BREPS & STEPwhat's up and coming ...

Gabriele CosmoCERN - IT/ASD

GEANT4 Workshop

September, 20th 1999

ESTEC, Noordwijk, The Netherlands

ESTEC Geant4 Workshop

BREPS & STEP, Gabriele Cosmo 2

Outline General overview on BREPS Overview on current design for

BREPS and STEP-interface BREPS: what we should achieve The proposed strategy Time schedule Who’s envolved

ESTEC Geant4 Workshop

BREPS & STEP, Gabriele Cosmo 3

BREPSWhat are they ? Boundary REPresented Solid

a solid specified by all its surfaces (e.g. a cube represented by 6 squares)

Surfaces may be planar, 2nd or higher order Splines, B-Splines, NURBS

(NonUnifoRm B-Splines)

ESTEC Geant4 Workshop

BREPS & STEP, Gabriele Cosmo 4

BREPSWhat are they useful for ?

Represent complex solids Provide capability of exchange

(import/export) solid models from CAD systems

Make Geant4 a STEP compliant solid modeler

ESTEC Geant4 Workshop

BREPS & STEP, Gabriele Cosmo 5

CAD systems The most powerful way to describe solid

models exact solid description used by engineers

Based on a Standard widespread usage

CAD support today: exchange BREP solids using the

portable STEP AP203 interface standard future: AP214 interface standard to allow

exchange of other type of solids (CSG)

ESTEC Geant4 Workshop

BREPS & STEP, Gabriele Cosmo 6

BREPS & STEPCurrent category design

STEP interface Uses the NIST STEP reader to import STEP

parameters from file the STEP file containing the solid descriptions and

positioning (solid model) Implements all solids creators to instantiate out of

the STEP file all supported BREP solids uses BREPS module

B R E P S S T E P(S T E P re a d e r)

S te p -In te rfa ce

ESTEC Geant4 Workshop

BREPS & STEP, Gabriele Cosmo 7

BREPSWhat I’d expect to see ...

Box, Cone, Cylinder, PCone, Polyhedra, Sphere, Thorus, ...

Bspline, Bezier, Conical, Cylindrical, Projected, Rectangular, Toroidal, Fplane, ...

Bspline, Composite, Circular, Conic, Line, Ellipse, Parabola,Hyperbola, ...

G 4 B o u n d a ries(cu rve s )

G 4 S u rfa ces

B R E Pso lid s

ESTEC Geant4 Workshop

BREPS & STEP, Gabriele Cosmo 8

The Project GOAL: Identify key problems affecting BREPS

and STEP-Interface and fix them attack both domains in parallel

STRATEGY: review of the code BREPS: adopt a top-down approach starting

from G4VSolid BREPSolid base classes combine for specific cases step-by-step

debug using existing tests and in case complement them systematically

review existing documentation and proper comment code along understanding

understand algorithm properties and verify their implementation

check coding style and design violations

ESTEC Geant4 Workshop

BREPS & STEP, Gabriele Cosmo 9

Short & medium-term developments Check correct reading of STEP

description parameters and construction fix current deficiencies

Add capability to write BREP geometry description to STEP file

Enable association of material with solid (needed for creation of logical volumes)

Visualization of BREPS Performance studies

ESTEC Geant4 Workshop

BREPS & STEP, Gabriele Cosmo 10

When … ?

By December ‘99

ESTEC Geant4 Workshop

BREPS & STEP, Gabriele Cosmo 11

People involved

Gabriele Cosmo (mainly) John Apostolakis Simone Giani

Volunteers ?