Logo ROOT   6.19/01
Reference Guide
TGenerator Class Reference

The interface to various event generators.

Is an base class, that defines the interface of ROOT to various
event generators. Every event generator should inherit from
TGenerator or its subclasses.
Derived class can overload the member function GenerateEvent
to do the actual event generation (e.g., call PYEVNT or similar).
The derived class should overload the member function
ImportParticles (both types) to read the internal storage of the
generated event into either the internal TObjArray or the passed
TClonesArray of TParticles.
If the generator code stores event data in the /HEPEVT/ common block Then the default implementation of ImportParticles should suffice.
The common block /HEPEVT/ is structed like

  // C                                                            
  typedef struct {                                                   
     Int_t    nevhep;           // Event number                      
     Int_t    nhep;             // # of particles                    
     Int_t    isthep[4000];     // Status flag of i'th particle      
     Int_t    idhep[4000];      // PDG # of particle                 
     Int_t    jmohep[4000][2];  // 1st & 2nd mother particle #       
     Int_t    jdahep[4000][2];  // 1st & 2nd daughter particle #     
     Double_t phep[4000][5];    // 4-momentum and 1 word             
     Double_t vhep[4000][4];    // 4-position of production          
  } HEPEVT_DEF;                                                      
                                                                     
                                                                     
  C Fortran                                                          
        COMMON/HEPEVT/NEVHEP,NHEP,ISTHEP(4000),IDHEP(4000),          
      +    JMOHEP(2,4000),JDAHEP(2,4000),PHEP(5,4000),VHEP(4,4000)   
        INTEGER NEVHEP,NHEP,ISTHEP,IDHEP,JMOHEP,JDAHEP               
        DOUBLE PRECISION PHEP,VHEP                                   

The generic member functions SetParameter and GetParameter can be overloaded to set and get parameters of the event generator.

Note, if the derived class interfaces a (set of) Fortran common blocks (like TPythia, TVenus does), one better make the derived class a singleton. That is, something like

    class MyGenerator : public TGenerator                            
    {                                                                
    public:                                                          
      static MyGenerator* Instance()                                 
      {                                                              
        if (!fgInstance) fgInstance = new MyGenerator;               
        return fgInstance;                                           
      }                                                              
      void  GenerateEvent() { ... }                                  
      void  ImportParticles(TClonesArray* a, Option_t opt="") {...}  
      Int_t ImportParticles(Option_t opt="") { ... }                 
      Int_t    SetParameter(const char* name, Double_t val) { ... }  
      Double_t GetParameter(const char* name) { ... }                
      virtual ~MyGenerator() { ... }                                 
    protected:                                                       
      MyGenerator() { ... }                                          
      MyGenerator(const MyGenerator& o) { ... }                      
      MyGenerator& operator=(const MyGenerator& o) { ... }           
      static MyGenerator* fgInstance;                                
      ClassDef(MyGenerator,0);                                       
    };                                                               

Having multiple objects accessing the same common blocks is not
safe.
Concrete TGenerator classes can be loaded in scripts and subseqent-
ly used in compiled code:

    // MyRun.h                                                       
    class MyRun : public TObject                                     
    {                                                                
    public:                                                          
      static MyRun* Instance() { ... }                               
      void SetGenerator(TGenerator* g) { fGenerator = g; }           
      void Run(Int_t n, Option_t* option="")                         
      {                                                              
        TFile*        file = TFile::Open("file.root","RECREATE");    
        TTree*        tree = new TTree("T","T");                     
        TClonesArray* p    = new TClonesArray("TParticles");         
        tree->Branch("particles", &p);                               
        for (Int_t event = 0; event < n; event++) {                  
          fGenerator->GenerateEvent();                               
          fGenerator->ImportParticles(p,option);                     
          tree->Fill();                                              
        }                                                            
        file->Write();                                               
        file->Close();                                               
      }                                                              
      ...                                                            
    protected:                                                       
      TGenerator* fGenerator;                                        
      ClassDef(MyRun,0);                                             
    };                                                               
                                                                     
    // Config.C                                                      
    void Config()                                                    
    {                                                                
       MyRun* run = MyRun::Instance();                               
       run->SetGenerator(MyGenerator::Instance());                   
    }                                                                
                                                                     
    // main.cxx                                                      
    int                                                              
    main(int argc, char** argv)                                      
    {                                                                
      TApplication app("", 0, 0);                                    
      gSystem->ProcessLine(".x Config.C");                           
      MyRun::Instance()->Run(10);                                    
      return 0;                                                      
    }                                                                

This is especially useful for example with TVirtualMC or similar.

