5 Commits
Author SHA1 Message Date
Nicholas ButzkeandClaude Opus 5 2a6b321984 fix(weapons): orient the support hand by frame, not by arc plus a twist
The support hand was upside down on the handguard. Its rotation was built
as a shortest arc from the hand's forearm line to the barrel, plus a
constant 0.5 rad twist. A shortest arc is the MINIMAL rotation between two
directions and says nothing at all about roll, so the entire roll of that
hand came from the constant — and a constant is right only for the one rig
it was tuned against.

Orienting a hand onto something it grips is a frame-to-frame problem, and
saying it that way leaves nothing free to guess. A hand wrapping a cylinder
has its curl axis along that cylinder, or the fingers close across the
handguard rather than around it; and its palm faces the cylinder, which for
a hand supporting from underneath means up. The third axis falls out of the
other two. Map the hand's rest anatomical frame onto that target and the
roll is determined rather than chosen.

The frame is the same one the finger curl already uses — along, palm, curl
— now stored whole instead of just its curl axis.

Verified by render on the mannequin (Rigify names, 0.524 m arm) and Kiyoko
(VRoid names, 0.470 m): fingers wrap the handguard from below and over the
top, stock at the shoulder, arms not crossing, consistent across idle, ADS
and run. L_HAND_TWIST is deleted rather than retuned — it was the bug.

Smoke 0 failures.

Co-Authored-By: Claude Opus 5 <[email protected]>
2026-07-26 19:50:25 -04:00
Nicholas ButzkeandClaude Opus 5 682597a0d2 feat(weapons): scale the gun to the arm, and close the hands around it
The hold was wrong on every character in three independent ways, all of
them a constant standing where a measurement belonged.

MOUNT. set_weapon seated the weapon with rotation_degrees = (0, 90, -90).
A bone attachment is expressed in the BONE's axes and no two rigs agree on
those, so one constant mounted the gun differently on every model. It never
needed to be right — the pose layer aims by rotating the wrist until the
weapon's forward lies on the aim line, so the identity means "forward is
the hand bone's -Z", true on any rig, and the wrist absorbs the roll.

SIZE. The set is modelled at real-world scale; an M4 is 0.84 m butt to
muzzle and these characters have 0.47 m arms against an adult 0.52. That
put the handguard 0.66 m from the support shoulder, 0.2 m past reach, so
the support hand was slid back down the weapon until it fitted — on Taila
from an authored 0.35 m to 0.083 m, which puts both fists together at the
grip. Two hands on a pistol, not a rifle.

Fixed by solving the support arm's triangle rather than picking a factor:
its hand must reach stock+fore ahead of the pocket from a shoulder half a
shoulder-width off the axis, so scale the gun to the largest that keeps the
handguard inside that reach. Taila and Kiyoko now come out at their own
scales (0.217 and 0.213 m of hand separation) with the support hand at its
FULL authored handguard distance and the slide-back loop never firing. The
loop also has a floor now: a straight support arm beats no handguard hold.

FINGERS. Nothing posed them — every hand was flat and open, which is the
loudest possible tell that a character is not holding anything. They close
now, about an axis derived from each hand's own anatomy in the rest pose:
along = wrist to middle knuckle, palm = middle knuckle to thumb tip (the
thumb opposes the fingers, so it marks the palm side by construction), curl
= along x palm. The trigger finger gets a much shallower curl than the
rest, because it lies along the trigger.

Finger bones resolve by ROLE across all three naming families met so far —
Rigify DEF-f_index.01.L, VRoid J_Bip_L_Index1, Blender IndexFinger1_L —
ordered by depth below the hand rather than by the number in the name,
which is not consistent between them.

Verified by render on Taila and by measurement on Kiyoko: stock at the
shoulder, trigger hand on the grip, support hand out on the handguard,
fingers wrapped, arms not crossing. Smoke 0 failures.

Co-Authored-By: Claude Opus 5 <[email protected]>
2026-07-26 19:02:11 -04:00
Nicholas ButzkeandClaude Opus 5 c8b0337aa7 fix(characters): rig-independent weapon mount, measured facing, revert Miku
WEAPON MOUNT, all models. set_weapon() seated the gun with a fixed
rotation_degrees = (0, 90, -90). A bone attachment is expressed in the
BONE's axes and no two rigs agree on those, so one constant mounted the
weapon differently on every character. It never needed to be right: the
pose layer aims the gun by rotating the wrist until the weapon's forward
lies on the aim line, so the identity means "forward is the hand bone's
-Z", which is true on any rig, and the wrist absorbs the roll. The grip
now sits at the bone origin, so the gun is in the hand rather than at an
offset from a differently-oriented bone. Verified by render on kiyoko:
rifle shouldered, both hands on it.

FACING. flatten_and_scale() now measures toes-versus-ankles and snaps the
character to face Blender -Y, the convention the runtime's blanket flip is
built around. Kiyoko was 180 degrees off. Snapped to the nearest quarter
turn so splayed feet in a rest pose are not read as a turned character.

