1 <!DOCTYPE html PUBLIC
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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>glEvalCoord
</title><meta name=
"generator" content=
"DocBook XSL Stylesheets V1.73.2" /></head><body><div class=
"refentry" lang=
"en" xml:
lang=
"en"><a id=
"glEvalCoord"></a><div class=
"titlepage"></div><div class=
"refnamediv"><h2>Name
</h2><p>glEvalCoord — evaluate enabled one- and two-dimensional maps
</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">glEvalCoord1f
</b>(
</code></td><td>GLfloat
</td><td><var class=
"pdparam">u
</var><code>)
</code>;
</td></tr></table></div><div class=
"funcsynopsis"><table border=
"0" summary=
"Function synopsis" cellspacing=
"0" cellpadding=
"0"><tr><td><code class=
"funcdef">void
<b class=
"fsfunc">glEvalCoord1d
</b>(
</code></td><td>GLdouble
</td><td><var class=
"pdparam">u
</var><code>)
</code>;
</td></tr></table></div><div class=
"funcsynopsis"><table border=
"0" summary=
"Function synopsis" cellspacing=
"0" cellpadding=
"0"><tr><td><code class=
"funcdef">void
<b class=
"fsfunc">glEvalCoord2f
</b>(
</code></td><td>GLfloat
</td><td><var class=
"pdparam">u
</var>,
</td></tr><tr><td> </td><td>GLfloat
</td><td><var class=
"pdparam">v
</var><code>)
</code>;
</td></tr></table></div><div class=
"funcsynopsis"><table border=
"0" summary=
"Function synopsis" cellspacing=
"0" cellpadding=
"0"><tr><td><code class=
"funcdef">void
<b class=
"fsfunc">glEvalCoord2d
</b>(
</code></td><td>GLdouble
</td><td><var class=
"pdparam">u
</var>,
</td></tr><tr><td> </td><td>GLdouble
</td><td><var class=
"pdparam">v
</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>u
</code></em></span></dt><dd><p>
4 Specifies a value that is the domain coordinate
5 <mml:math xmlns:
mml=
"http://www.w3.org/1998/Math/MathML" overflow=
"scroll"><mml:mi mathvariant=
"italic">u
</mml:mi></mml:math>
7 defined in a previous
<a class=
"citerefentry" href=
"glMap1.xml"><span class=
"citerefentry"><span class=
"refentrytitle">glMap1
</span></span></a> or
<a class=
"citerefentry" href=
"glMap2.xml"><span class=
"citerefentry"><span class=
"refentrytitle">glMap2
</span></span></a> command.
8 </p></dd><dt><span class=
"term"><em class=
"parameter"><code>v
</code></em></span></dt><dd><p>
9 Specifies a value that is the domain coordinate
10 <mml:math xmlns:
mml=
"http://www.w3.org/1998/Math/MathML" overflow=
"scroll"><mml:mi mathvariant=
"italic">v
</mml:mi></mml:math>
12 defined in a previous
<a class=
"citerefentry" href=
"glMap2.xml"><span class=
"citerefentry"><span class=
"refentrytitle">glMap2
</span></span></a> command.
13 This argument is not present in a
<code class=
"function">glEvalCoord1
</code> command.
14 </p></dd></dl></div></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">glEvalCoord1fv
</b>(
</code></td><td>const GLfloat *
</td><td><var class=
"pdparam">u
</var><code>)
</code>;
</td></tr></table></div><div class=
"funcsynopsis"><table border=
"0" summary=
"Function synopsis" cellspacing=
"0" cellpadding=
"0"><tr><td><code class=
"funcdef">void
<b class=
"fsfunc">glEvalCoord1dv
</b>(
</code></td><td>const GLdouble *
</td><td><var class=
"pdparam">u
</var><code>)
</code>;
</td></tr></table></div><div class=
"funcsynopsis"><table border=
"0" summary=
"Function synopsis" cellspacing=
"0" cellpadding=
"0"><tr><td><code class=
"funcdef">void
<b class=
"fsfunc">glEvalCoord2fv
</b>(
</code></td><td>const GLfloat *
</td><td><var class=
"pdparam">u
</var><code>)
</code>;
</td></tr></table></div><div class=
"funcsynopsis"><table border=
"0" summary=
"Function synopsis" cellspacing=
"0" cellpadding=
"0"><tr><td><code class=
"funcdef">void
<b class=
"fsfunc">glEvalCoord2dv
</b>(
</code></td><td>const GLdouble *
</td><td><var class=
"pdparam">u
</var><code>)
</code>;
</td></tr></table></div></div><div class=
"refsect1" lang=
"en" xml:
lang=
"en"><a id=
"parameters2"></a><h2>Parameters
</h2><div class=
"variablelist"><dl><dt><span class=
"term"><em class=
"parameter"><code>u
</code></em></span></dt><dd><p>
15 Specifies a pointer to an array containing
16 either one or two domain coordinates.
