OpenGL : Trim curves - outer/inner loop / winding

grid_2x2_single_hole_trim.3dm (23.4 KB)

I have a single surface with a single trim (creating a hole in the surface)

The data I gather indicates that there are two loops

One loop is for the circle (hole)

The other consist of 4 individual trim curves which looks to me to be the outer loop judging from the type of loop

my printout:
Loop type = 1
Loop trim count = 4
Loop type = 2
Loop trim count = 1

Is there a way/function to join Trim Curves into one single curve so that I can pass that to OpenGL?

What if the Trim Curves have different order, is that still possible with such function in OpenNURBS ?


My mistake, upon further reading of the OpenGL specification of gluBeginTrim()/gluEndTrim(), one can specify the loops in individual segments and of different types i.e. piece-wise-linear or NURBS.

The only requirement being that the segments CVs must connect and form a loop.

Hence the question above is unnecessary.