Table of Contents
gluNurbsCurve - define the shape of a NURBS curve
gluNurbsCurve( GLUnurbs* nurb,
GLenum type )
eqn not supported
to describe a NURBS curve.
- Specifies the NURBS object (created with
- Specifies the number of knots in knots. knotCount
equals the number of control points plus the order.
- Specifies an array
of knotCount nondecreasing knot values.
- Specifies the offset (as
a number of single-precision floating-point values) between successive curve
- Specifies a pointer to an array of control points.
The coordinates must agree with type, specified below.
- Specifies the
order of the NURBS curve. order equals degree + 1, hence a cubic curve has
an order of 4.
- 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 gluBeginTrim/gluEndTrim pair, the only valid
types are GLU_MAP1_TRIM_2 and GLU_MAP1_TRIM_3.
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.
The following commands
render a textured NURBS curve with normals:
gluNurbsCurve(nobj, ..., GL_MAP1_NORMAL);
gluNurbsCurve(nobj, ..., GL_MAP1_VERTEX_4);
To define trim curves which stitch well, use
Table of Contents