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<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"  
  "http://www.w3.org/TR/html4/loose.dtd">  
<html > 
<head><title>22 Snakes</title> 
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<meta name="date" content="2005-11-15 18:41:00"> 
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</head><body 
>
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   <h3 class="sectionHead"><span class="titlemark">22   </span> <a 
 id="x23-22900022"></a>Snakes</h3>
<!--l. 12--><p class="noindent">
   <h4 class="subsectionHead"><span class="titlemark">22.1   </span> <a 
 id="x23-23000022.1"></a>Overview</h4>
<!--l. 14--><p class="noindent">A <span 
class="cmti-10">snake </span>is a &#8220;way of adding a winding line to a path.&#8221; To be a bit more precise, you use snakes to extend the path
and the commands for using snakes start with <span class="obeylines-h"><span class="verb"><span 
class="cmtt-10">\pgfpath</span></span></span>. However, snakes do not necessarily extend the path using
line-to and curve-to operations; rather, they can also contain move-to operations and, thereby, cause the path to be
split into many subpaths.
<!--l. 21--><p class="indent">   As an example, let us consider a simple snake like the <span class="obeylines-h"><span class="verb"><span 
class="cmtt-10">zigzag</span></span></span> snake. It looks like this:
<!--l. 24--><p class="noindent"><div class="obeylines-v"></div><!--tex4ht:inline--><div class="tabular"><table class="tabular" 
cellspacing="0" cellpadding="0"  
frame="void" id="TBL-454-" ><colgroup id="TBL-454-1g"><col 
id="TBL-454-1"><col 
id="TBL-454-2"></colgroup><tr  
 valign="baseline" id="TBL-454-1-"><td  align="left" style="white-space:nowrap; text-align:left;" id="TBL-454-1-1"  
class="td11">  &nbsp;<object data="pgfmanual-531.svg" width="115.24718 " height="44.13002 " type="image/svg+xml"><p>SVG-Viewer needed.</p></object>&nbsp;  </td><td  align="left" style="white-space:nowrap; text-align:left;" id="TBL-454-1-2"  
class="td11">  <table class="minipage"><tr><td><div class="obeylines-v">
<br><span 
class="cmtt-8">\begin{tikzpicture}</span>
<br><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;\draw[snake=zigzag]</span><span 
class="cmtt-8">&nbsp;(0,0)</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;--</span><span 
class="cmtt-8">&nbsp;(3,0);</span>
<br><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;\draw[snake=zigzag]</span><span 
class="cmtt-8">&nbsp;(0,-.5)</span><span 
class="cmtt-8">&nbsp;--</span><span 
class="cmtt-8">&nbsp;(3,-1);</span>
<br><span 
class="cmtt-8">\end{tikzpicture}</span></div>                                                                                             </td></tr></table> </td>
</tr></table></div>
<!--l. 31--><p class="indent">   The above example demonstrates the two key features of snakes:
     <ol type="1" class="enumerate1" >
     <li class="enumerate" value="1" 
><a 
 id="x23-230002x1"></a>Snakes are made up from little segments that are repeated several times. For the <span class="obeylines-h"><span class="verb"><span 
class="cmtt-10">zigzag</span></span></span> snake these
     segements look like this: <object data="pgfmanual-532.svg" width="14.94733 " height="8.19995 " type="image/svg+xml"><p>SVG-Viewer needed.</p></object>.
     </li>
     <li class="enumerate" value="2" 
><a 
 id="x23-230004x2"></a>Snakes &#8220;follow along a straight to the target point.&#8221; Thus, when the target point is not to the right of
     the start point, the snake is rotated appropriately.</li></ol>
<!--l. 44--><p class="indent">   In order to use snakes, they first have to be <span 
class="cmti-10">declared</span>. This declaration contains a detailed description of
how each segement of the snake looks like and in what ordering the different possible segments are
used.
<!--l. 49--><p class="indent">   Once a snake has been declared, it can be used. For this you specify a target point and a snaked line will be
added from the last point current point to the target point.
<!--l. 54--><p class="noindent">
   <h4 class="subsectionHead"><span class="titlemark">22.2   </span> <a 
 id="x23-23100022.2"></a>Declaring a Snake</h4>
<!--l. 57--><p class="noindent">
   <h5 class="subsubsectionHead"><span class="titlemark">22.2.1   </span> <a 
 id="x23-23200022.2.1"></a>Segments</h5>
<!--l. 59--><p class="noindent">When you declare a snake, you provide a description of how the different segments of the snake will be rendered.
The description of each segment should be given in a way as if the target of the snaked line where at (+<span 
class="cmsy-10"><img 
src="cmsy10-31.png" alt=" oo " class="10x-x-31" /></span><span 
class="cmmi-10">,</span>0) and as
if the segment&#8217;s start where at the origin. Thus, for example, the segment of the <span class="obeylines-h"><span class="verb"><span 
class="cmtt-10">zigzag</span></span></span> might be defined using the
following code:
<!--l. 65--><p class="noindent"><div class="obeylines-v"></div><!--tex4ht:inline--><div class="tabular"><table class="tabular" 
cellspacing="0" cellpadding="0"  
frame="void" id="TBL-455-" ><colgroup id="TBL-455-1g"><col 
id="TBL-455-1"></colgroup><tr  
 valign="baseline" id="TBL-455-1-"><td  align="left" style="white-space:nowrap; text-align:left;" id="TBL-455-1-1"  
class="td11">  <table class="minipage"><tr><td><div class="obeylines-v">
<br><span 
class="cmtt-8">\pgfpathlineto{\pgfpoint{5pt}{5pt}}</span>
<br><span 
class="cmtt-8">\pgfpathlineto{\pgfpoint{15pt}{-5pt}}</span>
<br><span 
class="cmtt-8">\pgfpathlineto{\pgfpoint{20pt}{0pt}}</span></div>                                                                          </td></tr></table> </td>
</tr></table></div>
<!--l. 71--><p class="indent">   <span 
class="cmcsc-10"><small 
class="small-caps">P</small><small 
class="small-caps">G</small><small 
class="small-caps">F</small></span>&nbsp;will ensure that an appropriate coordinate transformation is in place when the snake segment is added to
the path such that the snake segment actually points in the right direction. Also subsequent snake segments will be
transformed such that they are &#8220;further along the line&#8221; toward the target. All transformations are setup
automatically.
