prologues := 3;
outputtemplate := "%j/%j-%c.svg";
outputformat := "svg";

verbatimtex
%&latex
\documentclass{article}
\usepackage{amsmath}
\usepackage[charter]{mathdesign}
\begin{document}
etex

u:=3cm;
path cercle, piri, hori, verti, horip, vertip, vertib, rayon;
cercle := fullcircle scaled 2u;
hori := 12[(-u,0),(u,0)]--12[(u,0),(-u,0)];
verti := 12[(0,-u),(0,u)]--12[(0,u),(0,-u)];

for i:=0 upto 360:
 beginfig(i);
  pair P,M,Q,O;
  numeric b;
  b:= 1/3*u;
  O:=(-u,0);
 pickup pencircle scaled 0.8pt;
  drawarrow (-1.3u,0)--(2u,0);
  drawarrow (-u,-1.5u)--(-u,1.5u);
 pickup pencircle scaled 0.6pt;
  draw cercle dashed evenly withcolor blue;
  P:=u*(cosd(i),sind(i));
  horip:= hori shifted P;
  vertip:= verti shifted P;
  vertib:= verti shifted (b,0);
  M = vertib intersectionpoint horip;
  rayon := 5[O,M]--5[M,O];
  Q = rayon intersectionpoint vertip;
  if i=0:
   piri:=Q;
  else:
   piri:=piri--Q;
  fi;
  if (xpart Q)>(xpart M):
   draw O--Q dashed evenly;
  else:
   draw O--M dashed evenly;
  fi;
  draw M--P dashed evenly;
  draw P--Q dashed evenly;
  draw (xpart M,-1.5u)--(xpart M,1.5u) dashed evenly;
 pickup pencircle scaled 1pt;
  draw piri withcolor red;
 dotlabel.lrt(btex $B(b,0)$ etex,(b,0));
 dotlabel.ulft(btex $O$ etex, O);
 dotlabel.urt(btex $Q$ etex,Q);
 dotlabel.ulft(btex $P$ etex,P);
 dotlabel.ulft(btex $M$ etex,M);
 dotlabel.lrt(btex $A(a,0)$ etex, (u,0));
 label.urt(btex $\mathcal{C}$ etex, (-u/2,0.95u));
 label.top(btex $x$ etex, (1.8u,0));
 label.lft(btex $y$ etex, (-u,1.3u));
 label(btex \itshape{Quartique piriforme} etex,(1.3u, 1.2u));
 label(btex $x^4-ax^3+b^2y^2=0$ etex, (1.3u,-1.2u));
 endfig;
endfor;
end