term% cat index.txt PIC(1) General Commands Manual PIC(1)
NAME
pic, tpic - troff and tex preprocessors for drawing pictures
SYNOPSIS
pic [ files ]
tpic [ files ]
DESCRIPTION
Pic is a troff(1) preprocessor for drawing figures on a typesetter.
Pic code is contained between .PS and .PE lines:
.PS optional-width optional-height
element-list
.PE
or in a file mentioned in a .PS line:
.PS optional-width optional-height <file
If optional-width is present, the picture is made that many inches
wide, regardless of any dimensions used internally. The height is
scaled in the same proportion unless optional-height is present. If
.PF is used instead of .PE, the typesetting position after printing is
restored to what it was upon entry.
An element-list is a list of elements:
primitive attribute-list
placename : element
placename : position
var = expr
direction
{ element-list }
[ element-list ]
for var = expr to expr by expr do { anything }
if expr then { anything } else { anything }
copy file, copy thru macro, copy file thru macro
sh { commandline }
print expr
reset optional var-list
troff-command
Elements are separated by newlines or semicolons; a long element may be
continued by ending the line with a backslash. Comments are introduced
by a # and terminated by a newline. Variable names begin with a lower
case letter; place names begin with upper case. Place and variable
names retain their values from one picture to the next.
After each primitive the current position moves in the current direc‐
tion (up,down, left,right (default)) by the size of the primitive. The
current position and direction are saved upon entry to a {...} block
and restored upon exit. Elements within a block enclosed in [...] are
treated as a unit; the dimensions are determined by the extreme points
of the contained objects. Names, variables, and direction of motion
within a block are local to that block.
Troff-command is any line that begins with a period. Such a line is
assumed to make sense in the context where it appears; generally, this
means only size and font changes.
The primitive objects are:
box circle ellipse arc line arrow spline move text-list
is a synonym for
An attribute-list is a sequence of zero or more attributes; each attri‐
bute consists of a keyword, perhaps followed by a value.
h(eigh)t expr wid(th) expr
rad(ius) expr diam(eter) expr
up opt-expr down opt-expr
right opt-expr left opt-expr
from position to position
at position with corner
by expr, expr then
dotted opt-expr dashed opt-expr
chop opt-expr -> <- <->
invis same
text-list expr
Missing attributes and values are filled in from defaults. Not all at‐
tributes make sense for all primitives; irrelevant ones are silently
ignored. The attribute causes the geometrical center to be put at the
specified place; causes the position on the object to be put at the
specified place. For lines, splines and arcs, and refer to arrowhead
size. A bare expr implies motion in the current direction.
Text is normally an attribute of some primitive; by default it is
placed at the geometrical center of the object. Stand-alone text is
also permitted. A text list is a list of text items:
text-item:
"..." positioning ...
sprintf("format", expr, ...) positioning ...
positioning:
center ljust rjust above below
If there are multiple text items for some primitive, they are arranged
vertically and centered except as qualified. Positioning requests ap‐
ply to each item independently. Text items may contain troff commands
for size and font changes, local motions, etc., but make sure that
these are balanced so that the entering state is restored before exit‐
ing.
A position is ultimately an x,y coordinate pair, but it may be speci‐
fied in other ways.
position:
expr, expr
place ± expr, expr
place ± ( expr, expr )
( position, position )x from one, y the other
expr [of the way] between position and position
expr < position , position >
( position )
place:
placename optional-corner
corner of placename
nth primitive optional-corner
corner of nth primitive
Here
An optional-corner is one of the eight compass points or the center or
the start or end of a primitive.
optional-corner:
.n .e .w .s .ne .se .nw .sw .c .start .end
corner:
top bot left right start end
Each object in a picture has an ordinal number; nth refers to this.
nth:
nth, nth last
The built-in variables and their default values are:
boxwid 0.75 boxht 0.5
circlerad 0.25 arcrad 0.25
ellipsewid 0.75 ellipseht 0.5
linewid 0.5 lineht 0.5
movewid 0.5 moveht 0.5
textwid 0 textht 0
arrowwid 0.05 arrowht 0.1
dashwid 0.1 arrowhead 2
scale 1
These may be changed at any time, and the new values remain in force
from picture to picture until changed again or reset by a statement.
Variables changed within [ and ] revert to their previous value upon
exit from the block. Dimensions are divided by scale during output.
Expressions in pic are evaluated in floating point. All numbers repre‐
senting dimensions are taken to be in inches.
expr:
expr op expr
- expr
! expr
( expr )
variable
number
place .x place .y place .ht place .wid place .rad
sin(expr) cos(expr) atan2(expr,expr) log(expr) exp(expr)
sqrt(expr) max(expr,expr) min(expr,expr) int(expr) rand()
op:
+ - * / % < <= > >= == != && ||
The define and undef statements are not part of the grammar.
define name { replacement text }
undef name
Occurrences of $1, $2, etc., in the replacement text will be replaced
by the corresponding arguments if name is invoked as
name(arg1, arg2, ...)
Non-existent arguments are replaced by null strings. Replacement text
may contain newlines. The undef statement removes the definition of a
macro.
Tpic is a tex(1) preprocessor that accepts pic language. It produces
Tex commands that define a box called \graph, which contains the pic‐
ture. The box may be output this way:
\centerline{\box\graph}
EXAMPLES
arrow "input" above; box "process"; arrow "output" above
move
A: ellipse
circle rad .1 with .w at A.e
circle rad .05 at 0.5 <A.c, A.ne>
circle rad .065 at 0.5 <A.c, A.ne>
spline from last circle.nw left .25 then left .05 down .05
arc from A.c to A.se rad 0.5
for i = 1 to 10 do { line from A.s+.025*i,.01*i down i/50 }
arrow "input" above; box "process"; arrow "output" above move A: el‐
lipse
circle rad .1 with .w at A.e
circle rad .05 at 0.5 <A.c, A.ne>
circle rad .065 at 0.5 <A.c, A.ne>
spline from last circle.nw left .25 then left .05 down .05
arc from A.c to A.se rad 0.5
for i = 1 to 10 do { line from A.s+.025*i,.01*i down i/50 }
SOURCE
/sys/src/cmd/pic
SEE ALSO
grap(1), doctype(1), troff(1)
B. W. Kernighan, ``PIC—a Graphics Language for Typesetting'', Unix Re‐
search System Programmer's Manual, Tenth Edition, Volume 2
PIC(1)