IDEAL(1) IDEAL(1)
NAME
ideal - troff preprocessor for drawing pictures
SYNOPSIS
ideal [ option ... ] [ file ... ]
DESCRIPTION
Ideal is a constraint-based troff(1) preprocessor for type-
setting figures in the complex plane. A line beginning
`.IS' marks the start of an ideal program, .IE or .IF marks
the end. .IE leaves the typesetting baseline below the bot-
tom of the picture; .IF (flyback) leaves it at the top. The
options are
-Tdev
Produce instructions for troff(1) device dev. -a is a
synonym for -Taps; -t for -T202.
-tex Produce output for tex(1).
-p Produce plot(1) instructions. Erases come unbidden at
every .IS.
-4 Produce instructions for a Tektronix 4014 and wait at
each .IE for an input character before erasing and
starting the next picture.
-n Produce raw ideal output, which passes unharmed through
nroff.
-v Print calculated values of variables on standard error.
Ideal programs are built of `boxes'; boxes look like C func-
tions, in that they are named and delimited by braces. They
may include the following kinds of statements, each termi-
nated by a semicolon:
var declares one or more complex variables local to the
box. Variable names are made up of letters and dig-
its, and start with a letter; do not use any of the
following keywords as variable names: `at',
`bdlist', `boundary', `box', `conn', `construct',
`draw', `exterior', `interior', `left', `opaque',
`put', `right', `spline', `text', `to', `using',
`var'
equation
declares relative positions of significant points of
the box
conn asks for a straight-line path through named points
pen asks for a box to be replicated along a line between
IDEAL(1) IDEAL(1)
two points
left left-justifies text with respect to a point
text centers text with respect to a point
right right-justifies text with respect to a point
spline draws a spline guided by the named points
put asks for an instance of a box to be drawn
opaque asks for a box to erase lines already in the picture
that are covered by its bounding polygon
boundary
specifies the bounding polygon for an opaque box
construct
builds a partial picture on a separate `sheet of
paper'
draw adds the contents of the named constructed box to
the current picture
Ideal expects all components of a picture to be specified as
boxes; instructions to draw the entire picture should com-
prise a box called `main'. Boxes are remembered across
.IS/.IE boundaries; if you won't need a box again, you can
reclaim the space it requires by including the command
...forget boxname on a line between any .IS/.IE pair after
the last use of boxname. Box `main' is an exception to this
rule: it is always forgotten at .IE.
During its first pass, ideal solves all the equations to
determine the locations of all points it needs to know.
These equations must be linear equations in complex vari-
ables, although they may include non-linear operators: ideal
plugs in for as many variables, and does as much function
evaluation, as it can before solving the linear equation.
It waits until it has absolutely no hope of reducing an
equation to a linear equation before complaining. Ideal
knows about the following functions:
f[z,w] == z+(w-z)f, fraction f of the way from z to w
re(z) real part of complex number
im(z) imaginary part of complex number
conj(z) complex conjugate of complex number
abs(z) absolute value (modulus) of complex number
cis(z) the unit vector cos(x) + i*sin(x) where x = re(z)
and x is measured in degrees (radians if the line
...radians appeared more recently in the file than
the line ...degrees)
E(x) == cis(360 x ) if x is measured in degrees
angle(z)
angle of complex number, arctan(im(z)/re(z))
During the second pass, ideal draws the picture.
To draw a circle, include the line ...libfile circle between
the .IS and .IE lines, and put the box named `circle',
IDEAL(1) IDEAL(1)
giving enough information that the circle can be determined;
for instance, give the center and the radius, or give three
points through which the circle passes, or give the center
and a point on the circle. The circle has center `center',
radius `radius', and passes through z1, z2, and z3.
To draw an arc, include the line ...libfile arc between the
.IS and .IE lines, and put the box named `arc', again giving
enough information to determine the arc; for instance, give
the center, radius, and starting and ending angles, or give
three points on the arc--where to start, where to end, and
somewhere in between. The arc has center `center', radius
`radius', starts at point `start', passes through point
`midway' at angle `midang', and ends at point `end' at angle
`endang'. If no `midway' is specified, the arc is drawn
counterclockwise from `start' to `end'.
The picture will be scaled to a default width of four inches
and centered in a column of six inches. The default width
can be changed by a ...width command, which includes a num-
ber in inches. The default column width can be changed by a
...colwid command. To defeat ideal's notion of the size of
the picture, you can include lines of the form ...minx,
...miny, ...maxx, or ...maxy; these give the various coordi-
nates of the bounding box of the picture in the coordinate
system used by the picture.
Ideal supports both C-style comments (between `/*' and `*/'
brackets - which nest), and shell-style comments (between
`#' and newline).
EXAMPLES
...libfile circle
triangle {
var z1, z2, z3;
conn z1 to z2 to z3 to z1;
}
main {
put T: triangle {
z1 = 0; z2 = 1; z3 = (2,2);
}
put circle {
z1 = T.z1; z2 = T.z2; z3 = T.z3;
}
}
SEE ALSO
troff(1), pic(1), ped(9.1), doctype(1)
C. J. Van Wyk, `IDEAL User's Manual', this manual, Volume 2
BUGS
Ideal is relatively unforgiving about syntax errors.
IDEAL(1) IDEAL(1)
Bounding box computation is naive for arcs and text strings.