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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="gluNurbsSurface"> | |
5 | <refmeta> | |
6 | <refmetainfo> | |
7 | <copyright> | |
8 | <year>1991-2006</year> | |
9 | <holder>Silicon Graphics, Inc.</holder> | |
10 | </copyright> | |
11 | </refmetainfo> | |
12 | <refentrytitle>gluNurbsSurface</refentrytitle> | |
13 | <manvolnum>3G</manvolnum> | |
14 | </refmeta> | |
15 | <refnamediv> | |
16 | <refname>gluNurbsSurface</refname> | |
17 | <refpurpose>define the shape of a NURBS surface</refpurpose> | |
18 | </refnamediv> | |
19 | <refsynopsisdiv><title>C Specification</title> | |
20 | <funcsynopsis> | |
21 | <funcprototype> | |
22 | <funcdef>void <function>gluNurbsSurface</function></funcdef> | |
23 | <paramdef>GLUnurbs* <parameter>nurb</parameter></paramdef> | |
24 | <paramdef>GLint <parameter>sKnotCount</parameter></paramdef> | |
25 | <paramdef>GLfloat* <parameter>sKnots</parameter></paramdef> | |
26 | <paramdef>GLint <parameter>tKnotCount</parameter></paramdef> | |
27 | <paramdef>GLfloat* <parameter>tKnots</parameter></paramdef> | |
28 | <paramdef>GLint <parameter>sStride</parameter></paramdef> | |
29 | <paramdef>GLint <parameter>tStride</parameter></paramdef> | |
30 | <paramdef>GLfloat* <parameter>control</parameter></paramdef> | |
31 | <paramdef>GLint <parameter>sOrder</parameter></paramdef> | |
32 | <paramdef>GLint <parameter>tOrder</parameter></paramdef> | |
33 | <paramdef>GLenum <parameter>type</parameter></paramdef> | |
34 | </funcprototype> | |
35 | </funcsynopsis> | |
36 | </refsynopsisdiv> | |
37 | <!-- eqn: ignoring delim $$ --> | |
38 | <refsect1 id="parameters"><title>Parameters</title> | |
39 | <variablelist> | |
40 | <varlistentry> | |
41 | <term><parameter>nurb</parameter></term> | |
42 | <listitem> | |
43 | <para> | |
44 | Specifies the NURBS object (created with <citerefentry><refentrytitle>gluNewNurbsRenderer</refentrytitle></citerefentry>). | |
45 | </para> | |
46 | </listitem> | |
47 | </varlistentry> | |
48 | <varlistentry> | |
49 | <term><parameter>sKnotCount</parameter></term> | |
50 | <listitem> | |
51 | <para> | |
52 | Specifies the number of knots in the parametric <emphasis>u</emphasis> direction. | |
53 | </para> | |
54 | </listitem> | |
55 | </varlistentry> | |
56 | <varlistentry> | |
57 | <term><parameter>sKnots</parameter></term> | |
58 | <listitem> | |
59 | <para> | |
60 | Specifies an array of <parameter>sKnotCount</parameter> nondecreasing knot values in the parametric | |
61 | <emphasis>u</emphasis> direction. | |
62 | </para> | |
63 | </listitem> | |
64 | </varlistentry> | |
65 | <varlistentry> | |
66 | <term><parameter>tKnotCount</parameter></term> | |
67 | <listitem> | |
68 | <para> | |
69 | Specifies the number of knots in the parametric <emphasis>v</emphasis> direction. | |
70 | </para> | |
71 | </listitem> | |
72 | </varlistentry> | |
73 | <varlistentry> | |
74 | <term><parameter>tKnots</parameter></term> | |
75 | <listitem> | |
76 | <para> | |
77 | Specifies an array of <parameter>tKnotCount</parameter> nondecreasing knot values in the parametric | |
78 | <emphasis>v</emphasis> direction. | |
79 | </para> | |
80 | </listitem> | |
81 | </varlistentry> | |
82 | <varlistentry> | |
83 | <term><parameter>sStride</parameter></term> | |
84 | <listitem> | |
85 | <para> | |
