gluNurbsCallback man page on RedHat
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GLUNURBSCALLBACK(3G) OpenGL Manual GLUNURBSCALLBACK(3G)
NAME
gluNurbsCallback - define a callback for a NURBS object
C SPECIFICATION
void gluNurbsCallback(GLUnurbs* nurb, GLenum which,
_GLUfuncptr CallBackFunc);
PARAMETERS
nurb
Specifies the NURBS object (created with gluNewNurbsRenderer()).
which
Specifies the callback being defined. Valid values are
GLU_NURBS_BEGIN, GLU_NURBS_VERTEX, GLU_NURBS_NORMAL,
GLU_NURBS_COLOR, GLU_NURBS_TEXTURE_COORD, GLU_NURBS_END,
GLU_NURBS_BEGIN_DATA, GLU_NURBS_VERTEX_DATA, GLU_NURBS_NORMAL_DATA,
GLU_NURBS_COLOR_DATA, GLU_NURBS_TEXTURE_COORD_DATA,
GLU_NURBS_END_DATA, and GLU_NURBS_ERROR.
CallBackFunc
Specifies the function that the callback calls.
DESCRIPTION
gluNurbsCallback is used to define a callback to be used by a NURBS
object. If the specified callback is already defined, then it is
replaced. If CallBackFunc is NULL, then this callback will not get
invoked and the related data, if any, will be lost.
Except the error callback, these callbacks are used by NURBS
tessellator (when GLU_NURBS_MODE is set to be GLU_NURBS_TESSELLATOR) to
return back the OpenGL polygon primitives resulting from the
tessellation. Note that there are two versions of each callback: one
with a user data pointer and one without. If both versions for a
particular callback are specified then the callback with the user data
pointer will be used. Note that ``userData'' is a copy of the pointer
that was specified at the last call to gluNurbsCallbackData.
The error callback function is effective no matter which value that
GLU_NURBS_MODE is set to. All other callback functions are effective
only when GLU_NURBS_MODE is set to GLU_NURBS_TESSELLATOR.
The legal callbacks are as follows:
GLU_NURBS_BEGIN
The begin callback indicates the start of a primitive. The function
takes a single argument of type GLenum, which can be one of
GLU_LINES, GLU_LINE_STRIP, GLU_TRIANGLE_FAN, GLU_TRIANGLE_STRIP,
GLU_TRIANGLES, or GLU_QUAD_STRIP. The default begin callback
function is NULL. The function prototype for this callback looks
like:
void begin( GLenum type );
GLU_NURBS_BEGIN_DATA
The same as the GLU_NURBS_BEGIN callback except that it takes an
additional pointer argument. This pointer is a copy of the pointer
that was specified at the last call to gluNurbsCallbackData. The
default callback function is NULL. The function prototype for this
callback function looks like:
void beginData(GLenum type, void *userData);
GLU_NURBS_VERTEX
The vertex callback indicates a vertex of the primitive. The
coordinates of the vertex are stored in the parameter ``vertex''.
All the generated vertices have dimension 3; that is, homogeneous
coordinates have been transformed into affine coordinates. The
default vertex callback function is NULL. The function prototype
for this callback function looks like:
void vertex( GLfloat *vertex );
GLU_NURBS_VERTEX_DATA
This is the same as the GLU_NURBS_VERTEX callback, except that it
takes an additional pointer argument. This pointer is a copy of the
pointer that was specified at the last call to
gluNurbsCallbackData. The default callback function is NULL. The
function prototype for this callback function looks like:
void vertexData( GLfloat *vertex, void *userData );
GLU_NURBS_NORMAL
The normal callback is invoked as the vertex normal is generated.
