Subversion Repositories planix.SVN

.TH PIC 1

.de PS	\" start picture

.	\" $1 is height, $2 is width, both in inches

.if \\$1>0 .sp .35

.ie \\$1>0 .nr $1 \\$1

.el .nr $1 0

.in (\\n(.lu-\\$2)/2u

.ne \\$1

..

.de PE	\" end of picture

.in

.if \\n($1>0 .sp .65

..

.SH NAME

pic, tpic \- troff and tex preprocessors for drawing pictures

.SH SYNOPSIS

.B pic

[

.I files

]

.PP

.B tpic

[

.I files

]

.SH DESCRIPTION

.I Pic

is a

.IR troff (1)

preprocessor for drawing figures on a typesetter.

.I Pic

code is contained between

.B .PS

and

.B .PE

lines:

.IP

.EX

\&.PS \f2optional-width\fP \f2optional-height\fP

\f2element-list\fP

\&.PE

.EE

.LP

or in a file mentioned in a

.B .PS

line:

.IP

.BI .PS " " < file

.LP

If

.IR 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

.IR optional-height

is present.

If

.B .PF

is used instead of

.BR .PE ,

the typesetting position after printing is restored to what it was

upon entry.

.PP

An

.IR element-list

is a list of elements:

.EX

	\f2primitive  attribute-list\fP

	\f2placename\fP : \f2element\fP

	\f2placename\fP : \f2position\fP

	\f2var\fP = \f2expr\fP

	\f2direction\fP

	{ \f2element-list\fP }

	[ \f2element-list\fP ]

	for \f2var\fP = \f2expr\fP to \f2expr\fP by \f2expr\fP do { \f2anything\fP }

	if \f2expr\fP then { \f2anything\fP } else { \f2anything\fP }

	copy \f2file,\fP  copy thru \f2macro,\fP  copy \f2file\fP thru \fPmacro\fP

	sh { \f2commandline\fP }

	print \f2expr\fP

	reset \f2optional var-list\fP

	\f2troff-command\fP

.EE

.PP

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

.BI #

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.

.PP

After each primitive

the current position moves in the current direction

.RB ( up , down ,

.BR left , right

(default)) by the size of the primitive.

The current position and direction are saved upon entry

to a

.BR { ... }

block and restored upon exit.

Elements within a block enclosed in

.BR [ ... ]

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.

.PP

.IR 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.

.PP

The

.I primitive

objects are:

.br

.EX

	box  circle  ellipse  arc  line  arrow  spline  move  \f2text-list\fP

.EE

.L arrow

is a synonym for

.LR "line ->" .

.PP

An

.IR attribute-list

is a sequence of zero or more attributes;

each attribute consists of a keyword, perhaps followed by a value.

.EX

.ta .5i 2.5i

	h(eigh)t \f2expr\fP	wid(th) \f2expr\fP

	rad(ius) \f2expr\fP	diam(eter) \f2expr\fP

	up \f2opt-expr\fP	down \f2opt-expr\fP

	right \f2opt-expr\fP	left \f2opt-expr\fP

	from \f2position\fP	to \f2position\fP

	at \f2position\fP	with \f2corner\fP

	by \f2expr, expr\fP	then

	dotted \f2opt-expr\fP	dashed \f2opt-expr\fP

	chop \f2opt-expr\fP	->  <-  <->

	invis	same

	fill \f2opt-expr\fP

	\f2text-list\fP	\f2expr\fP

.EE

Missing attributes and values are filled in from defaults.

Not all attributes make sense for all primitives;

irrelevant ones are silently ignored.

The attribute

.L at

causes the geometrical center to be put at the specified place;

.L with

causes the position on the object to be put at the specified place.

For lines, splines and arcs,

.L height

and

.L width

refer to arrowhead size.

A bare

.I expr

implies motion in the current direction.

.PP

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:

.EX

\f2  text-item\fP:

	"..." \f2positioning ...\fP

	sprintf("\f2format\fP", \f2expr\fP, \f2...\fP) \f2positioning ...\fP

\f2  positioning\fP:

	center  ljust  rjust  above  below

.EE

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 items may contain

.I 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.

