GLStarView is an OpenGL-based utility for visualizing N-body 
simulations.  It is available free on the web (alum.mit.edu/www/fregeau) 
and is licensed under the GNU GPL.

The input format is the Starlab story format, which is spoken by Starlab 
(of course) and Fewbody, a numerical toolkit for doing small-N 
gravitational dynamics (alum.mit.edu/www/fregeau).

GLStarView renders each star as a sphere, draws a rudimentary set of 
axes, and prints the current time and log info to stdout.  GLStarView 
allows you to generally explore your N-body simulation in 3D.  You can 
pause, unpause, step through frame-by-frame, zoom in and out, rotate, 
change the sizes of the stars, etc.

Here is the usage summary, along with the key- and mousebindings 
(obtained via "glstarview -h"):

USAGE:
  glstarview [options...]

OPTIONS:
  -f --fullscreen : full screen mode
  -p --paused     : start paused
  -a --noaxes     : start with axes off
  -t --time       : start with time display on
  -l --log        : start with log display on
  -d --debug      : turn on debugging
  -V --version    : print version info
  -h --help       : display this help text

KEYBINDINGS:
  PAGE (UP/DOWN) : zoom (out/in)
  ARROW KEYS     : rotate
  h              : print this help text
  q, ESCAPE      : quit
  p              : pause/unpause
  SPACE          : step through frames (while paused)
  b              : make stars bigger
  s              : make stars smaller
  m              : use more polygons to render stars
  f              : use fewer polygons to render stars
  a              : toggle axes
  t              : toggle time printout
  l              : toggle log printout
  <              : slow down animation
  >              : speed up animation

MOUSEBINDINGS:
  DRAG                   : rotate
  [SHIFT] DRAG (up/down) : zoom (in/out)