                                                                                         
                                                                                         
<!--l. 78--><p class="indent">   Note that we did not use a <span class="obeylines-h"><span class="verb"><span 
class="cmtt-10">\pgfpathmoveto{\pgfpointorigin}</span></span></span> at the beginning of the segment code. Doing so
would subdivide the path into numerous subpath. Rather, we assume that the previous segment caused the current
point to be at the origin.
<!--l. 83--><p class="indent">   While we can now describe segments, we still need a way to &#8220;stop&#8221; the snake. Also, <span 
class="cmcsc-10"><small 
class="small-caps">P</small><small 
class="small-caps">G</small><small 
class="small-caps">F</small></span>&nbsp;needs to know the
width of the different snake segments such that it can translate the next segment correctly. Even though it would be
possible to compute all this information automatically, <span 
class="cmcsc-10"><small 
class="small-caps">P</small><small 
class="small-caps">G</small><small 
class="small-caps">F</small></span>&nbsp;does not do so and you have to provide the information
&#8220;by hand&#8221; for each segment.
<!--l. 91--><p class="noindent">
   <h5 class="subsubsectionHead"><span class="titlemark">22.2.2   </span> <a 
 id="x23-23300022.2.2"></a>Snake Automata</h5>
<!--l. 93--><p class="noindent">Up to now our snakes only have one segment that is repeated again and again. However, we might also like to have
<span 
class="cmti-10">different </span>segments and use rules to describe which segment should be used where. For example, we might have
special segments at the start and at the end.
<!--l. 98--><p class="indent">   For snakes we use a mechanism known in computer science as <span 
class="cmti-10">finite automata </span>to describe which segment is used
in each part of the snake. The idea is the following: For the first segment we start in a special <span 
class="cmti-10">state</span>
called the <span 
class="cmti-10">initial state</span>. In this state, and also in all other state later, <span 
class="cmcsc-10"><small 
class="small-caps">P</small><small 
class="small-caps">G</small><small 
class="small-caps">F</small></span>&nbsp;first computes how much
space is left on the snake. That is, <span 
class="cmcsc-10"><small 
class="small-caps">P</small><small 
class="small-caps">G</small><small 
class="small-caps">F</small></span>&nbsp;keeps track of the distance to the target. Attached to each
state there is a set of rules of the following form: &#8220;If the remaining distance is less than <span 
class="cmmi-10">x</span>, switch to
state&nbsp;<span 
class="cmmi-10">q</span>.&#8221; <span 
class="cmcsc-10"><small 
class="small-caps">P</small><small 
class="small-caps">G</small><small 
class="small-caps">F</small></span>&nbsp;checks for each of these rules whether it applies and, if so, immediately switches to
state&nbsp;<span 
class="cmmi-10">q</span>.
<!--l. 110--><p class="indent">   Only if none of the rules tell us to switch to another state, <span 
class="cmcsc-10"><small 
class="small-caps">P</small><small 
class="small-caps">G</small><small 
class="small-caps">F</small></span>&nbsp;will execute the state&#8217;s code. This code will add
a segment to the path. In addition to the rules there is also width parameter attached to each state. <span 
class="cmcsc-10"><small 
class="small-caps">P</small><small 
class="small-caps">G</small><small 
class="small-caps">F</small></span>&nbsp;then
translates the coordinate system by this width and reduces the remaining distance. Then, <span 
class="cmcsc-10"><small 
class="small-caps">P</small><small 
class="small-caps">G</small><small 
class="small-caps">F</small></span>&nbsp;either stays in
the current state or switches to another state, depending on yet another property attached of the
state.
<!--l. 119--><p class="indent">   The whole process stops when a special state called <span class="obeylines-h"><span class="verb"><span 
class="cmtt-10">final</span></span></span> is reached. The segment of this state is added to the
path immediately (it is often empty, though) and the process ends.
<!--l. 123--><p class="noindent">
   <h5 class="subsubsectionHead"><span class="titlemark">22.2.3   </span> <a 
 id="x23-23400022.2.3"></a>The Snake Declaration Command</h5>
<!--l. 126--><p class="noindent">
     <dl class="description"><dt class="description">
<span 
class="colorbox" id="colorbox242"><span 
class="cmtt-10">\pgfdeclaresnake</span><span 
class="cmtt-10">{</span><span 
class="cmsy-10">&lt;</span><span 
class="cmti-10">name</span><span 
class="cmsy-10">&gt;</span><span 
class="cmtt-10">}{</span><span 
class="cmsy-10">&lt;</span><span 
class="cmti-10">initial state</span><span 
class="cmsy-10">&gt;</span><span 
class="cmtt-10">}{</span><span 
class="cmsy-10">&lt;</span><span 
class="cmti-10">states</span><span 
class="cmsy-10">&gt;</span><span 
class="cmtt-10">}</span></span> </dt><dd 
class="description">
<a 
 id="dx23-234001"></a>
     <!--l. 127--><p class="noindent">This command declares a new snake called <span 
class="cmsy-10">&lt;</span><span 
class="cmti-10">name</span><span 
class="cmsy-10">&gt;</span>. The <span 
class="cmsy-10">&lt;</span><span 
class="cmti-10">states</span><span 
class="cmsy-10">&gt; </span>argument contains a description of
     the snake automaton&#8217;s states and the transitions between them. The <span 
class="cmsy-10">&lt;</span><span 
class="cmti-10">initial state</span><span 
class="cmsy-10">&gt; </span>is the state in which
     the automaton starts.
