Logo ROOT  
Reference Guide
No Matches
run_alice_esd_split.C File Reference

Detailed Description

Complex example showing ALICE ESD visualization in several views.

alice_esd_split.C - a simple event-display for ALICE ESD tracks and clusters version with several windows in the same workspace

Only standard ROOT is used to process the ALICE ESD files.

No ALICE code is needed, only four simple coordinate-transformation functions declared in this macro.

A simple geometry of 10KB, extracted from the full TGeo-geometry, is used to outline the central detectors of ALICE.

All files are access from the web by using the "CACHEREAD" option.

Automatic building of ALICE ESD class declarations and dictionaries.

ALICE ESD is a TTree containing tracks and other event-related information with one entry per event. All these classes are part of the AliROOT offline framework and are not available to standard ROOT.

To be able to access the event data in a natural way, by using data-members of classes and object containers, the header files and class dictionaries are automatically generated from the TStreamerInfo classes stored in the ESD file by using the TFile::MakeProject() function. The header files and a shared library is created in the aliesd/ directory and can be loaded dynamically into the ROOT session.

See the run_alice_esd.C macro.

Creation of simple GUI for event navigation.

Most common use of the event-display is to browse through a collection of events. Thus a simple GUI allowing this is created in the function make_gui().

Eve uses the configurable ROOT-browser as its main window and so we create an extra tab in the left working area of the browser and provide backward/forward buttons.

Event-navigation functions.

As this is a simple macro, we store the information about the current event in the global variable 'Int_t esd_event_id'. The functions for event-navigation simply modify this variable and call the load_event() function which does the following:

  1. drop the old visualization objects;
  2. retrieve given event from the ESD tree;
  3. call alice_esd_read() function to create visualization objects for the new event.

Reading of ALICE data and creation of visualization objects.

This is performed in alice_esd_read() function, with the following steps:

