Slope along and Narrow along: a top that runs down to one end, sides that run in to one end

[plazmabokor]

Hi Stefan,

I wanted shapes like an arched roof whose height runs down along its length, and found no simple way to make them in layerling. So I built two new settings cards in a trial build, and after testing them for a while I'd like to ask whether you would want them in layerling.

Slope along: one end of the top goes down. The other end keeps the body's height. You set the height of the lower end in mm or as an angle, and a curve: 0 gives a straight top, above 0 it bulges up, below 0 it sags.

Narrow along: seen from above, both long sides run in evenly towards one end. You set the width of that end (0 makes a point), where along the length the narrowing starts (0 % at the wide end, 50 % in the middle), and the same kind of curve.

Both have an orange dot on the selected body that can be dragged like the height handle, and the two cards work together. They are offered where they make sense: box, rounded box, cylinder, ellipse, polygon, wedge and round roof. Tube and ring get the slope only (a slanted pipe end), because narrowing would thin their wall unevenly. A round roof and a wedge slope and narrow front or back only, since they lie along their depth. The picture below shows every shape with every variant, rendered in the trial build.

Exact CAD bodies (edge tool, STEP):

• box: slope or narrowing,
• wedge and round roof: slope, narrowing and both together,
• cylinder, ellipse, polygon, tube and ring: slope,
• rounded box: slope, when its top is not rounded.

For now the display mesh only covers the rest: narrowing the upright round bodies and the rounded box, and a box that slopes and narrows at the same time.

Tests:

• Kernel tests: 29 cases. Every volume agrees with the one worked out by hand from the top line and the outline, within 0.01 %.
• Exported STLs are closed.
• The full unit suite passes.
• The texts are in all languages, and there is a unit test for the new code.

If you'd like it, I'll send a pull request, or two if you'd rather review slope and narrowing separately. If anything should work or be named differently, please tell me.

Thanks!

[henmedia]

Hi @plazmabokor, thank you, this is a great addition, and the overview picture makes it easy to see what each card does. Yes, please send the pull request. One PR is fine since the two cards work together, but two separate commits (slope first, then narrow) would make it easier for me to review.

A few things that usually belong in a feature PR here, so nothing is left for later:

• an entry under "Unreleased" in docs/CHANGELOG.md,
• a short passage in the guide (German and English), where Taper is explained,
• the settings in the MCP tools (layerling_create_shape, layerling_update_object, layerling_read_scene),
• the line in the README feature list and on the start page, if you want it mentioned there.

The display-mesh-only cases (narrowing upright round bodies, the box that slopes and narrows at once) are fine for a first version. Just say so in the guide, as you did here.

Thanks again for the careful testing!