[NTG-context] Hatch an area with Metapost (Metafun)

Hi, How hatched trapezoid MBCD ? Best regards, Fabrice \starttext \startMPcode path p ; p=unitsquare scaled 4cm ; draw p ; pair z ; z=point 3.6 of p ; draw z--urcorner p ; label.llft(btex B etex,llcorner p) ; label.lrt(btex C etex,lrcorner p) ; label.ulft(btex A etex,ulcorner p) ; label.urt(btex D etex, urcorner p) ; label.lft(btex M etex, z) ; \stopMPcode \stoptext