gluNurbsSurface(3G) OpenGL Reference 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 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.
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.
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gluNurbsSurface(3G) OpenGL Reference gluNurbsSurface(3G)
type Specifies type of the surface. type can be any of the valid
two-dimensional evaluator types (such as GLMAP2VERTEX3 or
GLMAP2COLOR4).
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 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
GLMAP2VERTEX3 or GLMAP2VERTEX4).
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);
gluEndSurface(nobj);
SEE ALSO
gluBeginSurface, gluBeginTrim, gluNewNurbsRenderer, gluNurbsCurve,
gluPwlCurve
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