Hole in a nurbs circle

I’ve a curve-> nurbs circle and i want to make a hole in it, i tried to create a cylinder and select both and make the difference but seems that with a nurbs circle i don’t have this option…how can i do it?

Thanks :slight_smile:

just create another nurbs circle inside the object and position it where you want it
(add it in edit mode)

i did not know that you could do that

did a test and seem to work

only problem when you try to convert to mesh it refuses to convert it into a mesh?

any idea why ?


Perfect! Thank you :slight_smile:


it works every time for me
maybe try it in a fresh file (something may have gotten corrupted)

i tried with surface circles not curve circles

THe 2 types work fine

but with surface circles it refuse to convert - probably a bug !

see pics on the left are the curves and the right the mesh
except for the surfaces nurbs it is still a curves not a mesh
it’s refusing to convert to mesh !


it’s not a bug
there is just no surface to convert to a mesh
either skin the surface by selecting the CV’s and pressing F

add a circle (surface) > then in edit mode extrude the circle

now you have a surface that you can convert to a mesh
you also know the difference between the 2

but then why is it call a nurb surface if there are no surface !

i’ll test some more

this is not indicated in the wiki pages - there should be a few new pages
showing theses little tricks to work with nurbs

i’ll probably try to write some doc pages for thenew Nurbs tools later this year
hopefully it can be added to the wiki !

but it’s great to learn more about Nurbs

tested more and seems to work fine with filled faces

i can add vertices to a nurb circle curve but not to the nurb circle surface

not certain why this behavior!

is there some good doc somewhere giving more details like theses
showing what can be done or not done ?

Happy blendering

don’t know if there is a good doc

but the main difference is a surface is 3D and a curve is 2D
this is why you can add a single vert to a 2D curve but can’t to a surface
you can join another section to a surface (via skinning)
but the new section needs to the same resolution (same amount of Control Verts)

there is a fair bit of work going on with NURBS at the moment
I can’t remember who is working on them but if you want to help with the documentation
it might be worth finding out and having a chat with them
(search the forums, I think nurbana integration is planned for 2.5, but I don’t know who is working on it)

there is a post for the new Nurbs

but since a few weeks seems that no one is working on it or answering at the post
as such

so dont’ know what’s happening anymore!