OpenGL man pages
gluNurbsCurve - define the shape of a NURBS curve
void gluNurbsCurve( GLUnurbsObj *nobj,
GLenum type )
nobj Specifies the NURBS object (created with gluNewNurbsRenderer).
nknots Specifies the number of knots in knot. nknots equals the number
of control points plus the order.
knot Specifies an array of nknots nondecreasing knot values.
stride Specifies the offset (as a number of single-precision floating-
point values) between successive curve control points.
ctlarray 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 gluBeginTrim/gluEndTrim pair, the
only valid types are GLU_MAP1_TRIM_2 and GLU_MAP1_TRIM_3.
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
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_TEXTURE_COORD_2);
gluNurbsCurve(nobj, …, GL_MAP1_NORMAL);
gluNurbsCurve(nobj, …, GL_MAP1_VERTEX_4); gluEndCurve(nobj);
To define trim curves which stitch well use gluPwlCurve.
gluBeginCurve, gluBeginTrim, gluNewNurbsRenderer, gluPwlCurve
Fri Dec 6 11:18:03 EST 1996
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