Path: utzoo!yunexus!mathieu
From: mathieu@yunexus.UUCP (Pierre Mathieu)
Newsgroups: comp.text
Subject: Drawing a large circle in LaTeX
Keywords: circle latex metafont
Message-ID: <4369@yunexus.UUCP>
Date: 13 Oct 89 22:14:50 GMT
Article-I.D.: yunexus.4369
Organization: Center for Research in Experimental Space Science
Lines: 109

I am trying to get LaTeX to give me a large circle in \picture mode, 
larger than the largest which it appears to accept, apparently 40pt.
I would like to know if anyone has suggestions on the best way to proceed.
What I want is basically an 80pt circle.

I have tried using the TeXbook \path macro, which appears on page 390,
and producing new arcs in the lcircle10 font using METAFONT in the 
following way:

1) I used the \path macro. Note the use of the lcircle10 font
   and the characters 50, 51, 52, and 53 (40, 41, 42, 43 in decimal). 
   These are the new characters I tried to create with METAFONT 
   (see item 2). The biggest arcs provided in lcircle10 where 
   characters 44, 45, 46, and 47 (36, 37, 38, 39 in decimal).

%
% Path macro from TeXbook, p.390.
%
\font\qc=lcircle10
\catcode`\ =9 \endlinechar=-1 %ignore all spaces (temporarily)
\newcount\dir \newdimen\y \newdimen\w
\newif\ifvisible \let\B=\visibletrue \let\W=\visiblefalse
\newbox\NE \newbox\NW \newbox\SE \newbox\SW \newbox\NS \newbox\EW
\setbox\SW=\hbox{\qc \char'50} \setbox\NW=\hbox{\qc \char'51}
\setbox\NE=\hbox{\qc \char'52} \setbox\SE=\hbox{\qc \char'53}
\w=\wd\SW \dimen0=\fontdimen8\qc
\setbox\EW=\hbox{\kern-\dp\SW \vrule height\dimen0 width\wd\SW} \wd\EW=\w
\setbox\NS=\hbox{\vrule height\ht\SW depth\dp\SW width\dimen0} \wd\NS=\w
\def\L{\ifcase\dir \dy+\NW \or\dx-\SW \or\dy-\SE \or\dx+\NE\dd-4\fi \dd+1}
\def\S{\ifcase\dir \dx+\EW \or\dy+\NS \or\dx-\EW \or\dy-\NS \fi}
\def\R{\ifcase\dir \dy-\SW\dd+4 \or\dx+\SE \or\dy+\NE \or\dx-\NW\fi \dd-1}
\def\T{\ifcase\dir\kern-\w\dd+2\or\ey-\dd+2\or\kern\w\dd-2\or\ey+\dd-2\fi}
\edef\dd#1#2{\global\advance\dir#1#2\space}
\def\dx#1#2{\ifvisible\raise\y\copy#2 \if#1-\kern-2\w\fi\else\kern#1\w\fi}
\def\dy#1#2{\ifvisible\raise\y\copy#2 \kern-\w \fi \global\advance\y#1\w}
\def\ey#1{\global\advance\y#1\w}
\def\path#1{\hbox{\B \dir=0 \y=0pt #1}}
\catcode`\ =10 \endlinechar=`\^^M % resume normal spacing conventions

\newcount\n % the current order in the \dragon and \nogard macros
\def\dragon{\ifnum\n>0{\advance\n-1 \dragon\L\nogard}\fi}
\def\nogard{\ifnum\n>0{\advance\n-1 \dragon\R\nogard}\fi}


2) I then modified the METAFONT source for lcircle10 by adding the lines
   below, in the hope of creating 40pt arcs and, when pieced together
   with \path, an 80pt circle.


cmchar "40pt, top right";
qbeginchar(40,80pt#);
numeric delta;
pickup nib;
arcs;
draw z7{right}..z6{downright}..z5{down};
endchar;

cmchar "40pt, bottom right";
qbeginchar(41,80pt#);
numeric delta;
pickup nib;
arcs;
draw z1{down}..z8{downleft}..z7{left};
endchar;

cmchar "40pt, bottom left";
qbeginchar(42,80pt#);
numeric delta;
pickup nib;
arcs;
draw z3{left}..z2{upleft}..z1{up};
endchar;

cmchar "40pt, top left";
qbeginchar(43,80pt#);
numeric delta;
pickup nib;
arcs;
draw z5{up}..z4{upright}..z3{right};
endchar;


3) I also tried adding a straight 80pt circle in the lcircle10 font.

cmchar "80pt, circle";
beginchar(111,80pt#,0pt#,0pt#);
pickup nib;
draw fullcircle scaled w;
endchar;




Well, after running METAFONT and creating a new lcircle10.300gf font file,
I found that the above steps didn't work. Neither the new arcs nor the 80 pt 
circle showed up when I used the \path command in my code. HOWEVER, if I 
used some of the original font characters such as 44, 45, 46, 47, \path
would draw the circle of the right size quite nicely.

	Result, I'm confused. What am I doing wrong? Is there an easier
way of getting a large circle. HELP!


-----
			   
Pierre Mathieu            
CRESS, York University,  
Ontario, Canada         
mathieu@clid.yorku.ca