Boresight

06-21-2001, 07:16 AM

In gluNurbsCurve() and gluNurbsSurface you give a sequence of knots.

What exactly are knots in a NURBS?

What exactly are knots in a NURBS?

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Boresight

06-21-2001, 07:16 AM

In gluNurbsCurve() and gluNurbsSurface you give a sequence of knots.

What exactly are knots in a NURBS?

What exactly are knots in a NURBS?

micheal

06-21-2001, 09:47 AM

Knots are used for define the B spline functions. They should be a nondecreasing

sequence. If you would like your Nurbs Curve

passed by a Control Point(for example, let it start from the first Control Point and end at the Last Control Point), the corresponding Knot should have multiplicity n (n is order of your Nurbs curve.). You can control the

shape of Nurbs Curve by define different

multiplcity number, which you can refer

to the Book:

(The systems Programming series)

Computer graphics:Principles and Practice,

Foley, van Dam, Feiner Hughes

An example:

If the order of your Nurbs Curve is 3,

and you have 8 control points,

Then the knot sequence can be

0,0,0,1,2,3,4,5,6,6,6

which will make out a curve that passes by

the first and the last Control Points.

Originally posted by Boresight:

In gluNurbsCurve() and gluNurbsSurface you give a sequence of knots.

What exactly are knots in a NURBS?

sequence. If you would like your Nurbs Curve

passed by a Control Point(for example, let it start from the first Control Point and end at the Last Control Point), the corresponding Knot should have multiplicity n (n is order of your Nurbs curve.). You can control the

shape of Nurbs Curve by define different

multiplcity number, which you can refer

to the Book:

(The systems Programming series)

Computer graphics:Principles and Practice,

Foley, van Dam, Feiner Hughes

An example:

If the order of your Nurbs Curve is 3,

and you have 8 control points,

Then the knot sequence can be

0,0,0,1,2,3,4,5,6,6,6

which will make out a curve that passes by

the first and the last Control Points.

Originally posted by Boresight:

In gluNurbsCurve() and gluNurbsSurface you give a sequence of knots.

What exactly are knots in a NURBS?

Boresight

06-21-2001, 10:11 AM

Thanks so much, it's I need know

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