firejune/rig-parts

**AI-authored 2D character rigs from one anime painting, verified before they
are written.** rig-parts takes a single character painting and the layers
See-through decomposed it into,
merges them into measured rig-space parts, authors weighted meshes, bone chains
and a looping idle over them in rig-c's
spec, and hands that spec to rig-c to compile, gate, pack, render and check.
It is built for agents that cannot see the image: every stage prints named,
numeric findings, a refusal names the object, the value found and the value
required, nothing is written after a red, and no value is invented where the
input is silent.
What you get
The painting was generated for this repository with a public checkpoint (Hassaku XL
(Illustrious) v1.3 Style A, by Ikena, Fair AI Public License 1.0-SD) and no LoRA, on a
pose that holds the hands apart, then given one hand-detailer pass; its generation
record, See-through layers and licence are in
parts-examples .
See-through ran twice, once on the whole figure and once on a square head crop.
Then one command: rig-parts build --loop --lead-in 3 . The proposer's bones, meshes,
regions and motion were used as proposed but for one correction, written in the
config beside the values it replaced: the two outer skirt chains were moved out to
0.8 of the skirt's half-width (the proposal's, within 90 px of the centre of a skirt
449 px wide, swung it about its middle and failed TIP_OVER_ROOT , 0.442
against 1.4725; moved, 2.425). One input-stage edit: hair_back is taken
from the full run, because the twin tails leave the head crop sideways (a plan edit).
check printed, verbatim:
50 assertions: 24 measured (24 passed, 0 failed), 26 skipped, 0 not in profile "rig-play"
loop: idle 41 frame(s) at 12 fps, f0000 vs f0040 (t = 3.333333333333333s) with the rig's 29 physics constraint(s) left out (named on the loop physics: line; rendered with them, the ends need not meet — build --loop --lead-in <n>): max |d| 0 (0 required)
seam: setup pose at 654x1216, scale 0.9438: mean |d| 0.147 (<= 1.0), 0 px over 40, 0.00 rig px (the count / s²; <= 50), 0 px over 80 (reported)
pack: skeleton.png 1051x972, 23 region(s), 96.9% covered, padding 2, page edges free, shape polygon
The loop is that build's indexed APNG, 40 frames at 12 fps, 703,909 bytes, one
256-entry palette at a measured error of max 71, mean 0.636 per channel over every
frame (the lossless APNG beside it, the exactness record, is 4,449,233 bytes; the
GIF, at the same error, 760,058). The rig's hair, skirt, sleeves, bows and earrings
carry physics, which rigc's render starts from rest, so the idle is played three
periods ahead and the loop is the fourth: the frame one period after its first differs
from it by max 1 level, 0 px over 40 ( --lead-in ). Frame 29 (2.417 s) is the
closed eye: the blink holds for 0.084 s, one 12 fps frame rounded up; the painting is
shown at half size, resampled and written by this package's PNG codec (nothing here
encodes JPEG). rig-parts sheet made the contact sheet. Its
expected/ is this port's own build ( examples/demo ).
The hanging element, examples/scarf : Pony Diffusion V6 XL, no LoRA, a very long
red scarf whose ends hang free, and the first character run through this pipeline
with its proposal used unedited — the only hand corrections are four
assemble.patches , each answering an uncovered hole line.
check passes 9 of 9 with every mesh on the lattice and with every mesh
switched to the contour mode. It has no reference output: its expected/
is this port's own build ( examples/scarf ).
Two more characters are tracked as fixtures and not shown:
examples/reference-demo and examples/reference-sample , the two
the reference implementation ran (published as demo and sample
until issue #227, which took the clasped-hands painting off display). Their
expected/ is that implementation's own output, which the selftest holds
this port to.
What it takes in
- **One painting** — a PNG of one character that a rig can be cut from: front view,
arms clear of the body, hands apart and open, legs apart with a gap, on a plain
light background. docs/PAINTING.md says what each requirement
is for and what breaks without it, gives one generation recipe, and describes
rig-parts painting, which checks a painting against its body-18 joints before
See-through runs. To set up the machine that makes the painting and the layers,
see rig-c/getting-started.
- **Its See-through layers, twice**: one run on the whole figure (the painting padded