[quarterto]

Just need to add a Math.abs: https://www.dwitter.net/d/457

[vog]

Nice, but you don't need Math.abs to stay within the 140 chars limit:

  t?i++:i=0;for(j=1080;j--;){a=b=0;k=35;for(;k--&&a*a+b*b<4;)c=a*a-b*b+i/540-2,b=2*(a*b<0?-a*b:a*b)+j/540-1,a=c;x.fillRect(i,j,1,S(k/9))}