     <!--l. 132--><p class="noindent">The <span 
class="cmsy-10">&lt;</span><span 
class="cmti-10">states</span><span 
class="cmsy-10">&gt; </span>argument should consist of <span class="obeylines-h"><span class="verb"><span 
class="cmtt-10">\state</span></span></span> commands, one for each state of the snake automaton.
     The <span class="obeylines-h"><span class="verb"><span 
class="cmtt-10">\state</span></span></span> command is defined only when the <span 
class="cmsy-10">&lt;</span><span 
class="cmti-10">states</span><span 
class="cmsy-10">&gt; </span>argument is executed.
                                                                                         
                                                                                         
     <!--l. 136--><p class="noindent"><div class="obeylines-v"></div><!--tex4ht:inline--><div class="tabular"><table class="tabular" 
cellspacing="0" cellpadding="0"  
frame="void" id="TBL-456-" ><colgroup id="TBL-456-1g"><col 
id="TBL-456-1"><col 
id="TBL-456-2"></colgroup><tr  
 valign="baseline" id="TBL-456-1-"><td  align="left" style="white-space:nowrap; text-align:left;" id="TBL-456-1-1"  
class="td11">  &nbsp;   <object data="pgfmanual-533.svg" width="115.1629 " height="125.8888 " type="image/svg+xml"><p>SVG-Viewer needed.</p></object>&nbsp;  </td><td  align="left" style="white-space:nowrap; text-align:left;" id="TBL-456-1-2"  
class="td11">  <table class="minipage"><tr><td><div class="obeylines-v">
<br><span 
class="cmtt-8">\pgfdeclaresnake{example</span><span 
class="cmtt-8">&nbsp;snake}{initial}</span>
<br><span 
class="cmtt-8">{</span>
<br><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;\state{initial}[width=10pt]</span>
<br><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;{</span>
<br><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;\pgfpathlineto{\pgfpoint{0pt}{5pt}}</span>
<br><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;\pgfpathlineto{\pgfpoint{5pt}{5pt}}</span>
<br><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;\pgfpathlineto{\pgfpoint{5pt}{-5pt}}</span>
<br><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;\pgfpathlineto{\pgfpoint{10pt}{-5pt}}</span>
<br><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;\pgfpathlineto{\pgfpoint{10pt}{0pt}}</span>
<br><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;}</span>
<br><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;\state{final}</span>
<br><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;{</span>
<br><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;\pgfpathlineto{\pgfpoint{\pgfsnakeremainingdistance}{0pt}}</span>
<br><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;}</span>
<br><span 
class="cmtt-8">}</span>
<br><span 
class="cmtt-8">\tikz{\draw[snake=example</span><span 
class="cmtt-8">&nbsp;snake]</span><span 
class="cmtt-8">&nbsp;(0,0)</span><span 
class="cmtt-8">&nbsp;--</span><span 
class="cmtt-8">&nbsp;(3,0);</span>
<br><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;\draw[snake=example</span><span 
class="cmtt-8">&nbsp;snake]</span><span 
class="cmtt-8">&nbsp;(0,-1)</span><span 
class="cmtt-8">&nbsp;--</span><span 
class="cmtt-8">&nbsp;(3,-3);}</span></div>                                                           </td></tr></table> </td>
</tr></table></div>
     <!--l. 156--><p class="noindent">The <span class="obeylines-h"><span class="verb"><span 
class="cmtt-10">\state</span></span></span> command works as follows:
         <dl class="description"><dt class="description">
     <span 
class="colorbox" id="colorbox243"><span 
class="cmtt-10">\state</span><span 
class="cmtt-10">{</span><span 
class="cmsy-10">&lt;</span><span 
class="cmti-10">name</span><span 
class="cmsy-10">&gt;</span><span 
class="cmtt-10">}[</span><span 
class="cmsy-10">&lt;</span><span 
class="cmti-10">options</span><span 
class="cmsy-10">&gt;</span><span 
class="cmtt-10">]{</span><span 
class="cmsy-10">&lt;</span><span 
class="cmti-10">code</span><span 
class="cmsy-10">&gt;</span><span 
class="cmtt-10">}</span></span> </dt><dd 
class="description">
<a 
 id="dx23-234002"></a>
         <!--l. 158--><p class="noindent">This command declares a new state inside the current snake automaton. The state is names
         <span 
class="cmsy-10">&lt;</span><span 
class="cmti-10">name</span><span 
class="cmsy-10">&gt;</span>.
         <!--l. 161--><p class="noindent">When <span 
class="cmcsc-10"><small 
class="small-caps">P</small><small 
class="small-caps">G</small><small 
class="small-caps">F</small></span>&nbsp;is in state <span 
class="cmsy-10">&lt;</span><span 
class="cmti-10">name</span><span 
class="cmsy-10">&gt;</span>, the following things happen:
             <ol type="1" class="enumerate1" >
             <li class="enumerate" value="1" 
><a 
 id="x23-234004x1"></a>The <span 
class="cmsy-10">&lt;</span><span 
class="cmti-10">options</span><span 
class="cmsy-10">&gt; </span>are parsed. This may lead, see below, to a state switch. When this happens,
             the following steps are not executed. The <span 
class="cmsy-10">&lt;</span><span 
class="cmti-10">options</span><span 
class="cmsy-10">&gt; </span>are executed one after the other in the
             given order. If an option causes a state switch, the switch is immediate, even if later options
             might cause a different state switch.