  1. create the track container object - TEveTrackList;
  2. iterate over the ESD tracks, create TEveTrack objects and append them to the container;
  3. instruct the container to extrapolate the tracks and set their visual attributes.
#include "aliesd/AliESDEvent.h"
#include "aliesd/AliESDRun.h"
#include "aliesd/AliESDtrack.h"
TEveGeoShape *gGeoShape;
class AliESDEvent;
class AliESDfriend;
class AliESDtrack;
class AliExternalTrackParam;
void make_gui();
void load_event();
void update_projections();
void alice_esd_read();
TEveTrack* esd_make_track(TEveTrackPropagator* trkProp, Int_t index, AliESDtrack* at,
AliExternalTrackParam* tp=0);
Bool_t trackIsOn(AliESDtrack* t, Int_t mask);
void trackGetPos(AliExternalTrackParam* tp, Double_t r[3]);
void trackGetMomentum(AliExternalTrackParam* tp, Double_t p[3]);
Double_t trackGetP(AliExternalTrackParam* tp);
// Configuration and global variables.
const char* esd_file_name = "http://root.cern.ch/files/alice_ESDs.root";
const char* esd_friends_file_name = "http://root.cern.ch/files/alice_ESDfriends.root";
const char* esd_geom_file_name = "http://root.cern.ch/files/alice_ESDgeometry.root";
TFile *esd_file = nullptr;
TFile *esd_friends_file = nullptr;
TTree *esd_tree = nullptr;
AliESDEvent *esd = nullptr;
AliESDfriend *esd_friend = nullptr;
Int_t esd_event_id = 0; // Current event id.
TEveTrackList *track_list = nullptr;
TGTextEntry *gTextEntry = nullptr;
TGHProgressBar *gProgress = nullptr;
// Initialization and steering functions
void run_alice_esd_split(Bool_t auto_size=kFALSE)
// Main function, initializes the application.
// 1. Load the auto-generated library holding ESD classes and ESD dictionaries.
// 2. Open ESD data-files.
// 3. Load cartoon geometry.
// 4. Spawn simple GUI.
// 5. Load first event.
printf("*** Opening ESD ***\n");
esd_file = TFile::Open(esd_file_name, "CACHEREAD");
if (!esd_file)
printf("*** Opening ESD-friends ***\n");
esd_friends_file = TFile::Open(esd_friends_file_name, "CACHEREAD");
if (!esd_friends_file)
esd_tree = (TTree*) esd_file->Get("esdTree");
esd = (AliESDEvent*) esd_tree->GetUserInfo()->FindObject("AliESDEvent");
// Set the branch addresses.
TIter next(esd->fESDObjects);
TObject *el;
while ((el=(TNamed*)next()))
TString bname(el->GetName());
// AliESDfriend needs some '.' magick.
esd_tree->SetBranchAddress("ESDfriend.", esd->fESDObjects->GetObjectRef(el));
esd_tree->SetBranchAddress(bname, esd->fESDObjects->GetObjectRef(el));
// Adapt the main frame to the screen size...
if (auto_size)
Int_t qq;
UInt_t ww, hh;
gVirtualX->GetWindowSize(gVirtualX->GetDefaultRootWindow(), qq, qq, ww, hh);
Float_t screen_ratio = (Float_t)ww/(Float_t)hh;
if (screen_ratio > 1.5) {
gEve->GetBrowser()->MoveResize(100, 50, ww - 300, hh - 100);
} else {
gEve->GetBrowser()->Move(50, 50);
{ // Simple geometry
TFile* geom = TFile::Open(esd_geom_file_name, "CACHEREAD");
if (!geom)
TEveGeoShapeExtract* gse = (TEveGeoShapeExtract*) geom->Get("Gentle");
gGeoShape = TEveGeoShape::ImportShapeExtract(gse, 0);
delete geom;
// import the geometry in the projection managers
if (gRPhiMgr) {
gEve->GetScenes()->FindChild("R-Phi Projection")->AddElement(a);
if (gRhoZMgr) {
gEve->GetScenes()->FindChild("Rho-Z Projection")->AddElement(a);
gEve->Redraw3D(kTRUE); // Reset camera after the first event has been shown.
void load_event()
// Load event specified in global esd_event_id.
// The contents of previous event are removed.
printf("Loading event %d.\n", esd_event_id);
gTextEntry->SetText(Form("Loading event %d...",esd_event_id));
if (track_list)
gTextEntry->SetText(Form("Event %d loaded",esd_event_id));
void update_projections()
// cleanup then import geometry and event
// in the projection managers
if (gRPhiMgr && top) {
if (gRhoZMgr && top) {
// GUI
// EvNavHandler class is needed to connect GUI signals.
class EvNavHandler
void Fwd()
if (esd_event_id < esd_tree->GetEntries() - 1) {
} else {
gTextEntry->SetText("Already at last event");
printf("Already at last event.\n");
void Bck()
if (esd_event_id > 0) {
} else {
