105 lines
5.3 KiB
XML
105 lines
5.3 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="gluBeginSurface">
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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>gluBeginSurface</refentrytitle>
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<manvolnum>3G</manvolnum>
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</refmeta>
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<refnamediv>
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<refname>gluBeginSurface</refname>
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<refpurpose>delimit a NURBS surface 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>gluBeginSurface</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>gluEndSurface</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>gluBeginSurface</function> to mark the beginning of a NURBS
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surface definition. After
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calling <function>gluBeginSurface</function>, make one or more calls to
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<citerefentry><refentrytitle>gluNurbsSurface</refentrytitle></citerefentry> to define the attributes of the surface.
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Exactly one of these calls to <citerefentry><refentrytitle>gluNurbsSurface</refentrytitle></citerefentry> must have a
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surface type of <constant>GLU_MAP2_VERTEX_3</constant> or <constant>GLU_MAP2_VERTEX_4</constant>.
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To mark the end of the NURBS surface definition, call
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<citerefentry><refentrytitle>gluEndSurface</refentrytitle></citerefentry>.
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</para>
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<para>
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Trimming of NURBS surfaces is supported with <citerefentry><refentrytitle>gluBeginTrim</refentrytitle></citerefentry>,
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<citerefentry><refentrytitle>gluPwlCurve</refentrytitle></citerefentry>, <citerefentry><refentrytitle>gluNurbsCurve</refentrytitle></citerefentry>, and <citerefentry><refentrytitle>gluEndTrim</refentrytitle></citerefentry>. See the
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<citerefentry><refentrytitle>gluBeginTrim</refentrytitle></citerefentry> reference page for details.
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</para>
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<para>
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GL evaluators are used to render the NURBS surface as a set of polygons.
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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 surface with normals;
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the texture coordinates and normals are also described as NURBS surfaces:
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<programlisting>
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gluBeginSurface(nobj);
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gluNurbsSurface(nobj, ..., GL_MAP2_TEXTURE_COORD_2);
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gluNurbsSurface(nobj, ..., GL_MAP2_NORMAL);
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gluNurbsSurface(nobj, ..., GL_MAP2_VERTEX_4);
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gluEndSurface(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>gluBeginCurve</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>gluNurbsSurface</refentrytitle></citerefentry>,
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<citerefentry><refentrytitle>gluPwlCurve</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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