_t imin_
 Minimum index for which x0, x1... have been computed.
size_t i0_
 Index of initial condition in array.
size_t imax_
 Maximum index for which x0, x1... have been computed.
double delta_
 Initial integrating step ; defaults to 0.01.
double tlim_
 Minimum time for integration, stop integration if t<tlim ; defaults to 0.
double * cst_
 Worldline's csts of motion (if any)
size_t cst_n_
 Number of constants of motion.

Private Member Functions

void _allocateTransmission ()

Friends

class Gyoto::SmartPointer< Gyoto::Photon >

Detailed Description

A null geodesic transporting light.

This is the central object for ray-tracing.

Member Typedef Documentation

typedef Gyoto::SmartPointer<Gyoto::SmartPointee> Gyoto::SmartPointee::Subcontractor_t(Gyoto::FactoryMessenger *)
inherited

A subcontractor builds an object upon order from the Factory.

Various classes need to provide a subcontractor to be able to instanciate themselves upon order from the Factory. A subcontractor is a function (often a static member function) which accepts a pointer to a FactoryMessenger as unique parameter, communicates with the Factory using this messenger to read an XML description of the object to build, and returns this objet. SmartPointee::Subcontractor_t* is just generic enough a typedef to cast to and from other subcontractor types: Astrobj::Subcontractor_t, Metric::Subcontractor_t, Spectrum::Subcontractor_t. A subcontractor needs to be registered using the relevant Register() function: Astrobj::Register(), Metric::Register(), Spectrum::Register().

Constructor & Destructor Documentation

Gyoto::Photon::Photon ( )

Default constructor.

Allocates the default size (GYOTO_DEFAULT_X_SIZE) for x1, x2 etc.

Member Function Documentation

double Gyoto::Photon::findMin ( Functor::Double_constDoubleArray object,
double  t1,
double  t2,
double &  tmin,
double  threshold = DBL_MIN 
)

Find minimum of photon–object distance.

Return the minimum of object->Astrobj::operator()(this->getCoord()) between t1 and t2. The date of this minimum is returned in tmin.

Parameters
objectthe distance to minimize is given by object->Astrobj::operator()()
t1date
t2date
tminon output, date correspondig to the minimum
thresholdstop searching for a minimum if a value < threshold is found (very often, we just want to find a date below the threshold, not the accurate minimum).
void Gyoto::Photon::findValue ( Functor::Double_constDoubleArray object,
double  value,
double  tinside,
double &  toutside 
)

Find date for which the photon is at a given distance from the object.

Parameters
objectthe object
valuethe value to find
adate for which object->Astrobj::operator()(Photon::getCoord()) is < value
oninput: a date for which object->Astrobj::operator()(Photon::getCoord()) is > value. on output, (*object)(getCoord(toutside)) is < value, very close to value. toutside is closer to tinside on output than on input.
void Gyoto::Worldline::getCartesian ( double const *const  dates,
size_t const  n_dates,
double *const  x,
double *const  y,
double *const  z,
double *const  xprime = NULL,
double *const  yprime = NULL,
double *const  zprime = NULL 
)
inherited

Get the 6 Cartesian coordinates (x, y, z, dx/dt, dy/dt, dz/dt) for specific dates. The coordinates will be computed using the integrator, so they will be as accurate as possible. Transforming to Cartesian coordinates is not necessarily meaningful.

Parameters
dates,:the list of dates for which the coordinates are to be computed;
n_dates,:the number of dates to compute ;
x*,:arrays in which to store the result. These pointer may be set to NULL to retrieve only part of the information. They must be pre-allocated.

Reimplemented in Gyoto::Astrobj::Star.

void Gyoto::Worldline::getCoord ( double const *const  dates,
size_t const  n_dates,
double *const  x1dest,
double *const  x2dest,
double *const  x3dest,
double *const  x0dot = NULL,
double *const  x1dot = NULL,
double *const  x2dot = NULL,
double *const  x3dot = NULL 
)
inherited

Get 8-coordinates for spcific dates. The coordinates will be computed using the integrator, so they will be as accurate as possible. Some heuristics are used to speed up the process and it is presumably faster to call this routine with a sorted list of dates. The line will be integrated further as required. An error will be thrown if it is not possible to reach a certain date.

