Provided by: groff-base_1.18.1.1-16_i386 bug

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
       pictures  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
       supply 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.

       The following options supported by other versions of pic are ignored:

       -D     Draw  all  lines  using the \D escape sequence.  pic always does
              this.

       -T dev Generate output for the troff device dev.  This  is  unnecessary
              because the troff output generated by pic is device-independent.

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/share/doc/groff/1.18.1/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.  You must yourself print that vbox
       using, for example, the command

              \centerline{\box\graph}

       Actually,  since  the  vbox  has  a  height  of  zero this will produce
       slightly more vertical space above the picture than below it;

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

       would avoid this.

       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
       treatment.

   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
              arg must be an expression, a position, or text.  This is  useful
              for debugging.

       command arg...
              Concatenate  the  arguments  and  pass them through as a line to
              troff or TeX.  Each arg must be an expression,  a  position,  or
              text.   This  has a similar effect to a line beginning with . or
              \, but allows the values of variables to be passed through.

       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
              control 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.

       variable := expr
              This  is  similar  to = except variable must already be defined,
              and expr  will  be  assigned  to  variable  without  creating  a
              variable  local  to  the current block.  (By contrast, = defines
              the variable in the current block if it is not  already  defined
              there,  and  then  changes the value in the current block only.)
              For example, the following:

                     .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
       equivalent  to  dir expr,  where  dir  is  the  current direction.  For
       example

              line 2i

       means draw a line 2 inches long in the current direction.  The ‘i’  (or
       ‘I’)  character  is  ignored;  to use another measurement unit, set the
       scale variable to an appropriate value.

       The maximum width  and  height  of  the  picture  are  taken  from  the
       variables  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.

       Boxes can have rounded corners.  The rad attribute specifies the radius
       of the quarter-circles at each corner.  If no rad or diam attribute  is
       given, a radius of boxrad is used.  Initially, boxrad has a value of 0.
       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)
       appropriate 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
       the pointsize.  A zero value means  draw  the  thinnest  possible  line
       supported by the output device.  Initially it has a value of -1.  There
       is also a thick[ness] attribute.  For example,

              circle thickness 1.5

       would draw a circle using a line with a thickness of 1.5  points.   The
       thickness  of lines is not affected by the value of the scale variable,
       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
       proportionally 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

              circle shaded "green" outline "black"

       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).

       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
       therefore  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 ‘exprth is also allowed.  Note that ’th
       is a single token: no space is allowed between the ’ and the  th.   For
       example,

              for i = 1 to 4 do {
                 line fromith box.nw toi+1th box.se
              }

CONVERSION

       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
       transform your picture into PostScript® 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
       PostScript  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/groff/1.18.1/tmac/pic.tmac
              Example definitions of the PS and PE macros.

SEE ALSO

       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/>

       W. Richard Stevens - Turning PIC Into HTML
       <http://www.kohala.com/start/troff/pic2html.html>

       W. Richard Stevens - Examples of picMacros
       <http://www.kohala.com/start/troff/pic.examples.ps>

BUGS

       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
       edition Unix, which interprets 0 as black and 1 as white.

       PostScript® is a registered trademark of Adobe Systems Incorporation.