Definition at line 144 of file TGenerator.h.

Public Member Functions

 TGenerator ()
 
 TGenerator (const char *name, const char *title="Generator class")
 Event generator default constructor. More...
 
virtual ~TGenerator ()
 Event generator default destructor. More...
 
virtual void Browse (TBrowser *b)
 browse generator More...
 
virtual Int_t DistancetoPrimitive (Int_t px, Int_t py)
 Compute distance from point px,py to objects in event. More...
 
virtual void Draw (Option_t *option="")
 Insert one event in the pad list. More...
 
virtual void ExecuteEvent (Int_t event, Int_t px, Int_t py)
 Execute action corresponding to one event. More...
 
virtual void GenerateEvent ()
 must be implemented in concrete class (see eg TPythia6) More...
 
virtual TObjArrayGetListOfParticles () const
 
Int_t GetNumberOfParticles () const
 Return the number of particles in the stack. More...
 
virtual Double_t GetParameter (const char *) const
 
virtual TParticleGetParticle (Int_t i) const
 Returns pointer to primary number i;. More...
 
virtual TObjArrayGetPrimaries (Option_t *option="")
 
Float_t GetPtCut () const
 
virtual Int_t ImportParticles (TClonesArray *particles, Option_t *option="")
 It reads the /HEPEVT/ common block which has been filled by the GenerateEvent method. More...
 
virtual TObjArrayImportParticles (Option_t *option="")
 It reads the /HEPEVT/ common block which has been filled by the GenerateEvent method. More...
 
virtual void Paint (Option_t *option="")
 Paint one event. More...
 
virtual void SetParameter (const char *, Double_t)
 
virtual void SetPtCut (Float_t ptcut=0)
 Set Pt threshold below which primaries are not drawn. More...
 
virtual void SetViewRadius (Float_t rbox=1000)
 Set lower and upper values of the view range. More...
 
virtual void SetViewRange (Float_t xmin=-10000, Float_t ymin=-10000, Float_t zmin=-10000, Float_t xmax=10000, Float_t ymax=10000, Float_t zmax=10000)
 Set lower and upper values of the view range. More...
 
virtual void ShowNeutrons (Bool_t show=1)
 Set flag to display or not neutrons. More...
 
- Public Member Functions inherited from TNamed
 TNamed ()
 
 TNamed (const char *name, const char *title)
 
 TNamed (const TString &name, const TString &title)
 
 TNamed (const TNamed &named)
 TNamed copy ctor. More...
 
virtual ~TNamed ()
 TNamed destructor. More...
 
virtual void Clear (Option_t *option="")
 Set name and title to empty strings (""). More...
 
virtual TObjectClone (const char *newname="") const
 Make a clone of an object using the Streamer facility. More...
 
virtual Int_t Compare (const TObject *obj) const
 Compare two TNamed objects. More...
 
virtual void Copy (TObject &named) const
 Copy this to obj. More...
 
virtual void FillBuffer (char *&buffer)
 Encode TNamed into output buffer. More...
 
virtual const char * GetName () const
 Returns name of object. More...
 
virtual const char * GetTitle () const
 Returns title of object. More...
 
virtual ULong_t Hash () const
 Return hash value for this object. More...
 
virtual Bool_t IsSortable () const
 
virtual void ls (Option_t *option="") const
 List TNamed name and title. More...
 
TNamedoperator= (const TNamed &rhs)
 TNamed assignment operator. More...
 
virtual void Print (Option_t *option="") const
 Print TNamed name and title. More...
 
virtual void SetName (const char *name)
 Set the name of the TNamed. More...
 
virtual void SetNameTitle (const char *name, const char *title)
 Set all the TNamed parameters (name and title). More...
 
virtual void SetTitle (const char *title="")
 Set the title of the TNamed. More...
 
virtual Int_t Sizeof () const
 Return size of the TNamed part of the TObject. More...
 
- Public Member Functions inherited from TObject
 TObject ()
 TObject constructor. More...
 
 TObject (const TObject &object)
 TObject copy ctor. More...
 
virtual ~TObject ()
 TObject destructor. More...
 
void AbstractMethod (const char *method) const
 Use this method to implement an "abstract" method that you don't want to leave purely abstract. More...
 
virtual void AppendPad (Option_t *option="")
 Append graphics object to current pad. More...
 