The components of the normal are stored in the parameter
``normal.'' In the case of a NURBS curve, the callback function is
effective only when the user provides a normal map
(GLU_MAP1_NORMAL). In the case of a NURBS surface, if a normal map
(GLU_MAP2_NORMAL) is provided, then the generated normal is
computed from the normal map. If a normal map is not provided, then
a surface normal is computed in a manner similar to that described
for evaluators when GLU_AUTO_NORMAL is enabled. The default normal
callback function is NULL. The function prototype for this callback
function looks like:
void normal( GLfloat *normal );
GLU_NURBS_NORMAL_DATA
The same as the GLU_NURBS_NORMAL callback except that it takes an
additional pointer argument. This pointer is a copy of the pointer
that was specified at the last call to gluNurbsCallbackData. The
default callback function is NULL. The function prototype for this
callback function looks like:
void normalData( GLfloat *normal, void *userData );
GLU_NURBS_COLOR
The color callback is invoked as the color of a vertex is
generated. The components of the color are stored in the parameter
``color.'' This callback is effective only when the user provides a
color map (GLU_MAP1_COLOR_4 or GLU_MAP2_COLOR_4). ``color''
contains four components: R, G, B, A. The default color callback
function is NULL. The prototype for this callback function looks
like:
void color( GLfloat *color );
GLU_NURBS_COLOR_DATA
The same as the GLU_NURBS_COLOR callback except that it takes an
additional pointer argument. This pointer is a copy of the pointer
that was specified at the last call to gluNurbsCallbackData. The
default callback function is NULL. The function prototype for this
callback function looks like:
void colorData( GLfloat *color, void *userData );
GLU_NURBS_TEXTURE_COORD
The texture callback is invoked as the texture coordinates of a
vertex are generated. These coordinates are stored in the parameter
``texCoord.'' The number of texture coordinates can be 1, 2, 3, or
4 depending on which type of texture map is specified
(GLU_MAP1_TEXTURE_COORD_1, GLU_MAP1_TEXTURE_COORD_2,
GLU_MAP1_TEXTURE_COORD_3, GLU_MAP1_TEXTURE_COORD_4,
GLU_MAP2_TEXTURE_COORD_1, GLU_MAP2_TEXTURE_COORD_2,
GLU_MAP2_TEXTURE_COORD_3, GLU_MAP2_TEXTURE_COORD_4). If no texture
map is specified, this callback function will not be called. The
default texture callback function is NULL. The function prototype
for this callback function looks like:
void texCoord( GLfloat *texCoord );
GLU_NURBS_TEXTURE_COORD_DATA
This is the same as the GLU_NURBS_TEXTURE_COORD callback, except
that it takes an additional pointer argument. This pointer is a
copy of the pointer that was specified at the last call to
gluNurbsCallbackData. The default callback function is NULL. The
function prototype for this callback function looks like:
void texCoordData( GLfloat *texCoord, void *userData );
GLU_NURBS_END
The end callback is invoked at the end of a primitive. The default
end callback function is NULL. The function prototype for this
callback function looks like:
void end( void );
GLU_NURBS_END_DATA
This is the same as the GLU_NURBS_END callback, except that it
takes an additional pointer argument. This pointer is a copy of the
pointer that was specified at the last call to
gluNurbsCallbackData. The default callback function is NULL. The
function prototype for this callback function looks like:
void endData( void *userData );
GLU_NURBS_ERROR
The error function is called when an error is encountered. Its
single argument is of type GLenum, and it indicates the specific
error that occurred. There are 37 errors unique to NURBS, named
GLU_NURBS_ERROR1 through GLU_NURBS_ERROR37. Character strings
describing these errors can be retrieved with gluErrorString().
NOTES
gluNurbsCallback is available only if the GLU version is 1.2 or
greater.
GLU version 1.2 supports only the GLU_ERROR parameter for which. The
GLU_ERROR value is deprecated in GLU version 1.3 in favor of
GLU_NURBS_ERROR. All other accepted values for CallBackFunc are
available only if the GLU version is 1.3 or greater.
SEE ALSO
gluErrorString(), gluNewNurbsRenderer(), gluNurbsCallbackData,
gluNurbsProperty()
COPYRIGHT
Copyright © 1991-2006 Silicon Graphics, Inc. This document is licensed
under the SGI Free Software B License. For details, see
http://oss.sgi.com/projects/FreeB/.
AUTHORS
opengl.org
opengl.org 03/16/2013 GLUNURBSCALLBACK(3G)
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