help.txt

How to use the user interface:

set [alpha/beta] [angle] : set alpha/beta to the input angle in degree
  set alpha 90
  set beta 180

add [alpha/beta] [angle] : increment current alpha/beta by the input 
angle in degree 
  add alpha 15
  add beta -10

view [Sphere/Planar/Orthogonal] : change render views
  view Sphere

set center [xfloat] [yfloat] [zfloat] : set the sphere center to a new location, zfloat must be a positive value.
  move center 0. 1. 3.

set [paramname] [paramvalue] : set all the customizable parameters for the viewport
  set img_w 100 ,           this changes the ascii viewer width and height  
  set view_size 4 ,         the camera view size, e.g., in planar view we sees the [-view_size, view_size] x [-view_size, view_size] area
  set plane_bd 4 ,          the orthogonal view boudnary. This is to prevent the planer image occupies the whole orthogonal view 
  set half_edge_length 2 ,  the length of grid. The grid sit in the [-half_edge_length, half_edge_length] x [-half_edge_length, half_edge_length] area
  set line_w 0.25 ,         width of grid lines
  set grid_size 2 ,         number of lines. We will have grid_size^2 cells and (grid_size+1) vertical/horizontal lines
  set frame_rate 30 ,       the rate of animation playing per second
  set duration 2. ,         the time each animation should plays when calling add/set
  set supersampling true ,  whether to use the supersampling in the rasterizer

cool : this will play a cool animation :)

reset: reset all parameters

exit: exit the program