Visualisation, overlap detection are closely related to geometry conversion. So tools that do these should be mined for possibilities.
Drivers: OpenGL, HepRep, VRML, DAVID, DAWN
[blyth@cms01 visualization]$ du -hs *
1.3M OpenGL
1.1M HepRep
1.1M management
884K OpenInventor
812K modeling
508K XXX
428K VRML
420K RayTracer
380K externals
304K FukuiRenderer
132K History
184K Tree
8.0K GNUmakefile
[blyth@cms01 visualization]$ pwd
/data/env/local/dyb/trunk/external/build/LCG/geant4.9.2.p01/source/visualization
The Geant4 DAVID visualization tool can infact automatically detect the overlaps between the volumes defined in Geant4 and converted to a graphical representation for visualization purposes. The accuracy of the graphical representation can be tuned onto the exact geometrical description. In the debugging, physical-volume surfaces are automatically decomposed into 3D polygons, and intersections of the generated polygons are investigated. If a polygon intersects with another one, physical volumes which these polygons belong to are visualized in color (red is the default).
Paint by gl calls approach. Pre-2.0 glsl, so no explicit(useful) geometry conversion.
[blyth@cms01 src]$ vi G4OpenGLSceneHandler.cc
[blyth@cms01 src]$ pwd
/data/env/local/dyb/trunk/external/build/LCG/geant4.9.2.p01/source/visualization/OpenGL/src