gTextEntry->SetText("Already at first event");
printf("Already at first event.\n");
void make_gui()
// Create minimal GUI for event navigation.
gROOT->ProcessLine(".L SplitGLView.C+");
TEveBrowser* browser = gEve->GetBrowser();
browser->ExecPlugin("SplitGLView", 0, "new SplitGLView(gClient->GetRoot(), 600, 450, kTRUE)");
TGMainFrame* frmMain = new TGMainFrame(gClient->GetRoot(), 1000, 600);
frmMain->SetWindowName("XX GUI");
TString icondir( Form("%s/icons/", gSystem->Getenv("ROOTSYS")) );
EvNavHandler *fh = new EvNavHandler;
b = new TGPictureButton(hf, gClient->GetPicture(icondir + "GoBack.gif"));
hf->AddFrame(b, new TGLayoutHints(kLHintsLeft | kLHintsCenterY, 10, 2, 10, 10));
b->Connect("Clicked()", "EvNavHandler", fh, "Bck()");
b = new TGPictureButton(hf, gClient->GetPicture(icondir + "GoForward.gif"));
hf->AddFrame(b, new TGLayoutHints(kLHintsLeft | kLHintsCenterY, 2, 10, 10, 10));
b->Connect("Clicked()", "EvNavHandler", fh, "Fwd()");
gTextEntry = new TGTextEntry(hf);
kLHintsExpandX, 2, 10, 10, 10));
frmMain->AddFrame(hf, new TGLayoutHints(kLHintsTop | kLHintsExpandX,0,0,20,0));
gProgress = new TGHProgressBar(frmMain, TGProgressBar::kFancy, 100);
gProgress->ShowPosition(kTRUE, kFALSE, "%.0f tracks");
frmMain->AddFrame(gProgress, new TGLayoutHints(kLHintsExpandX, 10, 10, 5, 5));
browser->SetTabTitle("Event Control", 0);
// Code for reading AliESD and creating visualization objects
enum ESDTrackFlags {
void alice_esd_read()
// Read tracks and associated clusters from current event.
AliESDRun *esdrun = (AliESDRun*) esd->fESDObjects->FindObject("AliESDRun");
TClonesArray *tracks = (TClonesArray*) esd->fESDObjects->FindObject("Tracks");
// This needs further investigation. Clusters not shown.
// AliESDfriend *frnd = (AliESDfriend*) esd->fESDObjects->FindObject("AliESDfriend");
// printf("Friend %p, n_tracks:%d\n", frnd, frnd->fTracks.GetEntries());
if (track_list == 0) {
track_list = new TEveTrackList("ESD Tracks");
TEveTrackPropagator* trkProp = track_list->GetPropagator();
trkProp->SetMagField( 0.1 * esdrun->fMagneticField ); // kGaus to Tesla
for (Int_t n=0; n<tracks->GetEntriesFast(); ++n)
AliESDtrack* at = (AliESDtrack*) tracks->At(n);
// If ITS refit failed, take track parameters at inner TPC radius.
AliExternalTrackParam* tp = at;
if (! trackIsOn(at, kITSrefit)) {
tp = at->fIp;
TEveTrack* track = esd_make_track(trkProp, n, at, tp);
// This needs further investigation. Clusters not shown.
// if (frnd)
// {
// AliESDfriendTrack* ft = (AliESDfriendTrack*) frnd->fTracks->At(n);
// printf("%d friend = %p\n", ft);
// }
TEveTrack* esd_make_track(TEveTrackPropagator* trkProp,
Int_t index,
AliESDtrack* at,
AliExternalTrackParam* tp)
// Helper function creating TEveTrack from AliESDtrack.
// Optionally specific track-parameters (e.g. at TPC entry point)
// can be specified via the tp argument.
Double_t pbuf[3], vbuf[3];
if (tp == 0) tp = at;
rt.fLabel = at->fLabel;
rt.fIndex = index;
rt.fStatus = (Int_t) at->fFlags;
rt.fSign = (tp->fP[4] > 0) ? 1 : -1;
trackGetPos(tp, vbuf); rt.fV.Set(vbuf);
trackGetMomentum(tp, pbuf); rt.fP.Set(pbuf);
Double_t ep = trackGetP(at);
Double_t mc = 0.138; // at->GetMass(); - Complicated function, requiring PID.
rt.fBeta = ep/TMath::Sqrt(ep*ep + mc*mc);
TEveTrack* track = new TEveTrack(&rt, trkProp);
track->SetName(Form("TEveTrack %d", rt.fIndex));
return track;
Bool_t trackIsOn(AliESDtrack* t, Int_t mask)
// Check is track-flag specified by mask are set.
return (t->fFlags & mask) > 0;
void trackGetPos(AliExternalTrackParam* tp, Double_t r[3])
// Get global position of starting point of tp.
r[0] = tp->fX; r[1] = tp->fP[0]; r[2] = tp->fP[1];
Double_t cs=TMath::Cos(tp->fAlpha), sn=TMath::Sin(tp->fAlpha), x=r[0];
r[0] = x*cs - r[1]*sn; r[1] = x*sn + r[1]*cs;
void trackGetMomentum(AliExternalTrackParam* tp, Double_t p[3])
// Return global momentum vector of starting point of tp.
p[0] = tp->fP[4]; p[1] = tp->fP[2]; p[2] = tp->fP[3];
Double_t cs=TMath::Cos(tp->fAlpha), sn=TMath::Sin(tp->fAlpha);
Double_t r=TMath::Sqrt(1 - p[1]*p[1]);
p[0]=pt*(r*cs - p[1]*sn); p[1]=pt*(p[1]*cs + r*sn); p[2]=pt*p[2];
