OpenGL Programming Guide

Appendix CThe OpenGL Utility Library

NURBS Curves and Surfaces

NURBS routines provide general and powerful descriptions of curves and surfaces in two and three dimensions. They're used to represent geometry in many computer-aided mechanical design systems. The GLU NURBS routines can render such curves and surfaces in a variety of styles, and they can automatically handle adaptive subdivision that tessellates the domain into smaller triangles in regions of high curvature and near silhouette edges. All the GLU NURBS routines are described in Chapter 9 ; their prototypes are listed here.

Manage a NURBS object:

GLUnurbsObj* gluNewNurbsRenderer (void);

void gluDeleteNurbsRenderer (GLUnurbsObj *nobj);

void gluNurbsCallback (GLUnurbsObj *nobj, GLenum which, void (*fn)());

Create a NURBS curve:

void gluBeginCurve (GLUnurbsObj *nobj);

void gluEndCurve (GLUnurbsObj *nobj);

void gluNurbsCurve (GLUnurbsObj *nobj, GLint nknots, GLfloat *knot, GLint stride, GLfloat *ctlarray, GLint order, GLenum type);

Create a NURBS surface:

void gluBeginSurface (GLUnurbsObj *nobj);

void gluEndSurface (GLUnurbsObj *nobj);

void gluNurbsSurface (GLUnurbsObj *nobj, GLint uknot_count, GLfloat *uknot, GLint vknot_count, GLfloat *vknot, GLint u_stride, GLint v_stride, GLfloat *ctlarray, GLint uorder, GLint vorder, GLenum type);

Define a trimming region:

void gluBeginTrim (GLUnurbsObj *nobj);

void gluEndTrim (GLUnurbsObj *nobj);

void gluPwlCurve (GLUnurbsObj *nobj, GLint count, GLfloat *array, GLint stride, GLenum type);

Control NURBS rendering:

void gluLoadSamplingMatrices (GLUnurbsObj *nobj, const GLfloat modelMatrix[16], const GLfloat projMatrix[16], const GLint viewport[4]);

void gluNurbsProperty (GLUnurbsObj *nobj, GLenum property, GLfloat value);

void gluGetNurbsProperty (GLUnurbsObj *nobj, GLenum property, GLfloat *value);

OpenGL Programming Guide