PIC(1) 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 back-
slash. 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.
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After each primitive the current position moves in the cur-
rent direction (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
`arrow' is a synonym for `line ->'.
An attribute-list is a sequence of zero or more attributes;
each attribute 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 attributes make sense for all primitives; irrelevant
ones are silently ignored. The attribute `at' causes the
geometrical center to be put at the specified place; `with'
causes the position on the object to be put at the specified
place. For lines, splines and arcs, `height' and `width'
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 apply to each item independently. Text
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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 exiting.
A position is ultimately an x,y coordinate pair, but it may
be specified 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 `reset' 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 representing dimensions are taken to be in inches.
expr:
expr op expr
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PIC(1) PIC(1)
- 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 picture. 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: 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
}
SOURCE
/sys/src/cmd/pic
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SEE ALSO
grap(1), doctype(1), troff(1)
B. W. Kernighan, ``PIC-a Graphics Language for Typeset-
ting'', Unix Research System Programmer's Manual, Tenth Edi-
tion, Volume 2
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