100 lines
4.7 KiB
XML
100 lines
4.7 KiB
XML
<?xml version="1.0" encoding="UTF-8"?>
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<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook MathML Module V1.1b1//EN"
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"http://www.oasis-open.org/docbook/xml/mathml/1.1CR1/dbmathml.dtd">
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<refentry id="gluBeginCurve">
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<refmeta>
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<refmetainfo>
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<copyright>
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<year>1991-2006</year>
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<holder>Silicon Graphics, Inc.</holder>
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</copyright>
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</refmetainfo>
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<refentrytitle>gluBeginCurve</refentrytitle>
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<manvolnum>3G</manvolnum>
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</refmeta>
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<refnamediv>
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<refname>gluBeginCurve</refname>
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<refpurpose>delimit a NURBS curve definition</refpurpose>
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</refnamediv>
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<refsynopsisdiv><title>C Specification</title>
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<funcsynopsis>
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<funcprototype>
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<funcdef>void <function>gluBeginCurve</function></funcdef>
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<paramdef>GLUnurbs* <parameter>nurb</parameter></paramdef>
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</funcprototype>
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</funcsynopsis>
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</refsynopsisdiv>
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<refsynopsisdiv><title>C Specification</title>
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<funcsynopsis>
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<funcprototype>
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<funcdef>void <function>gluEndCurve</function></funcdef>
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<paramdef>GLUnurbs* <parameter>nurb</parameter></paramdef>
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</funcprototype>
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</funcsynopsis>
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</refsynopsisdiv>
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<!-- eqn: ignoring delim $$ -->
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<refsect1 id="parameters"><title>Parameters</title>
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<variablelist>
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<varlistentry>
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<term><parameter>nurb</parameter></term>
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<listitem>
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<para>
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Specifies the NURBS object (created with <citerefentry><refentrytitle>gluNewNurbsRenderer</refentrytitle></citerefentry>).
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</para>
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</listitem>
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</varlistentry>
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</variablelist>
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</refsect1>
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<refsect1 id="description"><title>Description</title>
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<para>
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Use <function>gluBeginCurve</function> to mark the beginning of a NURBS
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curve definition.
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After
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calling <function>gluBeginCurve</function>, make one or more calls to
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<citerefentry><refentrytitle>gluNurbsCurve</refentrytitle></citerefentry> to define the attributes of the curve.
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Exactly one of the calls to <citerefentry><refentrytitle>gluNurbsCurve</refentrytitle></citerefentry> must have
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a curve type of <constant>GLU_MAP1_VERTEX_3</constant> or <constant>GLU_MAP1_VERTEX_4</constant>.
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To mark the end of the NURBS curve definition, call <citerefentry><refentrytitle>gluEndCurve</refentrytitle></citerefentry>.
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</para>
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<para>
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GL evaluators are used to render the NURBS curve as a series of line
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segments.
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Evaluator state is preserved during rendering
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with <citerefentry><refentrytitle>glPushAttrib</refentrytitle></citerefentry>(<constant>GLU_EVAL_BIT</constant>) and
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<citerefentry><refentrytitle>glPopAttrib</refentrytitle></citerefentry>().
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See the <citerefentry><refentrytitle>glPushAttrib</refentrytitle></citerefentry> reference page for details on exactly what state
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these calls preserve.
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</para>
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</refsect1>
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<refsect1 id="example"><title>Example</title>
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<para>
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The following commands render a textured NURBS curve with normals;
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texture coordinates and normals are also specified as NURBS curves:
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<programlisting>
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gluBeginCurve(nobj);
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gluNurbsCurve(nobj, ..., GL_MAP1_TEXTURE_COORD_2);
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gluNurbsCurve(nobj, ..., GL_MAP1_NORMAL);
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gluNurbsCurve(nobj, ..., GL_MAP1_VERTEX_4);
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gluEndCurve(nobj);
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</programlisting>
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</para>
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</refsect1>
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<refsect1 id="seealso"><title>See Also</title>
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<para>
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<citerefentry><refentrytitle>gluBeginSurface</refentrytitle></citerefentry>,
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<citerefentry><refentrytitle>gluBeginTrim</refentrytitle></citerefentry>,
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<citerefentry><refentrytitle>gluNewNurbsRenderer</refentrytitle></citerefentry>,
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<citerefentry><refentrytitle>gluNurbsCurve</refentrytitle></citerefentry>,
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<citerefentry><refentrytitle>glPopAttrib</refentrytitle></citerefentry>,
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<citerefentry><refentrytitle>glPushAttrib</refentrytitle></citerefentry>
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</para>
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</refsect1>
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<refsect1 id="Copyright"><title>Copyright</title>
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<para>
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Copyright <trademark class="copyright"></trademark> 1991-2006
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Silicon Graphics, Inc. This document is licensed under the SGI
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Free Software B License. For details, see
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<ulink url="http://oss.sgi.com/projects/FreeB/">http://oss.sgi.com/projects/FreeB/</ulink>.
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</para>
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</refsect1>
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</refentry>
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