             </li>
             <li class="enumerate" value="2" 
><a 
 id="x23-234006x2"></a>The <span 
class="cmsy-10">&lt;</span><span 
class="cmti-10">code</span><span 
class="cmsy-10">&gt; </span>is executed. When this happens, the coordinate transformation will be setup such
             that the origin is at the start of the segment and such that the target lies in the direction
             &#8220;east.&#8221;
             </li>
             <li class="enumerate" value="3" 
><a 
 id="x23-234008x3"></a>After the <span 
class="cmsy-10">&lt;</span><span 
class="cmti-10">code</span><span 
class="cmsy-10">&gt; </span>has been executed, the state switches to whatever state has been specified
             inside the <span 
class="cmsy-10">&lt;</span><span 
class="cmti-10">options</span><span 
class="cmsy-10">&gt; </span>using the <span class="obeylines-h"><span class="verb"><span 
class="cmtt-10">next</span><span 
class="cmtt-10">&nbsp;state</span></span></span> option. If no <span class="obeylines-h"><span class="verb"><span 
class="cmtt-10">next</span><span 
class="cmtt-10">&nbsp;state</span></span></span> has been specified, the
             state stays the same.</li></ol>
         <!--l. 183--><p class="noindent">The following options are allowed inside the <span 
class="cmsy-10">&lt;</span><span 
class="cmti-10">options</span><span 
class="cmsy-10">&gt;</span>:
             <ul class="itemize1">
             <li class="itemize"><span 
class="cmtt-10">switch if less than</span><a 
 id="dx23-234009"></a><a 
 id="dx23-234010"></a><span class="obeylines-h"><span class="verb"><span 
class="cmtt-10">=</span></span></span><span 
class="cmsy-10">&lt;</span><span 
class="cmti-10">dimension</span><span 
class="cmsy-10">&gt;</span><span class="obeylines-h"><span class="verb"><span 
class="cmtt-10">&nbsp;to</span><span 
class="cmtt-10">&nbsp;</span></span></span><span 
class="cmsy-10">&lt;</span><span 
class="cmti-10">new  state</span><span 
class="cmsy-10">&gt; </span>When  this  option  is  encountered,
             <span 
class="cmcsc-10"><small 
class="small-caps">P</small><small 
class="small-caps">G</small><small 
class="small-caps">F</small></span>&nbsp;checks whether the remaining distance to the target is less than <span 
class="cmsy-10">&lt;</span><span 
class="cmti-10">dimension</span><span 
class="cmsy-10">&gt;</span>. If so, an
             immediate state switch to <span 
class="cmsy-10">&lt;</span><span 
class="cmti-10">new state</span><span 
class="cmsy-10">&gt; </span>occurs.
             </li>
             <li class="itemize"><span 
class="cmtt-10">width</span><a 
 id="dx23-234011"></a><a 
 id="dx23-234012"></a><span class="obeylines-h"><span class="verb"><span 
class="cmtt-10">=</span></span></span><span 
class="cmsy-10">&lt;</span><span 
class="cmti-10">dimension</span><span 
class="cmsy-10">&gt; </span>This option tells <span 
class="cmcsc-10"><small 
class="small-caps">P</small><small 
class="small-caps">G</small><small 
class="small-caps">F</small></span>&nbsp;the width of the segment if it is appended to the
             path. The coordinate system will, afterward, be translated by <span 
class="cmsy-10">&lt;</span><span 
class="cmti-10">dimension</span><span 
class="cmsy-10">&gt; </span>to ensure that the
             next segment starts where the current one ended.
             <!--l. 196--><p class="noindent">In  addition,  this  option  will  cause  an  immediate  switch  to  the  state  <span class="obeylines-h"><span class="verb"><span 
class="cmtt-10">final</span></span></span> if  the
             remaining  distance  is  less  than  <span 
class="cmsy-10">&lt;</span><span 
class="cmti-10">dimension</span><span 
class="cmsy-10">&gt;</span>.  The  effect  is  the  same  as  if  you  had  said
             <span class="obeylines-h"><span class="verb"><span 
class="cmtt-10">switch</span><span 
class="cmtt-10">&nbsp;if</span><span 
class="cmtt-10">&nbsp;less</span><span 
class="cmtt-10">&nbsp;than=</span></span></span><span 
class="cmsy-10">&lt;</span><span 
class="cmti-10">dimension</span><span 
class="cmsy-10">&gt;</span><span class="obeylines-h"><span class="verb"><span 
class="cmtt-10">&nbsp;to</span><span 
class="cmtt-10">&nbsp;final</span></span></span> just before the <span class="obeylines-h"><span class="verb"><span 
class="cmtt-10">width</span></span></span> option.
