ASCII Torus

Inspired by this guy's 3D torus rendered to an ASCII palette, I decided to spend an hour last night implementing something similar. Here's the source, and here's the result. It was a fun exercise:

                             @@@@@@@                            
                    @@@@$##*!!!===!!!*##$@@@@                   
               @@@$$#*!=;;:~~-~~-~~~:~:;==!*#$$@@@              
            $@$$$#*!=;:~~~-~-----~~~~~~:::;=!!*#$$$@$           
          $$$$$##*=;~~~-----~~~~:::::::::~::;=!**#$$$$$         
        *$$$$$#*!=:~~------~~~~~::::::::::::::;!**#$$$$$#       
       *#$$$$$#*=:~--,,,--             ~:::::::=!*##$$$$#*      
      !*#$$$$$#*=~-,,,                     ~:~::!*#$$$$$#*!     
     ;!*#$$$$$#*=,.                           ~~!*#$$$$$#*!;    
    -;!*#$$$$$$#!,                             ~*#$$$$$$#*!;,   
    ~:;==**#$$$@@@$                           #@@@$$$#**!=;~,   
    ~~~:;=!*###$$@@@@                       @@@@$$###*!=;:~-,   
     ~~~::;=!***#$$$@@@@@@             @@@@@@$$$#***!=;:~~--    
     :~~~~~::;=!!**###$$$$@@@@@@@@@@@@@$$$$###**!!=;;:~~---,    
      ::~~~~~~~:;;==!!****#############****!!==;;;:~~-----,     
        ::~~~~-~~~~::;;=====!!!!!!!!!=====;;:::~---------       
         :::~~~~~~~-----~~:::::::::::::~~~-------------,        
           :::::~~~~~-~------------------------------,          
              :::::~~~~~~~~-----------------------,             
                 :::::::~~~~~~~~~~~~~-----------                
                      :::::::~~~~~~~~~~~~~-   

And here it is rendered by the same utility to a higher resolution.