gluNurbsCurve function

The gluNurbsCurve function defines the shape of a Non-Uniform Rational B-Spline (NURBS) curve.

Syntax

void WINAPI gluNurbsCurve(
   GLUnurbs *nobj,
   GLint    nknots,
   GLfloat  *knot,
   GLint    stride,
   GLfloat  *ctlarray,
   GLint    order,
   GLenum   type
);

Parameters

nobj

The NURBS object (created with gluNewNurbsRenderer).

nknots

The number of knots in knot. The nknots parameter equals the number of control points plus the order.

knot

An array of nknots nondecreasing knot values.

stride

The offset (as a number of single-precision floating-point values) between successive curve control points.

ctlarray

A pointer to an array of control points. The coordinates must agree with type.

order

The order of the NURBS curve. The order parameter equals degree + 1; hence a cubic curve has an order of 4.

type

The type of the curve. If this curve is defined within a gluBeginCurve/gluEndCurve pair, then the type can be any of the valid one-dimensional evaluator types (such as GL_MAP1_VERTEX_3 or GL_MAP1_COLOR_4). Between a gluBeginTrim/gluEndTrim pair, the only valid types are GLU_MAP1_TRIM_2 and GLU_MAP1_TRIM_3.

Return value

This function does not return a value.

Remarks

When gluNurbsCurve appears between a gluBeginCurve/gluEndCurve pair, it describes a curve to be rendered. You associate positional, texture, and color coordinates by presenting each as a separate gluNurbsCurve between a gluBeginCurve/gluEndCurve pair. Do not make more than one call to gluNurbsCurve for color, position, and texture data within a single gluBeginCurve/gluEndCurve pair. Make exactly one call to describe the position of the curve (a type of GL_MAP1_VERTEX_3 or GL_MAP1_VERTEX_4).

When gluNurbsCurve appears between a gluBeginTrim/gluEndTrim pair, it describes a trimming curve on a NURBS surface. If type is GLU_MAP1_TRIM_2, it describes a curve in two-dimensional (u and v) parameter space. If it is GLU_MAP1_TRIM_3, it describes a curve in two-dimensional homogeneous (u, v, and w) parameter space. For more discussion about trimming curves, see gluBeginTrim.

Examples

The following functions render a textured NURBS curve with normals:

gluBeginCurve(nobj); 
    gluNurbsCurve(nobj, ..., GL_MAP1_TEXTURE_COORD_2); 
    gluNurbsCurve(nobj, ..., GL_MAP1_NORMAL); 
    gluNurbsCurve(nobj, ..., GL_MAP1_VERTEX_4);  
gluEndCurve(nobj); 

Requirements

See also

gluBeginCurve

gluBeginTrim

gluEndCurve

gluEndTrim

gluNewNurbsRenderer

gluPwlCurve