.PP

A position is ultimately an

.I x,y

coordinate pair, but it may be specified in other ways.

.EX

\f2  position\fP:

	\f2expr, expr\fP

	\f2place\fP ± \f2expr, expr\fP

	\f2place\fP ± ( \f2expr, expr\fP )

	( \f2position\fP,\f2 position\fP )	\f2x\fP\fR from one, \f2y\fP\fR the other\fP

	\f2expr\fP [\fLof the way\fP] between \f2position\fP and \f2position\fP

	\f2expr\fP < \f2position\fP , \f2position\fP >

	( \f2position\fP )

.EE

.PP

.EX

\f2  place\fP:

	\f2placename\fP \f2optional-corner\fP

	\f2corner\fP of \f2placename\fP

	\f2nth\fP \f2primitive\fP \f2optional-corner\fP

	\f2corner\fP of \f2nth\fP \f2primitive\fP

	Here

.EE

An

.IR optional-corner

is one of the eight compass points

or the center or the start or end of a primitive.

.EX

\f2  optional-corner\fP:

	.n  .e  .w  .s  .ne  .se  .nw  .sw  .c  .start  .end

\f2  corner\fP:

	top  bot  left  right  start  end

.EE

Each object in a picture has an ordinal number;

.IR nth

refers to this.

.EX

\f2  nth\fP:

	\f2n\fPth\f2,     n\fPth last

.EE

.PP

The built-in variables and their default values are:

.EX

.ta .5i 2.5i

	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

.EE

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

.L reset

statement.

Variables changed within

.B [

and

.B ]

revert to their previous value upon exit from the block.

Dimensions are divided by

.B scale

during output.

.PP

Expressions in

.I pic

are evaluated in floating point.

All numbers representing dimensions are taken to be in inches.

.EX

\f2  expr\fP:

	\f2expr\fP \f2op\fP \f2expr\fP

	- \f2expr\fP

	! \f2expr\fP

	( \f2expr\fP )

	variable

	number

	\f2place\fP .x  \f2place\fP .y  \f2place\fP .ht  \f2place\fP .wid  \f2place\fP .rad

	sin(\f2expr\fP)  cos(\f2expr\fP)  atan2(\f2expr,expr\fP)  log(\f2expr\fP)  exp(\f2expr\fP)

	sqrt(\f2expr\fP)  max(\f2expr,expr\fP)  min(\f2expr,expr\fP)  int(\f2expr\fP)  rand()

\f2  op\fP:

	+  -  *  /  %  <  <=  >  >=  ==  !=  &&  ||

.EE

.PP

The

.B define

and

.B undef

statements are not part of the grammar.

.EX

	define \f2name\fP { \f2replacement text\fP }

	undef \f2name\fP

.EE

Occurrences of

.BR $1 ,

.BR $2 ,

etc.,

in the replacement text

will be replaced by the corresponding arguments if

.I name

is invoked as

.EX

	\f2name\fP(\f2arg1\fP, \f2arg2\fP, ...)

.EE

Non-existent arguments are replaced by null strings.

Replacement text

may contain newlines.

The

.B undef

statement removes the definition of a macro.

.PP

.I Tpic

is a

.IR tex (1)

preprocessor that accepts

.IR pic

language.

It produces Tex commands that define a box called

.BR \egraph ,

which contains the picture.

The box may be output this way:

.IP

.L

\ecenterline{\ebox\egraph}

.SH EXAMPLES

.EX

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 } 

.EE

.PP

.PS

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 } 

.PE

.SH SOURCE

.B /sys/src/cmd/pic

.SH "SEE ALSO"

.IR grap (1), 

.IR doctype (1),

.IR troff (1)

.br

B. W. Kernighan,

``PIC\(ema Graphics Language for Typesetting'',

.I

Unix Research System Programmer's Manual,

Tenth Edition, Volume 2