             </li>
             <li class="itemize"><span 
class="cmtt-10">next state</span><a 
 id="dx23-234013"></a><a 
 id="dx23-234014"></a>=<span 
class="cmsy-10">&lt;</span><span 
class="cmti-10">new state</span><span 
class="cmsy-10">&gt; </span>After the segment has been added to the path, a state switch to
                                                                                         
                                                                                         
             <span 
class="cmsy-10">&lt;</span><span 
class="cmti-10">new state</span><span 
class="cmsy-10">&gt; </span>is performed. If this option is not given, the next state is the same as the current
             state.</li></ul>
         <!--l. 207--><p class="noindent">There are two dimensions that are useful inside snake automata:
             <dl class="description"><dt class="description">
         <span 
class="colorbox" id="colorbox244"><span 
class="cmtt-10">\pgfsnakeremainingdistance</span></span> </dt><dd 
class="description">
<a 
 id="dx23-234015"></a>
             <!--l. 209--><p class="noindent">This <span class="TEX">T<span 
class="E">E</span>X</span>&nbsp;dimension holds the remaining distance to the target. </dd></dl>
         <!--l. 211--><p class="noindent">
             <dl class="description"><dt class="description">
         <span 
class="colorbox" id="colorbox245"><span 
class="cmtt-10">\pgfsnakecompleteddistance</span></span> </dt><dd 
class="description">
<a 
 id="dx23-234016"></a>
             <!--l. 212--><p class="noindent">This <span class="TEX">T<span 
class="E">E</span>X</span>&nbsp;dimension holds the distance already completed on the snake. </dd></dl>
         </dd></dl>
     <!--l. 217--><p class="noindent">As a final example we present a more complicated snake that makes use of the different options:
                                                                                         
                                                                                         
     <!--l. 219--><p class="noindent"><div class="obeylines-v"></div><!--tex4ht:inline--><div class="tabular"><table class="tabular" 
cellspacing="0" cellpadding="0"  
frame="void" id="TBL-457-" ><colgroup id="TBL-457-1g"><col 
id="TBL-457-1"><col 
id="TBL-457-2"></colgroup><tr  
 valign="baseline" id="TBL-457-1-"><td  align="left" style="white-space:nowrap; text-align:left;" id="TBL-457-1-1"  
class="td11">  &nbsp;     <object data="pgfmanual-534.svg" width="119.80125 " height="244.3185 " type="image/svg+xml"><p>SVG-Viewer needed.</p></object>&nbsp;  </td><td  align="left" style="white-space:nowrap; text-align:left;" id="TBL-457-1-2"  
class="td11">  <table class="minipage"><tr><td><div class="obeylines-v">
<br><span 
class="cmtt-8">\pgfdeclaresnake{complicated</span><span 
class="cmtt-8">&nbsp;example</span><span 
class="cmtt-8">&nbsp;snake}{initial}</span>
<br><span 
class="cmtt-8">{</span>
<br><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;\state{initial}[width=5pt,next</span><span 
class="cmtt-8">&nbsp;state=up]</span>
<br><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;{</span><span 
class="cmtt-8">&nbsp;\pgfpathlineto{\pgfpoint{5pt}{0pt}}</span><span 
class="cmtt-8">&nbsp;}</span>
<br>
<br><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;\state{up}[width=5pt,next</span><span 
class="cmtt-8">&nbsp;state=down]</span>
<br><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;{</span>
<br><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;\ifdim\pgfsnakeremainingdistance&gt;\pgfsnakecompleteddistance</span>
<br><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmsltt-10x-x-80">%</span><span 
class="cmsltt-10x-x-80">&nbsp;Growing</span>
<br><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;\pgfpathlineto{\pgfpoint{0pt}{\pgfsnakecompleteddistance}}</span>
<br><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;\pgfpathlineto{\pgfpoint{5pt}{\pgfsnakecompleteddistance}}</span>
<br><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;\pgfpathlineto{\pgfpoint{5pt}{0pt}}</span>
<br><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;\else</span>
<br><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmsltt-10x-x-80">%</span><span 
class="cmsltt-10x-x-80">&nbsp;Shrinking</span>
<br><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;\pgfpathlineto{\pgfpoint{0pt}{\pgfsnakeremainingdistance}}</span>
<br><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;\pgfpathlineto{\pgfpoint{5pt}{\pgfsnakeremainingdistance}}</span>
<br><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;\pgfpathlineto{\pgfpoint{5pt}{0pt}}</span>
<br><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;\fi</span><span 
class="cmsltt-10x-x-80">%</span>
<br><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;}</span>
<br><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;\state{down}[width=5pt,next</span><span 
class="cmtt-8">&nbsp;state=up]</span>
<br><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;{</span>
<br><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;\ifdim\pgfsnakeremainingdistance&gt;\pgfsnakecompleteddistance</span>
<br><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmsltt-10x-x-80">%</span><span 
class="cmsltt-10x-x-80">&nbsp;Growing</span>
<br><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;\pgfpathlineto{\pgfpoint{0pt}{-\pgfsnakecompleteddistance}}</span>
<br><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;\pgfpathlineto{\pgfpoint{5pt}{-\pgfsnakecompleteddistance}}</span>
<br><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;\pgfpathlineto{\pgfpoint{5pt}{0pt}}</span>
<br><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;\else</span>
<br><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmsltt-10x-x-80">%</span><span 
class="cmsltt-10x-x-80">&nbsp;Shrinking</span>
<br><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;\pgfpathlineto{\pgfpoint{0pt}{-\pgfsnakeremainingdistance}}</span>
<br><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;\pgfpathlineto{\pgfpoint{5pt}{-\pgfsnakeremainingdistance}}</span>
<br><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;\pgfpathlineto{\pgfpoint{5pt}{0pt}}</span>
<br><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;\fi</span><span 
class="cmsltt-10x-x-80">%</span>
<br><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;}</span>
<br><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;\state{final}</span>
<br><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;{</span>
<br><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;\pgfpathlineto{\pgfpoint{\pgfsnakeremainingdistance}{0pt}}</span>
<br><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;}</span>
<br><span 
class="cmtt-8">}</span>
<br><span 
class="cmtt-8">\begin{tikzpicture}[snake=complicated</span><span 
class="cmtt-8">&nbsp;example</span><span 
class="cmtt-8">&nbsp;snake]</span>
<br><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;\draw[snake]</span><span 
class="cmtt-8">&nbsp;(0,0)</span><span 
class="cmtt-8">&nbsp;--</span><span 
class="cmtt-8">&nbsp;(3,0);</span>
<br><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;\fill[red!50,snake,rounded</span><span 
class="cmtt-8">&nbsp;corners=2pt]</span><span 
class="cmtt-8">&nbsp;(.5,-2)</span><span 
class="cmtt-8">&nbsp;--</span><span 
class="cmtt-8">&nbsp;++(2.5,-2.5)</span>
<br><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;[snake=none]</span><span 
class="cmtt-8">&nbsp;--</span><span 
class="cmtt-8">&nbsp;++(0,-.5)</span><span 
class="cmtt-8">&nbsp;-|</span><span 
class="cmtt-8">&nbsp;(0,-2)</span><span 
class="cmtt-8">&nbsp;--</span><span 
class="cmtt-8">&nbsp;cycle;</span>
<br><span 
class="cmtt-8">\end{tikzpicture}</span></div>                                                                                             </td></tr></table> </td>
</tr></table></div>
     </dd></dl>
<!--l. 267--><p class="noindent">
   <h5 class="subsubsectionHead"><span class="titlemark">22.2.4   </span> <a 
 id="x23-23500022.2.4"></a>Predefined Snakes</h5>
<!--l. 269--><p class="noindent">Only two very simple and basic snakes are predefined when you load <span 
class="cmcsc-10"><small 
class="small-caps">P</small><small 
class="small-caps">G</small><small 
class="small-caps">F</small></span>. For more interesting snakes you can use
the package <span class="obeylines-h"><span class="verb"><span 
class="cmtt-10">pgflibrarysnakes</span></span></span>.