86 | Specifies the offset (as a number of single-precision floating-point values) | |
87 | between successive control points in the parametric <emphasis>u</emphasis> direction | |
88 | in <parameter>control</parameter>. | |
89 | </para> | |
90 | </listitem> | |
91 | </varlistentry> | |
92 | <varlistentry> | |
93 | <term><parameter>tStride</parameter></term> | |
94 | <listitem> | |
95 | <para> | |
96 | Specifies the offset (in single-precision floating-point values) | |
97 | between successive control points in the parametric <emphasis>v</emphasis> direction | |
98 | in <parameter>control</parameter>. | |
99 | </para> | |
100 | </listitem> | |
101 | </varlistentry> | |
102 | <varlistentry> | |
103 | <term><parameter>control</parameter></term> | |
104 | <listitem> | |
105 | <para> | |
106 | Specifies an array containing control points for the NURBS surface. | |
107 | The offsets between successive control points in the parametric <emphasis>u</emphasis> | |
108 | and <emphasis>v</emphasis> directions are given by <parameter>sStride</parameter> and <parameter>tStride</parameter>. | |
109 | </para> | |
110 | </listitem> | |
111 | </varlistentry> | |
112 | <varlistentry> | |
113 | <term><parameter>sOrder</parameter></term> | |
114 | <listitem> | |
115 | <para> | |
116 | Specifies the order of the NURBS surface in the parametric <emphasis>u</emphasis> | |
117 | direction. The order is one more than the degree, hence | |
118 | a surface that is cubic in <emphasis>u</emphasis> has a <emphasis>u</emphasis> order of 4. | |
119 | </para> | |
120 | </listitem> | |
121 | </varlistentry> | |
122 | <varlistentry> | |
123 | <term><parameter>tOrder</parameter></term> | |
124 | <listitem> | |
125 | <para> | |
126 | Specifies the order of the NURBS surface in the parametric <emphasis>v</emphasis> | |
127 | direction. The order is one more than the degree, hence | |
128 | a surface that is cubic in <emphasis>v</emphasis> has a <emphasis>v</emphasis> order of 4. | |
129 | </para> | |
130 | </listitem> | |
131 | </varlistentry> | |
132 | <varlistentry> | |
133 | <term><parameter>type</parameter></term> | |
134 | <listitem> | |
135 | <para> | |
136 | Specifies type of the surface. <parameter>type</parameter> can be any of the valid | |
137 | two-dimensional evaluator types (such as <constant>GLU_MAP2_VERTEX_3</constant> or | |
138 | <constant>GLU_MAP2_COLOR_4</constant>). | |
139 | </para> | |
140 | </listitem> | |
141 | </varlistentry> | |
142 | </variablelist> | |
143 | </refsect1> | |
144 | <refsect1 id="description"><title>Description</title> | |
145 | <para> | |
146 | Use <function>gluNurbsSurface</function> within a NURBS (Non-Uniform Rational B-Spline) surface | |
147 | definition to describe the shape of a NURBS surface (before | |
148 | any trimming). To mark the beginning of | |
149 | a NURBS surface definition, use the <citerefentry><refentrytitle>gluBeginSurface</refentrytitle></citerefentry> command. | |
150 | To mark the end of a NURBS surface definition, use the | |
151 | <citerefentry><refentrytitle>gluEndSurface</refentrytitle></citerefentry> command. Call <function>gluNurbsSurface</function> within a NURBS | |
152 | surface definition only. | |
153 | </para> | |
154 | <para> | |
155 | Positional, texture, and color coordinates are associated | |
156 | with a surface by presenting each as a separate <function>gluNurbsSurface</function> between a | |
