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3 | <?xml-stylesheet type="text/xsl" href="mathml.xsl"?><html xmlns="http://www.w3.org/1999/xhtml" xmlns:pref="http://www.w3.org/2002/Math/preference" pref:renderer="mathplayer-dl"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /><title>gluNurbsSurface</title><meta name="generator" content="DocBook XSL Stylesheets V1.73.2" /></head><body><div class="refentry" lang="en" xml:lang="en"><a id="gluNurbsSurface"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>gluNurbsSurface — define the shape of a NURBS surface</p></div><div class="refsynopsisdiv"><h2>C Specification</h2><div class="funcsynopsis"><table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0"><tr><td><code class="funcdef">void <b class="fsfunc">gluNurbsSurface</b>(</code></td><td>GLUnurbs* </td><td><var class="pdparam">nurb</var>, </td></tr><tr><td> </td><td>GLint </td><td><var class="pdparam">sKnotCount</var>, </td></tr><tr><td> </td><td>GLfloat* </td><td><var class="pdparam">sKnots</var>, </td></tr><tr><td> </td><td>GLint </td><td><var class="pdparam">tKnotCount</var>, </td></tr><tr><td> </td><td>GLfloat* </td><td><var class="pdparam">tKnots</var>, </td></tr><tr><td> </td><td>GLint </td><td><var class="pdparam">sStride</var>, </td></tr><tr><td> </td><td>GLint </td><td><var class="pdparam">tStride</var>, </td></tr><tr><td> </td><td>GLfloat* </td><td><var class="pdparam">control</var>, </td></tr><tr><td> </td><td>GLint </td><td><var class="pdparam">sOrder</var>, </td></tr><tr><td> </td><td>GLint </td><td><var class="pdparam">tOrder</var>, </td></tr><tr><td> </td><td>GLenum </td><td><var class="pdparam">type</var><code>)</code>;</td></tr></table></div></div><div class="refsect1" lang="en" xml:lang="en"><a id="parameters"></a><h2>Parameters</h2><div class="variablelist"><dl><dt><span class="term"><em class="parameter"><code>nurb</code></em></span></dt><dd><p> | |
4 | Specifies the NURBS object (created with <a class="citerefentry" href="gluNewNurbsRenderer.xml"><span class="citerefentry"><span class="refentrytitle">gluNewNurbsRenderer</span></span></a>). | |
5 | </p></dd><dt><span class="term"><em class="parameter"><code>sKnotCount</code></em></span></dt><dd><p> | |
6 | Specifies the number of knots in the parametric <span class="emphasis"><em>u</em></span> direction. | |
7 | </p></dd><dt><span class="term"><em class="parameter"><code>sKnots</code></em></span></dt><dd><p> | |
8 | Specifies an array of <em class="parameter"><code>sKnotCount</code></em> nondecreasing knot values in the parametric | |
9 | <span class="emphasis"><em>u</em></span> direction. | |
10 | </p></dd><dt><span class="term"><em class="parameter"><code>tKnotCount</code></em></span></dt><dd><p> | |
11 | Specifies the number of knots in the parametric <span class="emphasis"><em>v</em></span> direction. | |
12 | </p></dd><dt><span class="term"><em class="parameter"><code>tKnots</code></em></span></dt><dd><p> | |
13 | Specifies an array of <em class="parameter"><code>tKnotCount</code></em> nondecreasing knot values in the parametric | |
14 | <span class="emphasis"><em>v</em></span> direction. | |
15 | </p></dd><dt><span class="term"><em class="parameter"><code>sStride</code></em></span></dt><dd><p> | |
16 | Specifies the offset (as a number of single-precision floating-point values) | |
17 | between successive control points in the parametric <span class="emphasis"><em>u</em></span> direction | |
18 | in <em class="parameter"><code>control</code></em>. | |
19 | </p></dd><dt><span class="term"><em class="parameter"><code>tStride</code></em></span></dt><dd><p> | |
