COMMENT ⊗   VALID 00002 PAGES
C REC  PAGE   DESCRIPTION
C00001 00001
C00002 00002	% halftone font with 33 levels of gray, characters "0" (white) to "P" (black)
C00004 ENDMK
C⊗;
% halftone font with 33 levels of gray, characters "0" (white) to "P" (black)

pair p[]; % the pixels in order (first p0 becomes black, then p1, etc)
p0=(1,1); p4=(2,0); p8=(1,0); p12=(0,0);
p16=(3,-1); p20=(2,-1); p24=(1,-1); p28=(2,-2);
transform r; r=identity rotatedaround ((1.5,1.5),90);

for i=0 step 4 until 28:
 p[i+1]=p[i] transformed r;
 p[i+3]=p[i+1] transformed r;
 p[i+2]=p[i+3] transformed r;
 endfor

w#:=8/pt; % that's 8 pixels
font_quad:=w#; designsize:=8w#;

picture prevchar; prevchar=nullpicture; % the pixels blackened so far
for i=0 upto 32:
 beginchar(i+ASCII"0",w#,.5w#,0); currentpicture:=prevchar;
 if i>0: addto currentpicture also unitpixel shifted p[i-1]; fi
 prevchar:=currentpicture; endchar;
 endfor