mode_setup; em#:=10pt#; cap#:=7pt#; thin#:=1/3pt#; thick#:=5/6pt#; o#:=1/5pt#; define_pixels(em,cap); define_blacker_pixels(thin,thick); define_corrected_pixels(o); curve_sidebar=round 1/18em; beginchar("O",0.8em#,cap#,0); "The letter O"; penpos1(thick,10); penpos2(.1[thin,thick],90-10); penpos3(thick,180+10); penpos4(thin,270-10); x1l=w-x3l=curve_sidebar; x2=x4=.5w; y1=.49h; y2l=-o; y3=.51h; y4l=h+o; penstroke z1e{down}..z2e{right} ..z3e{up}..z4e{left}..cycle; penlabels(1,2,3,4); endchar; def test_I(expr code,trial_stem,trial_width) = stem#:=trial_stem*pt#; define_blacker_pixels(stem); beginchar(code,trial_width*em#,cap#,0); "The letter I"; penpos1(stem,15); penpos2(.9stem,12); penpos3(stem,10); x1=x2=x3=.5w; y1=h; y2=.55h; y3=0; x2l:=1/6[x2l,x2]; penstroke z1e..z2e{down}..z3e; penlabels(1,2,3); endchar; enddef;