donut.c

#include <stdio.h>
#include <string.h>

int k;
double sin(),cos();

int main() {
  float A = 0, B = 0, i, j, z[1760];
  char b[1760];
  printf("\n1b[2J");
  for(;;) {
    memset(b, 32, 1760);
    memset(z, 0, 7040);
    for ( j = 0; 6.28 > j; j+= 0.004 ) {
      for ( i = 0; 6.28 > i; i += 0.035 ) {
        float c = sin(i), d = cos(j), e = sin(A), f = sin(j), g = cos(A), h = d + 2, D = 1 / (c * h * e + f * g + 5), l = cos(i),
              m = cos(B), n = sin(B), t = c * h * g - f * e;
        
        int x = 40 + 30 * D * (l * h * m -  t * n);
        int y = 12 + 15 * D * (l * h * n + t * m), o = x + 80 * y,
            N = 8 * ((f * e - c * d * g) * m - c * d * e - f * g - l * d * n);
        
        if (22 > y && y > 0 && 80 > x && x > 0 && D > z[o]) {
          z[o] = D;
          b[o] = ".,-~:;=!*#$@"[N > 0 ? N : 0];
        }
      }
    }

      printf("\x1b[H");
      for ( k = 0; 1761 > k; k++ ) 
        putchar(k % 80 ? b[k] : 10);
      A += 0.04;
      B += 0.02;
  }
  return 0;
}