The morph lane's blocking bug was believed to be coincident duplicate verts hidden
from the solver's convergence gate. Welding was necessary but nowhere near
sufficient: the previous relaxation could satisfy every stretch bar without posing
anything, so the numbers it reported were not measuring the thing they claimed.
Measured on Ariki_Female_QuatSkin_LowPoly_40, the tracked "left hand is fully
clean" baseline was a morph that moved fingertips 0.3cm, and the right hand was a
rigid 6.5cm translation of the whole hand with its shape intact. Gated Laplacian
diffusion of a delta field has a null space — constants — and edge stretch cannot
see any of it: a rigid translation stretches no edge and neither does a collapse to
zero. Both exits report perfect bars.
Six defects fixed, each with its measurement in the code comments:
weld_roi 356 duplicate groups solved twice, deltas up to 2.55cm apart
stitch_components hand is 6 overlapping sheets with 1-10mm gaps; Dijkstra
cannot cross one, so each bone saw only its own sheet
refit_fingers skeleton finger chain ran to 19.8cm; the flesh ends at 14.0cm,
so curl_02/curl_03 drove almost no weight (shipped skeleton
untouched — this is solver-local scaffolding)
solve_weights chain-arc partition of unity; the old 8mm isotropic kernels
left ZERO of 17,480 verts owned above 0.85, and a 3-way blend
averages the curl away. Plus a support cutoff: outside every
kernel, renormalized 1e-81 noise had handed a mid-palm vertex
index_02_r=0.50 and flung it 29cm
build_roi joint-sphere ROI, so the rim is a wrist band and not a fractal
of interior chart holes
relax strain-only edge projection + ROI-border seam constraints,
replacing the diffusion described above
All 8 shapes now pass every bar with real deformation: p99.9 <= 1.58x, zero edges
over 5x, zero needles with the sliver floor removed, seam <= 3.2mm, cross-hand
independence exactly 0.0000cm, mesh fingertip travel 4.6-6.2cm on fist and
3.5-4.7cm on grip (both hands). Gates now report mesh travel and seam alongside
stretch, because stretch alone cannot gate this lane.
Verified in anim_hand_test_bed: fist and grip read as a real curl on both hands,
static and mid-dance, no fins/shards/needles. It is a loose fist rather than a
clenched one — her fingers are ~4-5cm past the knuckles.
Demo GLB stays out of git (122.6 MB, ariki-game/scratchpad/). Ship decision, the
thumb-axis refit, and the TDR crash from 8 dense targets are open — see README.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
