vardef clock_roman primary h =
  if     h<5: ""  for i=1 upto h: & "I" endfor
  elseif h<9: "V" for i=6 upto h: & "I" endfor
  elseif h=9: "IX"
  else:       "X" for i=11 upto h: & "I" endfor
  fi
enddef;

path hand[];
hand1 = origin .. (.257,1/50) .. (.377,1/60)
       & (.377,1/60) {up} .. (.40,3/50)
       .. (.60, 1/40) .. {right} (.75,0);
hand1 := (hand1 .. reverse hand1 reflectedabout(left,right)
       .. cycle) scaled 50;
hand2 = origin  .. (.60, 1/64) .. {right} (.925,0);
hand2 := (hand2 .. reverse hand2 reflectedabout(left,right)
       .. cycle) scaled 50;

% hour of the day to degrees
vardef htod(expr hours)   = 30*((15-hours)   mod 12) enddef;
vardef mtod(expr minutes) =  6*((75-minutes) mod 60) enddef;

vardef clock(expr hours, minutes) = image(
 % face and outer ring
 fill fullcircle scaled 100 withcolor 1/256(240, 240, 230);
 draw fullcircle scaled  99 withcolor .8 white;
 draw fullcircle scaled 100 withpen pencircle scaled 7/8;
 % hour and minute marks
 for t=0 step  6 until 359:
   draw ((48,0)--(49,0)) rotated t;
 endfor
 for t=0 step 30 until 359:
   draw ((47,0)--(49,0)) rotated t withpen pencircle scaled 7/8;
 endfor
 % numerals
 for h=1 upto 12:
   label(decimal h infont "bchr8r", (40,0) rotated htod(h));
 endfor
 % hands rotated to the given time
 pickup pencircle scaled 7/8;
 filldraw hand1 rotated htod(hours+minutes/60);
 filldraw hand2 rotated mtod(minutes);
 % draw the center on top
   draw origin withpen pencircle scaled 5;
 undraw origin withpen pencircle scaled 3;
) enddef;