Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Remove curve2d.full_circle2 to avoid confusion #2

Open
orbingol opened this issue Jan 17, 2020 · 8 comments
Open

Remove curve2d.full_circle2 to avoid confusion #2

orbingol opened this issue Jan 17, 2020 · 8 comments
Assignees

Comments

@orbingol
Copy link
Owner

Ref: orbingol/NURBS-Python#67

@orbingol
Copy link
Owner Author

Seems like it is working fine but there is an important fine print here: it is not possible to generate a correct full circle using 7 control points. It will be always 3 arcs connected together. The NURBS Book also says the parameterization is not as good as the 9-point full circle.

That was a fun experiment for me at the time of the development, but considering today, I think it is best to remove curve2d.full_circle2 to avoid confusion.

The reference for 7-point full circle is on pages 301 and 302 of The NURBS Book, 2nd Edition.

@orbingol orbingol changed the title Test if curve2d.full_circle2 is working correctly with different radius values Remove curve2d.full_circle2 to avoid confusion Jan 17, 2020
@orbingol orbingol self-assigned this Jan 17, 2020
orbingol pushed a commit that referenced this issue Jan 17, 2020
@cshorler
Copy link

actually 7 point is possible - see the later comment.
orbingol/NURBS-Python#67 (comment)

@orbingol
Copy link
Owner Author

@cshorler I still don't believe that is a valid full circle. Using 9-points makes sure that you are creating the correct full circle at all times.

I think it would be the best to contribute that script to the examples repo.

@cshorler
Copy link

I also made some changes to the remaining function for compatibility with the 6.x branch.

Also - when developing the package name conflicts with a parallel (egg link) install of NURBS-Python / geomdl. I can submit a PR for this as well.

@orbingol
Copy link
Owner Author

geomdl-shapes will be merged with 6.x along with a couple of example curves, surfaces and volumes from the examples repository. It will still be maintained for 5.x

@orbingol
Copy link
Owner Author

Also - when developing the package name conflicts with a parallel (egg link) install of NURBS-Python / geomdl. I can submit a PR for this as well.

I'd be glad if you could open a new ticket for this.

@cshorler
Copy link

I now read the section in the NURBS book on these two circle constructions
The way I interpret it is that the 7 point circle construction is worse than the 9 point circle - due to two factors:

  • the parameterisation leads to a less regular interpolation (this can be seen looking at the figures)
  • the convex hull is looser

I guess the detail is in the discussion of higher order circles (later in the same chapter) and discontinuities in the basis functions.

@cshorler
Copy link

Also - when developing the package name conflicts with a parallel (egg link) install of NURBS-Python / geomdl. I can submit a PR for this as well.

I'd be glad if you could open a new ticket for this.

okay will do

Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment
Labels
None yet
Projects
None yet
Development

No branches or pull requests

2 participants