BREPS & STEP what's up and coming... Gabriele Cosmo CERN - IT/ASD GEANT4 Workshop September, 20th 1999 ESTEC, Noordwijk, The Netherlands

ESTEC Geant4 WorkshopBREPS & STEP, Gabriele Cosmo2 Outline n General overview on BREPS n Overview on current design for BREPS and STEP-interface n BREPS: what we should achieve n The proposed strategy n Time schedule n Who’s envolved

ESTEC Geant4 WorkshopBREPS & STEP, Gabriele Cosmo3 BREPS What are they ? n Boundary REPresented Solid u a solid specified by all its surfaces (e.g. a cube represented by 6 squares) n Surfaces may be u planar, 2nd or higher order u Splines, B-Splines, NURBS (NonUnifoRm B-Splines)

ESTEC Geant4 WorkshopBREPS & STEP, Gabriele Cosmo4 BREPS What are they useful for ? n Represent complex solids n Provide capability of exchange (import/export) solid models from CAD systems n Make Geant4 a STEP compliant solid modeler

ESTEC Geant4 WorkshopBREPS & STEP, Gabriele Cosmo5 CAD systems n The most powerful way to describe solid models u exact solid description u used by engineers n Based on a Standard u widespread usage n CAD support u today: exchange BREP solids using the portable STEP AP203 interface standard u future: AP214 interface standard to allow exchange of other type of solids (CSG)

ESTEC Geant4 WorkshopBREPS & STEP, Gabriele Cosmo6 BREPS & STEP Current category design n STEP interface u Uses the NIST STEP reader to import STEP parameters from file F the STEP file containing the solid descriptions and positioning (solid model) u Implements all solids creators to instantiate out of the STEP file all supported BREP solids F uses BREPS module

ESTEC Geant4 WorkshopBREPS & STEP, Gabriele Cosmo7 BREPS What I’d expect to see... n Box, Cone, Cylinder, PCone, Polyhedra, Sphere, Thorus,... n Bspline, Bezier, Conical, Cylindrical, Projected, Rectangular, Toroidal, Fplane,... n Bspline, Composite, Circular, Conic, Line, Ellipse, Parabola,Hyperbola,...

ESTEC Geant4 WorkshopBREPS & STEP, Gabriele Cosmo8 The Project n GOAL: Identify key problems affecting BREPS and STEP-Interface and fix them u attack both domains in parallel n STRATEGY: review of the code u BREPS: adopt a top-down approach starting from G4VSolid  BREPSolid base classes u combine for specific cases step-by-step debug using existing tests and in case complement them systematically u review existing documentation and proper comment code along understanding u understand algorithm properties and verify their implementation u check coding style and design violations

ESTEC Geant4 WorkshopBREPS & STEP, Gabriele Cosmo9 Short & medium-term developments n Check correct reading of STEP description parameters and construction u fix current deficiencies n Add capability to write BREP geometry description to STEP file n Enable association of material with solid (needed for creation of logical volumes) n Visualization of BREPS n Performance studies

ESTEC Geant4 WorkshopBREPS & STEP, Gabriele Cosmo10 When … ? n By December ‘99

ESTEC Geant4 WorkshopBREPS & STEP, Gabriele Cosmo11 People involved n Gabriele Cosmo (mainly) n John Apostolakis n Simone Giani n Volunteers ?