OpenNurbs basis function

can i get basis functions of a surface by a existing function in OpenNurbs ?
if existing , what it is ? thank u.

Maybe here

thank u @ Menno Deij - van Rijswijk
by the way ,how can i know a surface is NURBS or Bezeir ?

That depends on the context of your question. Do you have an object reference or pointer variable, then you should be able to use dynamic_cast<ON_BezierSurface*>(ptr).
In general, a Bezier surface has degree+1 control points in each direction and uniformly distributed knots. As far as I know, opennurbs does not have a specific function to help you with this.

A NURBS surface which is single span in each direction is exactly equivalet to a Bezier surface. Any NURBS surface can be split into Bezier surfaces.

Knot distribution has no meaning for single span surfaces and curves because all the knots are at the ends of the curves or at the edges of the surfaces.

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thank u @menno ,maybe i know it .

thank u too @davidcockey .u are kind . :grinning: