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## pic(1)

### NAME

       pic - compile pictures for troff or TeX



### SYNOPSIS

       pic [ -nvCSU ] [ filename ... ]
pic -t [ -cvzCSU ] [ filename ... ]



### DESCRIPTION

       This manual page describes the GNU version of pic, which is part of the
groff document formatting system.  pic compiles	descriptions  of  pic-
tures  embedded	within troff or TeX input files into commands that are
understood by TeX or troff.  Each picture starts with a line  beginning
with  .PS and ends with a line beginning with .PE.  Anything outside of
.PS and .PE is passed through without change.

It is the user's responsibility to provide appropriate  definitions  of
the  PS and PE macros.  When the macro package being used does not sup-
ply such definitions (for example, old versions	of  -ms),  appropriate
definitions can be obtained with -mpic: These will center each picture.



### OPTIONS

       Options that do not take arguments may be grouped behind  a  single  -.
The  special  option  -- can be used to mark the end of the options.  A
filename of - refers to the standard input.

-C     Recognize .PS and .PE even when followed by  a  character  other
than space or newline.

-S     Safer mode; do not execute sh commands.  This can be useful when
operating on untrustworthy input.  (enabled by default)

-U     Unsafe mode; revert the default option -S.

-n     Don't use the groff extensions to the  troff  drawing  commands.
You  should  use	this  if  you  are  using a postprocessor that
doesn't support these extensions.  The extensions are  described
in groff_out(5).	The -n option also causes pic not to use zero-
length lines to draw dots in troff mode.

-t     TeX mode.

-c     Be more compatible with tpic.  Implies -t.  Lines beginning with
\  are not passed through transparently.	Lines beginning with .
are passed through with the initial .  changed  to  \.   A  line
beginning  with  .ps  is	given  special	treatment: it takes an
optional integer argument specifying  the  line  thickness  (pen
size)  in  milliinches; a missing argument restores the previous
line thickness; the default line	thickness  is  8  milliinches.
The  line thickness thus specified takes effect only when a non-
negative line thickness has not been specified  by  use  of  the
thickness attribute or by setting the linethick variable.

-v     Print the version number.

-z     In TeX mode draw dots using zero-length lines.



### USAGE

       This section describes only the differences between  GNU  pic  and  the
original version of pic.  Many of these differences also apply to newer
versions of Unix pic.  A complete documentation	is  available  in  the
file

/usr/src/contrib/groff/doc/pic.ms

TeX mode
TeX  mode  is enabled by the -t option.	In TeX mode, pic will define a
vbox called \graph for each picture.  Use the figname command to change
the  name  of  the  vbox.  You must yourself print that vbox using, for
example, the command

\centerline{\box\graph}

Actually, since the vbox has a height  of  zero	(it  is  defined  with
\vtop) this will produce slightly more vertical space above the picture
than below it;

\centerline{\raise 1em\box\graph}

would avoid this.

To make the vbox having a positive height and a depth of zero (as  used
e.g. by LaTeX's graphics.sty), define the following macro in your docu-
ment:

\def\gpicbox#1{%
\vbox{\unvbox\csname #1\endcsname\kern 0pt}}

Now you can simply say \gpicbox{graph} instead of \box\graph.

You must use a TeX driver that supports the tpic specials, version 2.

Lines beginning with \ are passed through transparently; a %  is  added
to  the	end  of the line to avoid unwanted spaces.  You can safely use
this feature to change fonts or to change the value  of	\baselineskip.
Anything  else  may  well  produce undesirable results; use at your own
risk.  Lines beginning with a period are not given any  special	treat-
ment.

Commands
for variable = expr1 to expr2 [by [*]expr3] do X body X
Set variable to expr1.  While the value of variable is less than
or equal to expr2, do body and increment variable by  expr3;  if
by  is not given, increment variable by 1.  If expr3 is prefixed
by * then variable will instead be multiplied by expr3.	X  can
be any character not occurring in body.

if expr then X if-true X [else Y if-false Y]
Evaluate	expr;  if it is non-zero then do if-true, otherwise do
if-false.  X can be any character not occurring in  if-true.   Y
can be any character not occurring in if-false.

print arg...
Concatenate  the	arguments and print as a line on stderr.  Each

sh X command X
Pass command to a shell.	X can be any character	not  occurring
in command.

copy "filename"
Include filename at this point in the file.

copy ["filename"] thru X body X [until "word"]
copy ["filename"] thru macro [until "word"]
This  construct  does  body  once for each line of filename; the
line is split into blank-delimited words, and occurrences of  $i in body, for i between 1 and 9, are replaced by the i-th word of the line. If filename is not given, lines are taken from the current input up to .PE. If an until clause is specified, lines will be read only until a line the first word of which is word; that line will then be discarded. X can be any character not occurring in body. For example, .PS copy thru % circle at ($1,\$2) % until "END"
1 2
3 4
5 6
END
box
.PE

is equivalent to

.PS
circle at (1,2)
circle at (3,4)
circle at (5,6)
box
.PE

The commands to be performed for each line  can  also  be  taken
from  a macro defined earlier by giving the name of the macro as
the argument to thru.

reset
reset variable1[,] variable2 ...
Reset pre-defined variables variable1, variable2	...  to  their
default  values.	 If  no  arguments  are  given, reset all pre-
defined variables to their default values.  Note that  assigning
a value to scale also causes all pre-defined variables that con-
trol dimensions to be reset to their default  values  times  the
new value of scale.

plot expr ["text"]
This  is	a  text object which is constructed by using text as a
format string for sprintf with an argument of expr.  If text  is
omitted  a  format  string  of  "%g" is used.  Attributes can be
specified in the same way as for a normal text object.  Be  very
careful  that you specify an appropriate format string; pic does
only very limited checking of the string.  This is deprecated in
favour of sprintf.

.PS
x = 3
y = 3
[
x := 5
y = 5
]
print x " " y
.PE

prints 5 3.

Arguments of the form

X anything X

are also allowed to be of the form

{ anything }

In this case anything can contain balanced  occurrences	of  {  and  }.
Strings may contain X or imbalanced occurrences of { and }.

Expressions
The syntax for expressions has been significantly extended:

x ^ y (exponentiation)
sin(x)
cos(x)
atan2(y, x)
log(x) (base 10)
exp(x) (base 10, ie 10^x)
sqrt(x)
int(x)
rand() (return a random number between 0 and 1)
rand(x) (return a random number between 1 and x; deprecated)
srand(x) (set the random number seed)
max(e1, e2)
min(e1, e2)
!e
e1 && e2
e1 || e2
e1 == e2
e1 != e2
e1 >= e2
e1 > e2
e1 <= e2
e1 < e2
"str1" == "str2"
"str1" != "str2"

String comparison expressions must be parenthesised in some contexts to
avoid ambiguity.

Other Changes
A bare expression, expr, is acceptable as an attribute; it  is  equiva-
lent to dir expr, where dir is the current direction.  For example
ables maxpswid and maxpsht.  Initially these have values 8.5 and 11.

Scientific notation is allowed for numbers.  For example
x = 5e-2

Text attributes can be compounded.  For example,
"foo" above ljust
is legal.

There is no limit to the depth to which blocks can  be  examined.   For
example,
[A: [B: [C: box ]]] with .A.B.C.sw at 1,2
circle at last [].A.B.C
is acceptable.

Arcs  now have compass points determined by the circle of which the arc
is a part.

Circles and arcs can be dotted or dashed.  In TeX mode splines  can  be
dotted or dashed.

of the quarter-circles at each corner.  If no rad or diam attribute  is
A box with rounded corners can be dotted or dashed.

The .PS line can have a second argument specifying a maximum height for
the  picture.   If  the	width  of  zero is specified the width will be
ignored in computing the scaling factor for the picture.  Note that GNU
pic  will  always scale a picture by the same amount vertically as well
as horizontally.  This is different from the  DWB  2.0  pic  which  may
scale a picture by a different amount vertically than horizontally if a
height is specified.

Each text object has an invisible box associated with it.  The  compass
points  of  a  text  object  are  determined by this box.  The implicit
motion associated with the object is also determined by this box.   The
dimensions  of this box are taken from the width and height attributes;
if the width attribute is not supplied then the width will be taken  to
be  textwid;  if  the  height attribute is not supplied then the height
will be taken to be the number of  text	strings  associated  with  the
object times textht.  Initially textwid and textht have a value of 0.

In  (almost  all)  places  where  a  quoted text string can be used, an
expression of the form

sprintf("format", arg,...)

can also be used; this will produce the arguments  formatted  according
to format, which should be a string as described in printf(3) appropri-
ate for the number of arguments supplied.

The thickness of the lines used to draw objects is  controlled  by  the
linethick  variable.   This  gives the thickness of lines in points.  A
negative value means use the default thickness:	in  TeX  output  mode,
this  means  use  a thickness of 8 milliinches; in TeX output mode with
the -c option, this means use  the  line  thickness  specified  by  .ps
lines; in troff output mode, this means use a thickness proportional to
nor by the width or height given in the .PS line.

