%@AUTEUR: Christophe Poulain (4 février 2003)
 
 vardef hachurage(expr chemin, angle, ecart, trace)suffix couleur =
   save $;
   picture $;
   path support;
   support=(((-37cm,0))--((37cm,0))) rotated angle;
   if trace=1:
     drawoptions(dashed evenly);
   elseif trace=2:
     drawoptions(dashed dashpattern(on12bp off6bp on3bp off6bp));
   fi;
   $ = image(
     for j=-200 upto 200:
      if ((support shifted (ecart*j*(1,0))) intersectiontimes chemin)<>(-1,-1):
        draw support shifted (ecart*j*(1,0)) 
            withcolor if str couleur="":(0,0,0) else:couleur fi;
      fi
     endfor;
   );
   clip $ to chemin;
   drawoptions();
   $
 enddef;
 
 color rouge;
 rouge = (1,0,0);
 
 

 beginfig(1);
   path p,q;
   p = fullcircle scaled 3cm;
   draw hachurage(p,45,2mm,0)rouge;
   draw p;
   q = (p scaled 0.5) shifted (4cm,2cm);
   draw hachurage(q,30,4mm,1);
   draw q;
 endfig;
 
 def dessine(expr p,a,e,t,s)(text couleurs)  =
     save co,n;
     color co[];
     numeric n;
     n := 0; forsuffixes c = couleurs: co[incr n] = c; endfor;
     if n = 1: co2 = co1; fi;
     draw hachurage(p,a,e,t) co1;
     draw p withpen pencircle scaled s withcolor co2;
 enddef;
     
 

 beginfig(2);
  path carre,cercle;
  cercle = fullcircle scaled 2cm;
  carre = ((0,0)--(3cm,0)--(3cm,3cm)--(0,3cm)--cycle) shifted (3cm,-1cm);
  dessine(((3cm,1cm)..(4cm,3cm)..(1cm,2cm)..cycle),30,4mm,3,1pt,black);
  dessine(cercle,60,3mm,0,2pt,green);
  dessine(carre,45,5mm,2,1pt,blue,red);
 endfig;
 end