upstream-man-pages/man2/gluNurbsCurve.xml

   1 <?xml version="1.0" encoding="UTF-8"?>
   2 <!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook MathML Module V1.1b1//EN"
   3               "http://www.oasis-open.org/docbook/xml/mathml/1.1CR1/dbmathml.dtd">
   4 <refentry id="gluNurbsCurve">
   5     <refmeta>
   6         <refmetainfo>
   7             <copyright>
   8                 <year>1991-2006</year>
   9                 <holder>Silicon Graphics, Inc.</holder>
  10             </copyright>
  11         </refmetainfo>
  12         <refentrytitle>gluNurbsCurve</refentrytitle>
  13         <manvolnum>3G</manvolnum>
  14     </refmeta>
  15     <refnamediv>
  16         <refname>gluNurbsCurve</refname>
  17         <refpurpose>define the shape of a NURBS curve</refpurpose>
  18     </refnamediv>
  19     <refsynopsisdiv><title>C Specification</title>
  20         <funcsynopsis>
  21             <funcprototype>
  22                 <funcdef>void <function>gluNurbsCurve</function></funcdef>
  23                 <paramdef>GLUnurbs* <parameter>nurb</parameter></paramdef>
  24                 <paramdef>GLint <parameter>knotCount</parameter></paramdef>
  25                 <paramdef>GLfloat * <parameter>knots</parameter></paramdef>
  26                 <paramdef>GLint <parameter>stride</parameter></paramdef>
  27                 <paramdef>GLfloat * <parameter>control</parameter></paramdef>
  28                 <paramdef>GLint <parameter>order</parameter></paramdef>
  29                 <paramdef>GLenum <parameter>type</parameter></paramdef>
  30             </funcprototype>
  31         </funcsynopsis>
  32     </refsynopsisdiv>
  33     <!-- eqn: ignoring delim $$ -->
  34     <refsect1 id="parameters"><title>Parameters</title>
  35         <variablelist>
  36         <varlistentry>
  37             <term><parameter>nurb</parameter></term>
  38             <listitem>
  39                 <para>
  40                     Specifies the NURBS object (created with <citerefentry><refentrytitle>gluNewNurbsRenderer</refentrytitle></citerefentry>).
  41                 </para>
  42             </listitem>
  43         </varlistentry>
  44         <varlistentry>
  45             <term><parameter>knotCount</parameter></term>
  46             <listitem>
  47                 <para>
  48                     Specifies the number of knots in <parameter>knots</parameter>.
  49                     <parameter>knotCount</parameter> equals the number of control points plus the order.
  50                 </para>
  51             </listitem>
  52         </varlistentry>
  53         <varlistentry>
  54             <term><parameter>knots</parameter></term>
  55             <listitem>
  56                 <para>
  57                     Specifies an array of <parameter>knotCount</parameter> nondecreasing knot values.
  58                 </para>
  59             </listitem>
  60         </varlistentry>
  61         <varlistentry>
  62             <term><parameter>stride</parameter></term>
  63             <listitem>
  64                 <para>
  65                     Specifies the offset (as a number of single-precision floating-point values)
  66                     between successive curve control points.
  67                 </para>
  68             </listitem>
  69         </varlistentry>
  70         <varlistentry>
  71             <term><parameter>control</parameter></term>
  72             <listitem>
  73                 <para>
  74                     Specifies a pointer to an array of control points. The coordinates must
  75                     agree with <parameter>type</parameter>, specified below.
  76                 </para>
  77             </listitem>
  78         </varlistentry>
  79         <varlistentry>
  80             <term><parameter>order</parameter></term>
  81             <listitem>
  82                 <para>
  83                     Specifies the order of the NURBS curve. <parameter>order</parameter> equals degree + 1, hence
  84                     a cubic curve has an order of 4.
  85                 </para>
  86             </listitem>
  87         </varlistentry>
  88         <varlistentry>
  89             <term><parameter>type</parameter></term>
  90             <listitem>
  91                 <para>
  92                     Specifies the type of the curve. If this curve is defined within a
  93                     <citerefentry><refentrytitle>gluBeginCurve</refentrytitle></citerefentry>/<citerefentry><refentrytitle>gluEndCurve</refentrytitle></citerefentry> pair, then
  94                     the type can be any of the valid
  95                     one-dimensional evaluator types (such as <constant>GLU_MAP1_VERTEX_3</constant> or
  96                     <constant>GLU_MAP1_COLOR_4</constant>). Between a <citerefentry><refentrytitle>gluBeginTrim</refentrytitle></citerefentry>/<citerefentry><refentrytitle>gluEndTrim</refentrytitle></citerefentry> pair,
  97                     the only valid types are <constant>GLU_MAP1_TRIM_2</constant> and <constant>GLU_MAP1_TRIM_3</constant>.
