<?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook MathML Module V1.1b1//EN" "http://www.oasis-open.org/docbook/xml/mathml/1.1CR1/dbmathml.dtd"> <refentry id="gluNurbsSurface"> <refmeta> <refmetainfo> <copyright> <year>1991-2006</year> <holder>Silicon Graphics, Inc.</holder> </copyright> </refmetainfo> <refentrytitle>gluNurbsSurface</refentrytitle> <manvolnum>3G</manvolnum> </refmeta> <refnamediv> <refname>gluNurbsSurface</refname> <refpurpose>define the shape of a NURBS surface</refpurpose> </refnamediv> <refsynopsisdiv><title>C Specification</title> <funcsynopsis> <funcprototype> <funcdef>void <function>gluNurbsSurface</function></funcdef> <paramdef>GLUnurbs* <parameter>nurb</parameter></paramdef> <paramdef>GLint <parameter>sKnotCount</parameter></paramdef> <paramdef>GLfloat* <parameter>sKnots</parameter></paramdef> <paramdef>GLint <parameter>tKnotCount</parameter></paramdef> <paramdef>GLfloat* <parameter>tKnots</parameter></paramdef> <paramdef>GLint <parameter>sStride</parameter></paramdef> <paramdef>GLint <parameter>tStride</parameter></paramdef> <paramdef>GLfloat* <parameter>control</parameter></paramdef> <paramdef>GLint <parameter>sOrder</parameter></paramdef> <paramdef>GLint <parameter>tOrder</parameter></paramdef> <paramdef>GLenum <parameter>type</parameter></paramdef> </funcprototype> </funcsynopsis> </refsynopsisdiv> <!-- eqn: ignoring delim $$ --> <refsect1 id="parameters"><title>Parameters</title> <variablelist> <varlistentry> <term><parameter>nurb</parameter></term> <listitem> <para> Specifies the NURBS object (created with <citerefentry><refentrytitle>gluNewNurbsRenderer</refentrytitle></citerefentry>). </para> </listitem> </varlistentry> <varlistentry> <term><parameter>sKnotCount</parameter></term> <listitem> <para> Specifies the number of knots in the parametric <emphasis>u</emphasis> direction. </para> </listitem> </varlistentry> <varlistentry> <term><parameter>sKnots</parameter></term> <listitem> <para> Specifies an array of <parameter>sKnotCount</parameter> nondecreasing knot values in the parametric <emphasis>u</emphasis> direction. </para> </listitem> </varlistentry> <varlistentry> <term><parameter>tKnotCount</parameter></term> <listitem> <para> Specifies the number of knots in the parametric <emphasis>v</emphasis> direction. </para> </listitem> </varlistentry> <varlistentry> <term><parameter>tKnots</parameter></term> <listitem> <para> Specifies an array of <parameter>tKnotCount</parameter> nondecreasing knot values in the parametric <emphasis>v</emphasis> direction. </para> </listitem> </varlistentry> <varlistentry> <term><parameter>sStride</parameter></term> <listitem> <para> Specifies the offset (as a number of single-precision floating-point values) between successive control points in the parametric <emphasis>u</emphasis> direction in <parameter>control</parameter>. </para> </listitem> </varlistentry> <varlistentry> <term><parameter>tStride</parameter></term> <listitem> <para> Specifies the offset (in single-precision floating-point values) between successive control points in the parametric <emphasis>v</emphasis> direction in <parameter>control</parameter>. </para> </listitem> </varlistentry> <varlistentry> <term><parameter>control</parameter></term> <listitem> <para> Specifies an array containing control points for the NURBS surface. The offsets between successive control points in the parametric <emphasis>u</emphasis> and <emphasis>v</emphasis> directions are given by <parameter>sStride</parameter> and <parameter>tStride</parameter>. </para> </listitem> </varlistentry> <varlistentry> <term><parameter>sOrder</parameter></term> <listitem> <para> Specifies the order of the NURBS surface in the parametric <emphasis>u</emphasis> direction. The order is one more than the degree, hence a surface that is cubic in <emphasis>u</emphasis> has a <emphasis>u</emphasis> order of 4. </para> </listitem> </varlistentry> <varlistentry> <term><parameter>tOrder</parameter></term> <listitem> <para> Specifies the order of the NURBS surface in the parametric <emphasis>v</emphasis> direction. The order is one