ULong_t CheckedHash ()
 Check and record whether this class has a consistent Hash/RecursiveRemove setup (*) and then return the regular Hash value for this object. More...
 
virtual const char * ClassName () const
 Returns name of class to which the object belongs. More...
 
virtual void Delete (Option_t *option="")
 Delete this object. More...
 
virtual void DrawClass () const
 Draw class inheritance tree of the class to which this object belongs. More...
 
virtual TObjectDrawClone (Option_t *option="") const
 Draw a clone of this object in the current selected pad for instance with: gROOT->SetSelectedPad(gPad). More...
 
virtual void Dump () const
 Dump contents of object on stdout. More...
 
virtual void Error (const char *method, const char *msgfmt,...) const
 Issue error message. More...
 
virtual void Execute (const char *method, const char *params, Int_t *error=0)
 Execute method on this object with the given parameter string, e.g. More...
 
virtual void Execute (TMethod *method, TObjArray *params, Int_t *error=0)
 Execute method on this object with parameters stored in the TObjArray. More...
 
virtual void Fatal (const char *method, const char *msgfmt,...) const
 Issue fatal error message. More...
 
virtual TObjectFindObject (const char *name) const
 Must be redefined in derived classes. More...
 
virtual TObjectFindObject (const TObject *obj) const
 Must be redefined in derived classes. More...
 
virtual Option_tGetDrawOption () const
 Get option used by the graphics system to draw this object. More...
 
virtual const char * GetIconName () const
 Returns mime type name of object. More...
 
virtual char * GetObjectInfo (Int_t px, Int_t py) const
 Returns string containing info about the object at position (px,py). More...
 
virtual Option_tGetOption () const
 
virtual UInt_t GetUniqueID () const
 Return the unique object id. More...
 
virtual Bool_t HandleTimer (TTimer *timer)
 Execute action in response of a timer timing out. More...
 
Bool_t HasInconsistentHash () const
 Return true is the type of this object is known to have an inconsistent setup for Hash and RecursiveRemove (i.e. More...
 
virtual void Info (const char *method, const char *msgfmt,...) const
 Issue info message. More...
 
virtual Bool_t InheritsFrom (const char *classname) const
 Returns kTRUE if object inherits from class "classname". More...
 
virtual Bool_t InheritsFrom (const TClass *cl) const
 Returns kTRUE if object inherits from TClass cl. More...
 
virtual void Inspect () const
 Dump contents of this object in a graphics canvas. More...
 
void InvertBit (UInt_t f)
 
virtual Bool_t IsEqual (const TObject *obj) const
 Default equal comparison (objects are equal if they have the same address in memory). More...
 
virtual Bool_t IsFolder () const
 Returns kTRUE in case object contains browsable objects (like containers or lists of other objects). More...
 
R__ALWAYS_INLINE Bool_t IsOnHeap () const
 
R__ALWAYS_INLINE Bool_t IsZombie () const
 
void MayNotUse (const char *method) const
 Use this method to signal that a method (defined in a base class) may not be called in a derived class (in principle against good design since a child class should not provide less functionality than its parent, however, sometimes it is necessary). More...
 
virtual Bool_t Notify ()
 This method must be overridden to handle object notification. More...
 
void Obsolete (const char *method, const char *asOfVers, const char *removedFromVers) const
 Use this method to declare a method obsolete. More...
 
void operator delete (void *ptr)
 Operator delete. More...
 
void operator delete[] (void *ptr)
 Operator delete []. More...
 
voidoperator new (size_t sz)
 
voidoperator new (size_t sz, void *vp)
 
voidoperator new[] (size_t sz)
 
voidoperator new[] (size_t sz, void *vp)
 
TObjectoperator= (const TObject &rhs)
 TObject assignment operator. More...
 
virtual void Pop ()
 Pop on object drawn in a pad to the top of the display list. More...
 
virtual Int_t Read (const char *name)
 Read contents of object with specified name from the current directory. More...
 
virtual void RecursiveRemove (TObject *obj)
 Recursively remove this object from a list. More...
 
void ResetBit (UInt_t f)
 
virtual void SaveAs (const char *filename="", Option_t *option="") const
 Save this object in the file specified by filename. More...
 
virtual void SavePrimitive (std::ostream &out, Option_t *option="")
 Save a primitive as a C++ statement(s) on output stream "out". More...
 
void SetBit (UInt_t f, Bool_t set)
 Set or unset the user status bits as specified in f. More...
 
void SetBit (UInt_t f)
 
virtual void SetDrawOption (Option_t *option="")
 Set drawing option for object. More...
 
virtual void SetUniqueID (UInt_t uid)
 Set the unique object id. More...
 
virtual void SysError (const char *method, const char *msgfmt,...) const
 Issue system error message. More...
 
