Wishlist: curve merge/average modifier

[Artis Rozentāls]

A modifier that can 'merge' several curves into one continuous would be useful for sketching and situations where a large number of segments need to be joined and precision isn't paramount.

Such a modifier would basically produce a smoothed version averaging the provided curves (see attachment).

For sketching it would fit in with the already existing modifier button for spiro, a gesture (such as a tap) and keyboard shortcut would be needed for optimal workflow though. However, it would enable interactive adjustment of freehand strokes with extra, exaggerated strokes to re-average into the desired shape.

Basically a simplified, 2D version of this: http://www.dgp.toronto.edu/~shbae/ilovesketch.htm

[su_v (suv-lp)]

> with the already existing modifier button for spiro

Are you referring to the 'sketch mode' (with 'Alt' pressed) of the pencil tool? It is not limited nor related to the Spiro mode:
«Holding down the Alt key while drawing enables the Sketch mode. While in this mode, all strokes are averaged to create a final stroke, temporarily shown as a red path. Releasing the Alt key finalizes the path. This feature is considered experimental and does not give the expected result if one strokes a line back and forth. Instead, draw all your strokes in the same direction. »
<http://tavmjong.free.fr/INKSCAPE/MANUAL/html/Paths-Creating.html#Paths-Pencil>

The 'Spiro' mode auto-applies the 'Spiro Splines' path effect:
<http://tavmjong.free.fr/INKSCAPE/MANUAL/html/Paths-LivePathEffects-SpiroSpline.html>

[Artis Rozentāls (artis)]

For one that suffers from the same problem as freehand stroke smoothing (#505180), when you are done it's set in stone and that's that. Furthermore, it can't be applied retroactively. A path effect (sorry about the 'modifier', too much Blender) on the other hand is much more general and could be used, among other things, to interactively reshape existing curves.

It also seems to only useful for relatively minor, parallel adjustments, trying to extend breaks it badly, for example. The ability to extend and join curves as in the second example in the attachment would be the major feature of this path effect, the interactive and after-the-fact parts are just benefits of using the modern path effect infrastructure.