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1.1 root 1: .EQ
2: delim $$
3: .EN
4: .TH IDEAL 1
5: .SH NAME
6: ideal \- troff preprocessor for drawing pictures
7: .SH SYNOPSIS
8: .B ideal
9: [
10: .BI \-p
11: ]
12: [
13: .BI \-4
14: ]
15: [
16: .BI \-n
17: ]
18: [
19: .BI \-a
20: ]
21: [
22: .BI \-s
23: ]
24: [ files ]
25: .SH DESCRIPTION
26: .I Ideal
27: is yet another
28: .IR troff (1)
29: preprocessor for drawing figures on a typesetter.
30: When invoked with the
31: .I \-s
32: option,
33: it tries to decompose the figure into sorted short
34: straight lines for fast typesetting.
35: A line beginning `.IS' marks the start of an
36: .I ideal
37: program.
38: An
39: .I ideal
40: program ends with `.IE' or `.IF';
41: `.IE' leaves you below the bottom of the picture,
42: while `.IF' (flyback)
43: leaves you at the same place you were when you said `.IS'.
44: .PP
45: When invoked
46: with the
47: .I \-p
48: option,
49: .I ideal
50: produces
51: .IR plot (1)
52: instructions.
53: The erases come at every `.IS', and they come fast and
54: furious, so you might prefer using the
55: .I \-4
56: option, which produces instructions for a Tektronix
57: 4014, and waits at each `.IE' for an input character
58: before erasing and starting the next picture.
59: The
60: .I \-n
61: option produces raw
62: .IR ideal
63: output, which passes unharmed through
64: .IR nroff (1).
65: The
66: .I \-a
67: option produces output suitable for processing on the Autologic APS-5,
68: instead of the Mergenthaler Linotron 202.
69: .PP
70: The building block for
71: .I ideal
72: programs is a ``box'';
73: boxes look like C functions,
74: in that they are named, and delimited by braces.
75: They may include the following kinds of statements,
76: each terminated by a semicolon:
77: .TP
78: .I var
79: declares one or more complex variables local to the box.
80: Variable names are made up of letters and digits, and
81: start with a letter; do not use any of the following
82: keywords as variable names:
83: at,
84: bdlist,
85: boundary,
86: box,
87: conn,
88: construct,
89: draw,
90: exterior,
91: interior,
92: left,
93: opaque,
94: put,
95: right,
96: spline,
97: text,
98: to,
99: using,
100: var
101: .TP
102: .I equation
103: declares relative positions of significant points of the box
104: .TP
105: .I conn
106: asks for a straight-line path through named points
107: .TP
108: .I pen
109: asks for a box to be replicated along a line between two points
110: .TP
111: .I left
112: left-justifies text with respect to a point
113: .TP
114: .I text
115: centers text with respect to a point
116: .TP
117: .I right
118: right-justifies text with respect to a point
119: .TP
120: .I spline
121: draws a spline guided by the named points
122: .TP
123: .I put
124: asks for an instance of a box to be drawn
125: .TP
126: .I opaque
127: asks for a box to erase lines already in the picture that
128: are covered by its bounding polygon
129: .TP
130: .I boundary
131: specifies the bounding polygon for an opaque box
132: .TP
133: .I construct
134: builds a partial picture on a separate ``sheet of paper''
135: .TP
136: .I draw
137: adds the contents of the named constructed box to the current picture
138: .PP
139: .I Ideal
140: expects all components of a picture to be specified as boxes;
141: instructions to draw the entire picture should comprise a box called ``main.''
142: Boxes are remembered across .IS-.IE boundaries;
143: if you won't need a box again, you can reclaim the
144: space it requires by including the command
145: `...forget boxname' on a line between any .IS-.IE
146: pair after the last use of boxname.
147: Box
148: .I main
149: is an exception to this rule:
150: it is always forgotten when the .IE is processed.
151: .PP
152: During its first pass,
153: .I ideal
154: solves all the equations to determine the locations of all points
155: it needs to know.
156: These equations must be linear equations in complex variables,
157: although they may include non-linear operators:
158: .I ideal
159: plugs in for as many variables, and does as much function evaluation,
160: as it can before solving the linear equation.
161: It waits until it has absolutely no hope of reducing an equation
162: to a linear equation before complaining.
163: .I Ideal
164: knows about the following functions:
165: .TP
166: $ alpha [ z , w ] $
167: $ ~ == z + alpha ( w - z )$, $alpha$ of the way from $z$ to $w$
168: .TP
169: .I re (z)
170: real part of complex number
171: $z$
172: .TP
173: .I im (z)
174: imaginary part of complex number
175: $z$
176: .TP
177: .I conj (z)
178: complex conjugate of complex number
179: $z$
180: .TP
181: .I abs (z)
182: absolute value (modulus) of complex number
183: $z$
184: .TP
185: .I cis (x)
186: a unit vector in the direction of the real part of its argument $x$,
187: which is an angle in degrees
188: (radians if the line `...radians' appeared more
189: recently in the file than the line
190: `...degrees')
191: .TP
192: .I E (x)
193: $== cis ( 360 x )$
194: if $x$ is measured in degrees
195: .TP
196: .I int (x)
197: integer part of the real part of its argument $x$
198: .TP
199: .I angle (z)
200: arctangent of $im ( z ) / re ( z )$
201: .PP
202: During the second pass,
203: .I ideal
204: draws the picture.
205: .PP
206: To draw a circle,
207: include the line `...libfile circle' between the .IS and .IE lines,
208: and
209: .I put
210: the box named
211: .I circle,
212: giving enough information that
213: the circle can be determined;
214: for instance, give the center and the radius,
215: or give three points through which the circle passes,
216: or give the center and a point on the circle.
217: The circle has center $center$, radius $radius$, and passes
218: through $z1$, $z2$, and $z3$.
219: .PP
220: To draw an arc,
221: include the line `...libfile arc' between the .IS and .IE lines,
222: and
223: .I put
224: the box named
225: .I arc,
226: again giving enough information to determine the arc;
227: for instance, give the center, radius, and starting and ending angles,
228: or give three points on the arc--where to start, where to end, and somewhere
229: in between.
230: The arc has center $center$, radius $radius$,
231: starts at point $start$ at angle $startang$,
232: passes through point $midway$ at angle $midang$,
233: and ends at point $end$ at angle $endang$.
234: If no $midway$ is specified, the arc is drawn counterclockwise
235: from $start$ to $end$.
236: .PP
237: The picture will be scaled to a default width of four inches
238: and centered in a column of six inches.
239: The default width can be changed by a `...width' command,
240: which includes a number in inches.
241: The default column width can be changed by a `...colwid' command.
242: To defeat
243: \f2ideal\fP's
244: notion of the size of the picture, you can include lines of
245: the form `...minx', `...miny', `...maxx', or `...maxy';
246: these give the various coordinates of the bounding box of the
247: picture in the coordinate system used by the picture.
248: .PP
249: .I Ideal
250: supports both C-style comments (between /* and */ brackets, and they nest),
251: and shell-style comments (between # and newline).
252: .SH "SEE ALSO"
253: C. J. Van Wyk,
254: .I "A Graphics Language for Typesetting" (TM 79-1274-10),
255: C. J. Van Wyk,
256: .I "A Graphics Typesetting Language" (TM 80-1272-20),
257: C. J. Van Wyk,
258: .I "A Language for Typesetting Graphics" (Stanford Ph.D. Dissertation),
259: .SH BUGS
260: .I Ideal
261: is relatively unforgiving about syntax errors.
262: Bounding box computation is naive for arcs and text strings.
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