R__ALWAYS_INLINE Bool_t TestBit (UInt_t f) const
 
Int_t TestBits (UInt_t f) const
 
virtual void UseCurrentStyle ()
 Set current style settings in this object This function is called when either TCanvas::UseCurrentStyle or TROOT::ForceStyle have been invoked. More...
 
virtual void Warning (const char *method, const char *msgfmt,...) const
 Issue warning message. More...
 
virtual Int_t Write (const char *name=0, Int_t option=0, Int_t bufsize=0)
 Write this object to the current directory. More...
 
virtual Int_t Write (const char *name=0, Int_t option=0, Int_t bufsize=0) const
 Write this object to the current directory. More...
 

Protected Member Functions

 TGenerator (const TGenerator &tg)
 
TGeneratoroperator= (const TGenerator &tg)
 
- Protected Member Functions inherited from TObject
virtual void DoError (int level, const char *location, const char *fmt, va_list va) const
 Interface to ErrorHandler (protected). More...
 
void MakeZombie ()
 

Protected Attributes

TObjArrayfParticles
 display neutrons if true More...
 
Float_t fPtCut
 
Bool_t fShowNeutrons
 Pt cut. Do not show primaries below. More...
 
- Protected Attributes inherited from TNamed
TString fName
 
TString fTitle
 

Additional Inherited Members

- Public Types inherited from TObject
enum  {
  kIsOnHeap = 0x01000000, kNotDeleted = 0x02000000, kZombie = 0x04000000, kInconsistent = 0x08000000,
  kBitMask = 0x00ffffff
}
 
enum  { kSingleKey = BIT(0), kOverwrite = BIT(1), kWriteDelete = BIT(2) }
 
enum  EDeprecatedStatusBits { kObjInCanvas = BIT(3) }
 
enum  EStatusBits {
  kCanDelete = BIT(0), kMustCleanup = BIT(3), kIsReferenced = BIT(4), kHasUUID = BIT(5),
  kCannotPick = BIT(6), kNoContextMenu = BIT(8), kInvalidObject = BIT(13)
}
 
- Static Public Member Functions inherited from TObject
static Long_t GetDtorOnly ()
 Return destructor only flag. More...
 
static Bool_t GetObjectStat ()
 Get status of object stat flag. More...
 
static void SetDtorOnly (void *obj)
 Set destructor only flag. More...
 
static void SetObjectStat (Bool_t stat)
 Turn on/off tracking of objects in the TObjectTable. More...
 

#include <TGenerator.h>

Inheritance diagram for TGenerator:
[legend]

Constructor & Destructor Documentation

◆ TGenerator() [1/3]

TGenerator::TGenerator ( const TGenerator tg)
inlineprotected

Definition at line 151 of file TGenerator.h.

◆ TGenerator() [2/3]

TGenerator::TGenerator ( )
inline

Definition at line 163 of file TGenerator.h.

◆ TGenerator() [3/3]

TGenerator::TGenerator ( const char *  name,
const char *  title = "Generator class" 
)

Event generator default constructor.

Definition at line 160 of file TGenerator.cxx.

◆ ~TGenerator()

TGenerator::~TGenerator ( )
virtual

Event generator default destructor.

Definition at line 176 of file TGenerator.cxx.

Member Function Documentation

◆ Browse()

void TGenerator::Browse ( TBrowser b)
virtual

browse generator

Reimplemented from TObject.

Definition at line 324 of file TGenerator.cxx.

◆ DistancetoPrimitive()

Int_t TGenerator::DistancetoPrimitive ( Int_t  px,
Int_t  py 
)
virtual

Compute distance from point px,py to objects in event.

Reimplemented from TObject.

Definition at line 334 of file TGenerator.cxx.

◆ Draw()

void TGenerator::Draw ( Option_t option = "")
virtual

Insert one event in the pad list.

Reimplemented from TObject.

Definition at line 348 of file TGenerator.cxx.

◆ ExecuteEvent()

void TGenerator::ExecuteEvent ( Int_t  event,
Int_t  px,
Int_t  py 
)
virtual

Execute action corresponding to one event.

Reimplemented from TObject.

Definition at line 495 of file TGenerator.cxx.

