Donut math C

Help Donut.c

/* Learn Donut */
/* file: donut.c */
/* compile: gcc donut.c -o donut.exe */
/* out: 2024 */
/* Refrense: 
  - https://www.youtube.com/watch?v=DEqXNfs_HhY
  - https://www.a1k0n.net/2011/07/20/donut-math.html
  - https://gist.github.com/gcr/1075131  
*/

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

int k;
double sin(), cos();
int main()
{
    float A = 0, B = 0, i, j, z[1760];
    char b[1760];
    printf("\x1b[2J");
    for (;;)
    {
        memset(b, 32, 1760);
        memset(z, 0, 7040);
        for (j = 0; 6.28 > j; j += 0.07)
        {
            for (i = 0; 6.28 > i; i += 0.02)
            {
                float sini = sin(i),
                      cosj = cos(j),
                      sinA = sin(A),
                      sinj = sin(j),
                      cosA = cos(A),
                      cosj2 = cosj + 2,
                      mess = 1 / (sini * cosj2 * sinA + sinj * cosA + 5),
                      cosi = cos(i),
                      cosB = cos(B),
                      sinB = sin(B),
                      t = sini * cosj2 * cosA - sinj * sinA;
                int x = 40 + 30 * mess * (cosi * cosj2 * cosB - t * sinB),
                    y = 12 + 15 * mess * (cosi * cosj2 * sinB + t * cosB),
                    o = x + 80 * y,
                    N = 8 * ((sinj * sinA - sini * cosj * cosA) * cosB - sini * cosj * sinA - sinj * cosA - cosi * cosj * sinB);
                if (22 > y && y > 0 && x > 0 && 80 > x && mess > z[o])
                {
                    z[o] = mess;
                    b[o] = ".,-~:;=!*#$@"[N > 0 ? N : 0];
                }
            }
        }
        printf("\x1b[d");
        for (k = 0; 1761 > k; k++)
            putchar(k % 80 ? b[k] : 10);
        A += 0.04;
        B += 0.02;
    }
}