GLUNURBSSURFACE(3G) GLUNURBSSURFACE(3G)
NAME
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 parametric u direction.
sKnots Specifies an array of sKnotCount nondecreasing knot values in the parametric u direction.
tKnotCount Specifies 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 suc-cessive successive
cessive control points in the parametric u direction in control.
tStride Specifies the offset (in single-precision floating-point values) between successive con-trol control
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 cubic in u has a u order of 4.
tOrder Specifies 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 GL_MAP2_VERTEX_3 or GL_MAP2_COLOR_4).
DESCRIPTION
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 sep-arate separate
arate 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) times (tKnotCount - tOrder)
control points.
EXAMPLE
The following commands render a textured NURBS surface with normals; the texture coordinates and nor-mals normals
mals are also 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
gluBeginSurface(3G), gluBeginTrim(3G), gluNewNurbsRenderer(3G), gluNurbsCurve(3G), gluPwlCurve(3G)
GLUNURBSSURFACE(3G)
|