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doc/gl-docs/GLU/begincurve.3gl

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+'\" e
+'\"! eqn | mmdoc
+'\"macro stdmacro
+.ds Vn Version 1.2
+.ds Dt 6 March 1997
+.ds Re Release 1.2.0
+.ds Dp May 02 11:53
+.ds Dm 37 begincurv
+.ds Xs 19309 4 begincurve.gl
+.TH GLUBEGINCURVE 3G
+.SH NAME
+.B "gluBeginCurve, gluEndCurve
+\- delimit a NURBS curve definition
+
+.SH C SPECIFICATION
+void \f3gluBeginCurve\fP(
+GLUnurbs* \fInurb\fP )
+.nf
+.fi
+
+void \f3gluEndCurve\fP(
+GLUnurbs* \fInurb\fP )
+.nf
+.fi
+
+.EQ
+delim $$
+.EN
+.SH PARAMETERS
+.TP \w'\f2nurb\fP\ \ 'u 
+\f2nurb\fP
+Specifies the NURBS object (created with \%\f3gluNewNurbsRenderer\fP).
+.SH DESCRIPTION
+Use \%\f3gluBeginCurve\fP to mark the beginning of a NURBS 
+curve definition.
+After 
+calling \%\f3gluBeginCurve\fP, make one or more calls to
+\%\f3gluNurbsCurve\fP to define the attributes of the curve.
+Exactly one of the calls to \%\f3gluNurbsCurve\fP must have
+a curve type of \%\f3GL_MAP1_VERTEX_3\fP or \%\f3GL_MAP1_VERTEX_4\fP.
+To mark the end of the NURBS curve definition, call \%\f3gluEndCurve\fP.
+.P
+GL evaluators are used to render the NURBS curve as a series of line
+segments.
+Evaluator state is preserved during rendering
+with \f3glPushAttrib\fP(\%\f3GL_EVAL_BIT\fP) and 
+\f3glPopAttrib\fP().  
+See the \f3glPushAttrib\fP reference page for details on exactly what state
+these calls preserve.
+.SH EXAMPLE
+The following commands render a textured NURBS curve with normals;
+texture coordinates and normals are also specified as NURBS curves:
+.sp
+.Ex
+gluBeginCurve(nobj);
+   gluNurbsCurve(nobj, ..., GL_MAP1_TEXTURE_COORD_2);
+   gluNurbsCurve(nobj, ..., GL_MAP1_NORMAL);
+   gluNurbsCurve(nobj, ..., GL_MAP1_VERTEX_4);
+gluEndCurve(nobj);
+.Ee
+.SH SEE ALSO
+\%\f3gluBeginSurface(3G)\fP, \%\f3gluBeginTrim(3G)\fP, \%\f3gluNewNurbsRenderer(3G)\fP, 
+\%\f3gluNurbsCurve(3G)\fP, 
+\f3glPopAttrib(3G)\fP, \f3glPushAttrib(3G)\fP
+