GLUNURBSSURFACE(3G) UNIX Programmer's Manual 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 succes-
sive control points in the parametric u direc-
tion 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 succes-
sive 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
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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 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 sin-
gle 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 ord-
ers 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(3G), gluBeginTrim(3G),
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GLUNURBSSURFACE(3G) UNIX Programmer's Manual GLUNURBSSURFACE(3G)
gluNewNurbsRenderer(3G), gluNurbsCurve(3G), gluPwlCurve(3G)
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