% File: lambda.mp beginfig(1); r = 2cm; path c; c = fullcircle scaled 2r; z.lambda.top = (0,(r-2mm)) rotated 15; z.lambda.lft = (0,-(r-2mm)) rotated -40; z.lambda.rt = (0,-(r-2mm)) rotated 40; z.pi = (0,r+3mm); path d; d = quartercircle scaled 2r rotated -90 & halfcircle scaled 2r; fill c withcolor red; z.lambda.mid = .5[z.lambda.top,z.lambda.rt]; path lambda.top, lambda.rt; lambda.top = z.lambda.mid .. (0,(r+1mm)) rotated 15; lambda.rt = z.lambda.mid .. (0,-(r+1mm)) rotated 40; path bluepart; bluepart = buildcycle(lambda.top, d, lambda.rt); fill bluepart withcolor blue; drawdblarrow (-r,-(r+6mm)) -- (r, -(r+6mm)); label.bot(btex $1$ etex, (0,-(r+7mm))); drawarrow z.pi rotated 8 .. z.pi rotated 80 .. z.pi rotated 178; drawarrow z.pi rotated -8 .. z.pi rotated -80 .. z.pi rotated -178; label(btex $\pi$ etex, z.pi); pickup pencircle scaled 4mm; draw z.lambda.top .. z.lambda.rt withcolor white; draw .4[z.lambda.top,z.lambda.rt] .. z.lambda.lft withcolor white; endfig; end.