v0.17.0

0.17.0 (2026-09-05)

A part can state its own depth, and rigc will tell you how far it turns.

Until now a 2.5D turn read one radius shared by a whole column of vertices — a
cylinder standing in for a surface. A generator can now name a depth map, and
yaw/pitch read a z per vertex off it. The lattice that carries those
vertices is generated rather than hand-numbered. A painted mask says
which region is soft, so a physics constraint answers an impact over exactly
that area. And build and explain now print the turn ceiling: the largest
angle this geometry on this sheet takes before a triangle reverses, per axis and
per direction, naming the triangle that goes first.

That last one changes the loop. The angle was previously found by writing a key,
building, reading A39's refusal and guessing again; it is closed form —
tan t = A₀/A_axis — and the compiler now says it up front.

Features

• deform: a depth map gives every vertex its own z, and yaw/pitch read it (#383) (e0371e8), closes #382
• mesh: a grid generator, so the lattice stops being hand-numbered (#386) (b0ec75a), closes #382
• depth: a painted mask marks a soft region, and a physics constraint on its bone answers an impact over it (#390, #391) (843aad4)
• depth: report the turn a sheet supports, before a key is written (#393) (cc79286)
• docs: FACE.md §2.2 and AUTHORING.md §3.4 — the fold angle belongs to the depth map's steepest slope, not to the mesh density (#392) (e409077)

The one rule to read before using any of it

The angle a part can turn through is a property of its depth map, not of how
finely it is meshed — approximately 1 / max|dz/du|, the reciprocal of the
sheet's steepest slope. Refining a lattice does not lower the ceiling; it finds
slopes that were always there. A map that reaches its floor with a vertical
edge — a dome, a hemisphere, anything traced straight off a rendered normal —
folds at any angle you like once it is meshed finely enough, while a map whose
slope is bounded holds the same angle at every density. Measured over a 1,300×
range of vertex counts: 62° → 14° for the first, a steady 63–64° for the second.

So a ceiling you cannot live with is fixed by editing the sheet, not the
mesh. rigc will not flatten a map for you; a depth map is a measurement, and the
compiler never invents a value that is not in the spec.

What this release does not do

• None of it has met real art. Every figure quoted for the depth work was
  measured on generated fixtures — analytic ramps, domes and checkerboard blobs.
• The angle and the jiggle cannot ride one attachment yet. A mesh carried by
  a soft-region bone has two influences on some vertices, and a transform key
  needs one bind space, so per part it is one or the other
  (#389).
• A dense mesh is a large file. 449 bytes per vertex, plus ~1.77 MB per
  deform key at 32,761 vertices. The gate itself stays linear and green to
  64,800 triangles; the artifact is what grows.

Bug Fixes

• ignore scratch as a path, not only as a directory (#385) (87bb21f) — repository housekeeping, no effect on the published package

Withdrawn inside this release

Two commits in the log add things that do not exist in 0.17.0. They were
built and taken back out before release, and are listed here only so a reader of
the commit history is not left looking for them:

• parallax as a deform kind (#388, removed in #391) — it was a yaw with a term dropped, and baking a pointer-driven value into time keys is a category error. Parallax is camera work and belongs to whatever draws the result.
• a soft region chosen by a depth threshold (#390, replaced in #391) — softness is not prominence. The most prominent thing on a face is the nose, and a nose does not wobble. The region is painted now.