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?
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:
- First create your ellipse and convert to path.
- Check your snapping options so you can easily overlap a rectangle over the left half.
- Select both objects and Path -> Difference.
- Edit the path to remove any unwanted segments.
- Clone your half shape (Alt-D), and flip the clone horizontally (H).
- Move the clone so it snaps in place.
- 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.
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.
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.