157 | <citerefentry><refentrytitle>gluBeginSurface</refentrytitle></citerefentry>/<citerefentry><refentrytitle>gluEndSurface</refentrytitle></citerefentry> pair. No more than | |
158 | one call to <function>gluNurbsSurface</function> for each of color, position, and texture | |
159 | data can be made within a single <citerefentry><refentrytitle>gluBeginSurface</refentrytitle></citerefentry>/<citerefentry><refentrytitle>gluEndSurface</refentrytitle></citerefentry> | |
160 | pair. Exactly one call must be made to describe the position of the | |
161 | surface (a <parameter>type</parameter> of <constant>GLU_MAP2_VERTEX_3</constant> or <constant>GLU_MAP2_VERTEX_4</constant>). | |
162 | </para> | |
163 | <para> | |
164 | A NURBS surface can be trimmed by using the commands | |
165 | <citerefentry><refentrytitle>gluNurbsCurve</refentrytitle></citerefentry> and <citerefentry><refentrytitle>gluPwlCurve</refentrytitle></citerefentry> between calls to | |
166 | <citerefentry><refentrytitle>gluBeginTrim</refentrytitle></citerefentry> and <citerefentry><refentrytitle>gluEndTrim</refentrytitle></citerefentry>. | |
167 | </para> | |
168 | <para> | |
169 | Note that a <function>gluNurbsSurface</function> with <parameter>sKnotCount</parameter> knots in the <emphasis>u</emphasis> direction | |
170 | and <parameter>tKnotCount</parameter> knots in the <emphasis>v</emphasis> direction with orders | |
171 | <parameter>sOrder</parameter> and <parameter>tOrder</parameter> must have | |
172 | (<parameter>sKnotCount</parameter> - <parameter>sOrder</parameter>) | |
173 | <inlineequation><mml:math><mml:mi mathvariant="italic">times</mml:mi></mml:math></inlineequation> | |
174 | (<parameter>tKnotCount</parameter> - <parameter>tOrder</parameter>) control points. | |
175 | </para> | |
176 | </refsect1> | |
177 | <refsect1 id="example"><title>Example</title> | |
178 | <para> | |
179 | The following commands render a textured NURBS surface with normals; | |
180 | the texture coordinates and normals are also NURBS surfaces: | |
181 | <programlisting> | |
182 | gluBeginSurface(nobj); | |
183 | gluNurbsSurface(nobj, ..., GL_MAP2_TEXTURE_COORD_2); | |
184 | gluNurbsSurface(nobj, ..., GL_MAP2_NORMAL); | |
185 | gluNurbsSurface(nobj, ..., GL_MAP2_VERTEX_4); | |
186 | gluEndSurface(nobj); | |
187 | </programlisting> | |
188 | </para> | |
189 | </refsect1> | |
190 | <refsect1 id="seealso"><title>See Also</title> | |
191 | <para> | |
192 | <citerefentry><refentrytitle>gluBeginSurface</refentrytitle></citerefentry>, | |
193 | <citerefentry><refentrytitle>gluBeginTrim</refentrytitle></citerefentry>, | |
194 | <citerefentry><refentrytitle>gluNewNurbsRenderer</refentrytitle></citerefentry>, | |
195 | <citerefentry><refentrytitle>gluNurbsCurve</refentrytitle></citerefentry>, | |
196 | <citerefentry><refentrytitle>gluPwlCurve</refentrytitle></citerefentry> | |
197 | </para> | |
198 | </refsect1> | |
199 | <refsect1 id="Copyright"><title>Copyright</title> | |
200 | <para> | |
201 | Copyright <trademark class="copyright"></trademark> 1991-2006 | |
202 | Silicon Graphics, Inc. This document is licensed under the SGI | |
203 | Free Software B License. For details, see | |
204 | <ulink url="http://oss.sgi.com/projects/FreeB/">http://oss.sgi.com/projects/FreeB/</ulink>. | |
205 | </para> | |
206 | </refsect1> | |
207 | </refentry> |