Double_t trackGetP(AliExternalTrackParam* tp)
// Return magnitude of momentum of tp.
return TMath::Sqrt(1.+ tp->fP[3]*tp->fP[3])/TMath::Abs(tp->fP[4]);
#define R__EXTERN
Definition DllImport.h:27
ULong_t Pixel_t
Pixel value.
Definition GuiTypes.h:40
ROOT::R::TRInterface & r
Definition Object.C:4
#define b(i)
Definition RSha256.hxx:100
#define a(i)
Definition RSha256.hxx:99
int Int_t
Definition RtypesCore.h:45
unsigned int UInt_t
Definition RtypesCore.h:46
const Bool_t kFALSE
Definition RtypesCore.h:92
bool Bool_t
Definition RtypesCore.h:63
double Double_t
Definition RtypesCore.h:59
float Float_t
Definition RtypesCore.h:57
const Bool_t kTRUE
Definition RtypesCore.h:91
@ kYellow
Definition Rtypes.h:66
R__EXTERN TEveManager * gEve
#define gClient
Definition TGClient.h:166
@ kDeepCleanup
Definition TGFrame.h:50
@ kLHintsLeft
Definition TGLayout.h:31
@ kLHintsCenterY
Definition TGLayout.h:35
@ kLHintsTop
Definition TGLayout.h:34
@ kLHintsExpandX
Definition TGLayout.h:37
#define gROOT
Definition TROOT.h:406
char * Form(const char *fmt,...)
R__EXTERN TSystem * gSystem
Definition TSystem.h:559
#define gVirtualX
Definition TVirtualX.h:338
An array of clone (identical) objects.
TObject * Get(const char *namecycle) override
Return pointer to object identified by namecycle.
Specialization of TRootBrowser for Eve.
Base class for TEveUtil visualization elements, providing hierarchy management, rendering control and...
Definition TEveElement.h:36
virtual void AddElement(TEveElement *el)
Add el to the list of children.
virtual void DestroyElements()
Destroy all children of this element.
TEveElement * FindChild(const TString &name, const TClass *cls=0)
Find the first child with given name.
Globally positioned TGeoShape with rendering attributes and an optional list of daughter shape-extrac...
Wrapper for TGeoShape with absolute positioning and color attributes allowing display of extracted TG...
static TEveGeoShape * ImportShapeExtract(TEveGeoShapeExtract *gse, TEveElement *parent=0)
Import a shape extract 'gse' under element 'parent'.
void AddElement(TEveElement *element, TEveElement *parent=0)
Add an element.
TEveSceneList * GetScenes() const
void AddGlobalElement(TEveElement *element, TEveElement *parent=0)
Add a global element, i.e.
TEveBrowser * GetBrowser() const
static TEveManager * Create(Bool_t map_window=kTRUE, Option_t *opt="FIV")
If global TEveManager* gEve is not set initialize it.
void Redraw3D(Bool_t resetCameras=kFALSE, Bool_t dropLogicals=kFALSE)
TEveEventManager * GetCurrentEvent() const
Axes for non-linear projections.
Manager class for steering of projections and managing projected objects.
TEveVectorT< TT > fP
TEveVectorT< TT > fV
A list of tracks supporting change of common attributes and selection based on track parameters.
Definition TEveTrack.h:140
virtual void SetMarkerStyle(Style_t s)
Set marker style for the list and the elements.
virtual void SetMarkerColor(Color_t c)
Set marker color for the list and the elements.
void MakeTracks(Bool_t recurse=kTRUE)
Regenerate the visual representations of tracks.
virtual void SetMainColor(Color_t c)
Set main (line) color for the list and the elements.
TEveTrackPropagator * GetPropagator()
Definition TEveTrack.h:175
virtual void SetMarkerSize(Size_t s)
Set marker size for the list and the elements.
Holding structure for a number of track rendering parameters.
void SetMagField(Double_t bX, Double_t bY, Double_t bZ)
Set constant magnetic field and rebuild tracks.
Visual representation of a track.
Definition TEveTrack.h:33
void SetAttLineAttMarker(TEveTrackList *tl)
Set line and marker attributes from TEveTrackList.
virtual void SetStdTitle()
Set standard track title based on most data-member values.
void Set(const Float_t *v)
Definition TEveVector.h:82
A ROOT file is a suite of consecutive data records (TKey instances) with a well defined format.
Definition TFile.h:54
static Bool_t SetCacheFileDir(ROOT::Internal::TStringView cacheDir, Bool_t operateDisconnected=kTRUE, Bool_t forceCacheread=kFALSE)
