Glu.NurbsSurface (gb.opengl.glu)

Define the shape of a NURBS surface.

Parameters

nurb

Specifies the NURBS object (created with Glu.NewNurbsRenderer).

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 Glu.NurbsSurface 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 Glu.BeginSurface command. To mark the end of a NURBS surface definition, use the Glu.EndSurface command. Call Glu.NurbsSurface within a NURBS surface definition only.

Positional, texture, and color coordinates are associated with a surface by presenting each as a separate Glu.NurbsSurface between a Glu.BeginSurface/Glu.EndSurface pair. No more than one call to Glu.NurbsSurface for each of color, position, and texture data can be made within a single Glu.BeginSurface/Glu.EndSurface 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 Glu.NurbsCurve and Glu.PwlCurve between calls to Glu.BeginTrim and Glu.EndTrim.

Note that a Glu.NurbsSurface with sKnotCount knots in the u direction and tKnotCount knots in the v direction with orders sOrder and tOrder must have (sKnotCount - sOrder) $\mathit{times}$ (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

See original documentation on OpenGL website