20 | Specifies the offset (in single-precision floating-point values) | |
21 | between successive control points in the parametric <span class="emphasis"><em>v</em></span> direction | |
22 | in <em class="parameter"><code>control</code></em>. | |
23 | </p></dd><dt><span class="term"><em class="parameter"><code>control</code></em></span></dt><dd><p> | |
24 | Specifies an array containing control points for the NURBS surface. | |
25 | The offsets between successive control points in the parametric <span class="emphasis"><em>u</em></span> | |
26 | and <span class="emphasis"><em>v</em></span> directions are given by <em class="parameter"><code>sStride</code></em> and <em class="parameter"><code>tStride</code></em>. | |
27 | </p></dd><dt><span class="term"><em class="parameter"><code>sOrder</code></em></span></dt><dd><p> | |
28 | Specifies the order of the NURBS surface in the parametric <span class="emphasis"><em>u</em></span> | |
29 | direction. The order is one more than the degree, hence | |
30 | a surface that is cubic in <span class="emphasis"><em>u</em></span> has a <span class="emphasis"><em>u</em></span> order of 4. | |
31 | </p></dd><dt><span class="term"><em class="parameter"><code>tOrder</code></em></span></dt><dd><p> | |
32 | Specifies the order of the NURBS surface in the parametric <span class="emphasis"><em>v</em></span> | |
33 | direction. The order is one more than the degree, hence | |
34 | a surface that is cubic in <span class="emphasis"><em>v</em></span> has a <span class="emphasis"><em>v</em></span> order of 4. | |
35 | </p></dd><dt><span class="term"><em class="parameter"><code>type</code></em></span></dt><dd><p> | |
36 | Specifies type of the surface. <em class="parameter"><code>type</code></em> can be any of the valid | |
37 | two-dimensional evaluator types (such as <code class="constant">GLU_MAP2_VERTEX_3</code> or | |
38 | <code class="constant">GLU_MAP2_COLOR_4</code>). | |
39 | </p></dd></dl></div></div><div class="refsect1" lang="en" xml:lang="en"><a id="description"></a><h2>Description</h2><p> | |
40 | Use <code class="function">gluNurbsSurface</code> within a NURBS (Non-Uniform Rational B-Spline) surface | |
41 | definition to describe the shape of a NURBS surface (before | |
42 | any trimming). To mark the beginning of | |
43 | a NURBS surface definition, use the <a class="citerefentry" href="gluBeginSurface.xml"><span class="citerefentry"><span class="refentrytitle">gluBeginSurface</span></span></a> command. | |
44 | To mark the end of a NURBS surface definition, use the | |
45 | <a class="citerefentry" href="gluEndSurface.xml"><span class="citerefentry"><span class="refentrytitle">gluEndSurface</span></span></a> command. Call <code class="function">gluNurbsSurface</code> within a NURBS | |
46 | surface definition only. | |
47 | </p><p> | |
48 | Positional, texture, and color coordinates are associated | |
49 | with a surface by presenting each as a separate <code class="function">gluNurbsSurface</code> between a | |
50 | <a class="citerefentry" href="gluBeginSurface.xml"><span class="citerefentry"><span class="refentrytitle">gluBeginSurface</span></span></a>/<a class="citerefentry" href="gluEndSurface.xml"><span class="citerefentry"><span class="refentrytitle">gluEndSurface</span></span></a> pair. No more than | |
51 | one call to <code class="function">gluNurbsSurface</code> for each of color, position, and texture | |
52 | data can be made within a single <a class="citerefentry" href="gluBeginSurface.xml"><span class="citerefentry"><span class="refentrytitle">gluBeginSurface</span></span></a>/<a class="citerefentry" href="gluEndSurface.xml"><span class="citerefentry"><span class="refentrytitle">gluEndSurface</span></span></a> | |