<!--l. 273--><p class="indent">
                                                                                         
                                                                                         
     <dl class="description"><dt class="description">
<span 
class="colorbox" id="colorbox246">Snake <span 
class="cmtt-10">lineto</span></span> </dt><dd 
class="description">
<a 
 id="dx23-235001"></a>
<a 
 id="dx23-235002"></a>
     <!--l. 274--><p class="noindent">This most trivial of all snakes is simply a straight line. This snake is typically not used in a &#8220;stand
     alone&#8221; fashion. Rather, it is useful as a &#8220;subsnake&#8221; of the <span class="obeylines-h"><span class="verb"><span 
class="cmtt-10">\pgfsnakesto</span></span></span> command. </dd></dl>
<!--l. 279--><p class="indent">
     <dl class="description"><dt class="description">
<span 
class="colorbox" id="colorbox247">Snake <span 
class="cmtt-10">moveto</span></span> </dt><dd 
class="description">
<a 
 id="dx23-235003"></a>
<a 
 id="dx23-235004"></a>
     <!--l. 280--><p class="noindent">Arguably, this snake is even simpler than the previous snake. This snake consists of a simple move-to
     operation. Like the <span class="obeylines-h"><span class="verb"><span 
class="cmtt-10">lineto</span></span></span> snake, it is useful as a &#8220;subsnake&#8221; of the <span class="obeylines-h"><span class="verb"><span 
class="cmtt-10">\pgfsnakesto</span></span></span> command. </dd></dl>
<!--l. 288--><p class="noindent">
   <h4 class="subsectionHead"><span class="titlemark">22.3   </span> <a 
 id="x23-23600022.3"></a>Using Snakes</h4>
<!--l. 290--><p class="noindent">Three commands can be used to use a snake.
<!--l. 292--><p class="indent">
     <dl class="description"><dt class="description">
<span 
class="colorbox" id="colorbox248"><span 
class="cmtt-10">\pgfpathsnakealongvector</span><span 
class="cmtt-10">{</span><span 
class="cmsy-10">&lt;</span><span 
class="cmti-10">snake</span><span 
class="cmsy-10">&gt;</span><span 
class="cmtt-10">}{</span><span 
class="cmsy-10">&lt;</span><span 
class="cmti-10">length</span><span 
class="cmsy-10">&gt;</span><span 
class="cmtt-10">}{</span><span 
class="cmsy-10">&lt;</span><span 
class="cmti-10">vector</span><span 
class="cmsy-10">&gt;</span><span 
class="cmtt-10">}</span></span> </dt><dd 
class="description">
<a 
 id="dx23-236001"></a>
     <!--l. 293--><p class="noindent">This command will append the <span 
class="cmsy-10">&lt;</span><span 
class="cmti-10">snake</span><span 
class="cmsy-10">&gt; </span>to the current path. The length of the snake is given by <span 
class="cmsy-10">&lt;</span><span 
class="cmti-10">length</span><span 
class="cmsy-10">&gt;</span>. The
     <span 
class="cmsy-10">&lt;</span><span 
class="cmti-10">vector</span><span 
class="cmsy-10">&gt; </span>should be a normalizes vector (a vector having length <span class="obeylines-h"><span class="verb"><span 
class="cmtt-10">1pt</span></span></span>) pointing in the direction in which the
     snake should grow.
