@options;
  chgt_etat_bloc("a",{v},M1,N1,P1,poly1,sPP1,sMM1,sNN1);
  chgt_etat_bloc("b",{v},M1,N1,P1,poly1,sPP1,sMM1,sNN1,M',N',P',sM1M',sN1N',sP1P',poly2);
  chgt_etat_bloc("c",{v},sMM',sNN',sPP',poly2,M',N',P');

@figure;
  A = point( -1.15 , 3.4 )  { rond2 };
  B = point( 1.7 , 0.3 )  { rond2 };
  M = point( -5.85 , 1.77 )  { croix0 , (-0.37,-0.07) };
  N = point( -6.45 , 5.3 )  { croix0 , (-0.37,-0.77) };
  P = point( -1.57 , 1.27 )  { croix0 , (-0.03,-0.13) };
  poly0 = polygone( M , N , P  )  { rouge , plein30 };
  M1 = symetrique( M , A )  { croix0 , (0.11,-0.83) , i };
  N1 = symetrique( N , A )  { croix0 , (-0.37,-0.07) , i };
  P1 = symetrique( P , A )  { croix0 , (-0.5,-0.73) , i };
  poly1 = polygone( M1 , N1 , P1  )  { rouge , plein30 , i };
  sPP1 = segment( P , P1 )  { 7 , i };
  sMM1 = segment( M , M1 )  { 7 , i };
  sNN1 = segment( N , N1 )  { 7 , i };
  P' = symetrique( P1 , B )  { croix0 , (-0.37,-0.07) , i };
  N' = symetrique( N1 , B )  { croix0 , (-0.56,-0.61) , i };
  M' = symetrique( M1 , B )  { croix0 , (-0.37,-0.07) , i };
  poly2 = polygone( M' , N' , P'  )  { rouge , plein30 , i };
  sN1N' = segment( N1 , N' )  { 7 , i };
  sM1M' = segment( M1 , M' )  { 7 , i };
  sP1P' = segment( P1 , P' )  { 7 , i };
  sMM' = segment( M , M' )  { 7 , i };
  sNN' = segment( N , N' )  { 7 , i };
  sPP' = segment( P , P' )  { 7 , i };