  98                 </para>
  99             </listitem>
 100         </varlistentry>
 101         </variablelist>
 102     </refsect1>
 103     <refsect1 id="description"><title>Description</title>
 104         <para>
 105             Use <function>gluNurbsCurve</function> to describe a NURBS curve.
 106         </para>
 107         <para>
 108             When <function>gluNurbsCurve</function> appears between a <citerefentry><refentrytitle>gluBeginCurve</refentrytitle></citerefentry>/<citerefentry><refentrytitle>gluEndCurve</refentrytitle></citerefentry> pair, it is
 109             used to describe a curve to be rendered.
 110             Positional, texture, and color coordinates are associated
 111             by presenting each as a separate <function>gluNurbsCurve</function> between a
 112             <citerefentry><refentrytitle>gluBeginCurve</refentrytitle></citerefentry>/<citerefentry><refentrytitle>gluEndCurve</refentrytitle></citerefentry> pair. No more than
 113             one call to <function>gluNurbsCurve</function> for each of color, position, and texture
 114             data can be made within a single <citerefentry><refentrytitle>gluBeginCurve</refentrytitle></citerefentry>/<citerefentry><refentrytitle>gluEndCurve</refentrytitle></citerefentry>
 115             pair. Exactly one call must be made to describe the position of the
 116             curve (a <parameter>type</parameter> of <constant>GLU_MAP1_VERTEX_3</constant> or <constant>GLU_MAP1_VERTEX_4</constant>).
 117         </para>
 118         <para>
 119             When <function>gluNurbsCurve</function> appears between a <citerefentry><refentrytitle>gluBeginTrim</refentrytitle></citerefentry>/<citerefentry><refentrytitle>gluEndTrim</refentrytitle></citerefentry> pair, it is
 120             used to describe a trimming curve on a NURBS surface. If <parameter>type</parameter> is
 121             <constant>GLU_MAP1_TRIM_2</constant>, then it describes a curve in two-dimensional (<emphasis>u</emphasis>
 122             and <emphasis>v</emphasis>)
 123             parameter space. If it is <constant>GLU_MAP1_TRIM_3</constant>, then it describes a
 124             curve in two-dimensional homogeneous (<emphasis>u</emphasis>, <emphasis>v</emphasis>, and <emphasis>w</emphasis>)
 125             parameter space.
 126             See the <citerefentry><refentrytitle>gluBeginTrim</refentrytitle></citerefentry> reference page for more discussion about trimming
 127             curves.
 128         </para>
 129     </refsect1>
 130     <refsect1 id="example"><title>Example</title>
 131         <para>
 132             The following commands render a textured NURBS curve with normals:
 133             <programlisting>
 134 gluBeginCurve(nobj);
 135    gluNurbsCurve(nobj, ..., GL_MAP1_TEXTURE_COORD_2);
 136    gluNurbsCurve(nobj, ..., GL_MAP1_NORMAL);
 137    gluNurbsCurve(nobj, ..., GL_MAP1_VERTEX_4);
 138 gluEndCurve(nobj);
 139             </programlisting>
 140         </para>
 141     </refsect1>
 142     <refsect1 id="notes"><title>Notes</title>
 143         <para>
 144             To define trim curves that stitch well, use <citerefentry><refentrytitle>gluPwlCurve</refentrytitle></citerefentry>.
 145         </para>
 146     </refsect1>
 147     <refsect1 id="seealso"><title>See Also</title>
 148         <para>
 149             <citerefentry><refentrytitle>gluBeginCurve</refentrytitle></citerefentry>,
 150             <citerefentry><refentrytitle>gluBeginTrim</refentrytitle></citerefentry>,
 151             <citerefentry><refentrytitle>gluNewNurbsRenderer</refentrytitle></citerefentry>,
 152             <citerefentry><refentrytitle>gluPwlCurve</refentrytitle></citerefentry>
 153         </para>
 154     </refsect1>
 155     <refsect1 id="Copyright"><title>Copyright</title>
 156         <para>
 157             Copyright <trademark class="copyright"></trademark> 1991-2006
 158             Silicon Graphics, Inc. This document is licensed under the SGI
 159             Free Software B License. For details, see
 160             <ulink url="http://oss.sgi.com/projects/FreeB/">http://oss.sgi.com/projects/FreeB/</ulink>.
 161         </para>
 162     </refsect1>
 163 </refentry>