     <!--l. 297--><p class="noindent"><div class="obeylines-v"></div><!--tex4ht:inline--><div class="tabular"><table class="tabular" 
cellspacing="0" cellpadding="0"  
frame="void" id="TBL-458-" ><colgroup id="TBL-458-1g"><col 
id="TBL-458-1"><col 
id="TBL-458-2"></colgroup><tr  
 valign="baseline" id="TBL-458-1-"><td  align="left" style="white-space:nowrap; text-align:left;" id="TBL-458-1-1"  
class="td11">  &nbsp;<object data="pgfmanual-535.svg" width="115.07718 " height="77.27367 " type="image/svg+xml"><p>SVG-Viewer needed.</p></object>&nbsp;  </td><td  align="left" style="white-space:nowrap; text-align:left;" id="TBL-458-1-2"  
class="td11">  <table class="minipage"><tr><td><div class="obeylines-v">
<br><span 
class="cmtt-8">\begin{tikzpicture}</span>
<br><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;\draw[help</span><span 
class="cmtt-8">&nbsp;lines]</span><span 
class="cmtt-8">&nbsp;(0,0)</span><span 
class="cmtt-8">&nbsp;grid</span><span 
class="cmtt-8">&nbsp;(3,2);</span>
<br><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;\pgfpathmoveto{\pgfpoint{1cm}{1cm}}</span>
<br><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;\pgfpathsnakealongvector{zigzag}{2cm}{\pgfpointpolar{30}{1pt}}</span>
<br><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;\pgfusepath{stroke}</span>
<br><span 
class="cmtt-8">\end{tikzpicture}</span></div>                                                                                             </td></tr></table> </td>
</tr></table></div>
     </dd></dl>
<!--l. 307--><p class="indent">
     <dl class="description"><dt class="description">
<span 
class="colorbox" id="colorbox249"><span 
class="cmtt-10">\pgfpathsnakesto</span><span 
class="cmtt-10">{</span><span 
class="cmsy-10">&lt;</span><span 
class="cmti-10">snake list</span><span 
class="cmsy-10">&gt;</span><span 
class="cmtt-10">}{</span><span 
class="cmsy-10">&lt;</span><span 
class="cmti-10">target</span><span 
class="cmsy-10">&gt;</span><span 
class="cmtt-10">}</span></span> </dt><dd 
class="description">
<a 
 id="dx23-236002"></a>
     <!--l. 308--><p class="noindent">This command will append the snakes in the <span 
class="cmsy-10">&lt;</span><span 
class="cmti-10">snake list</span><span 
class="cmsy-10">&gt; </span>to the current path such that it ends at
     <span 
class="cmsy-10">&lt;</span><span 
class="cmti-10">point</span><span 
class="cmsy-10">&gt;</span>. This command calls the previous one (repeatedly, possibly) after having computed the distance
     from the current point to <span 
class="cmsy-10">&lt;</span><span 
class="cmti-10">target</span><span 
class="cmsy-10">&gt; </span>and normalized the vector connecting the current point to the target.
     <!--l. 314--><p class="noindent">The <span 
class="cmsy-10">&lt;</span><span 
class="cmti-10">snake list</span><span 
class="cmsy-10">&gt; </span>is a comma-separated list of pairs consisting of a snake name in curly braces and a
     distance in curly braces. For example, a snake list might be <span class="obeylines-h"><span class="verb"><span 
class="cmtt-10">{lineto}{1cm},{moveto}{2cm}</span></span></span>. This is
     interpreted as follows: Use a <span class="obeylines-h"><span class="verb"><span 
class="cmtt-10">lineto</span></span></span> snake for the first centimeter of the way to the <span 
class="cmsy-10">&lt;</span><span 
class="cmti-10">target</span><span 
class="cmsy-10">&gt;</span>, then use
     the <span class="obeylines-h"><span class="verb"><span 
class="cmtt-10">moveto</span></span></span> snake for the next two centimeters.
     <!--l. 321--><p class="noindent">No attempt is made to check or ensure that the distances of the &#8220;subsnakes&#8217; add up to the distnace
     from the current point to the <span 
class="cmsy-10">&lt;</span><span 
class="cmti-10">target</span><span 
class="cmsy-10">&gt;</span>. However, it is possible to refer to this distance inside the <span 
class="cmsy-10">&lt;</span><span 
class="cmti-10">snake</span>
     <span 
class="cmti-10">list</span><span 
class="cmsy-10">&gt;</span>: While the snake list is processed, the two <span class="TEX">T<span 
class="E">E</span>X</span>-dimensions <span class="obeylines-h"><span class="verb"><span 
class="cmtt-10">\pgfsnakeremainingdistance</span></span></span> and
     <span class="obeylines-h"><span class="verb"><span 
class="cmtt-10">\pgfsnakecompleteddistance</span></span></span> will be set to the correct values. For example, consider the example
                                                                                         
                                                                                         
     from a above, consisting of a <span class="obeylines-h"><span class="verb"><span 
class="cmtt-10">lineto</span></span></span> and a <span class="obeylines-h"><span class="verb"><span 
class="cmtt-10">moveto</span></span></span> snake. Suppose the distance to <span 
class="cmsy-10">&lt;</span><span 
class="cmti-10">target</span><span 
class="cmsy-10">&gt; </span>where 5cm.
     Then, when the length of the first subsnake is computed, the remaining distance willbe set to 5cm and
     the completed distance to 0cm. When the length of the second subsnake is computed, the remaining
     distance wil be 4cm and the completed distance will be 1cm.
     <!--l. 335--><p class="noindent">Here are some useful examles: <span class="obeylines-h"><span class="verb"><span 
class="cmtt-10">{zigzag}{\pgfsnakeremainingdistance}</span></span></span> is a <span 
class="cmsy-10">&lt;</span><span 
class="cmti-10">snake list</span><span 
class="cmsy-10">&gt; </span>that consists only of
     a <span class="obeylines-h"><span class="verb"><span 
class="cmtt-10">zigzag</span></span></span> snake whose length is the total distance from the current point to the <span 
class="cmsy-10">&lt;</span><span 
class="cmti-10">target</span><span 
class="cmsy-10">&gt;</span>. Next, to get a snake
     that is a <span class="obeylines-h"><span class="verb"><span 
class="cmtt-10">zigzag</span></span></span> snake that is preceeded and succeeded by 3mm of <span class="obeylines-h"><span class="verb"><span 
class="cmtt-10">lineto</span></span></span>, you can use the
     following:
     <!--l. 341--><p class="noindent"><div class="obeylines-v"></div><!--tex4ht:inline--><div class="tabular"><table class="tabular" 
cellspacing="0" cellpadding="0"  
frame="void" id="TBL-459-" ><colgroup id="TBL-459-1g"><col 
id="TBL-459-1"><col 
id="TBL-459-2"></colgroup><tr  
 valign="baseline" id="TBL-459-1-"><td  align="left" style="white-space:nowrap; text-align:left;" id="TBL-459-1-1"  
class="td11">  &nbsp;<object data="pgfmanual-536.svg" width="115.21051 " height="77.27367 " type="image/svg+xml"><p>SVG-Viewer needed.</p></object>&nbsp;  </td><td  align="left" style="white-space:nowrap; text-align:left;" id="TBL-459-1-2"  
class="td11">  <table class="minipage"><tr><td><div class="obeylines-v">
<br><span 
class="cmtt-8">\begin{tikzpicture}</span>
<br><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;\draw[help</span><span 
class="cmtt-8">&nbsp;lines](0,0)</span><span 
class="cmtt-8">&nbsp;grid</span><span 
class="cmtt-8">&nbsp;(3,2);</span>
<br><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;\pgfpathmoveto{\pgfpointorigin}</span>
<br><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;\pgfpathsnakesto{</span><span 
class="cmsltt-10x-x-80">%</span>
<br><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;{lineto}{3mm},</span><span 
class="cmsltt-10x-x-80">%</span>
<br><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;{zigzag}{\pgfsnakeremainingdistance-6mm},</span><span 
class="cmsltt-10x-x-80">%</span>
<br><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;{lineto}{3mm}}</span>
<br><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;{\pgfpoint{3cm}{2cm}}</span>
<br><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;\pgfusepath{stroke}</span>
<br><span 
class="cmtt-8">\end{tikzpicture}</span></div>                                                                                             </td></tr></table> </td>
</tr></table></div>
     <!--l. 354--><p class="noindent">Note that the computation of the distance may be imprecise. In general, the placement precision of the snakes
     will not be perfect. </dd></dl>
<!--l. 358--><p class="indent">
     <dl class="description"><dt class="description">
<span 
class="colorbox" id="colorbox250"><span 
class="cmtt-10">\pgfpathsnaketo</span><span 
class="cmtt-10">{</span><span 
class="cmsy-10">&lt;</span><span 
class="cmti-10">snake</span><span 
class="cmsy-10">&gt;</span><span 
class="cmtt-10">}{</span><span 
class="cmsy-10">&lt;</span><span 
class="cmti-10">target</span><span 
class="cmsy-10">&gt;</span><span 
class="cmtt-10">}</span></span> </dt><dd 
class="description">
<a 
 id="dx23-236003"></a>
     <!--l. 359--><p class="noindent">This command is just a shortcut for calling <span class="obeylines-h"><span class="verb"><span 
class="cmtt-10">\pgfpathsnakesto</span></span></span> for a single snake whose length is
     <span class="obeylines-h"><span class="verb"><span 
class="cmtt-10">\pgfsnakeremainingdistance</span></span></span>.
     <!--l. 361--><p class="noindent"><div class="obeylines-v"></div><!--tex4ht:inline--><div class="tabular"><table class="tabular" 
cellspacing="0" cellpadding="0"  
frame="void" id="TBL-460-" ><colgroup id="TBL-460-1g"><col 
id="TBL-460-1"><col 
id="TBL-460-2"></colgroup><tr  
 valign="baseline" id="TBL-460-1-"><td  align="left" style="white-space:nowrap; text-align:left;" id="TBL-460-1-1"  
class="td11">  &nbsp;<object data="pgfmanual-537.svg" width="115.2013 " height="77.2684 " type="image/svg+xml"><p>SVG-Viewer needed.</p></object>&nbsp;  </td><td  align="left" style="white-space:nowrap; text-align:left;" id="TBL-460-1-2"  
class="td11">  <table class="minipage"><tr><td><div class="obeylines-v">
<br><span 
class="cmtt-8">\begin{tikzpicture}</span>
<br><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;\draw[help</span><span 
class="cmtt-8">&nbsp;lines]</span><span 
class="cmtt-8">&nbsp;(0,0)</span><span 
class="cmtt-8">&nbsp;grid</span><span 
class="cmtt-8">&nbsp;(3,2);</span>
<br><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;\pgfpathmoveto{\pgfpoint{1cm}{1cm}}</span>
<br><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;\pgfpathsnaketo{zigzag}{\pgfpoint{3cm}{2cm}}</span>
<br><span 
class="cmtt-8">&nbsp;</span><span 
class="cmtt-8">&nbsp;\pgfusepath{stroke}</span>
<br><span 
class="cmtt-8">\end{tikzpicture}</span></div>                                                                                             </td></tr></table> </td>
</tr></table></div>
     </dd></dl>
<!--l. 371--><p class="indent">   As was already mentioned, when each segment of the snake is added to the path, an appropriate coordinate
transformation will be in force. It is sometimes useful to add an additional transformation locally. For
example, by reflecting everything around the <span 
class="cmmi-10">x</span>-axis right before each segment is added, the snake will
effectively be mirrored along the path. The following command allows you to install such a &#8220;last minute
transformation.&#8221;
<!--l. 379--><p class="indent">
     <dl class="description"><dt class="description">
<span 
class="colorbox" id="colorbox251"><span 
class="cmtt-10">\pgfsetsnakesegmenttransformation</span><span 
class="cmtt-10">{</span><span 
class="cmsy-10">&lt;</span><span 
class="cmti-10">code</span><span 
class="cmsy-10">&gt;</span><span 
class="cmtt-10">}</span></span> </dt><dd 
class="description">
<a 
 id="dx23-236004"></a>
     <!--l. 380--><p class="noindent">The <span 
class="cmsy-10">&lt;</span><span 
class="cmti-10">code</span><span 
class="cmsy-10">&gt; </span>will be executed at the very beginning of each segment. Normally, this be a transformation
     command that changes the <span 
class="cmmi-10">y</span>-axis in some way. </dd></dl>
                                                                                         
                                                                                         
                                                                                         
                                                                                         
                                                                                         
                                                                                         
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