Nurbs curve feature by hefniraera · Pull Request #10840 · qgis/QGIS-Documentation

hefniraera · 2026-03-16T07:38:55Z

Goal:

Ticket(s): #

Backport to LTR documentation is requested

lbartoletti · 2026-03-16T13:35:19Z

docs/user_manual/working_with_vector/editing_geometry_attributes.rst

  click and the ending right click are necessary in this mode.
 * The |digitizeShape| :sup:`Digitize Shape`: triggers tools on the
  :ref:`Shape Digitizing Toolbar <shape_edit>` to draw a polygon of a regular shape.
+* The |digitizeWithNURBS| :sup:`Digitize with NURBS Curve`: creates smooth curves using


Thanks @hefniraera !

Are you planning to include Bézier curves in this PR as well, or do you want to create a separate one for that?

Im probably going to include it in this PR @lbartoletti

OK, how can I help you?

I was wondering if you're going to open a PR related to Bezier curve as you mentioned here. Could you also please clarify what the 'Weight' represents? Thank you.

If you want, I can write a short paragraph about Bézier right here.

As for the weight, it’s important to know that there’s a map tool shortcut associated with the W key + mouse wheel (Ctrl modifier: fine adjustment / Shift modifier: coarse adjustment ) that lets you move closer to or farther from a control point. This determines the weight. If a point has a higher weight, the curve will be pulled more toward that point than if it has a lower weight.

If you want, I can write a short paragraph about Bézier right here.

Yes, please.

As for the weight, it’s important to know that there’s a map tool shortcut associated with the W key + mouse wheel (Ctrl modifier: fine adjustment / Shift modifier: coarse adjustment ) that lets you move closer to or farther from a control point. This determines the weight. If a point has a higher weight, the curve will be pulled more toward that point than if it has a lower weight.

That helps. Let me try on my side. Thanks

@lbartoletti Speaking about weight, I'm not sure how broadly it applies across different tools. After testing it in QGIS, it applies to nurbs curve only, at least for now. I'm also quite unfamiliar with bezier curve. After digging into it a bit, I'm wondering what kind of bezier does QGIS implement? From what I've read, there are different kinds, including rational bezier which supports weight (not like bezier in QGIS). Given that, do you think the name "Digitize with Bézier Curve" is too generic?

cc @DelazJ

After testing it in QGIS, it applies to nurbs curve only, at least for now.

Yes, it is.

Given that, do you think the name "Digitize with Bézier Curve" is too generic?

No, I think it's ok.

I can propose something like (AI has been used to help me):

- The |digitizeWithNURBS| :sup:Digitize with Bézier Curve: creates smooth curves by placing anchor points with control handles, similar to the pen tool in vector graphics editors. Each anchor has two handles that define how the curve enters and leaves that point.

And if we want to describe the actions:

- Click and drag on empty space to add a new anchor point. The drag direction defines symmetric handles: the right handle follows the mouse while the left handle mirrors it on the opposite side. - Click and drag on an existing anchor to move it. Both handles move along with the anchor, preserving the curve shape. - :kbd:Alt + click and drag on an existing anchor to redefine its handles symmetrically, without moving the anchor itself. - Click and drag on a handle to move it independently, adjusting only one side of the curve at that anchor. - Right-click to finish the curve.

And if we want to describe the actions:

IMHO this is a must-do. We should explain how technically people are expected to use these techniques/tools and the parameters they have to deal with. But I wouldn't put the details here because this simply introduces the various drawing techniques. Should probably have a dedicated sub-section in "adding features" and/or "vertex tool" features?

- Click and drag on an existing anchor to move it. Both handles move along with the anchor, preserving the curve shape.

This action does not work on my end (windows). I can move each handle but not the anchor. Since you said it's AI generated, could you please confirm if this behavior is correct? @lbartoletti

DelazJ

@hefniraera TBH I am not familiar with this kind of drawing tools and just made a quick test right now to comment (and won't have time to do more soon).

Some limitations that need to be mentioned: better store features in a nurbscurve layer (any other fully supporting layer type, Loïc?) if you don't want segmented lines and be able to properly edit with vertex tool.

DelazJ · 2026-03-19T09:28:34Z

docs/user_manual/working_with_vector/editing_geometry_attributes.rst

 The selected technique remains while switching among the digitizing tools.
 You can combine any of the first three methods while drawing the same geometry.


These statements seem to have gotten some changes. Can you check and adjust?
And for completeness, you would need to walk through the existing tools and check whether their description complies with these new techniques or not.

DelazJ · 2026-03-19T09:44:14Z

docs/user_manual/working_with_vector/editing_geometry_attributes.rst

  click and the ending right click are necessary in this mode.
 * The |digitizeShape| :sup:`Digitize Shape`: triggers tools on the
  :ref:`Shape Digitizing Toolbar <shape_edit>` to draw a polygon of a regular shape.
+* The |digitizeWithNURBS| :sup:`Digitize with NURBS Curve`: creates smooth curves using


And if we want to describe the actions:

IMHO this is a must-do. We should explain how technically people are expected to use these techniques/tools and the parameters they have to deal with. But I wouldn't put the details here because this simply introduces the various drawing techniques. Should probably have a dedicated sub-section in "adding features" and/or "vertex tool" features?

DelazJ · 2026-03-19T10:08:38Z

@lbartoletti some issues I think I found when testing and no time to properly report upstream:

using nurbscurve layer, unable to auto-snap on drawn vertex in order, e.g., to close a line
using nurbscurve layer, unable to draw a feature with only straight lines. Got:

Ajouter une entité: Le type de géométrie numérisée (CompoundCurve) ne correspond pas au type de géométrie de la couche (NurbsCurve).

Actually, seems that using anything other than nurbs tools on a nurbs layer draws nothing
unable to start a feature with straight lines then switch to nurbs methods. drawing restarts when tool is switched.
trying to add a part to a nurbs feature... well, I couldn't do anything, and at some point got a yellow cursor, and I couldn't release the tool or remove the rubberband

lbartoletti · 2026-03-19T12:43:35Z

using nurbscurve layer, unable to auto-snap on drawn vertex in order, e.g., to close a line

mm, seems ok to me, activating "Enable self-snapping"

Actually, seems that using anything other than nurbs tools on a nurbs layer draws nothing

It's normal

unable to start a feature with straight lines then switch to nurbs methods. drawing restarts when tool is switched.

It's also normal

trying to add a part to a nurbs feature... well, I couldn't do anything, and at some point got a yellow cursor, and I couldn't release the tool or remove the rubberband

Yes, you couldn't add a part to a nurbs. I tried but haven't had the issues you encounter.

Nurbs curve feature

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hefniraera mentioned this pull request Mar 16, 2026

Feature/add nurbscurve gui control points (Request in QGIS) #10692

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lbartoletti reviewed Mar 16, 2026

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DelazJ reviewed Mar 19, 2026

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		The selected technique remains while switching among the digitizing tools.
		You can combine any of the first three methods while drawing the same geometry.

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hefniraera Mar 27, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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DelazJ commented Mar 19, 2026

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lbartoletti commented Mar 19, 2026

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hefniraera commented Mar 16, 2026 •

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hefniraera Mar 27, 2026 •

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