gluNurbsCurve(3) gluNurbsCurve(3)
NAME
gluNurbsCurve - define the shape of a NURBS curve
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 float-
ing-point values) between successive curve control points.
control Specifies a pointer to an array of control points. The coor-
dinates 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.
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.
EXAMPLE
The following commands 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);
NOTES
To define trim curves which stitch well, use gluPwlCurve.
SEE ALSO
gluBeginCurve(3), gluBeginTrim(3), gluNewNurbsRenderer(3), gluPwlCurve(3)
gluNurbsCurve(3)
Mac OS X 10.6 - Generated Thu Sep 17 20:20:34 CDT 2009