How to cut/break a curve?

Hello again. I searched for this, but could find no info, perhaps someone can help me.

I have a circular shape that is composed of two curves (both closed) one atop the other - the inner is smaller than the outer - they form a thick “O” shape.

I want to cut a section out of one side so that the shape becomes a “C” shape.

Is there a way, in curve editing, to:

  1. Add a new node at a point I click.
  2. Break that node, so the curve breaks - just like you would do when editing vectors in Freehand or Inkscape or whatever - this results in 2 nodes at the same point, and you can drag one away from the other and there is no segment/line in between them. The shape is “broken” and I can now re-shape that curve?

Does that make any sense?

It can be done but not in the method you describe. Instead of “cutting” and moving you would move and “cut”. Here’s what I mean:

  1. Create a new node (and thus a new segment - which will be deleted in the next step) and then position all nodes as you need them.

  2. Select the two nodes of the segment you wish to remove and press X-Key and then select “Segment”. This will remove the selected segment and you will have an open curve.

How do you create a new node at a certain point?
I could only find curve>segments>subdivide.

  1. Select the two nodes of the segment you wish to remove and press X-Key and then select “Segment”. This will remove the selected segment and you will have an open curve.

Thanks! That’s grand - it does change the shape of the curve when you delete the segment - is there a way to leave the curve alone, just remove the segment?

Subdividing between two nodes is the only way I know of creating a new one. And yes, removing the segment will alter the poistions of the ends slightly. I don’t know of a way around this but you should be able to re-create their original positions without much difficulty. Either by sight or if you need precision simply record each vertex position (each node has three for bezier) prior to the removal of the unwanted segment. The transform properties panel (NKEY) will show you the information you need to record.

Probably not the best or most efficient way but it’s the only way I know of (that’s not to say their isn’t another way though, just that I’m not aware of one).

To add nodes to a curve, select a node and ctrl-lmb where you want the new node. The new node will be made with a segment connecting it to the old one. To delete only a node, select it and hit X. This deletes teh segments connected to it as they don’t have two nodes anymore, and therefor can’t exist.

Grand. With the help from these comments, I should be able to cut into my shape.
I will duplicate it in-place and use the old one to re-align the new one.

It looks like Blender’s node-editing tools can do with some work. Another GPL app (sodipodi) could show them how to do it.
One nice thing would be to be able to distinguish a control-point handle from a vertex! Make one a bigger square, or make it another colour maybe.

Anyway - stuff to do!