17 The first coordinate is
18 <mml:math xmlns:
mml=
"http://www.w3.org/1998/Math/MathML" overflow=
"scroll"><mml:mi mathvariant=
"italic">u
</mml:mi></mml:math>.
19 The second coordinate is
20 <mml:math xmlns:
mml=
"http://www.w3.org/1998/Math/MathML" overflow=
"scroll"><mml:mi mathvariant=
"italic">v
</mml:mi></mml:math>,
21 which is present only in
<code class=
"function">glEvalCoord2
</code> versions.
22 </p></dd></dl></div></div><div class=
"refsect1" lang=
"en" xml:
lang=
"en"><a id=
"description"></a><h2>Description
</h2><p>
23 <code class=
"function">glEvalCoord1
</code> evaluates enabled one-dimensional maps at argument
24 <em class=
"parameter"><code>u
</code></em>.
25 <code class=
"function">glEvalCoord2
</code> does the same for two-dimensional maps using
27 <em class=
"parameter"><code>u
</code></em> and
<em class=
"parameter"><code>v
</code></em>.
28 To define a map, call
<a class=
"citerefentry" href=
"glMap1.xml"><span class=
"citerefentry"><span class=
"refentrytitle">glMap1
</span></span></a> and
<a class=
"citerefentry" href=
"glMap2.xml"><span class=
"citerefentry"><span class=
"refentrytitle">glMap2
</span></span></a>; to enable and
29 disable it, call
<a class=
"citerefentry" href=
"glEnable.xml"><span class=
"citerefentry"><span class=
"refentrytitle">glEnable
</span></span></a> and
<a class=
"citerefentry" href=
"glDisable.xml"><span class=
"citerefentry"><span class=
"refentrytitle">glDisable
</span></span></a>.
31 When one of the
<code class=
"function">glEvalCoord
</code> commands is issued,
32 all currently enabled maps of the indicated dimension are evaluated.
35 it is as if the corresponding GL command had been issued with the
38 if
<code class=
"constant">GL_MAP1_INDEX
</code> or
39 <code class=
"constant">GL_MAP2_INDEX
</code> is enabled,
40 a
<a class=
"citerefentry" href=
"glIndex.xml"><span class=
"citerefentry"><span class=
"refentrytitle">glIndex
</span></span></a> command is simulated.
41 If
<code class=
"constant">GL_MAP1_COLOR_4
</code> or
42 <code class=
"constant">GL_MAP2_COLOR_4
</code> is enabled,
43 a
<a class=
"citerefentry" href=
"glColor.xml"><span class=
"citerefentry"><span class=
"refentrytitle">glColor
</span></span></a> command is simulated.
44 If
<code class=
"constant">GL_MAP1_NORMAL
</code> or
<code class=
"constant">GL_MAP2_NORMAL
</code> is enabled,
45 a normal vector is produced,
47 <code class=
"constant">GL_MAP1_TEXTURE_COORD_1
</code>,
48 <code class=
"constant">GL_MAP1_TEXTURE_COORD_2
</code>,
49 <code class=
"constant">GL_MAP1_TEXTURE_COORD_3
</code>,
50 <code class=
"constant">GL_MAP1_TEXTURE_COORD_4
</code>,
51 <code class=
"constant">GL_MAP2_TEXTURE_COORD_1
</code>,
52 <code class=
"constant">GL_MAP2_TEXTURE_COORD_2
</code>,
53 <code class=
"constant">GL_MAP2_TEXTURE_COORD_3
</code>, or
54 <code class=
"constant">GL_MAP2_TEXTURE_COORD_4
</code> is enabled, then an appropriate
<a class=
"citerefentry" href=
"glTexCoord.xml"><span class=
"citerefentry"><span class=
"refentrytitle">glTexCoord
</span></span></a> command is simulated.
