gluNurbsSurface - define the shape of a NURBS surface
void gluNurbsSurface( | GLUnurbs* | nurb, |
| GLint | sKnotCount, | |
| GLfloat* | sKnots, | |
| GLint | tKnotCount, | |
| GLfloat* | tKnots, | |
| GLint | sStride, | |
| GLint | tStride, | |
| GLfloat* | control, | |
| GLint | sOrder, | |
| GLint | tOrder, | |
| GLenum | type); |
nurbSpecifies the NURBS object (created with gluNewNurbsRenderer).
sKnotCountSpecifies the number of knots in the parametric u direction.
sKnots
Specifies an array of sKnotCount nondecreasing knot values in the parametric
u direction.
tKnotCountSpecifies the number of knots in the parametric v direction.
tKnots
Specifies an array of tKnotCount nondecreasing knot values in the parametric
v direction.
sStride
Specifies the offset (as a number of single-precision floating-point values)
between successive control points in the parametric u direction
in control.
tStride
Specifies the offset (in single-precision floating-point values)
between successive control points in the parametric v direction
in control.
control
Specifies an array containing control points for the NURBS surface.
The offsets between successive control points in the parametric u
and v directions are given by sStride and tStride.
sOrderSpecifies the order of the NURBS surface in the parametric u direction. The order is one more than the degree, hence a surface that is cubic in u has a u order of 4.
tOrderSpecifies the order of the NURBS surface in the parametric v direction. The order is one more than the degree, hence a surface that is cubic in v has a v order of 4.
type
Specifies type of the surface. type can be any of the valid
two-dimensional evaluator types (such as GLU_MAP2_VERTEX_3 or
GLU_MAP2_COLOR_4).
Use gluNurbsSurface within a NURBS (Non-Uniform Rational B-Spline) surface
definition to describe the shape of a NURBS surface (before
any trimming). To mark the beginning of
a NURBS surface definition, use the gluBeginSurface command.
To mark the end of a NURBS surface definition, use the
gluEndSurface command. Call gluNurbsSurface within a NURBS
surface definition only.
Positional, texture, and color coordinates are associated
with a surface by presenting each as a separate gluNurbsSurface between a
gluBeginSurface/gluEndSurface pair. No more than
one call to gluNurbsSurface for each of color, position, and texture
data can be made within a single gluBeginSurface/gluEndSurface
pair. Exactly one call must be made to describe the position of the
surface (a type of GLU_MAP2_VERTEX_3 or GLU_MAP2_VERTEX_4).
A NURBS surface can be trimmed by using the commands gluNurbsCurve and gluPwlCurve between calls to gluBeginTrim and gluEndTrim.
Note that a gluNurbsSurface with sKnotCount knots in the u direction
and tKnotCount knots in the v direction with orders
sOrder and tOrder must have
(sKnotCount - sOrder) times
(tKnotCount - tOrder) control points.
The following commands render a textured NURBS surface with normals; the texture coordinates and normals are also NURBS surfaces:
gluBeginSurface(nobj);
gluNurbsSurface(nobj, ..., GLU_MAP2_TEXTURE_COORD_2);
gluNurbsSurface(nobj, ..., GLU_MAP2_NORMAL);
gluNurbsSurface(nobj, ..., GLU_MAP2_VERTEX_4);
gluEndSurface(nobj);
Copyright c 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/.