Coin3D is the suggested implementation of Open Inventor, but the Geant4 source does not compile with it on Windows. To fix:

in G4OpenInventorWin.cc, line 53:
    GetInteractorManager () -> 
           RemoveDispatcher((G4DispatchFunction)G4Win32::dispatchWin32Event);
becomes:
#if !defined(COIN_DLL) && !defined(COIN_NOT_DLL)
    GetInteractorManager () -> 
           RemoveDispatcher((G4DispatchFunction)G4Win32::dispatchWin32Event);
#endif

(Note that to get it to compile at all, the user must manually add one of those two preprocessor defines to the _G4OpenInventor-archive project in VisualStudio. Plus either SOWIN_DLL or SOWIN_NOT_DLL. The choice depends on how Coin3D was built. This should be documented.)



When transparency is used, the default rendering is both misleading and wrong. On all platforms. To fix:

G4OpenInventorWinViewer.cc: At the end of Initialise() add
    fViewer->setTransparencyType(SoGLRenderAction::SORTED_OBJECT_ADD);

G4OpenInventorXtViewer.cc: At the end of Initialise() add
    fViewer->setTransparencyType(SoGLRenderAction::SORTED_OBJECT_ADD);

(This does not affect rendering when no transparency is used, but makes a HUGE difference when it is. Note the user can still change the transparency rendering via the right-button menu; this just changes its initial value to be correct. I have no idea why they implemented several incorrect renderings, and made one the default.)