add extremes

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Modeling - Editing

Add Extremes (command)

Put an anchor wherever a spline reaches furthest and has none.

Command palette: Add Extremes | In depth: Splines

Important

Under construction. Splines are new and this page describes work in progress. Nothing here is a promise about the finished feature.

What an extreme is, and why one wants an anchor

An extreme is a point where the outline turns around in x or in y: the leftmost, rightmost, topmost and bottommost points of a curve. A spline can pass through its own extreme without an anchor sitting there, and nothing looks wrong when it does.

What goes wrong is everything measured from the shape. A bounding box drawn around an outline whose extremes carry no anchor is loose, and an offset of that outline moves unpredictably at the turn. Both read as the drawing disagreeing with itself.

How to use it

Select the splines you want it to work over and run it. With nothing selected it works over every spline in the drawing, which is the usual way to run it: the point of the command is that none are missing, not that one particular turn is served.

• It adds an anchor only where an extreme lacks one, so running it twice changes nothing the second time.
• It never adds one at an anchor that is already there, for the same reason the Pen refuses to stack two anchors in one place.
• The whole pass is one undo step, however many anchors it adds.
• It reports what it did: how many anchors, across how many splines, or that every extreme already had one.

The pass before export

This is the one to run before a drawing leaves Locus. The per-anchor commands are for the turn you are looking at: Shift-click with the Pen, or Slide to Extreme on the path menu. Add Extremes is for the question you cannot answer by looking, which is whether any are missing at all.

What it turns down

It works on splines only. Run it with nothing but circles selected and it says to select a spline rather than reporting that there was nothing to do. A circle has no anchors, so there is nothing to add one to.

Locked and managed splines are skipped.

Related

• Splines: anchors, handles and what the marks mean.
• the path menu: Slide to Extreme, the one-anchor version.
• The Pen: Shift-click, which inserts at the nearest extreme or inflection.
• Correct Path Direction: the other pre-export pass.

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