gluNurbsSurface - define the shape of a NURBS surface
C SPECIFICATION
void gluNurbsSurface( GLUnurbs* nurb,
GLint sKnotCount,
GLfloat* sKnots,
GLint tKnotCount,
GLfloat* tKnots,
GLint sStride,
GLint tStride,
GLfloat* control,
GLint sOrder,
GLint tOrder,
GLenum type )
PARAMETERS
nurb Specifies the NURBS object (created with
gluNewNurbsRenderer).
sKnotCount Specifies the number of knots in the paramet-
ric u direction.
sKnots Specifies an array of sKnotCount nondecreasing
knot values in the parametric u direction.
tKnotCount Specifies the number of knots in the paramet-
ric 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 suc-
cessive control points in the parametric u
direction in control.
tStride Specifies the offset (in single-precision
floating-point values) between successive con-
trol 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.
sOrder Specifies the order of the NURBS surface in
the parametric u direction. The order is one
more than the degree, hence a surface that is
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 GL_MAP2_VERTEX_3 or GL_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) x
(tKnotCount - tOrder) control points.
EXAMPLE
The following commands render a textured NURBS surface
with normals; the texture coordinates and normals are also
NURBS surfaces:
gluBeginSurface(nobj);
gluNurbsSurface(nobj, ..., GL_MAP2_TEXTURE_COORD_2);
gluNurbsSurface(nobj, ..., GL_MAP2_NORMAL);
gluNurbsSurface(nobj, ..., GL_MAP2_VERTEX_4); gluEnd-
Surface(nobj);
SEE ALSO
gluBeginSurface, gluBeginTrim, gluNewNurbsRenderer,
gluNurbsCurve, gluPwlCurve
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