Coil Interference

https://www.dwitter.net/d/15306

for(c.width|=i=7;i--;)for(k=j=1;j;j+=k,j-99?0:k=-1)x.arc(960,540,j*13,a=i/2+j/2-t/2+9*S(j/5+t*5)*k/49,a)
x.rect(0,0,2e3,2e3)
x.fill`evenodd`