MIKU. Re-imported without --grow-cloth. Her grown hair chains were the
cause of the stretching: cloth_bones.py clears a vertex's body weights and
re-assigns it to the fitted polyline, so a poor fit does not degrade to
"stiff", it degrades to "torn". She now has no hair simulation — stiff but
correct — until that tool blends against the weights it replaces instead
of destroying them.

ARIA'S SKIRT IS NOT SIMULATED. Worth recording plainly, because it looks
better than Taila's and the obvious conclusion is the wrong one: aria has
ZERO cloth chains. Her skirt never clips because it is rigidly skinned and
follows the legs it is weighted to. There is nothing to port to Taila
except switching her simulation off.

Co-Authored-By: Claude Opus 5 <[email protected]>
2026-07-26 16:29:04 -04:00
Nicholas ButzkeandClaude Opus 5 27c4117c25 fix(pipeline): stand the character up before scaling; reach bones by role
Fixes the two root causes behind four of the seven reported breakages, and
rejects the source that cannot be fixed.

STAND UP FIRST. flatten_and_scale() now derives the up axis from the
skeleton and rotates the model upright before measuring anything. Aria and
Momo are correct: 1.75 m tall, 1.43 x 0.41 and 1.52 x 0.39 across, verified
by render.

The up vector is measured from the FEET to the HIPS, not from the hips to
the head. The head is not a reliable landmark — the spine walk ends on the
last non-cosmetic bone in the chain, which on a rig with a facial skeleton
can sit BELOW the hips. Momo's did, so the first cut of this fix stood her
neatly on her head: right size, right proportions, upside down. Feet cannot
be mistaken.

REACH BONES BY ROLE. SkinnedPlayerModel gained _role_bone(), and set_weapon
uses it. Four characters could not hold a gun because one hardcoded lookup
knew three spellings and their hands are called "Right wrist" and
"J_Bip_R_Hand" — both resolved perfectly in the sidecar the whole time.

HIKARI IS REJECTED. She now fails the gate: her feet and spine disagree
about which way is up, so the stand-up correction cannot resolve her
either, on top of zero-length cosmetic bones and a second armature that was
smuggling its own clips into the export. That is not a tuning problem, it
is a file that has been through two toolchains. De-registered and removed
rather than shipped broken — which is what the gate is for.

Six GLB skins remain, all passing. Smoke 0 failures, 11/11 movement tests.

Still open, recorded in the skill: kiyoko faces backwards, miku's grown
hair stretches under animation, the mannequin's rifle hold does not
convince, and taila's front skirt clipping.

Co-Authored-By: Claude Opus 5 <[email protected]>
2026-07-26 16:06:51 -04:00
Nicholas ButzkeandClaude Opus 5 2b3e29dd30 fix(pipeline): check that a character is CORRECT, not merely well-formed
Seven characters shipped "All checks passed" and four were visibly broken
in game — lying on their backs at seven times scale, facing backwards, or
holding a gun that floated near their chest. Nothing in the suite was
wrong; it just never asked the questions that mattered. That distinction
is the whole lesson, and it is now written down in the skill as
references/failure-modes.md, generalised per failure.

Two root causes are measured and certain:

- flatten_and_scale() normalises the bounding box along Blender Z because
  Z is up. For a model that arrives lying along Y that measures the
  character's THICKNESS, so it scales by ~7 and leaves them on their back.
  One assumption, both symptoms. The trap is that the normalised number
  always comes out right — the exporter maps Blender Z to glTF Y, so "is
  the height 1.75" passes on a character who is 7.5 m tall lying down.
  All three casualties are VRM files that went through a Blender
  round-trip and came back with a baked axis rotation.

- SkinnedPlayerModel.set_weapon() finds the hand with three hardcoded
  spellings, which match none of the four non-Rigify rigs — their hands
  resolve perfectly in the sidecar as "Right wrist" and "J_Bip_R_Hand".
  When it misses, the weapon is parented to the model root at a fixed
  chest offset, so it is not attached to the character at all. Same class
  of bug as the leg check that name-matched thigh/shin. rig_map.py exists
  so nothing downstream has to guess a bone name; only some consumers read
  the roles it publishes.

Three new hard checks, none needing more than the vertices and the
sidecar:

  character stands up in world space   — against WORLD up, not against the
      model's own proportions. "Is the spine the longest axis?" catches
      nothing: a model rotated as a whole is internally consistent and
      passes it comfortably.
  character is a plausible size / height
  every role the runtime needs is resolved

They separate the four good characters from the three broken ones on the
first run. Also fixed the posture measurement to read vertices rather than
object.bound_box, which is cached and still stale right after an import —
it reported a 1.75 m character as 1.18 m tall.

Recorded but not yet fixed: kiyoko faces backwards (facing is inferred by
two independent mechanisms and verified by neither), miku's grown hair
chains stretch under animation (generated chains are never validated
against the geometry they drive), and the mannequin's rifle hold does not
convince despite resolving correctly.

Co-Authored-By: Claude Opus 5 <[email protected]>
2026-07-26 16:02:06 -04:00