Definition TFile.h:324
static TFile * Open(const char *name, Option_t *option="", const char *ftitle="", Int_t compress=ROOT::RCompressionSetting::EDefaults::kUseCompiledDefault, Int_t netopt=0)
Create / open a file.
Definition TFile.cxx:3997
void Close(Option_t *option="") override
Close a file.
Definition TFile.cxx:879
virtual void AddFrame(TGFrame *f, TGLayoutHints *l=0)
Add frame to the composite frame using the specified layout hints.
Definition TGFrame.cxx:1102
virtual void SetCleanup(Int_t mode=kLocalCleanup)
Turn on automatic cleanup of child frames in dtor.
Definition TGFrame.cxx:1057
virtual void MapSubwindows()
Map all sub windows that are part of the composite frame.
Definition TGFrame.cxx:1149
virtual void Move(Int_t x, Int_t y)
Move frame.
Definition TGFrame.cxx:578
virtual void Resize(UInt_t w=0, UInt_t h=0)
Resize the frame.
Definition TGFrame.cxx:590
virtual void MoveResize(Int_t x, Int_t y, UInt_t w=0, UInt_t h=0)
Move and/or resize the frame.
Definition TGFrame.cxx:614
virtual void MapWindow()
map window
Definition TGFrame.h:228
void ShowPosition(Bool_t set=kTRUE, Bool_t percent=kTRUE, const char *format="%.2f")
Show postion text, either in percent or formatted according format.
void SetWindowName(const char *name=0)
Set window name. This is typically done via the window manager.
Definition TGFrame.cxx:1749
void Increment(Float_t inc)
Increment progress position.
virtual void SetBarColor(Pixel_t color)
Set progress bar color.
void SetMax(Float_t max)
virtual void Reset()
Reset progress bar (i.e. set pos to 0).
void SetEnabled(Bool_t flag=kTRUE)
virtual void SetTextColor(Pixel_t color, Bool_t local=kTRUE)
Changes text color.
virtual void SetText(const char *text, Bool_t emit=kTRUE)
Sets text entry to text, clears the selection and moves the cursor to the end of the line.
virtual TObject * FindObject(const char *name) const
Find an object in this list using its name.
Definition TList.cxx:578
The TNamed class is the base class for all named ROOT classes.
Definition TNamed.h:29
virtual TObject * FindObject(const char *name) const
Find an object in this collection using its name.
Mother of all ROOT objects.
Definition TObject.h:37
virtual const char * GetName() const
Returns name of object.
Definition TObject.cxx:359
virtual void SetName(const char *name)
Change (i.e.
void StartEmbedding(Int_t pos=kRight, Int_t subpos=-1) override
Start embedding external frame in the tab "pos" and tab element "subpos".
void SetTabTitle(const char *title, Int_t pos=kRight, Int_t subpos=-1)
Set text "title" of Tab "subpos" in TGTab "pos".
void StopEmbedding(const char *name=nullptr) override
virtual void ShowCloseTab(Bool_t show)
Long_t ExecPlugin(const char *name=nullptr, const char *fname=nullptr, const char *cmd=nullptr, Int_t pos=kRight, Int_t subpos=-1) override
Execute a macro and embed the created frame in the tab "pos" and tab element "subpos".
Basic string class.
Definition TString.h:136
virtual const char * Getenv(const char *env)
Get environment variable.
Definition TSystem.cxx:1661
virtual Bool_t ProcessEvents()
Process pending events (GUI, timers, sockets).
Definition TSystem.cxx:417
A TTree represents a columnar dataset.
Definition TTree.h:79
virtual Int_t SetBranchAddress(const char *bname, void *add, TBranch **ptr=0)
Change branch address, dealing with clone trees properly.
Definition TTree.cxx:8349
virtual Int_t GetEntry(Long64_t entry=0, Int_t getall=0)
Read all branches of entry and return total number of bytes read.
Definition TTree.cxx:5618
virtual TList * GetUserInfo()
Return a pointer to the list containing user objects associated to this tree.
Definition TTree.cxx:6337
TPaveText * pt
Double_t x[n]
Definition legend1.C:17
const Int_t n
Definition legend1.C:16
Double_t Sqrt(Double_t x)
Definition TMath.h:691
Double_t Cos(Double_t)
Definition TMath.h:643
Double_t Sin(Double_t)
Definition TMath.h:639
Short_t Abs(Short_t d)
Definition TMathBase.h:120
void tracks()
Definition tracks.C:49
Bertrand Bellenot

Definition in file run_alice_esd_split.C.