1. EVE as the base of
AliEve and Fireworks
event-displays
Matevž Tadel

2. M. Tadel: All about EVE ... [SFT-GM, CERN]
Contents
Intro - what is EVE
History / contributors
Main features / services [with demos]
AliEve demo
Fireworks demo
End
M. Tadel: All about EVE ... [SFT-GM, CERN]

3. Event Visualization Environment
Framework for object management
hierarchy / structure
interaction, visualization (GUI/OpenGL (2D/3D))
creation and coherency of derived representations
Toolkit satisfying HEP requirements
Geometry and view markup
Sim/Rec data (points, tracks) with 2D-projections
Raw-data visualization
Stand-alone application on top of ROOT
Use only ROOT-provided libraries to access data.
Gives portability and minimizes deployment issues.
M. Tadel: All about EVE ... [SFT-GM, CERN]

4. M. Tadel: All about EVE ... [SFT-GM, CERN]
EVE in ALICE & CMS
ALICE - AliEve
EVE used as framework / toolkit / application:
Detector-specific code for raw-data visualization
Interface to reconstruction / track-fitting
CINT macros used extensively => configurability
CMS – Fireworks
EVE used mostly as toolkit:
Tightly control data-access, data-processing and creation of visualization objects
Expose only well-defined interface to the users
M. Tadel: All about EVE ... [SFT-GM, CERN]

5. History & contributors
’05 – ALICE vis in Gled
’06 – Prototype of ALICE vis using ROOT
Learning ROOT GUI, most urgent fixes to ROOT-GL.
In spirit close to final design but very crude.
Lived in AliRoot CVS as Reve, AliEve modules.
’07 – Major rewrite/extension of critical systems
ROOT-GL – refactoring; scene/viewer mgmt.; overlay.
Projections, tools for raw-data visualization.
Reve moved to ROOT as EVE. Fireworks project started.
’08 – High-level features, consolidation, optimization
Compound objects
Selection / highlight
Visualization parameter database
Fancy GUI stuff
Should have full functionality by the end of the year.
Alja
Bertrand
M. Tadel: All about EVE ... [SFT-GM, CERN]

6. TEveElement – Basic functionality
Base-class TEveElement
not a TObject, but all derived classes are
holds together:
visualization data
GL-renderer
GED (object editor)
List-tree entries / browsable representations
Basic demos.
M. Tadel: All about EVE ... [SFT-GM, CERN]

7. TEveElement – Hierarchy I.
Children – list<TEveElement*>
Rendering control
Collection management
Sub-classes can override Add/RemoveElements()
Control state of children
Demo: TEvePointSetArray, TEveTrackList
Parents
Propagation of change / redraw requests
Also list<TEveElement*>!
Multiple control agents can share an element
Different roles played by an object
Demo: TEveScene, TEveSelection
M. Tadel: All about EVE ... [SFT-GM, CERN]

8. TEveElement – Hierarchy II.
Reference counting:
Number of parents
Number of top-level list-tree items
Extra external references
Automatic destruction enabled by default.
Demo: track-list destruction with gDebug=1
Framework services are also TEveElements:
Get standard GUI representation (GED, list-trees)
Uniform object management
M. Tadel: All about EVE ... [SFT-GM, CERN]

9. Interface to GL and update propagation
elements
TEveScene
TGLScene
list of entry points
into element hierarchy
flat list of GL renderers,
some pointing back to
source elements
Full repaint – drop TGLScene contents and repopulate
Expensive, often a big overkill.
Minimal update – push changes into existing GL renderers
Stamp changes: color (highlight!), position (bounding-box, visibility), visual properties (GL display-list)
M. Tadel: All about EVE ... [SFT-GM, CERN]

10. M. Tadel: All about EVE ... [SFT-GM, CERN]
Projections
Master – TEveProjectable Projection mgr
Replica – TEveProjected TEveProjectionManager
Need to take care of two types of updates:
Changes in projection parameters
re-project -> from mgr
Changes in master – 3D track
copy vis parameters
-> from master
Demo: alice_esd_split.C
M. Tadel: All about EVE ... [SFT-GM, CERN]

11. Visualization-parameter DB - VizDB
virtual void CopyVizParams(TEveElement*);
like limited operator=()
Allows:
Each user to
easiliy change
defaults
2. Persistency
across
sessions
3. Sharing of
settings among users
M. Tadel: All about EVE ... [SFT-GM, CERN]

12. M. Tadel: All about EVE ... [SFT-GM, CERN]
Demos
AliEve – visual scanning application
Fireworks
M. Tadel: All about EVE ... [SFT-GM, CERN]

13. M. Tadel: All about EVE ... [SFT-GM, CERN]
End
M. Tadel: All about EVE ... [SFT-GM, CERN]