gfx_engine - A simple 3D visualizer
Copyright Joakim Lindblad

Usage:   gfx_engine [world ops] <obj1.nff> [obj1 ops] [<obj2.nff> obj2 ops ...]

World options:
        -h,-?,--help this text
        -n <name> title of the window
        -f flat shading from start
        -w wireframe on from start
        -l "(x,y,z, amb.r,amb.g,amb.b, diff.r,g,b, spec.r,g,b)"
                 (if not supplied default lights are used)
        -L "(x,y,z, amb.r,amb.g,amb.b, diff.r,g,b, spec.r,g,b, a,b,c)"
                 (if not supplied default lights are used)
        -o "(eye.x,eye.y,eye.z, z,at.x,at.y,at.z, up.x,up.y,up.z)"
                 position observer
        -s <scale> overall scale factor
        -d <z-coord> view plane z-coordinate (default=-1000)
        -A <steps> steps for one complete turn in animation (default=64)
        -c capture direct to file
        -C capture animation direct to files (use with -A option)
        -g geometry of window XxY
        -G geometry of screen capture XxY

Object options:
        -p "(pos.x,pos.y,pos.z)"
                 position object
        -P "(pos.x,pos.y,pos.z, xdir.x,xdir.y,xdir,z,zdir.x, zdir.y,zdir.z)"
                 position object (in lookat fashion)
        -s <scale> object scale factor
        -S <specular> object specular value
        -t <texture_file.pnm> <dir> texture map (2 parameters)
                 <dir> is texture mapping direction x=0, y=1, z=2
        -a <alpha> overrule alpha setting from file
        -c <hexcolor> overrule colour setting from file
        -C center object in the model coordinate system

Example: gfx_engine -o "(600,300,350, 0,0,0, 0,0,1)" teapot.nff -s 30 -t tux.pnm 1

Note that all options are followed by a space (to allow for long options)
The filename 'stdin' is used to read from standard input


Keyboard interface:
  q = quit program
  v = verbose
  s/S = start/stop and reverse animation
  f = start/stop frame rate testing
  r = reset view matrix

  x/X = move observer along WorldCoordinate system x-axis
  y/Y = move observer along WC y-axis
  z/Z = move observer along WC z-axis

  i/I = rotate observer around ViewC x-axis
  o/O = rotate observer around VC y-axis
  p/P = rotate observer around VC z-axis

  a/A = move observer forward / backward

  j/J = rotate object around ObjectC x-axis
  k/K = rotate object around OC y-axis
  l/L = rotate object around OC z-axis

  +/- = scale object
  d/D = change perspective distance

  1,2,3 = turn on/off ambient,diffuse and specular light
  *// = increase / decrease active illumiation
  4 = turn on/off suface rendering (use with 'w')

  g = Gouraud / flat shading
  w = wireframe on / off
  b = backface culling on / off
  B = white / black Background
  t = texture rendering on / off
  T = cycle solid/alpha/transparency rendering