Hi all, I'm looking for a few functionalities with respect to nodes.

• When drawing a rectangle (and converting it to a path), I would like to start a new path from one of the four nodes of this rectangle. How should I do this?
  
• Is it possible to "sweep" an object/path? This means that nodes which are (almost) exactly in the same place are automatically joined. I know this option from programs for mesh generation. This would be very useful when working with fractals creating by the L-System extension. By the way, I am familiar with the "Simplify (Ctrl + L)" function, but the idea behind this function is a little different than a "sweep" function
  
• Is there an extension for mesh generation (from nodes)? I'm thinking about methods like Delaunay triangulation.

When drawing a rectangle (and converting it to a path), I would like to start a new path from one of the four nodes of this rectangle. How should I do this?

• Select the node from which you would like to continue a path.
• Click the 4th icon from the left on the node tool control bar, which is "Break path at selected node".
• Switch to the Pen tool, and you'll see a tiny square in place of the node. And actually, there are 2 squares, exactly on top of each other there. So before switching to Pen tool, you may want to separate the nodes slightly, if it matters which one you use to continue the path.
• Hover the Pen tool over the tiny square, and it becomes filled with a dark red color (depending on cursor, might be hard to see it turn red). That indicates that when you click, it will continue that path and not start a new one. (If you are not exactly in the right place, while the square is not red, when you click, you'll just start a new path

Is it possible to "sweep" an object/path? This means that nodes which are (almost) exactly in the same place are automatically joined. I know this option from programs for mesh generation. This would be very useful when working with fractals creating by the L-System extension. By the way, I am familiar with the "Simplify (Ctrl + L)" function, but the idea behind this function is a little different than a "sweep" function

• Select the 2 nodes which you want to be joined, with the Node tool
• Click 3rd bottom from left on node tool control bar, which is "Join selected nodes". (Simplify, in Inkscape, is not similar or related to what I've described, so I might not have answered your question correctly.)

But I don't think you will have to do any of this, when using the L-System extension. When I was experimenting with it yesterday, to answer your other topic, the path appeared to be automatically continued, and the nodes automatically joined. Although as I indicated in that topic, I hardly know what I'm doing with that extension

Is there an extension for mesh generation (from nodes)? I'm thinking about methods like Delaunay triangulation.

Not that I know of.

Thanks for your answer

1.) Nice, that's what I was looking for.

2.) I know the Join Nodes function, but I wondered whether it is possible to do this automatically (i.e. select all pairs/groups of nodes that lie on top of each other, and join them).
Some fractals consist of multiple paths, like the Pythagoras Tree (or, at least that's the way I set up the Axiom and Rules). Therefore, there are quite some overlapping nodes. File: PythagorasTree.svg - unfortunately my host refuses to support SVG images, so you have to right-click the link and save it.

3.) Ah, ok. I just noticed the Voronoi Extension, maybe I can create something out of that Extension.

By the way, is there a quick way to select a node that lies under another node? I thought I read something about that somewhere, but I don't know where

Therefore, there are quite some overlapping nodes.

Oh, do you mean join them all?
No, at this time Inkscape cannot join more than 2 nodes. The only workaround is to have them on top of each other.

By the way, is there a quick way to select a node that lies under another node?

There are probably several tricks, and I can describe 2 of them. Maybe others can chime in too?
1 - Select them both; If they are precisely on top of each other, when they are both selected, there will appear to be no node there at all; Shift + click the spot where the nodes used to appear (when mouse is properly over correct spot, node will flash red), this will leave only the lower one selected (and then it will be visible again - an aqua colored ouline is evident if you carefully mouseover the edge of the node, and look closely, this is the selected and highlighted node peeking out behind the one on top; but this is not necessary to select, just a way to confirm that it's selected.)
2 - Select the segment which contains the lower node; Shift + click the node that you don't need, this leaves the lower node selected. It's blue when it's selected, but hard to see, but if you carefully mouseover the edge (without clicking), you can see it flash red when it's highlighted. Not necessary for selection, just a way to confirm that it's selected, since the blue can be hard to see.

#2 is probably the easiest.
-You could also select them both, and carefully mouseover the edge of the nodes, until you see the bottom one flash a red outline around the top node, then click while highlighted red.
-You could also select the segment, carefully mouseover the edge until you see a faint aqua highlight of the lower one, and click.
However, I think these latter 2 are what you are trying to avoid!

brynn wrote:No, at this time Inkscape cannot join more than 2 nodes. The only workaround is to have them on top of each other.

So, it is only possible for two (no more) segments/lines to share a node? Because I have joined 2 x 2 nodes (so 2 nodes left now), but I cannot join these nodes again (because then the node would be shared by four segments/lines). Do you know whether there are any plans to change this? Because without this option, one cannot create a useful mesh - and I think a mesh Extension would be shiny.

brynn wrote:There are probably several tricks, and I can describe 2 of them.

Ah thanks, both methods are useful. Unfortunately, at some places I have 6 overlapping nodes ... But since I cannot join them, it doesn't matter anyway

Ailurus wrote:Do you know whether there are any plans to change this? Because without this option, one cannot create a useful mesh - and I think a mesh Extension would be shiny

The limitation is in the current SVG specification which does not have a definition for meshes: regular paths in SVG are linear, with only max. two segments joining in one node.

So, it is only possible for two (no more) segments/lines to share a node?

Yes, that's correct.

Whoops, I see ~suv has commented, and probably is much more informed than I. But for some reason, I thought someone was working on developing mesh for Inkscape....or maybe it was something like a mesh? But if you're interested, you could at least read the mailing list archives, or even join the mailing list: http://inkscape.org/mailing_lists.php?lang=en

brynn wrote:But for some reason, I thought someone was working on developing mesh for Inkscape....or maybe it was something like a mesh?

Gradient meshes maybe (known from Adobe Illustrator and supported by the PDF file format)?

Gradients and Patterns
(…)
Since 2008, there has been discussion among professional users of SVG that either gradient meshes or preferably diffusion curves could usefully be added to the SVG specification. It is said that a "simple representation [using diffusion curves] is capable of representing even very subtle shading effects" and that "Diffusion curve images are comparable both in quality and coding efficiency with gradient meshes, but are simpler to create (according to several artists who have used both tools), and can be captured from bitmaps fully automatically."

(earlier mentioned e.g. in Re: Gradient Mesh in Inkscape: the patches that make up such colored meshes are regular closed paths with 4 nodes/segments, but blurred to achieve the color transitions and clipped to keep the contour sharp)

More recent efforts propose diffusion curves for advanced gradients in future SVG specifications.

Aaaahh, gradient mesh!
Thanks ~suv