donut.py

import os
from math import sin, cos

def main():
    a=0
    b=0

    height=24
    width=80
    # height=int(input("Enter Screen Height : "))
    # width=int(input("Enter Screen Width : "))
    
    # for clearing console (windows and unix systems)
    clear = "cls"
    if os.name == "posix":
        clear = "clear"

    os.system(clear)
    while True:
        z = [0 for _ in range(4*height*width)]
        screen = [' ' for _ in range(height*width)]

        j=0
        while j<6.28:
            j+=0.07
            i=0
            while i<6.28:
                i+=0.02

                sinA=sin(a)
                cosA=cos(a)
                cosB=cos(b)
                sinB=sin(b)

                sini=sin(i)
                cosi=cos(i)
                cosj=cos(j)
                sinj=sin(j)

                cosj2=cosj+2
                mess=1/(sini*cosj2*sinA+sinj*cosA+5)
                t=sini*cosj2*cosA-sinj* sinA

                # 40 is the left screen shift
                x = int(40+30*mess*(cosi*cosj2*cosB-t*sinB))
                # 12 is the down screen shift
                y = int(11+15*mess*(cosi*cosj2*sinB +t*cosB))
                # all are casted to int, ie floored
                o = int(x+width*y)
				# multiplying by 8 to bring in range 0-11 as 8*(sqrt(2))=11
				# because we have 11 luminance characters
                N = int(8*((sinj*sinA-sini*cosj*cosA)*cosB-sini*cosj*sinA-sinj*cosA-cosi *cosj*sinB))
				# if x,y inside screen and previous z-buffer is < mess 
				# i.e. when z[o] is 0 or the prev point is behind the new point
				# so we change it to the point nearer to the eye/ above prev point 
                if 0<y<height and 0<x<width and z[o] < mess:
                    z[o]=mess
                    screen[o]=".,-~:;=!*#$@"[N if N>0 else 0]

        # prints
        os.system(clear)
        for index, char in enumerate(screen):
            if index % width == 0:
                print()
            else:
                print(char, end='')

        # increments
        a+=0.04
        b+=0.02

if __name__ == "__main__":
    main()