NAME
gpic - compile pictures for troff or TeX
SYNOPSIS
gpic [ -nvC ] [ filename ... ]
gpic -t [ -cvzC ] [ 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.
-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.
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 orTeX. 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 the value of variable will be changed only
in the innermost block in which it is defined. (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.)
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 10x)
sqrt(x)
int(x)
rand() (return a random number between 0 and 1)
rand(x) (return a random number between 1 and x; deprecated)
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 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 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 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, using only the e, f, g or % format characters.
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 then 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.
Arrow heads will be drawn as solid triangles if the variable
arrowhead is non-zero and either TeX mode is enabled or the
-x option has been given. Initially arrowhead has a value
of 1.
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
when 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 is a single token: no space is allowed between
the ' and the th. For example,
for i = 1 to 4 do {
line from `i'th box.nw to `i+1'th box.se
}
FILES
/usr/products/src2/gcc/AIX.d/lib/groff/tmac/tmac.pic
Example definitions of the PS and PE macros.
SEE ALSO
gtroff(1), groff_out(5), tex(1)
Tpic: Pic for TeX
AT&T Bell Laboratories, Computing Science Technical Report
No. 116, PIC - A Graphics Language for Typesetting. (This
can be obtained by sending a mail message to
netlib@research.att.com with a body of
`send 116 from research/cstr'.)
BUGS
Input characters that are illegal for groff (ie those with
ASCII code 0 or between 013 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.