gluBeginCurve, gluEndCurve
The gluBeginCurve and gluEndCurve functions delimit a Non-Uniform Rational B-Spline (NURBS) curve definition.
void gluBeginCurve(
GLUnurbsObj *nobj);void gluEndCurve( GLUnurbsObj *nobj);
Parameters
- nobj
The NURBS object (created with gluNewNurbsRenderer).
Remarks
Use gluBeginCurve to mark the beginning of a NURBS curve definition. After calling gluBeginCurve, make one or more calls to gluNurbsCurve to define the attributes of the curve. Exactly one of the calls to gluNurbsCurve must have a curve type of GL_MAP1_VERTEX_3 or GL_MAP1_VERTEX_4. To mark the end of the NURBS curve definition, call gluEndCurve.
OpenGL evaluators are used to render the NURBS curve as a series of line segments. Evaluator state is preserved during rendering with glPushAttrib(GL_EVAL_BIT) and glPopAttrib. For information on exactly what state these calls preserve, see glPushAttrib.
Example
The following functions render a textured NURBS curve with normals; texture coordinates and normals are also specified as NURBS curves:
gluBeginCurve(nobj); gluNurbsCurve(nobj, . . ., GL_MAP1_TEXTURE_COORD_2); gluNurbsCurve(nobj, . . ., GL_MAP1_NORMAL); gluNurbsCurve(nobj, . . ., GL_MAP1_VERTEX_4); gluEndCurve(nobj);
Requirements
** Windows NT/2000:** Requires Windows NT 3.5 or later.
** Windows 95/98:** Requires Windows 95 or later. Available as a redistributable for Windows 95.
** Header:** Declared in Glu.h.
** Library:** Use Glu32.lib.
See Also
glPopAttrib, glPushAttrib, gluBeginSurface, gluBeginTrim, gluNewNurbsRenderer, gluNurbsCurve