import geometry;
import animate;
settings.tex="pdflatex";

animation A;
size(12cm);

for (int a=1; a < 20; ++a) {
  save();
  point P=(-4.5,0); dot(P);
  inversion inv=inversion(1,P);
  line l1=line((0,0),(-0.35,1)), l2=line((0,0),(0.35,1));
  path g1=inv*l1, g2=inv*l2;
  fill(g1^^g2,evenodd+lightgrey); draw(g1,linewidth(bp));
  draw(g2,linewidth(bp));

  for (int i:new int[]{-1,1}) {
    point P=(0,3i/a);
    triangle t=triangle(shift(P)*hline,l1,l2);
    int n=a;
    for (int j=0; j <= n; ++j) {
      circle C=excircle(t.AB);
      t=triangle(shift(angpoint(C,i*90))*hline,l1,l2);
      circle Cp=inv*C;
      path g=Cp;
      fill(g,0.95*yellow);
      draw(g,bp+red); draw(g,blue);
    }
  }
  picture pic;
  add(pic,bbox(5mm,Fill(rgb(0.95,0.95,0.8))));
  A.add(pic);
  restore();
}

A.pdf(keep=true);