◆ GenerateEvent()

void TGenerator::GenerateEvent ( )
virtual

must be implemented in concrete class (see eg TPythia6)

Reimplemented in TPythia6, and TPythia8.

Definition at line 189 of file TGenerator.cxx.

◆ GetListOfParticles()

virtual TObjArray* TGenerator::GetListOfParticles ( ) const
inlinevirtual

Definition at line 176 of file TGenerator.h.

◆ GetNumberOfParticles()

Int_t TGenerator::GetNumberOfParticles ( ) const

Return the number of particles in the stack.

Definition at line 506 of file TGenerator.cxx.

◆ GetParameter()

virtual Double_t TGenerator::GetParameter ( const char *  ) const
inlinevirtual

Definition at line 171 of file TGenerator.h.

◆ GetParticle()

TParticle * TGenerator::GetParticle ( Int_t  i) const
virtual

Returns pointer to primary number i;.

Definition at line 515 of file TGenerator.cxx.

◆ GetPrimaries()

virtual TObjArray* TGenerator::GetPrimaries ( Option_t option = "")
inlinevirtual

Definition at line 177 of file TGenerator.h.

◆ GetPtCut()

Float_t TGenerator::GetPtCut ( ) const
inline

Definition at line 178 of file TGenerator.h.

◆ ImportParticles() [1/2]

Int_t TGenerator::ImportParticles ( TClonesArray particles,
Option_t option = "" 
)
virtual

It reads the /HEPEVT/ common block which has been filled by the GenerateEvent method.

If the event generator does not use the HEPEVT common block, This routine has to be overloaded by the subclasses.

The function loops on the generated particles and store them in the TClonesArray pointed by the argument particles. The default action is to store only the stable particles (ISTHEP = 1) This can be demanded explicitly by setting the option = "Final" If the option = "All", all the particles are stored.

Reimplemented in TPythia6, and TPythia8.

Definition at line 270 of file TGenerator.cxx.

◆ ImportParticles() [2/2]

TObjArray * TGenerator::ImportParticles ( Option_t option = "")
virtual

It reads the /HEPEVT/ common block which has been filled by the GenerateEvent method.

If the event generator does not use the HEPEVT common block, This routine has to be overloaded by the subclasses.

The default action is to store only the stable particles (ISTHEP = 1) This can be demanded explicitly by setting the option = "Final" If the option = "All", all the particles are stored.

Reimplemented in TPythia6, and TPythia8.

Definition at line 205 of file TGenerator.cxx.

◆ operator=()

TGenerator& TGenerator::operator= ( const TGenerator tg)
inlineprotected

Definition at line 153 of file TGenerator.h.

◆ Paint()

void TGenerator::Paint ( Option_t option = "")
virtual

Paint one event.

Reimplemented from TObject.

Definition at line 528 of file TGenerator.cxx.

◆ SetParameter()

virtual void TGenerator::SetParameter ( const char *  ,
Double_t   
)
inlinevirtual

Definition at line 180 of file TGenerator.h.

◆ SetPtCut()

void TGenerator::SetPtCut ( Float_t  ptcut = 0)
virtual

Set Pt threshold below which primaries are not drawn.

Definition at line 537 of file TGenerator.cxx.

◆ SetViewRadius()

void TGenerator::SetViewRadius ( Float_t  rbox = 1000)
virtual

Set lower and upper values of the view range.

Definition at line 549 of file TGenerator.cxx.

◆ SetViewRange()

void TGenerator::SetViewRange ( Float_t  xmin = -10000,
Float_t  ymin = -10000,
Float_t  zmin = -10000,
Float_t  xmax = 10000,
Float_t  ymax = 10000,
Float_t  zmax = 10000 
)
virtual

Set lower and upper values of the view range.

Definition at line 559 of file TGenerator.cxx.

◆ ShowNeutrons()

void TGenerator::ShowNeutrons ( Bool_t  show = 1)
virtual

Set flag to display or not neutrons.

Definition at line 574 of file TGenerator.cxx.

Member Data Documentation

◆ fParticles

TObjArray* TGenerator::fParticles
protected

display neutrons if true

Definition at line 149 of file TGenerator.h.

◆ fPtCut

Float_t TGenerator::fPtCut
protected

Definition at line 147 of file TGenerator.h.

◆ fShowNeutrons

Bool_t TGenerator::fShowNeutrons
protected

Pt cut. Do not show primaries below.

Definition at line 148 of file TGenerator.h.

Libraries for TGenerator:
[legend]

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