Parameters
dates,:the list of dates for which the coordinates are to be computed;
n_dates,:the number of dates to compute ;
x*,:arrays in which to store the result. These pointer may be set to NULL to retrieve only part of the information. They must be pre-allocated.
void Gyoto::Worldline::getCoord ( double *  x0,
double *  x1,
double *  x2,
double *  x3 
) const
inherited

Get all the pre-computed 8 coordinates (e.g. thanks to a prior call to xFill()) of this worldline.

double const* Gyoto::Worldline::getCst ( ) const
inherited

Returns the worldline's cst of motion (if any)

Return pointer to array holding the previously set Metric-specific constants of motion

double Gyoto::Photon::getTransmission ( size_t  i) const

get transmission for freqobs

Get either the transmission at freqObs (with i=-1) or the transmission at spectro_->getMidpoints()[i].

Parameters
ichannel number of the requested frequency, -1 for getFreqObs().
double const* Gyoto::Photon::getTransmission ( ) const

get pointer to transmission array

For i!=-1: getTansmission()[i] == getTransmission(size_t i)

void Gyoto::Photon::resetTransmission ( )

Set transmission to 1 for each channel as well as scalar transmission

void Gyoto::Worldline::setCst ( double const *  cst,
size_t const  ncsts 
)
inherited

Set Metric-specific constants of motion

void Gyoto::Photon::setInitialCondition ( SmartPointer< Metric::Generic gg,
SmartPointer< Astrobj::Generic obj,
const double  coord[8] 
)

Set or re-set the initial condition prior to integration.

Set initial condition for this Photon :

Parameters
gg: Gyoto::SmartPointer to the Gyoto::Metric in this universe;
obj: Gyoto::SmartPointer to the target Gyoto::Astrobj;
coord: 8 element array containing the initial condition, i.e. the 4-position and the 4-velocity of the Photon at the receiving end;
void Gyoto::Photon::setInitialCondition ( SmartPointer< Metric::Generic gg,
SmartPointer< Astrobj::Generic obj,
SmartPointer< Screen >  screen,
double  d_alpha,
double  d_delta 
)

Set or re-set the initial condition prior to integration.

Set initial condition for this Photon :

Parameters
ggGyoto::SmartPointer to the Gyoto::Metric in this universe;
objGyoto::SmartPointer to the target Gyoto::Astrobj;
t0Arrival date at observer's position
d_alphaDirection of arrival (RA offset) in radians
d_deltaDirection of arrival (Dec offset) in radians
void Gyoto::Worldline::setInitialCondition ( SmartPointer< Metric::Generic gg,
const double  coord[8],
const int  dir 
)
inherited

Set or re-set the initial condition prior to integration.

Set initial condition for this Photon :

Parameters
gg: Gyoto::SmartPointer to the Gyoto::Metric in this universe;
coord: 8 element array containing the initial condition, i.e. the 4-position and the 4-velocity of the Photon at the receiving end;
sys: an integer stating in which coordinate system coord is given.
virtual void Gyoto::Photon::transmit ( size_t  i,
double  t 
)
virtual

Update transmission in a given channel:

getTransmission(size_t i) *= t.

Parameters
ichannel number. -1 for getFreqObs().
ttransmission of this fluid element.

Reimplemented in Gyoto::Photon::Refined.

void Gyoto::Worldline::xAllocate ( )
protectedinherited

Allocate x0, x1 etc. with default size.

The default size is GYOTO_DEFAULT_X_SIZE

void Gyoto::Worldline::xAllocate ( size_t  size)
protectedinherited

Allocate x0, x1 etc. with a specified size.

Parameters
size: number of cells in each array x0, x1 etc.
size_t Gyoto::Worldline::xExpand ( int  dir)
protectedinherited

Expand x0, x1 etc... to hold more elements.

Double the size of arrays x0, x1 etc. and copy old version of the array in the first half if dir =1 and in the second half if dir =-1.

Parameters
dir: 1 to expand after last element, -1 to expand before first element
Returns
ind : if dir=1, new index of old last element, if dir=-1, new index of old first element

The documentation for this class was generated from the following file: