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GLUNURBSSURFACE(3G) OpenGL 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
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.
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).
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 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.
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()
COPYRIGHT
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/.
AUTHORS
opengl.org
opengl.org 06/10/2014 GLUNURBSSURFACE(3G) |
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