gluNurbsCurve.3G man page

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);



Specifies the NURBS object (created with gluNewNurbsRenderer()).


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 control points.


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 GLU_MAP1_VERTEX_3 or GLU_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 GLU_MAP1_VERTEX_3 or GLU_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_TEXTURE_COORD_2);
   gluNurbsCurve(nobj, ..., GL_MAP1_NORMAL);
   gluNurbsCurve(nobj, ..., GL_MAP1_VERTEX_4);


To define trim curves that stitch well, use gluPwlCurve().

See Also

gluBeginCurve(), gluBeginTrim(), gluNewNurbsRenderer(), gluPwlCurve()



07/13/2018 OpenGL Manual