59 and texture coordinates the GL uses evaluated values instead of current values for those evaluations
61 and current values otherwise,
63 the evaluated values do not update the current values.
64 Thus, if
<a class=
"citerefentry" href=
"glVertex.xml"><span class=
"citerefentry"><span class=
"refentrytitle">glVertex
</span></span></a> commands are interspersed with
<code class=
"function">glEvalCoord
</code>
67 and texture coordinates associated with the
<a class=
"citerefentry" href=
"glVertex.xml"><span class=
"citerefentry"><span class=
"refentrytitle">glVertex
</span></span></a> commands are not
68 affected by the values generated by the
<code class=
"function">glEvalCoord
</code> commands,
69 but only by the most recent
70 <a class=
"citerefentry" href=
"glColor.xml"><span class=
"citerefentry"><span class=
"refentrytitle">glColor
</span></span></a>,
71 <a class=
"citerefentry" href=
"glIndex.xml"><span class=
"citerefentry"><span class=
"refentrytitle">glIndex
</span></span></a>,
72 <a class=
"citerefentry" href=
"glNormal.xml"><span class=
"citerefentry"><span class=
"refentrytitle">glNormal
</span></span></a>, and
73 <a class=
"citerefentry" href=
"glTexCoord.xml"><span class=
"citerefentry"><span class=
"refentrytitle">glTexCoord
</span></span></a> commands.
75 No commands are issued for maps that are not enabled.
76 If more than one texture evaluation is enabled for a particular dimension
77 (for example,
<code class=
"constant">GL_MAP2_TEXTURE_COORD_1
</code> and
78 <code class=
"constant">GL_MAP2_TEXTURE_COORD_2
</code>),
79 then only the evaluation of the map that produces the larger
81 (in this case,
<code class=
"constant">GL_MAP2_TEXTURE_COORD_2
</code>)
83 <code class=
"constant">GL_MAP1_VERTEX_4
</code> overrides
<code class=
"constant">GL_MAP1_VERTEX_3
</code>,
85 <code class=
"constant">GL_MAP2_VERTEX_4
</code> overrides
<code class=
"constant">GL_MAP2_VERTEX_3
</code>,
87 If neither a three- nor a four-component vertex map is enabled for the
89 the
<code class=
"function">glEvalCoord
</code> command is ignored.
91 If you have enabled automatic normal generation,
92 by calling
<a class=
"citerefentry" href=
"glEnable.xml"><span class=
"citerefentry"><span class=
"refentrytitle">glEnable
</span></span></a> with argument
<code class=
"constant">GL_AUTO_NORMAL
</code>,
93 <code class=
"function">glEvalCoord2
</code> generates surface normals analytically,
94 regardless of the contents or enabling of the
<code class=
"constant">GL_MAP2_NORMAL
</code> map.
97 </p><div class=
"informalequation"><mml:math xmlns:
mml=
"http://www.w3.org/1998/Math/MathML" overflow=
"scroll">
100 <mml:mi mathvariant=
"bold">m
</mml:mi>
103 <mml:mfenced open=
"" close=
"">
105 <mml:mfenced open=
"" close=
"">
108 <mml:mi mathvariant=
"bold">p
</mml:mi>
111 <mml:mfenced open=
"" close=
"">
114 <mml:mi mathvariant=
"italic">u
</mml:mi>
120 <mml:mfenced open=
"" close=
"">
122 <mml:mfenced open=
"" close=
"">
125 <mml:mi mathvariant=
"bold">p
</mml:mi>
128 <mml:mfenced open=
"" close=
"">
131 <mml:mi mathvariant=
"italic">v
</mml:mi>
140 Then the generated normal
141 <mml:math xmlns:
mml=
"http://www.w3.org/1998/Math/MathML" overflow=
"scroll">
143 <mml:mi mathvariant=
"bold">n
</mml:mi>
146 <mml:math xmlns:
mml=
"http://www.w3.org/1998/Math/MathML" overflow=
"scroll">
149 <mml:mi mathvariant=
"bold">n
</mml:mi>
152 <mml:mi mathvariant=
"bold">m
</mml:mi>
153 <mml:mfenced open=
"" close=
"">
154 <mml:mfenced open=
"∥" close=
"∥">
155 <mml:mi mathvariant=
"bold">m
</mml:mi>
162 If automatic normal generation is disabled,
163 the corresponding normal map
<code class=
"constant">GL_MAP2_NORMAL
</code>,
165 is used to produce a normal.
