---

Manual Reference Pages  - GLUNURBSSURFACE (3G)

---

gluNurbsSurface - define the shape of a NURBS surface

CONTENTS

C Specification
Parameters
Description
Example
See Also

void gluNurbsSurface( GLUnurbs* nurb,

                    GLint sKnotCount,
                    GLfloat* sKnots,
                    GLint tKnotCount,
                    GLfloat* tKnots,
                    GLint sStride,
                    GLint tStride,
                    GLfloat* control,
                    GLint sOrder,
                    GLint tOrder,
                    GLenum type )

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  GL_MAP2_VERTEX_3 or  GL_MAP2_COLOR_4).

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  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.

The following commands render a textured NURBS surface with normals; the texture coordinates and normals are also NURBS surfaces:

.Ex gluBeginSurface(nobj);
gluNurbsSurface(nobj, ..., GL_MAP2_TEXTURE_COORD_2);
gluNurbsSurface(nobj, ..., GL_MAP2_NORMAL);
gluNurbsSurface(nobj, ..., GL_MAP2_VERTEX_4); gluEndSurface(nobj);
.Ee

 gluBeginSurface(3G),  gluBeginTrim(3G),  gluNewNurbsRenderer(3G),  gluNurbsCurve(3G),  gluPwlCurve(3G)

Jump to page    or go to Top of page |  Section 3G |  Main Index.