gluNurbsSurface
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## 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`);`

## Python Specification

``gluNurbsSurface`` | `(` | ``nurb`, `sKnots`[], `tKnots`[], `control`[][], `type`) → `None``

## 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 `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 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`) × (`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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