gluNurbsSurface  1.D7GGX

[New - Windows 95, OEM Service Release 2]

The gluNurbsSurface function defines the shape of a NURBS surface.

void gluNurbsSurface(

Parameters

nobj

The NURBS object (created with gluNewNurbsRenderer1Y9AJ3Z).

sknot_count

The number of knots in the parametric u direction.

sknot

An array of sknot_count nondecreasing knot values in the parametric u direction.

tknot_count

The number of knots in the parametric v direction.

tknot

An array of tknot_count nondecreasing knot values in the parametric v direction.

s_stride

The offset (as a number of single-precision floating-point values) between successive control points in the parametric u direction in ctlarray.

t_stride

The offset (in single-precision floating-point values) between successive control points in the parametric v direction in ctlarray.

ctlarray

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 s_stride and t_stride.

sorder

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

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

The type of the surface. The type parameter can be any of the valid two-dimensional evaluator types (such as GL_MAP2_VERTEX_3 or GL_MAP2_COLOR_4).

Remarks

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 gluBeginSurfaceBRU9N. function. To mark the end of a NURBS surface definition, use the gluEndSurfaceBRU9N. function. Call gluNurbsSurface within a NURBS surface definition only.

You associate positional, texture, and color coordinates with a surface by presenting each as a separate gluNurbsSurface between a gluBeginSurface/gluEndSurface pair. Within a single gluBeginSurface/gluEndSurface pair, you can make only one call to gluNurbsSurface for color, position, and texture data. Make exactly one call to describe the position of the surface (a type of GL_MAP2_VERTEX_3 or GL_MAP2_VERTEX_4).

You can trim a NURBS surface by using the gluNurbsCurve5N1M_IB and gluPwlCurve1NDZ2UV functions between calls to gluBeginTrim14DY_E1 and gluEndTrim14DY_E1.

Note  A gluNurbsSurface with sknot_count knots in the u direction and tknot_count knots in the v direction with orders sorder and torder must have (sknot_count - sorder) multipied by (tknot_count - torder) control points.

Example

The following functions 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

gluBeginSurfaceBRU9N., gluBeginTrim14DY_E1, gluEndSurfaceBRU9N., gluEndTrim14DY_E1, gluNewNurbsRenderer1Y9AJ3Z, gluNurbsCurve5N1M_IB, gluPwlCurve1NDZ2UV