gluNurbsCallback(3g)

1GLUNURBSCALLBACK(3G)             OpenGL Manual            GLUNURBSCALLBACK(3G)
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NAME

6       gluNurbsCallback - define a callback for a NURBS object
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C SPECIFICATION

9       void gluNurbsCallback(GLUnurbs* nurb, GLenum which,
10                             _GLUfuncptr CallBackFunc);
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PARAMETERS

13       nurb
14           Specifies the NURBS object (created with gluNewNurbsRenderer()).
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16       which
17           Specifies the callback being defined. Valid values are
18           GLU_NURBS_BEGIN, GLU_NURBS_VERTEX, GLU_NURBS_NORMAL,
19           GLU_NURBS_COLOR, GLU_NURBS_TEXTURE_COORD, GLU_NURBS_END,
20           GLU_NURBS_BEGIN_DATA, GLU_NURBS_VERTEX_DATA, GLU_NURBS_NORMAL_DATA,
21           GLU_NURBS_COLOR_DATA, GLU_NURBS_TEXTURE_COORD_DATA,
22           GLU_NURBS_END_DATA, and GLU_NURBS_ERROR.
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24       CallBackFunc
25           Specifies the function that the callback calls.
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DESCRIPTION

28       gluNurbsCallback is used to define a callback to be used by a NURBS
29       object. If the specified callback is already defined, then it is
30       replaced. If CallBackFunc is NULL, then this callback will not get
31       invoked and the related data, if any, will be lost.
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33       Except the error callback, these callbacks are used by NURBS
34       tessellator (when GLU_NURBS_MODE is set to be GLU_NURBS_TESSELLATOR) to
35       return back the OpenGL polygon primitives resulting from the
36       tessellation. Note that there are two versions of each callback: one
37       with a user data pointer and one without. If both versions for a
38       particular callback are specified then the callback with the user data
39       pointer will be used. Note that ``userData'' is a copy of the pointer
40       that was specified at the last call to gluNurbsCallbackData.
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42       The error callback function is effective no matter which value that
43       GLU_NURBS_MODE is set to. All other callback functions are effective
44       only when GLU_NURBS_MODE is set to GLU_NURBS_TESSELLATOR.
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46       The legal callbacks are as follows:
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48       GLU_NURBS_BEGIN
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50           The begin callback indicates the start of a primitive. The function
51           takes a single argument of type GLenum, which can be one of
52           GLU_LINES, GLU_LINE_STRIP, GLU_TRIANGLE_FAN, GLU_TRIANGLE_STRIP,
53           GLU_TRIANGLES, or GLU_QUAD_STRIP. The default begin callback
54           function is NULL. The function prototype for this callback looks
55           like:
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57               void begin( GLenum type );
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61       GLU_NURBS_BEGIN_DATA
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63           The same as the GLU_NURBS_BEGIN callback except that it takes an
64           additional pointer argument. This pointer is a copy of the pointer
65           that was specified at the last call to gluNurbsCallbackData. The
66           default callback function is NULL. The function prototype for this
67           callback function looks like:
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69               void beginData(GLenum type, void *userData);
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73       GLU_NURBS_VERTEX
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75           The vertex callback indicates a vertex of the primitive. The
76           coordinates of the vertex are stored in the parameter ``vertex''.
77           All the generated vertices have dimension 3; that is, homogeneous
78           coordinates have been transformed into affine coordinates. The
79           default vertex callback function is NULL. The function prototype
80           for this callback function looks like:
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82               void vertex( GLfloat *vertex );
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86       GLU_NURBS_VERTEX_DATA
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88           This is the same as the GLU_NURBS_VERTEX callback, except that it
89           takes an additional pointer argument. This pointer is a copy of the
90           pointer that was specified at the last call to
91           gluNurbsCallbackData. The default callback function is NULL. The
92           function prototype for this callback function looks like:
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94               void vertexData( GLfloat *vertex, void *userData );
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98       GLU_NURBS_NORMAL
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100           The normal callback is invoked as the vertex normal is generated.
101           The components of the normal are stored in the parameter
102           ``normal.'' In the case of a NURBS curve, the callback function is
103           effective only when the user provides a normal map
104           (GLU_MAP1_NORMAL). In the case of a NURBS surface, if a normal map
105           (GLU_MAP2_NORMAL) is provided, then the generated normal is
106           computed from the normal map. If a normal map is not provided, then
107           a surface normal is computed in a manner similar to that described
108           for evaluators when GLU_AUTO_NORMAL is enabled. The default normal
109           callback function is NULL. The function prototype for this callback
110           function looks like:
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112               void normal( GLfloat *normal );
