# glunurbscurve(3g) [osx man page]

GLUNURBSCURVE(3G) GLUNURBSCURVE(3G)NAME

gluNurbsCurve - define the shape of a NURBS curveC 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 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.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, gluBeginTrim, gluNewNurbsRenderer, gluPwlCurve GLUNURBSCURVE(3G)

## Check Out this Related Man Page

GLUPWLCURVE(3G) OpenGL Manual GLUPWLCURVE(3G)NAME

gluPwlCurve - describe a piecewise linear NURBS trimming curveC SPECIFICATION

void gluPwlCurve(GLUnurbs* nurb, GLint count, GLfloat* data, GLint stride, GLenum type);PARAMETERS

nurb Specifies the NURBS object (created with gluNewNurbsRenderer()). count Specifies the number of points on the curve. data Specifies an array containing the curve points. stride Specifies the offset (a number of single-precision floating-point values) between points on the curve. type Specifies the type of curve. Must be either GLU_MAP1_TRIM_2 or GLU_MAP1_TRIM_3.DESCRIPTION

gluPwlCurve describes a piecewise linear trimming curve for a NURBS surface. A piecewise linear curve consists of a list of coordinates of points in the parameter space for the NURBS surface to be trimmed. These points are connected with line segments to form a curve. If the curve is an approximation to a curve that is not piecewise linear, the points should be close enough in parameter space that the resulting path appears curved at the resolution used in the application. 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 information about trimming curves.NOTES

To describe a trim curve that closely follows the contours of a NURBS surface, call gluNurbsCurve().SEE ALSO

gluBeginCurve(), gluBeginTrim(), gluNewNurbsRenderer(), gluNurbsCurve()COPYRIGHT

Copyright (C) 1991-2006 Silicon Graphics, Inc. This document is licensed under the SGI Free Software B License. For details, see http://oss.sgi.com/projects/FreeB/.AUTHORS

opengl.orgopengl.org06/10/2014 GLUPWLCURVE(3G)