fgluNurbsSurface(3G) OpenGL Reference fgluNurbsSurface(3G)NAMEfgluNurbsSurface - define the shape of a NURBS surface
FORTRAN SPECIFICATION
SUBROUTINE fgluNurbsSurface( CHARACTER*8 nurb,
INTEGER*4 sKnotCount,
CHARACTER*8 sKnots,
INTEGER*4 tKnotCount,
CHARACTER*8 tKnots,
INTEGER*4 sStride,
INTEGER*4 tStride,
CHARACTER*8 control,
INTEGER*4 sOrder,
INTEGER*4 tOrder,
INTEGER*4 type )
PARAMETERS
nurb Specifies the NURBS object (created with
fgluNewNurbsRenderer).
sKnotCount Specifies the number of knots in the parametric u direction.
sKnots Specifies an array of sKnotCount nondecreasing knot values in
the parametric u direction.
tKnotCount Specifies the number of knots in the parametric v direction.
tKnots Specifies an array of tKnotCount nondecreasing knot values in
the parametric v direction.
sStride Specifies the offset (as a number of single-precision
floating point values) between successive control points in
the parametric u direction in control.
tStride Specifies the offset (in single-precision floating-point
values) between successive control points in the parametric v
direction in control.
control Specifies an array containing control points for the NURBS
surface. The offsets between successive control points in
the parametric u and v directions are given by sStride and
tStride.
sOrder Specifies the order of the NURBS surface in the parametric u
direction. The order is one more than the degree, hence a
surface that is cubic in u has a u order of 4.
tOrder Specifies the order of the NURBS surface in the parametric v
direction. The order is one more than the degree, hence a
surface that is cubic in v has a v order of 4.
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fgluNurbsSurface(3G) OpenGL Reference fgluNurbsSurface(3G)
type Specifies type of the surface. type can be any of the valid
two-dimensional evaluator types (such as GL_MAP2_VERTEX_3 or
GL_MAP2_COLOR_4).
DESCRIPTION
Use fgluNurbsSurface 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
fgluBeginSurface command. To mark the end of a NURBS surface definition,
use the fgluEndSurface command. Call fgluNurbsSurface within a NURBS
surface definition only.
Positional, texture, and color coordinates are associated with a surface
by presenting each as a separate fgluNurbsSurface between a
fgluBeginSurface/fgluEndSurface pair. No more than one call to
fgluNurbsSurface for each of color, position, and texture data can be
made within a single fgluBeginSurface/fgluEndSurface pair. Exactly one
call must be made to describe the position of the surface (a type of
GL_MAP2_VERTEX_3 or GL_MAP2_VERTEX_4).
A NURBS surface can be trimmed by using the commands fgluNurbsCurve and
fgluPwlCurve between calls to fgluBeginTrim and fgluEndTrim.
Note that a fgluNurbsSurface with sKnotCount knots in the u direction and
tKnotCount knots in the v direction with orders sOrder and tOrder must
have (sKnotCount - sOrder) x (tKnotCount - tOrder) control points.
EXAMPLE
The following commands render a textured NURBS surface with normals; the
texture coordinates and normals are also NURBS surfaces:
gluBeginSurface(nobj);
gluNurbsSurface(nobj, ..., GL_MAP2_TEXTURE_COORD_2);
gluNurbsSurface(nobj, ..., GL_MAP2_NORMAL);
gluNurbsSurface(nobj, ..., GL_MAP2_VERTEX_4);
gluEndSurface(nobj);
SEE ALSO
fgluBeginSurface, fgluBeginTrim, fgluNewNurbsRenderer, fgluNurbsCurve,
fgluPwlCurve
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