Building an Event Display with GAUDI

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Building an Event Display with GAUDI

• LHCb Software Week
• 24-26 November 1999
• P. Mato

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Outline

• Visualization Model in GAUDI
• Functionality
• Status

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Architectural choice

• We do not want to tell a Data Object to draw
  itself
• A Data Object does not know where to be drawn,
  how to be drawn, with which graphical properties
  (color, texture, projection,), which graphical
  package, ...
• Instead we want to decouple Data Object from its
  graphical representation.
• Same pattern as for persistency using adapter
  classes (Converters)
• We need to write a Converter for each Data Object
  class and each visualization package.

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Visualization Model
Interactive User Interface
Algorithm
xxLabSvc
Algorithm
Algorithm
TransientEvent Data
GraphicalScene
SoCnvSvc
SoXXCnv
SoXXCnv
SoXXCnv
TransientDetector Data
SoXXCnv
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Converter Example SoDetElemCnv
StatusCode SoDetElemCnvcreateRep( DataObject
aObject,IOpaqueAddress) DetectorElement
de dynamic_castltDetectorElementgt(aObject)
ISolid sl de-gtgeometry()-gtlvolume()-gts
olid()-gtcoverTop() SolidBox box
dynamic_castltSolidBoxgt(sl) SoSeparator
separator new SoSeparator SoTransform trans
new SoTransform Hep3Vector c
de-gtgeometry()-gtmatrix().getTranslation()
-1.0 Hep3Vector v double angle
de-gtgeometry()-gtmatrix().getRotation().getAngleAxi
s(angle , v ) trans-gttranslation.setValue(
c.x(), c.y(), c.z()) trans-gtrotation
SbRotation( SbVec3f(v.x(),v.y(),v.z()), angle)
separator-gtaddChild(trans) SoCube cube
new SoCube() cube-gtwidth box-gtxHalfLength()
2 cube-gtheight box-gtyHalfLength() 2
cube-gtdepth box-gtzHalfLength() 2
separator-gtaddChild(cube)
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Managing the two stores
Graphical Store
Bi-directional opaque address
TransientEvent Data
G
pick()
update()
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Potential Functionality

• What can be displayed?
• In principle anything that is in any of the
  transient stores (event, detector, histogram,)
  can be displayed. Needed corresponding converter.
• Objects not in the transient stores could also be
  drawn if driven by algorithms.
• How much interactivity?
• Not the business of data visualization. The
  interactive user interface is another service.

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GaudiLab Status

• Prototype exists based on Open Scientist()
• Proof of concept
• Could be useful for debugging. E.g. geometry,
  algorithms
• More work is needed to make it complete and
  usable.

() OpenGL, OpenInventor, HEPVis, Lab, ...