125 lines
4.1 KiB
Plaintext
125 lines
4.1 KiB
Plaintext
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'\" e
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'\"! eqn | mmdoc
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'\"macro stdmacro
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.ds Vn Version 1.2
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.ds Dt 6 March 1997
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.ds Re Release 1.2.0
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.ds Dp May 02 11:53
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.ds Dm 37 nurbssurf
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.ds Xs 28728 6 nurbssurface.gl
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.TH GLUNURBSSURFACE 3G
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.SH NAME
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.B "gluNurbsSurface
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\- define the shape of a NURBS surface
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.SH C SPECIFICATION
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void \f3gluNurbsSurface\fP(
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GLUnurbs* \fInurb\fP,
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.nf
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.ta \w'\f3void \fPgluNurbsSurface( 'u
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GLint \fIsKnotCount\fP,
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GLfloat* \fIsKnots\fP,
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GLint \fItKnotCount\fP,
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GLfloat* \fItKnots\fP,
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GLint \fIsStride\fP,
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GLint \fItStride\fP,
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GLfloat* \fIcontrol\fP,
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GLint \fIsOrder\fP,
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GLint \fItOrder\fP,
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GLenum \fItype\fP )
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.fi
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.EQ
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delim $$
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.EN
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.SH PARAMETERS
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.TP \w'\fIsKnotCount\fP\ \ 'u
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\f2nurb\fP
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Specifies the NURBS object (created with \%\f3gluNewNurbsRenderer\fP).
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.TP
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\f2sKnotCount\fP
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Specifies the number of knots in the parametric \f2u\fP direction.
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.TP
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\f2sKnots\fP
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Specifies an array of \f2sKnotCount\fP nondecreasing knot values in the parametric
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\f2u\fP direction.
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.TP
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\f2tKnotCount\fP
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Specifies the number of knots in the parametric \f2v\fP direction.
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.TP
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\f2tKnots\fP
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Specifies an array of \f2tKnotCount\fP nondecreasing knot values in the parametric
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\f2v\fP direction.
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.TP
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\f2sStride\fP
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Specifies the offset (as a number of single-precision floating point values)
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between successive control points in the parametric \f2u\fP direction
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in \f2control\fP.
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.TP
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\f2tStride\fP
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Specifies the offset (in single-precision floating-point values)
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between successive control points in the parametric \f2v\fP direction
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in \f2control\fP.
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.TP
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\f2control\fP
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Specifies an array containing control points for the NURBS surface.
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The offsets between successive control points in the parametric \f2u\fP
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and \f2v\fP directions are given by \f2sStride\fP and \f2tStride\fP.
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.TP
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\f2sOrder\fP
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Specifies the order of the NURBS surface in the parametric \f2u\fP
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direction. The order is one more than the degree, hence
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a surface that is cubic in \f2u\fP has a \f2u\fP order of 4.
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.TP
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\f2tOrder\fP
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Specifies the order of the NURBS surface in the parametric \f2v\fP
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direction. The order is one more than the degree, hence
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a surface that is cubic in \f2v\fP has a \f2v\fP order of 4.
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.TP
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\f2type\fP
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Specifies type of the surface. \f2type\fP can be any of the valid
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two-dimensional evaluator types (such as \%\f3GL_MAP2_VERTEX_3\fP or
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\%\f3GL_MAP2_COLOR_4\fP).
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.SH DESCRIPTION
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Use \%\f3gluNurbsSurface\fP within a NURBS (Non-Uniform Rational B-Spline) surface
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definition to describe the shape of a NURBS surface (before
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any trimming). To mark the beginning of
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a NURBS surface definition, use the \%\f3gluBeginSurface\fP command.
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To mark the end of a NURBS surface definition, use the
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\%\f3gluEndSurface\fP command. Call \%\f3gluNurbsSurface\fP within a NURBS
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surface definition only.
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.P
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Positional, texture, and color coordinates are associated
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with a surface by presenting each as a separate \%\f3gluNurbsSurface\fP between a
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\%\f3gluBeginSurface\fP/\%\f3gluEndSurface\fP pair. No more than
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one call to \%\f3gluNurbsSurface\fP for each of color, position, and texture
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data can be made within a single \%\f3gluBeginSurface\fP/\%\f3gluEndSurface\fP
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pair. Exactly one call must be made to describe the position of the
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surface (a \f2type\fP of \%\f3GL_MAP2_VERTEX_3\fP or \%\f3GL_MAP2_VERTEX_4\fP).
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.P
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A NURBS surface can be trimmed by using the commands
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\%\f3gluNurbsCurve\fP and \%\f3gluPwlCurve\fP between calls to
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\%\f3gluBeginTrim\fP and \%\f3gluEndTrim\fP.
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.P
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Note that a \%\f3gluNurbsSurface\fP with \f2sKnotCount\fP knots in the \f2u\fP direction
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and \f2tKnotCount\fP knots in the \f2v\fP direction with orders
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\f2sOrder\fP and \f2tOrder\fP must have
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(\f2sKnotCount\fP - \f2sOrder\fP) $times$ (\f2tKnotCount\fP - \f2tOrder\fP) control points.
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.SH EXAMPLE
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The following commands render a textured NURBS surface with normals;
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the texture coordinates and normals are also NURBS surfaces:
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.sp
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.Ex
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gluBeginSurface(nobj);
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gluNurbsSurface(nobj, ..., GL_MAP2_TEXTURE_COORD_2);
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gluNurbsSurface(nobj, ..., GL_MAP2_NORMAL);
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gluNurbsSurface(nobj, ..., GL_MAP2_VERTEX_4);
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gluEndSurface(nobj);
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.Ee
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.sp
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.SH SEE ALSO
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\%\f3gluBeginSurface(3G)\fP, \%\f3gluBeginTrim(3G)\fP, \%\f3gluNewNurbsRenderer(3G)\fP,
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\%\f3gluNurbsCurve(3G)\fP,
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\%\f3gluPwlCurve(3G)\fP
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