import geometry; size(7cm,0); path chemin=(0,0){dir(45)}..(1,0)..(1,.5)..(1.5,1)..(0,1)..cycle; pen stylo1=red, stylo2=blue; point p1=(0.5,0.5), p2=(0.5,0.8); real r1=.5, r2=0.85; circle c1=circle(p1,r1), c2=circle(p2,r2); radialshade(chemin,stylo1,p1,r1,stylo2,p2,r2); draw(chemin); dot(chemin); draw(c1^^c2,1bp+dashed); dot(p1^^p2,4bp+green);