53 | pair. Exactly one call must be made to describe the position of the | |
54 | surface (a <em class="parameter"><code>type</code></em> of <code class="constant">GLU_MAP2_VERTEX_3</code> or <code class="constant">GLU_MAP2_VERTEX_4</code>). | |
55 | </p><p> | |
56 | A NURBS surface can be trimmed by using the commands | |
57 | <a class="citerefentry" href="gluNurbsCurve.xml"><span class="citerefentry"><span class="refentrytitle">gluNurbsCurve</span></span></a> and <a class="citerefentry" href="gluPwlCurve.xml"><span class="citerefentry"><span class="refentrytitle">gluPwlCurve</span></span></a> between calls to | |
58 | <a class="citerefentry" href="gluBeginTrim.xml"><span class="citerefentry"><span class="refentrytitle">gluBeginTrim</span></span></a> and <a class="citerefentry" href="gluEndTrim.xml"><span class="citerefentry"><span class="refentrytitle">gluEndTrim</span></span></a>. | |
59 | </p><p> | |
60 | Note that a <code class="function">gluNurbsSurface</code> with <em class="parameter"><code>sKnotCount</code></em> knots in the <span class="emphasis"><em>u</em></span> direction | |
61 | and <em class="parameter"><code>tKnotCount</code></em> knots in the <span class="emphasis"><em>v</em></span> direction with orders | |
62 | <em class="parameter"><code>sOrder</code></em> and <em class="parameter"><code>tOrder</code></em> must have | |
63 | (<em class="parameter"><code>sKnotCount</code></em> - <em class="parameter"><code>sOrder</code></em>) | |
64 | <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">times</mml:mi></mml:math> | |
65 | (<em class="parameter"><code>tKnotCount</code></em> - <em class="parameter"><code>tOrder</code></em>) control points. | |
66 | </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="example"></a><h2>Example</h2><p> | |
67 | The following commands render a textured NURBS surface with normals; | |
68 | the texture coordinates and normals are also NURBS surfaces: | |
69 | </p><pre class="programlisting"> | |
70 | gluBeginSurface(nobj); | |
71 | gluNurbsSurface(nobj, ..., GL_MAP2_TEXTURE_COORD_2); | |
72 | gluNurbsSurface(nobj, ..., GL_MAP2_NORMAL); | |
73 | gluNurbsSurface(nobj, ..., GL_MAP2_VERTEX_4); | |
74 | gluEndSurface(nobj); | |
75 | </pre><p> | |
76 | </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="seealso"></a><h2>See Also</h2><p> | |
77 | <a class="citerefentry" href="gluBeginSurface.xml"><span class="citerefentry"><span class="refentrytitle">gluBeginSurface</span></span></a>, | |
78 | <a class="citerefentry" href="gluBeginTrim.xml"><span class="citerefentry"><span class="refentrytitle">gluBeginTrim</span></span></a>, | |
79 | <a class="citerefentry" href="gluNewNurbsRenderer.xml"><span class="citerefentry"><span class="refentrytitle">gluNewNurbsRenderer</span></span></a>, | |
80 | <a class="citerefentry" href="gluNurbsCurve.xml"><span class="citerefentry"><span class="refentrytitle">gluNurbsCurve</span></span></a>, | |
81 | <a class="citerefentry" href="gluPwlCurve.xml"><span class="citerefentry"><span class="refentrytitle">gluPwlCurve</span></span></a> | |
82 | </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="Copyright"></a><h2>Copyright</h2><p> | |
83 | Copyright <span class="trademark"></span>© 1991-2006 | |
84 | Silicon Graphics, Inc. This document is licensed under the SGI | |
85 | Free Software B License. For details, see | |
86 | <a class="ulink" href="http://oss.sgi.com/projects/FreeB/" target="_top">http://oss.sgi.com/projects/FreeB/</a>. | |
87 | </p></div></div></body></html> |