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<STRONG>NAME</STRONG>
<STRONG>gluBeginSurface,</STRONG> <STRONG>gluEndSurface</STRONG> - delimit a NURBS surface
definition
<STRONG>C</STRONG> <STRONG>SPECIFICATION</STRONG>
void <STRONG>gluBeginSurface</STRONG>( GLUnurbs* <EM>nurb</EM> )
void <STRONG>gluEndSurface</STRONG>( GLUnurbs* <EM>nurb</EM> )
<STRONG>PARAMETERS</STRONG>
<EM>nurb</EM> Specifies the NURBS object (created with
<STRONG>gluNewNurbsRenderer</STRONG>).
<STRONG>DESCRIPTION</STRONG>
Use <STRONG>gluBeginSurface</STRONG> to mark the beginning of a NURBS surface
definition. After calling <STRONG>gluBeginSurface</STRONG>, make one or more
calls to <STRONG>gluNurbsSurface</STRONG> to define the attributes of the
surface. Exactly one of these calls to <STRONG>gluNurbsSurface</STRONG> must
have a surface type of <STRONG>GL_MAP2_VERTEX_3</STRONG> or <STRONG>GL_MAP2_VERTEX_4</STRONG>.
To mark the end of the NURBS surface definition, call
<STRONG>gluEndSurface</STRONG>.
Trimming of NURBS surfaces is supported with <STRONG>gluBeginTrim</STRONG>,
<STRONG>gluPwlCurve</STRONG>, <STRONG>gluNurbsCurve</STRONG>, and <STRONG>gluEndTrim</STRONG>. See the
<STRONG>gluBeginTrim</STRONG> reference page for details.
GL evaluators are used to render the NURBS surface as a set
of polygons. Evaluator state is preserved during rendering
with <STRONG>glPushAttrib</STRONG>(<STRONG>GL_EVAL_BIT</STRONG>) and <STRONG>glPopAttrib</STRONG>(). See the
<STRONG>glPushAttrib</STRONG> reference page for details on exactly what
state these calls preserve.
<STRONG>EXAMPLE</STRONG>
The following commands render a textured NURBS surface with
normals; the texture coordinates and normals are also
described as NURBS surfaces:
gluBeginSurface(nobj);
gluNurbsSurface(nobj, ..., GL_MAP2_TEXTURE_COORD_2);
gluNurbsSurface(nobj, ..., GL_MAP2_NORMAL);
gluNurbsSurface(nobj, ..., GL_MAP2_VERTEX_4);
gluEndSurface(nobj);
<STRONG>SEE</STRONG> <STRONG>ALSO</STRONG>
<STRONG>gluBeginCurve</STRONG>, <STRONG>gluBeginTrim</STRONG>, <STRONG>gluNewNurbsRenderer</STRONG>,
<STRONG>gluNurbsCurve</STRONG>, <STRONG>gluNurbsSurface</STRONG>, <STRONG>gluPwlCurve</STRONG>
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