ch17_03.htm

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<a name="unut-ch-17-sect-3.5" /><div class="sect2"><h3 class="sect2">17.3.5. Text</h3><p>Text must be placed within quotes.  To break the line, break into two
(or more) sets of quotes.
Text always appears centered within the object, unless given one of the
following arguments:</p>

<table border="1" cellpadding="3">

<tr><td><tt class="literal">ljust</tt></td><td><p>Text appears flush left, vertically centered.</p>
</td></tr>
<tr><td><tt class="literal">rjust</tt></td><td><p>Text appears flush right, vertically centered.</p>
</td></tr>
<tr><td><tt class="literal">above</tt></td><td><p>Text appears above the center.</p>
</td></tr>
<tr><td><tt class="literal">below</tt></td><td><p>Text appears below the center.</p>
</td></tr>
</table><p>
</div>

<a name="unut-ch-17-sect-3.6" /><div class="sect2"><h3 class="sect2">17.3.6. Object Blocks</h3><p>Several primitives can be combined to make a complex object 
(for example, an octagon).  This complex object can be treated 
as a single object by declaring it as a block:</p>
<blockquote><pre class="code">Object: [
     <em class="replaceable"><tt>description</tt></em>
      .
      .
      .
]</pre></blockquote>
<p>Brackets are used as delimiters.  Note that the object is declared as
the name of a place, and hence it must begin with a capital letter.</p>
</div>

<a name="unut-ch-17-sect-3.7" /><div class="sect2"><h3 class="sect2">17.3.7. Macros</h3><p>The same sequence of commands can be repeated by
using macros.  The syntax is:</p>
<blockquote><pre class="code">define <em class="replaceable"><tt>sequence</tt></em> %
      <em class="replaceable"><tt>description</tt></em>
          .
          .
          . 
      %</pre></blockquote>
<p>Here the percent sign (<tt class="literal">%</tt>) is the delimiter, but you can use
any character that isn't in the description.</p>
<p>Macros can take parameters, expressed in the definition
as <tt class="literal">$1</tt> through 
<tt class="literal">$9</tt>.  Invoke the macro with the syntax:</p>
<blockquote><pre class="code"><em class="replaceable"><tt>sequence</em>(<em class="replaceable">value1</em>,<em class="replaceable">value2</em>,<em class="replaceable">...</tt></em>)</pre></blockquote>
</div>

<a name="unut-ch-17-sect-3.8" /><div class="sect2"><h3 class="sect2">17.3.8. Positioning</h3><p>
<a name="IXT-17-123464" />In a <tt class="literal">pic</tt> description, the first action begins at (0,0) unless
otherwise specified with coordinates.  Thus, 
as objects are placed above and left of the first object,
the point (0,0) moves down and right on the drawing.</p>
<p>All points are ultimately translated by the formatter into x- and y-coordinates.
You may therefore refer to a specific point in the picture by incrementing
or decrementing the coordinates.  For example:</p>
<blockquote><pre class="code">2nd ellipse + (.5,0)</pre></blockquote>
<p>This refers to the position 1/2 inch to the right of the center
of the second ellipse.</p>
<p>The x- and y-coordinates of an object are the point
where the center of the object is placed.
You may refer to the x- and y-coordinates of an
object by placing <tt class="literal">.x</tt>
or <tt class="literal">.y</tt> at the end.  For example: </p>
<blockquote><pre class="code">last box.x</pre></blockquote>
<p>refers to the x-coordinate of the most recent box drawn.
You can refer to some of the object's physical attributes in a similar way:</p>

