doc/parts/extensions/Shapes-Graphics-metapostarrow.sxml

   1 <?xml version="1.0" encoding="UTF-8"?>
   2 <?xml-stylesheet type="text/xsl" href="formats/html.xsl"?>
   3
   4 <!-- This file is part of Shapes.                                           -->
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  18 <!--                                                                        -->
  19 <!-- Copyright 2008, 2014, 2015 Henrik Tidefelt                             -->
  20
  21
  22 <book>
  23   <namespace>..Shapes..Graphics</namespace>
  24   <extension>metapostarrow</extension>
  25   <description>
  26     <p>Arrowheads available through the prelude.</p>
  27   </description>
  28   <prelude />
  29   <needs></needs>
  30
  31   <title><self /></title>
  32   <meta-selflink><self-href /></meta-selflink>
  33   <up-link><parent-namespace /></up-link>
  34   <base href=<!--#expand-next-string-->"$(BASE)" />
  35   <examples-home href=<!--#expand-next-string-->"$(EXAMPLES)" />
  36   <shapes-version number=<!--#expand-next-string-->"$(SHAPES_VERSION)" />
  37   <external>
  38     <!--#include virtual="^/toc.xml" -->
  39   </external>
  40
  41   <top>
  42     <alphabetical-index/>
  43     <p>Please refer to <a extension="arrowheads" /> for an introduction to arrowheads.</p>
  44   </top>
  45
  46         <section id="extensions/arrowheads/2D">
  47                 <title>Arrowheads in <str-2D /></title>
  48                 <body>
  49                         <p>This arrowhead is for use in <str-2D />.</p>
  50
  51                 <system-binding name="MetaPostArrow">
  52                         <function>
  53                                 <case>
  54                                         <arguments>
  55                                                 <arg identifier="p">
  56                                                         <type><named-type name="Path" /></type>
  57                                                 </arg>
  58                                                 <arg identifier="ahLength">
  59                                                         <type><named-type name="Length" /></type>
  60                                                         <default><value name="void" /></default>
  61                                                 </arg>
  62                                                 <arg identifier="ahAngle">
  63                                                         <type><named-type name="Float" /></type>
  64                                                         <default><eq>30°</eq></default>
  65                                                 </arg>
  66                                                 <arg identifier="fillAsStroking">
  67                                                         <type><named-type name="Boolean" /></type>
  68                                                         <default><eq><const-true /></eq></default>
  69                                                 </arg>
  70                                         </arguments>
  71                                         <result>
  72                                                 <type>
  73                                                         <structure-type>
  74                                                                 <field name="picture"><type><named-type name="Drawable" /></type></field>
  75                                                                 <field name="cut"><type><named-type name="Length" /></type></field>
  76                                                         </structure-type>
  77                                                 </type>
  78                                         </result>
  79                                         <dynamic-references>Whole graphics state</dynamic-references>
  80                                         <description>
  81                                                 <p>As the name of this function indicates, this arrowhead design is borrowed from <str-MetaPost />, although there are differences.  The main idea with the design is that the arrowhead should bend with the path, please refer to the canonical illustration on the <str-MetaPost /> <a href="http://ect.bell-labs.com/who/hobby/MetaPost.html">home page</a>. The argument <arg name="ahLength" /> suggests how long the arrowhead should be (this will only be overridden in exceptional cases when the path is too short).  If it is not provided, its value will be computed based on the width of the stroke and <arg name="ahAngle" /> — exactly how will remain subject to change for some time.  <arg name="ahAngle" /> is the angle at the tip of the arrowhead.  When <arg name="fillAsStroking" /> is true, the fill color of the arrowhead will be <dynamic name="stroking" /> instead of <dynamic name="nonstroking" />.</p>
  82                                         </description>
  83                                 </case>
  84                         </function>
  85                 </system-binding>
  86
  87                 </body>
  88                 </section> <!-- End of  -->
  89
  90
  91         <section id="extensions/arrowheads/3D">
  92                 <title>Arrowheads in <str-3D /></title>
  93                 <body>
  94                         <p>This arrowhead is for use in <str-3D />.</p>
  95
  96                 <system-binding name="MetaPostArrow3D">
  97                         <function>
  98                                 <case>
  99                                         <arguments>
 100                                                 <arg identifier="normal">
 101                                                         <type><named-type name="FloatTriple" /></type>
 102                                                 </arg>
 103                                                 <arg identifier="p">
 104                                                         <type><named-type name="Path3D" /></type>
 105                                                 </arg>
 106                                                 <arg identifier="ahLength">
 107                                                         <type><named-type name="Length" /></type>
 108                                                         <default><value name="void" /></default>
 109                                                 </arg>
 110                                                 <arg identifier="ahAngle">
 111                                                         <type><named-type name="Float" /></type>
 112                                                         <default><eq>30°</eq></default>
 113                                                 </arg>
 114                                                 <arg identifier="fillAsStroking">
 115                                                         <type><named-type name="Boolean" /></type>
 116                                                         <default><eq><const-true /></eq></default>
 117                                                 </arg>
 118                                         </arguments>
 119                                         <result>
 120                                                 <type>
 121                                                         <structure-type>
 122                                                                 <field name="picture"><type><named-type name="Drawable3D" /></type></field>
 123                                                                 <field name="cut"><type><named-type name="Length" /></type></field>
 124                                                         </structure-type>
 125                                                 </type>
 126                                         </result>
 127                                         <dynamic-references>Whole graphics state</dynamic-references>
 128                                         <description>
 129                                                 <p>This is a generalization of <value name="MetaPostArrow" /> to <str-3D /> (let us not look closer at what this really means).  Note that the mandatory <arg name="normal" /> means that this function is not a <named-type name="ArrowHead3D" /> until this argument has been bound.</p>
 130                                                 <p>Please refer to the discussion about <str-3D /> arrowheads in <a extension="arrowheads" id="extensions/arrowheads/3D"/> for ways to avoid the need to specify the surface normal.</p>
 131                                         </description>
 132                                 </case>
 133                         </function>
 134                 </system-binding>
 135
 136                 </body>
 137         </section> <!-- End of  -->
 138
 139 </book>