166 If neither automatic normal generation nor a normal map is enabled,
167 no normal is generated for
168 <code class=
"function">glEvalCoord2
</code> commands.
169 </p></div><div class=
"refsect1" lang=
"en" xml:
lang=
"en"><a id=
"associatedgets"></a><h2>Associated Gets
</h2><p>
170 <a class=
"citerefentry" href=
"glIsEnabled.xml"><span class=
"citerefentry"><span class=
"refentrytitle">glIsEnabled
</span></span></a> with argument
<code class=
"constant">GL_MAP1_VERTEX_3
</code>
172 <a class=
"citerefentry" href=
"glIsEnabled.xml"><span class=
"citerefentry"><span class=
"refentrytitle">glIsEnabled
</span></span></a> with argument
<code class=
"constant">GL_MAP1_VERTEX_4
</code>
174 <a class=
"citerefentry" href=
"glIsEnabled.xml"><span class=
"citerefentry"><span class=
"refentrytitle">glIsEnabled
</span></span></a> with argument
<code class=
"constant">GL_MAP1_INDEX
</code>
176 <a class=
"citerefentry" href=
"glIsEnabled.xml"><span class=
"citerefentry"><span class=
"refentrytitle">glIsEnabled
</span></span></a> with argument
<code class=
"constant">GL_MAP1_COLOR_4
</code>
178 <a class=
"citerefentry" href=
"glIsEnabled.xml"><span class=
"citerefentry"><span class=
"refentrytitle">glIsEnabled
</span></span></a> with argument
<code class=
"constant">GL_MAP1_NORMAL
</code>
180 <a class=
"citerefentry" href=
"glIsEnabled.xml"><span class=
"citerefentry"><span class=
"refentrytitle">glIsEnabled
</span></span></a> with argument
<code class=
"constant">GL_MAP1_TEXTURE_COORD_1
</code>
182 <a class=
"citerefentry" href=
"glIsEnabled.xml"><span class=
"citerefentry"><span class=
"refentrytitle">glIsEnabled
</span></span></a> with argument
<code class=
"constant">GL_MAP1_TEXTURE_COORD_2
</code>
184 <a class=
"citerefentry" href=
"glIsEnabled.xml"><span class=
"citerefentry"><span class=
"refentrytitle">glIsEnabled
</span></span></a> with argument
<code class=
"constant">GL_MAP1_TEXTURE_COORD_3
</code>
186 <a class=
"citerefentry" href=
"glIsEnabled.xml"><span class=
"citerefentry"><span class=
"refentrytitle">glIsEnabled
</span></span></a> with argument
<code class=
"constant">GL_MAP1_TEXTURE_COORD_4
</code>
188 <a class=
"citerefentry" href=
"glIsEnabled.xml"><span class=
"citerefentry"><span class=
"refentrytitle">glIsEnabled
</span></span></a> with argument
<code class=
"constant">GL_MAP2_VERTEX_3
</code>
190 <a class=
"citerefentry" href=
"glIsEnabled.xml"><span class=
"citerefentry"><span class=
"refentrytitle">glIsEnabled
</span></span></a> with argument
<code class=
"constant">GL_MAP2_VERTEX_4
</code>
192 <a class=
"citerefentry" href=
"glIsEnabled.xml"><span class=
"citerefentry"><span class=
"refentrytitle">glIsEnabled
</span></span></a> with argument
<code class=
"constant">GL_MAP2_INDEX
</code>
194 <a class=
"citerefentry" href=
"glIsEnabled.xml"><span class=
"citerefentry"><span class=
"refentrytitle">glIsEnabled
</span></span></a> with argument
<code class=
"constant">GL_MAP2_COLOR_4
</code>
196 <a class=
"citerefentry" href=
"glIsEnabled.xml"><span class=
"citerefentry"><span class=
"refentrytitle">glIsEnabled
</span></span></a> with argument
<code class=
"constant">GL_MAP2_NORMAL
</code>
198 <a class=
"citerefentry" href=
"glIsEnabled.xml"><span class=
"citerefentry"><span class=