more than the degree, hence a surface that is cubic in <emphasis>v</emphasis> has a <emphasis>v</emphasis> order of 4. </para> </listitem> </varlistentry> <varlistentry> <term><parameter>type</parameter></term> <listitem> <para> Specifies type of the surface. <parameter>type</parameter> can be any of the valid two-dimensional evaluator types (such as <constant>GLU_MAP2_VERTEX_3</constant> or <constant>GLU_MAP2_COLOR_4</constant>). </para> </listitem> </varlistentry> </variablelist> </refsect1> <refsect1 id="description"><title>Description</title> <para> Use <function>gluNurbsSurface</function> within a NURBS (Non-Uniform Rational B-Spline) surface definition to describe the shape of a NURBS surface (before any trimming). To mark the beginning of a NURBS surface definition, use the <citerefentry><refentrytitle>gluBeginSurface</refentrytitle></citerefentry> command. To mark the end of a NURBS surface definition, use the <citerefentry><refentrytitle>gluEndSurface</refentrytitle></citerefentry> command. Call <function>gluNurbsSurface</function> within a NURBS surface definition only. </para> <para> Positional, texture, and color coordinates are associated with a surface by presenting each as a separate <function>gluNurbsSurface</function> between a <citerefentry><refentrytitle>gluBeginSurface</refentrytitle></citerefentry>/<citerefentry><refentrytitle>gluEndSurface</refentrytitle></citerefentry> pair. No more than one call to <function>gluNurbsSurface</function> for each of color, position, and texture data can be made within a single <citerefentry><refentrytitle>gluBeginSurface</refentrytitle></citerefentry>/<citerefentry><refentrytitle>gluEndSurface</refentrytitle></citerefentry> pair. Exactly one call must be made to describe the position of the surface (a <parameter>type</parameter> of <constant>GLU_MAP2_VERTEX_3</constant> or <constant>GLU_MAP2_VERTEX_4</constant>). </para> <para> A NURBS surface can be trimmed by using the commands <citerefentry><refentrytitle>gluNurbsCurve</refentrytitle></citerefentry> and <citerefentry><refentrytitle>gluPwlCurve</refentrytitle></citerefentry> between calls to <citerefentry><refentrytitle>gluBeginTrim</refentrytitle></citerefentry> and <citerefentry><refentrytitle>gluEndTrim</refentrytitle></citerefentry>. </para> <para> Note that a <function>gluNurbsSurface</function> with <parameter>sKnotCount</parameter> knots in the <emphasis>u</emphasis> direction and <parameter>tKnotCount</parameter> knots in the <emphasis>v</emphasis> direction with orders <parameter>sOrder</parameter> and <parameter>tOrder</parameter> must have (<parameter>sKnotCount</parameter> - <parameter>sOrder</parameter>) <inlineequation><mml:math><mml:mi mathvariant="italic">times</mml:mi></mml:math></inlineequation> (<parameter>tKnotCount</parameter> - <parameter>tOrder</parameter>) control points. </para> </refsect1> <refsect1 id="example"><title>Example</title> <para> The following commands render a textured NURBS surface with normals; the texture coordinates and normals are also NURBS surfaces: <programlisting> gluBeginSurface(nobj); gluNurbsSurface(nobj, ..., GL_MAP2_TEXTURE_COORD_2); gluNurbsSurface(nobj, ..., GL_MAP2_NORMAL); gluNurbsSurface(nobj, ..., GL_MAP2_VERTEX_4); gluEndSurface(nobj); </programlisting> </para> </refsect1> <refsect1 id="seealso"><title>See Also</title> <para> <citerefentry><refentrytitle>gluBeginSurface</refentrytitle></citerefentry>, <citerefentry><refentrytitle>gluBeginTrim</refentrytitle></citerefentry>, <citerefentry><refentrytitle>gluNewNurbsRenderer</refentrytitle></citerefentry>, <citerefentry><refentrytitle>gluNurbsCurve</refentrytitle></citerefentry>, <citerefentry><refentrytitle>gluPwlCurve</refentrytitle></citerefentry> </para> </refsect1> <refsect1 id="Copyright"><title>Copyright</title> <para> Copyright <trademark class="copyright"></trademark> 1991-2006 Silicon Graphics, Inc. This document is licensed under the SGI Free Software B License. For details, see <ulink url="http://oss.sgi.com/projects/FreeB/">http://oss.sgi.com/projects/FreeB/</ulink>. </para> </refsect1> </refentry>