<table border="1" cellpadding="3">

<tr><td><tt class="literal">.x</tt></td><td><p>x-coordinate of object's center.</p>
</td></tr>
<tr><td><tt class="literal">.y</tt></td><td><p>y-coordinate of object's center.</p>
</td></tr>
<tr><td><tt class="literal">.ht</tt></td><td><p>Height of object.</p>
</td></tr>
<tr><td><tt class="literal">.wid</tt></td><td><p>Width of object.</p>
</td></tr>
<tr><td><tt class="literal">.rad</tt></td><td><p>Radius of object.</p>
</td></tr>
<tr><td><tt class="literal">.</tt><em class="replaceable"><tt>corner</tt></em></td><td><p>One of the object's corners.
Corners are described below.</p>
</td></tr>
</table><p>
<p>Unless otherwise positioned, each object begins at the point where
the last object left off.  However, if a command (or sequence of commands) 
is set off by curly braces (<tt class="literal">{ }</tt>),
<tt class="literal">pic</tt> then returns to
the position before the first brace.</p>

<a name="unut-ch-17-sect-3.8.1" /><div class="sect3"><h3 class="sect3">17.3.8.1. Positioning between objects</h3><p>There are two ways
to refer to a previous object.</p>
<ul><li><p>Refer to it by order.  For example:</p>


<blockquote><pre class="code">1st box 
3rd box 
last box 
2nd last box</pre></blockquote>
</li><li><p>Declare it with a name, in initial caps, on its declaration line.
For example:</p>


<blockquote><pre class="code">Line1: line 1.5 right from last box.sw</pre></blockquote>
</li></ul>
<p>To refer to a point between two objects, or between two points on
the same object, you may write:</p>
<blockquote><pre class="code"><em class="replaceable"><tt>fraction of the way between first.position and second.position</tt></em></pre></blockquote>
<p>or (abbreviated):</p>
<blockquote><pre class="code"><em class="replaceable"><tt>fraction &lt;first.position, second.position&gt;</tt></em></pre></blockquote>
</div>

<a name="unut-ch-17-sect-3.8.2" /><div class="sect3"><h3 class="sect3">17.3.8.2. Corners</h3><p>When you refer to a previous object, <tt class="literal">pic</tt> assumes you mean 
the object's center unless you specify a corner.  To specify a 
corner, use either of these forms:</p>
<blockquote><pre class="code"><em class="replaceable"><tt>.corner</em> <tt class="userinput"><b>of</b></tt> <em class="replaceable">object</tt></em>
<em class="replaceable"><tt>object.corner</tt></em></pre></blockquote>
<p>For example:</p>
<blockquote><pre class="code"><tt class="userinput"><b>.sw of last box
last box.sw</b></tt></pre></blockquote>


<p>Valid corners can be specified as any of the following:</p>

<table border="1" cellpadding="3"><tr><td><tt class="literal">n</tt></td><td>North</td></tr>
<tr><td><tt class="literal">s</tt></td><td>South</td></tr>
<tr><td><tt class="literal">e</tt></td><td>East</td></tr>
<tr><td><tt class="literal">w</tt></td><td>West</td></tr>
<tr><td><tt class="literal">ne</tt></td><td>Northeast</td></tr>
<tr><td><tt class="literal">nw</tt></td><td>Northwest</td></tr>
<tr><td><tt class="literal">se</tt></td><td>Southeast</td></tr>
<tr><td><tt class="literal">sw</tt></td><td>Southwest</td></tr>
<tr><td><tt class="literal">t</tt></td><td>Top (same as <tt class="literal">n</tt>)</td></tr>
<tr><td><tt class="literal">b</tt></td><td>Bottom (same as <tt class="literal">s</tt>)</td></tr>
<tr><td><tt class="literal">r</tt></td><td>Right (same as <tt class="literal">e</tt>)</td></tr>
<tr><td><tt class="literal">l</tt></td><td>Left (same as <tt class="literal">w</tt>)</td></tr>
<tr><td><tt class="literal">start</tt></td><td>Point where drawing of object began</td></tr>
<tr><td><tt class="literal">end</tt></td><td>Point where drawing of object ended</td></tr>
</table><p>
<p>You may also refer to the following parts of an object:</p>

<table border="1" cellpadding="3"><tr><td><tt class="literal">upper right</tt></td><td><tt class="literal">lower right</tt></td></tr>
<tr><td><tt class="literal">upper left</tt></td><td><tt class="literal">lower left</tt></td></tr>
</table><p>
</div>
</div>