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116       GLU_NURBS_NORMAL_DATA
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118           The same as the GLU_NURBS_NORMAL callback except that it takes an
119           additional pointer argument. This pointer is a copy of the pointer
120           that was specified at the last call to gluNurbsCallbackData. The
121           default callback function is NULL. The function prototype for this
122           callback function looks like:
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124               void normalData( GLfloat *normal, void *userData );
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128       GLU_NURBS_COLOR
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130           The color callback is invoked as the color of a vertex is
131           generated. The components of the color are stored in the parameter
132           ``color.'' This callback is effective only when the user provides a
133           color map (GLU_MAP1_COLOR_4 or GLU_MAP2_COLOR_4). ``color''
134           contains four components: R, G, B, A. The default color callback
135           function is NULL. The prototype for this callback function looks
136           like:
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138               void color( GLfloat *color );
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142       GLU_NURBS_COLOR_DATA
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144           The same as the GLU_NURBS_COLOR callback except that it takes an
145           additional pointer argument. This pointer is a copy of the pointer
146           that was specified at the last call to gluNurbsCallbackData. The
147           default callback function is NULL. The function prototype for this
148           callback function looks like:
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150               void colorData( GLfloat *color, void *userData );
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153
154       GLU_NURBS_TEXTURE_COORD
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156           The texture callback is invoked as the texture coordinates of a
157           vertex are generated. These coordinates are stored in the parameter
158           ``texCoord.'' The number of texture coordinates can be 1, 2, 3, or
159           4 depending on which type of texture map is specified
160           (GLU_MAP1_TEXTURE_COORD_1, GLU_MAP1_TEXTURE_COORD_2,
161           GLU_MAP1_TEXTURE_COORD_3, GLU_MAP1_TEXTURE_COORD_4,
162           GLU_MAP2_TEXTURE_COORD_1, GLU_MAP2_TEXTURE_COORD_2,
163           GLU_MAP2_TEXTURE_COORD_3, GLU_MAP2_TEXTURE_COORD_4). If no texture
164           map is specified, this callback function will not be called. The
165           default texture callback function is NULL. The function prototype
166           for this callback function looks like:
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168               void texCoord( GLfloat *texCoord );
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172       GLU_NURBS_TEXTURE_COORD_DATA
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174           This is the same as the GLU_NURBS_TEXTURE_COORD callback, except
175           that it takes an additional pointer argument. This pointer is a
176           copy of the pointer that was specified at the last call to
177           gluNurbsCallbackData. The default callback function is NULL. The
178           function prototype for this callback function looks like:
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180               void texCoordData( GLfloat *texCoord, void *userData );
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183
184       GLU_NURBS_END
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186           The end callback is invoked at the end of a primitive. The default
187           end callback function is NULL. The function prototype for this
188           callback function looks like:
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190               void end( void );
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194       GLU_NURBS_END_DATA
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196           This is the same as the GLU_NURBS_END callback, except that it
197           takes an additional pointer argument. This pointer is a copy of the
198           pointer that was specified at the last call to
199           gluNurbsCallbackData. The default callback function is NULL. The
200           function prototype for this callback function looks like:
201
202               void endData( void  *userData );
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206       GLU_NURBS_ERROR
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208           The error function is called when an error is encountered. Its
209           single argument is of type GLenum, and it indicates the specific
210           error that occurred. There are 37 errors unique to NURBS, named
211           GLU_NURBS_ERROR1 through GLU_NURBS_ERROR37. Character strings
212           describing these errors can be retrieved with gluErrorString().
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NOTES

215       gluNurbsCallback is available only if the GLU version is 1.2 or
216       greater.
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218       GLU version 1.2 supports only the GLU_ERROR parameter for which. The
219       GLU_ERROR value is deprecated in GLU version 1.3 in favor of
220       GLU_NURBS_ERROR. All other accepted values for CallBackFunc are
221       available only if the GLU version is 1.3 or greater.
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COPYRIGHT

228       Copyright © 1991-2006 Silicon Graphics, Inc. This document is licensed
229       under the SGI Free Software B License. For details, see
230       http://oss.sgi.com/projects/FreeB/.
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AUTHORS

233       opengl.org
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237opengl.org                        06/10/2014              GLUNURBSCALLBACK(3G)