usage:

viewer mesh_file scale_factor

example:

viewer ../meshes/bunny_nf4000.noff 10




commands:

change view points : 'v' 


there are two viewpoints, view from the camera, and view from (0,10,0).
type 'v' will toggle view points.

select object to manipulate


refined geometry :'g'
camera           :'s'

select coordinates system , the manipulation is relative to the selected
  one

camera : 'S'
world  : 'W'
object itself : 'L'

define manipulation

 rotation : left button
 translation: right button
 translation: both left and right button
 
menu

press middle button : "show faces" will show faces; "show edges "
will show all the edges.