[VECGEOM-597] Fixed uniformity issue in SamplePointOnSurface()
UnplacedTube::SamplePointOnSurface()
- flat sampling along R
has been changed to sampling along R^2
to have a uniform distribution at the bases.
UnplacedTube::SamplePointOnSurface()
- flat sampling along R
has been changed to sampling along R^2
to have a uniform distribution at the bases.