---

Manual Reference Pages  - GLUNURBSCURVE (3G)

---

gluNurbsCurve - define the shape of a NURBS curve

CONTENTS

C Specification
Parameters
Description
Example
Notes
See Also

void gluNurbsCurve( GLUnurbs* nurb,

                  GLint knotCount,
                  GLfloat *knots,
                  GLint stride,
                  GLfloat *control,
                  GLint order,
                  GLenum type )

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  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  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:

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

To define trim curves which stitch well, use  gluPwlCurve.

 gluBeginCurve(3G),  gluBeginTrim(3G),  gluNewNurbsRenderer(3G),  gluPwlCurve(3G)

Jump to page    or go to Top of page |  Section 3G |  Main Index.