'\" e '\"macro stdmacro .ds Vn Version 1.2 .ds Dt 6 March 1997 .ds Re Release 1.2.0 .ds Dp May 22 14:54 .ds Dm 9 May 22 14: .ds Xs 28728 6 .TH GLUNURBSSURFACE 3G .SH NAME .B "gluNurbsSurface \- define the shape of a NURBS surface .SH C SPECIFICATION void \f3gluNurbsSurface\fP( GLUnurbs* \fInurb\fP, .nf .ta \w'\f3void \fPgluNurbsSurface( 'u GLint \fIsKnotCount\fP, GLfloat* \fIsKnots\fP, GLint \fItKnotCount\fP, GLfloat* \fItKnots\fP, GLint \fIsStride\fP, GLint \fItStride\fP, GLfloat* \fIcontrol\fP, GLint \fIsOrder\fP, GLint \fItOrder\fP, GLenum \fItype\fP ) .fi .EQ delim $$ .EN .SH PARAMETERS .TP \w'\fIsKnotCount\fP\ \ 'u \f2nurb\fP Specifies the NURBS object (created with \%\f3gluNewNurbsRenderer\fP). .TP \f2sKnotCount\fP Specifies the number of knots in the parametric \f2u\fP direction. .TP \f2sKnots\fP Specifies an array of \f2sKnotCount\fP nondecreasing knot values in the parametric \f2u\fP direction. .TP \f2tKnotCount\fP Specifies the number of knots in the parametric \f2v\fP direction. .TP \f2tKnots\fP Specifies an array of \f2tKnotCount\fP nondecreasing knot values in the parametric \f2v\fP direction. .TP \f2sStride\fP Specifies the offset (as a number of single-precision floating point values) between successive control points in the parametric \f2u\fP direction in \f2control\fP. .TP \f2tStride\fP Specifies the offset (in single-precision floating-point values) between successive control points in the parametric \f2v\fP direction in \f2control\fP. .TP \f2control\fP Specifies an array containing control points for the NURBS surface. The offsets between successive control points in the parametric \f2u\fP and \f2v\fP directions are given by \f2sStride\fP and \f2tStride\fP. .TP \f2sOrder\fP Specifies the order of the NURBS surface in the parametric \f2u\fP direction. The order is one more than the degree, hence a surface that is cubic in \f2u\fP has a \f2u\fP order of 4. .TP \f2tOrder\fP Specifies the order of the NURBS surface in the parametric \f2v\fP direction. The order is one more than the degree, hence a surface that is cubic in \f2v\fP has a \f2v\fP order of 4. .TP \f2type\fP Specifies type of the surface. \f2type\fP can be any of the valid two-dimensional evaluator types (such as \%\f3GL_MAP2_VERTEX_3\fP or \%\f3GL_MAP2_COLOR_4\fP). .SH DESCRIPTION Use \%\f3gluNurbsSurface\fP within a NURBS (Non-Uniform Rational B-Spline) surface definition to describe the shape of a NURBS surface (before any trimming). To mark the beginning of a NURBS surface definition, use the \%\f3gluBeginSurface\fP command. To mark the end of a NURBS surface definition, use the \%\f3gluEndSurface\fP command. Call \%\f3gluNurbsSurface\fP within a NURBS surface definition only. .P Positional, texture, and color coordinates are associated with a surface by presenting each as a separate \%\f3gluNurbsSurface\fP between a \%\f3gluBeginSurface\fP/\%\f3gluEndSurface\fP pair. No more than one call to \%\f3gluNurbsSurface\fP for each of color, position, and texture data can be made within a single \%\f3gluBeginSurface\fP/\%\f3gluEndSurface\fP pair. Exactly one call must be made to describe the position of the surface (a \f2type\fP of \%\f3GL_MAP2_VERTEX_3\fP or \%\f3GL_MAP2_VERTEX_4\fP). .P A NURBS surface can be trimmed by using the commands \%\f3gluNurbsCurve\fP and \%\f3gluPwlCurve\fP between calls to \%\f3gluBeginTrim\fP and \%\f3gluEndTrim\fP. .P Note that a \%\f3gluNurbsSurface\fP with \f2sKnotCount\fP knots in the \f2u\fP direction and \f2tKnotCount\fP knots in the \f2v\fP direction with orders \f2sOrder\fP and \f2tOrder\fP must have (\f2sKnotCount\fP - \f2sOrder\fP) $times$ (\f2tKnotCount\fP - \f2tOrder\fP) control points. .SH EXAMPLE The following commands render a textured NURBS surface with normals; the texture coordinates and normals are also NURBS surfaces: .sp .Ex gluBeginSurface(nobj); gluNurbsSurface(nobj, ..., GL_MAP2_TEXTURE_COORD_2); gluNurbsSurface(nobj, ..., GL_MAP2_NORMAL); gluNurbsSurface(nobj, ..., GL_MAP2_VERTEX_4); gluEndSurface(nobj); .Ee .sp .SH SEE ALSO \%\f3gluBeginSurface\fP, \%\f3gluBeginTrim\fP, \%\f3gluNewNurbsRenderer\fP, \%\f3gluNurbsCurve\fP, \%\f3gluPwlCurve\fP