Nurbs Circle not a perfect circle #38496

New Issue

Andy · 2014-02-05T09:37:02+01:00

Andy commented

2014-02-05 09:37:02 +01:00

Blender Version
Broken: 2.69 88843ca

Short description of error
The curve added by "Add > Curve > Nurbs Circle" does not represent an exact circle as the name suggests. Also, this menu entry seems to be somewhat redundant as the similarly named entry "Add > Curve > Circle" does result in an exact circle created.

As far as I know, using Bezier segments with weights (as the "Circle" option does) is the only way to generate an exact circle with Nurbs (compared to the single, continuous curve produced by "Nurbs Circle", which is not a circle).

This might not be a big problem in practice, as the difference is quite small, but it is confusing if you expect an exact circle but get a different result (I used it for a simulation that required an exact circle and misbehaved using the created Nurbs Circle).

Exact steps for others to reproduce the error

Open new file and delete everything
Go into Top-View
Add Mesh circle (Add > Mesh > Circle) - set it to about 100 vertices to get a high-res circle
Add Nurbs circle (Add > Curve > Nurbs Circle)
Zoom in to compare the two circles -> the Nurbs Circle clearly deviates from the exact circle

**Blender Version** Broken: 2.69 88843ca **Short description of error** The curve added by "Add > Curve > Nurbs Circle" does not represent an exact circle as the name suggests. Also, this menu entry seems to be somewhat redundant as the similarly named entry "Add > Curve > Circle" does result in an exact circle created. As far as I know, using Bezier segments with weights (as the "Circle" option does) is the only way to generate an exact circle with Nurbs (compared to the single, continuous curve produced by "Nurbs Circle", which is not a circle). This might not be a big problem in practice, as the difference is quite small, but it is confusing if you expect an exact circle but get a different result (I used it for a simulation that required an exact circle and misbehaved using the created Nurbs Circle). **Exact steps for others to reproduce the error** - Open new file and delete everything - Go into Top-View - Add Mesh circle (Add > Mesh > Circle) - set it to about 100 vertices to get a high-res circle - Add Nurbs circle (Add > Curve > Nurbs Circle) - Zoom in to compare the two circles -> the Nurbs Circle clearly deviates from the exact circle

Andy commented

2014-02-05 09:37:02 +01:00

Changed status to: 'Open'

Andy commented

2014-02-05 09:37:02 +01:00

Added subscriber: @andy-rs

Brecht Van Lommel commented

2014-02-05 13:02:40 +01:00

Changed status from 'Open' to: 'Archived'

Brecht Van Lommel closed this issue

2014-02-05 13:02:40 +01:00

Brecht Van Lommel self-assigned this 2014-02-05 13:02:40 +01:00

Brecht Van Lommel commented

2014-02-05 13:02:40 +01:00

It's on the To Do list here:
http://wiki.blender.org/index.php/Dev:2.5/Source/Development/Todo/Tools#Curves

NURBS basically have no maintainer at the moment so there aren't many fixes happening there.

It's on the To Do list here: http://wiki.blender.org/index.php/Dev:2.5/Source/Development/Todo/Tools#Curves NURBS basically have no maintainer at the moment so there aren't many fixes happening there.

Ilya Portnov commented

2020-08-03 17:44:22 +02:00

Added subscriber: @portnov

Ilya Portnov commented

2020-08-03 17:44:22 +02:00

Hello.
@brecht , could you please describe current status of this issue? As far as I see, currently "nurbs circle" is still not a circle in 2.82... The link you gave goes to 404.
And are there any changes in NURBS development/maintanance status/plans in blender?

Hello. @brecht , could you please describe current status of this issue? As far as I see, currently "nurbs circle" is still not a circle in 2.82... The link you gave goes to 404. And are there any changes in NURBS development/maintanance status/plans in blender?

Brecht Van Lommel commented

2020-08-03 17:57:05 +02:00

That list moved to #55362 (Blender development todo list -- Tools (migrated from wiki)).

But NURBS is still low priority in Blender development, it's unlikely to be fixed soon.

That list moved to #55362 (Blender development todo list -- Tools (migrated from wiki)). But NURBS is still low priority in Blender development, it's unlikely to be fixed soon.

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Nurbs Circle not a perfect circle #38496