# Region styles

Classes that define geometric regions are derived from the Region class.
Regions are used elsewhere in LAMMPS to group atoms, delete atoms to
create a void, insert atoms in a specified region, etc. New styles can
be created to add new region shapes to LAMMPS.

Region_sphere.cpp is an example of a spherical region.

Here is a brief description of methods you define in your new derived
class. See region.h for details.

  ------------------ -------------------------------------------------------
  inside             determine whether a point is in the region

  surface_interior   determine if a point is within a cutoff distance inside
                     of surface

  surface_exterior   determine if a point is within a cutoff distance
                     outside of surface

  shape_update       change region shape if set by time-dependent variable
  ------------------ -------------------------------------------------------