Glu.BeginSurface (gb.opengl.glu)
Static Sub BeginSurface ( Nurb As GluNurb )
Delimit a NURBS surface definition.
Parameters
- nurb
-
Specifies the NURBS object (created with Glu.NewNurbsRenderer).
Description
Use
Glu.BeginSurface to mark the beginning of a NURBS
surface definition. After
calling
Glu.BeginSurface, make one or more calls to
Glu.NurbsSurface to define the attributes of the surface.
Exactly one of these calls to Glu.NurbsSurface must have a
surface type of Glu.MAP2_VERTEX_3 or Glu.MAP2_VERTEX_4.
To mark the end of the NURBS surface definition, call
Glu.EndSurface.
Trimming of NURBS surfaces is supported with Glu.BeginTrim,
Glu.PwlCurve, Glu.NurbsCurve, and Glu.EndTrim. See the
Glu.BeginTrim 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 Gl.PushAttrib(Glu.EVAL_BIT) and
Gl.PopAttrib.
See the Gl.PushAttrib reference page for details on exactly what state
these calls preserve.
Example
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);
See also
Glu.BeginTrim,
Glu.NurbsCurve,
Glu.NurbsSurface,
Glu.PwlCurve,
Gl.PushAttrib