"refentrytitle">glIsEnabled
</span></span></a> with argument
<code class=
"constant">GL_MAP2_TEXTURE_COORD_1
</code>
200 <a class=
"citerefentry" href=
"glIsEnabled.xml"><span class=
"citerefentry"><span class=
"refentrytitle">glIsEnabled
</span></span></a> with argument
<code class=
"constant">GL_MAP2_TEXTURE_COORD_2
</code>
202 <a class=
"citerefentry" href=
"glIsEnabled.xml"><span class=
"citerefentry"><span class=
"refentrytitle">glIsEnabled
</span></span></a> with argument
<code class=
"constant">GL_MAP2_TEXTURE_COORD_3
</code>
204 <a class=
"citerefentry" href=
"glIsEnabled.xml"><span class=
"citerefentry"><span class=
"refentrytitle">glIsEnabled
</span></span></a> with argument
<code class=
"constant">GL_MAP2_TEXTURE_COORD_4
</code>
206 <a class=
"citerefentry" href=
"glIsEnabled.xml"><span class=
"citerefentry"><span class=
"refentrytitle">glIsEnabled
</span></span></a> with argument
<code class=
"constant">GL_AUTO_NORMAL
</code>
208 <a class=
"citerefentry" href=
"glGetMap.xml"><span class=
"citerefentry"><span class=
"refentrytitle">glGetMap
</span></span></a>
209 </p></div><div class=
"refsect1" lang=
"en" xml:
lang=
"en"><a id=
"seealso"></a><h2>See Also
</h2><p>
210 <a class=
"citerefentry" href=
"glBegin.xml"><span class=
"citerefentry"><span class=
"refentrytitle">glBegin
</span></span></a>,
211 <a class=
"citerefentry" href=
"glColor.xml"><span class=
"citerefentry"><span class=
"refentrytitle">glColor
</span></span></a>,
212 <a class=
"citerefentry" href=
"glEnable.xml"><span class=
"citerefentry"><span class=
"refentrytitle">glEnable
</span></span></a>,
213 <a class=
"citerefentry" href=
"glEvalMesh.xml"><span class=
"citerefentry"><span class=
"refentrytitle">glEvalMesh
</span></span></a>,
214 <a class=
"citerefentry" href=
"glEvalPoint.xml"><span class=
"citerefentry"><span class=
"refentrytitle">glEvalPoint
</span></span></a>,
215 <a class=
"citerefentry" href=
"glIndex.xml"><span class=
"citerefentry"><span class=
"refentrytitle">glIndex
</span></span></a>,
216 <a class=
"citerefentry" href=
"glMap1.xml"><span class=
"citerefentry"><span class=
"refentrytitle">glMap1
</span></span></a>,
217 <a class=
"citerefentry" href=
"glMap2.xml"><span class=
"citerefentry"><span class=
"refentrytitle">glMap2
</span></span></a>,
218 <a class=
"citerefentry" href=
"glMapGrid.xml"><span class=
"citerefentry"><span class=
"refentrytitle">glMapGrid
</span></span></a>,
219 <a class=
"citerefentry" href=
"glNormal.xml"><span class=
"citerefentry"><span class=
"refentrytitle">glNormal
</span></span></a>,
220 <a class=
"citerefentry" href=
"glTexCoord.xml"><span class=
"citerefentry"><span class=
"refentrytitle">glTexCoord
</span></span></a>,
221 <a class=
"citerefentry" href=
"glVertex.xml"><span class=
"citerefentry"><span class=
"refentrytitle">glVertex
</span></span></a>
222 </p></div><div class=
"refsect1" lang=
"en" xml:
lang=
"en"><a id=
"Copyright"></a><h2>Copyright
</h2><p>
223 Copyright
<span class=
"trademark"></span>©
1991-
2006
224 Silicon Graphics, Inc. This document is licensed under the SGI
225 Free Software B License. For details, see
226 <a class=
"ulink" href=
"http://oss.sgi.com/projects/FreeB/" target=
"_top">http://oss.sgi.com/projects/FreeB/
</a>.
227 </p></div></div></body></html>