% --- start of displayed preamble in the book --- vardef star(expr n) = for i_:=0 upto 2n-1: if odd i_: 1/2 fi (right rotated (180*(i_/n))) -- endfor cycle enddef; vardef blur(expr p,w,col)= for i:=10 downto 1: pickup pencircle scaled ((i*i/100)*w); draw p withcolor ((i/10)[col,white]); endfor; enddef; % --- end of displayed preamble in the book --- defaultfont:="ptmr8r"; warningcheck:=0; beginfig(1) blur (unitsquare scaled 3cm,.5mm,red); blur (fullcircle scaled 4cm,1mm,blue); blur (star(10) xscaled 30mm yscaled 20mm rotated 20,2mm,black); endfig; end;