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I want to adjust opposite nodes on a path, made from a shape tool, simultaneously to maintain symmetry. For example I make an ellipse, convert the ellipse to a path, then select the two nodes opposite each other and make them symmetric nodes then lengthen one handle by 50% or so, I want the other selected node to do the same. Is there a way to do this?

before

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  • This is a very good question. If Inkscape would ever let users select node handles, or even multiple-select node handles, and then "work" them like nodes (by keyboard, or by numerical entry, etc.) that would make an awesome new feature. Your question about symmetry is just a special case but it shows that lack in Inkscape. I love both answers, which you have triggered (so far). Welcome to this forum. – Martin Zaske Oct 7 '18 at 12:46
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My technique is to draw only half of the shape, and use a clone for the other half. This way you can edit the original half and the clone will update accordingly:

enter image description here

  1. First create your ellipse and convert to path.
  2. Check your snapping options so you can easily overlap a rectangle over the left half.
  3. Select both objects and Path -> Difference.
  4. Edit the path to remove any unwanted segments.
  5. Clone your half shape (Alt-D), and flip the clone horizontally (H).
  6. Move the clone so it snaps in place.
  7. Now you can edit your original path and the clone should follow.

If, when finished, you want to convert the whole thing into a single path, you can select the clone, then Edit -> Clone -> Unlink, then combine the two paths into one, and optionally check for resulting double nodes with the path tool.

Another technique is to use a path effect called mirror symmetry, which gives more flexibility but is trickier to use.

  • Isn't there a simpler way? That's very complex for something that I would expect to be simple and easy. – Voila Oct 7 '18 at 12:45
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Not simultaneously, but it's simple to do it manually by using guides, the snapping option: Snap Nodes Paths and Handles, and by holding down CTRL as you click and drag the Bézier handles to constrain the angle.

enter image description here

There is also a rather convoluted way to make symmetrical shapes automatically. It's probably too complex for your particular scenario, but certainly useful for more complex symmetry.

You can create a half ellipse, clone it, reflect it, move into position. Then the edits made to the clone source will update automatically in the reflected clone.

enter image description here

  • The guides seem like an okay work around for my case, but why does it have to be complex to do more complex shapes? This seems like it'd be very simple to implement a couple toggles or modes for when adjusting nodes. – Voila Oct 7 '18 at 12:48
  • Remember, Inkscape is essentially an SVG editor. If such features are not implemented in the SVG standards, then most often it will not appear in Inkscape. Clones are a part of the SVG standard already. – Billy Kerr Oct 7 '18 at 12:57
  • SVGs are graphics, right? So then graphic designers would be using Inkscape. And graphic designers would very likely use symmetry tools, especially in vector images. So yes, I would expect these tools to be in Inkscape. It's a shame that they aren't, since this is not the first time I've had this issue. This is just what got me to go, "There has to be an easier way!" – Voila Oct 7 '18 at 13:08
  • I don't think you understand what I'm saying. The Inkscape developers don't control SVG standards, they try to work within in them, so that Inkscape can produce SVGs which can be rendered properly in browsers which support these standards. Actually SVGs are not really graphics as such, they are actually code (a kind of XML in fact), somewhat like HTML. – Billy Kerr Oct 7 '18 at 13:19
  • In SVG, clones are certainly the way to go for complex symmetry, and not just bilateral symmetry. I've used it to create complex designs like this example here. Clones also help keep file sizes smaller so they render quicker - so they serve more than one purpose. – Billy Kerr Oct 7 '18 at 13:26
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Would the Mirror Live Path effect do what you need?

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