<a name="unut-ch-17-sect-3.9" /><div class="sect2"><h3 class="sect2">17.3.9. Expressions</h3><p>Expressions may be used anywhere <tt class="literal">pic</tt>
needs a numeric value (such as when specifying coordinates
or amounts of motion).
Expressions consist of numeric constants, variables, and operators.</p>
<p><tt class="literal">pic</tt> recognizes the following operators.</p>

<table border="1" cellpadding="3"><tr><td><tt class="literal">+</tt></td><td>Addition</td></tr>
<tr><td><tt class="literal">-</tt></td><td>Subtraction</td></tr>
<tr><td><tt class="literal">*</tt></td><td>Multiplication</td></tr>
<tr><td><tt class="literal">/</tt></td><td>Division</td></tr>
<tr><td><tt class="literal">%</tt></td><td>Modulus (remainder after division)</td></tr>
<tr><td><tt class="literal">^</tt></td><td><p>Exponentiation</p>
</td></tr>
</table><p>
</div>

<a name="unut-ch-17-sect-3.10" /><div class="sect2"><h3 class="sect2">17.3.10. Default Values</h3><p>Various system
variables control
the default dimensions of objects.
You can change these defaults by typing a description
line of the form:</p>
<blockquote><pre class="code"><em class="replaceable"><tt>variable</em> = <em class="replaceable">value</tt></em></pre></blockquote>
<table border="1" cellpadding="3">
<tr><th><em class="emphasis">Variable</em></th>
<th><em class="emphasis">Default</em></th><th><em class="emphasis">Variable</em></th><th><em class="emphasis">Default</em></th></tr>

<tr><td><tt class="literal">arcrad</tt></td>
<td>0.25</td><td><tt class="literal">ellipsewid</tt></td><td>0.75</td></tr>
<tr><td><tt class="literal">arrowwid</tt></td>
<td>0.05</td><td><tt class="literal">linewid</tt></td><td>0.5</td></tr>
<tr><td><tt class="literal">arrowht</tt></td>
<td>0.1</td><td><tt class="literal">lineht</tt></td><td>0.5</td></tr>
<tr><td><tt class="literal">boxwid</tt></td>
<td>0.75</td><td><tt class="literal">movewid</tt></td><td>0.5</td></tr>
<tr><td><tt class="literal">boxht</tt></td>
<td>0.5</td><td><tt class="literal">moveht</tt></td><td>0.5</td></tr>
<tr><td><tt class="literal">circlerad</tt></td>
<td>0.25</td><td><tt class="literal">scale</tt></td><td>1</td></tr>
<tr><td><tt class="literal">dashwid</tt></td>
<td>0.05</td><td><tt class="literal">textht</tt></td><td>0</td></tr>
<tr><td><tt class="literal">ellipseht</tt></td>
<td>0.5</td><td><tt class="literal">textwid</tt></td><td>0</td></tr>
</table><p>
</div>

<a name="unut-ch-17-sect-3.11" /><div class="sect2"><h3 class="sect2">17.3.11. pic Examples</h3><p>Input:</p>
<blockquote><pre class="code">.PS
define smile %
a = $1
circle radius a at 0,0
arc cw radius a*.75 from a*.5,-a*.25 to -a*.5,-a*.25
"\(bu" at a*.33,a*.25
"\(bu" at a*-.33,a*.25
%
smile(.5)
.PE</pre></blockquote>
<p>Result:</p>
<img src="figs/smile.gif" alt="Figure 17.3.11" /><p>Input (from CSTR #116):</p>
<blockquote><pre class="code">.PS
ellipse "document"
arrow
box "PIC"
arrow
box "TBL/EQN" "(optional)" dashed
arrow
box "TROFF"
arrow
ellipse "typesetter"
.PE</pre></blockquote>


<p>Result:</p>
<img src="figs/typesetter.gif" alt="Figure 17.3.11" />
<a name="IXT-17-123465" />
<a name="IXT-17-123466" />
<a name="IXT-17-123467" />
<a name="IXT-17-123468" />
<a name="IXT-17-123469" />
<a name="IXT-17-123470" /></div>


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