Boxes (including boxes with rounded corners), circles and ellipses  can
be  filled  by  giving  them  an  attribute of fill[ed].  This takes an
optional argument of an expression with a value between 0 and 1; 0 will
fill  it with white, 1 with black, values in between with a proportion-
ally gray shade.  A value greater than 1 can also be used:  this  means
fill  with  the shade of gray that is currently being used for text and
lines.  Normally this will be black, but output devices may  provide  a
mechanism  for  changing  this.	Without an argument, then the value of
the variable fillval will be used.  Initially this has a value of  0.5.
The  invisible  attribute  does not affect the filling of objects.  Any
text associated with a filled object will be added after the object has
been filled, so that the text will not be obscured by the filling.

Three  additional  modifiers  are available to specify colored objects:
outline[d] sets the color of the outline, shaded the  fill  color,  and
colo[u]r[ed]  sets both.  All three keywords expect a suffix specifying
the color, for example

Currently, color support isn't available in TeX mode.  Predefined color
names  for  groff  are  in the device macro files, for example ps.tmac;
additional colors can be defined with the .defcolor  request  (see  the
manual page of troff(1) for more details).

To  change  the	name  of the vbox in TeX mode, set the pseudo-variable
figname (which is actually a specially parsed command)  within  a  pic-
ture.  Example:

.PS
figname = foobar;
...
.PE

The picture is then available in the box \foobar.

pic  assumes  that  at  the  beginning of a picture both glyph and fill
color are set to the default value.

Arrow heads will be drawn as solid triangles if the variable  arrowhead
is  non-zero  and  either  TeX mode is enabled or the -n option has not
been given.  Initially arrowhead has a value  of 1.   Note  that  solid
arrow heads are always filled with the current outline color.

The troff output of pic is device-independent.  The -T option is there-
fore redundant.	All numbers are taken to be  in  inches;  numbers  are
never interpreted to be in troff machine units.

Objects	can  have  an  aligned	attribute.  This will only work if the
postprocessor is grops.	Any text associated with an object having  the
aligned	attribute  will  be  rotated about the center of the object so
that it is aligned in the direction from the start  point  to  the  end
point  of the object.  Note that this attribute will have no effect for
objects whose start and end points are coincident.

In places where nth is allowed expr'th is also allowed.  Note that 'th
To obtain a stand-alone picture from a pic file, enclose your pic  code
with  .PS and .PE requests; roff configuration commands may be added at
the beginning of the file, but no roff text.

It is necessary to feed this file into groff without  adding  any  page
information,  so you must check which .PS and .PE requests are actually
called.	For example, the mm macro package adds a page number, which is
very annoying.  At the moment, calling standard groff without any macro
package works.  Alternatively, you can define your own  requests,  e.g.
to do nothing:

.de PS
..
.de PE
..

groff  itself  does  not  provide direct conversion into other graphics
file formats.  But there are lots of possibilities if you first	trans-
form  your  picture  into  PostScript(R)  format using the groff option
-Tps.  Since this ps-file lacks BoundingBox information it is not  very
useful  by  itself,  but  it may be fed into other conversion programs,
usually named ps2other or pstoother or the like.  Moreover,  the  Post-
Script  interpreter  ghostscript  (gs) has built-in graphics conversion
devices that are called with the option

gs -sDEVICE=<devname>

Call
gs --help

for a list of the available devices.

As the Encapsulated PostScript File Format EPS is getting more and more
important,  and	the conversion wasn't regarded trivial in the past you
might be interested to know that  there	is  a  conversion  tool  named
ps2eps  which  does  the  right	job.   It is much better than the tool
ps2epsi packaged with gs.

For bitmapped graphic formats, you should use  pstopnm;	the  resulting
(intermediate) PNM file can be then converted to virtually any graphics
format using the tools of the netpbm package .



### FILES

       /usr/share/tmac/pic.tmac   Example definitions of the PS and PE macros.



       troff(1),   groff_out(5),   tex(1),   gs(1),   ps2eps(1),   pstopnm(1),
ps2epsi(1), pnm(5)

Tpic: Pic for TeX

Brian W. Kernighan, PIC -- A Graphics Language  for  Typesetting  (User
Manual).   AT&T	Bell  Laboratories, Computing Science Technical Report
No. 116	<http://cm.bell-labs.com/cm/cs/cstr/116.ps.gz>	(revised  May,
1991).

ps2eps is available from CTAN mirrors, e.g.
<ftp://ftp.dante.de/tex-archive/support/ps2eps/>
Input  characters  that are invalid for groff (ie those with ASCII code
0, or 013 octal, or between 015 and 037 octal, or between 0200 and 0237
octal) are rejected even in TeX mode.

The interpretation of fillval is incompatible with the pic in 10th edi-
tion Unix, which interprets 0 as black and 1 as white.

`