Ozan's hair system rebinds Quaternius styles (100% rigid to one Head bone) onto
whichever body loads, corrected by three hand-tuned constants in
CharacterBuildData.HeadFit. Those constants are only valid against the skull they
were tuned on, and nothing re-checks them when a body is rebaked. Both ship bodies
are currently wrong, in opposite directions.
tools/measure_head_shell.py:
--fit solve HeadScale/HairOffset from two cranium landmarks. A scale-about-
pivot plus a translate has exactly two degrees of freedom per axis, so
the crown + widest-cranium slice determine both outright -- no bed pass.
--sweep score every style against the clearance it was AUTHORED with on its own
stock rig (a mohawk stands proud, a beard hangs at the chin -- absolute
crown height is not the test).
default full Head-weighted shell AND the cranium band. The full shell is what
MakoHeadFit quotes; it is inflated several cm by jaw/ear/neck weight
bleed and is not the surface a cap sits on.
Measured against the shipped GLBs:
Lena cranium needs Y 0.960, carries 1.431 (+49%) -- every style floats 4.4-7.3cm
Mako cranium needs Y 1.186, carries 1.346 (+13%) -- every style sinks, buzz cut
2.2cm into his skull, moustache 8.0cm low
Solved constants take Mako to 0.00cm worst error over 10 styles, Lena to 0.29cm mean.
docs/characters/head-features-contract.md records the system, the measurements, and
what a 3-constant fit still cannot reach: Lena needs 1.613 in X but 1.311 in Z, a
23% anisotropy that stretches an authored cap sideways and drags ear cutouts along a
diagonal. That is Ozan's logged residual and wants a per-body geometry bake. Mako's
anisotropy is only 3%, so constants alone should suffice for him.
Also noted: the whole hair set shares just two base textures, so "authored per-colour
hair textures" -- the fix the wiki writes off in favour of the /0.55 swatch hack --
is 16 PNGs.
Crown placement is rest-pose arithmetic; X/Z and the in-bed look are unverified.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
