gluNurbsCurve

gluNurbsCurve: define the shape of a NURBS curve.

C Specification | Parameters | Description | Notes | See Also

C Specification

void gluNurbsCurve(
    GLUnurbs*	 nurb,
    GLint	 knotCount,
    GLfloat	 *knots,
    GLint	 stride,
    GLfloat	 *control,
    GLint	 order,
    GLenum	 type)

Parameters

nurb: Specifies the NURBS object (created with gluNewNurbsRenderer).
knotCount: Specifies the number of knots in knots. knotCount equals the number of control points plus the order.
knots: Specifies an array of knotCount nondecreasing knot values.
stride: Specifies the offset (as a number of single-precision floating-point values) between successive curve control points.
control: Specifies a pointer to an array of control points. The coordinates must agree with type, specified below.
order: Specifies the order of the NURBS curve. order equals degree + 1, hence a cubic curve has an order of 4.
type: Specifies 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 gluBeginCurve/gluEndCurve pair, the only valid types are GLU_MAP1_TRIM_2 and GLU_MAP1_TRIM_3.

Description

Use gluNurbsCurve to describe a NURBS curve.

When gluNurbsCurve appears between a gluBeginCurve/gluEndCurve pair, it is used to describe a curve to be rendered. Positional, texture, and color coordinates are associated by presenting each as a separate gluNurbsCurve between a gluBeginCurve/gluEndCurve pair. No more than one call to gluNurbsCurve for each of color, position, and texture data can be made within a single gluBeginCurve/gluEndCurve pair. Exactly one call must be made 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 is used to describe a trimming curve on a NURBS surface. If type is GLU_MAP1_TRIM_2, then it describes a curve in two-dimensional (u and v) parameter space. If it is GLU_MAP1_TRIM_3, then it describes a curve in two-dimensional homogeneous (u, v, and w) parameter space. See the gluBeginTrim reference page for more discussion about trimming curves.

Notes

To define trim curves that stitch well, use gluPwlCurve.