Chrome Extension v0.4.1 - The 3D avatar actually signs now

If you use the 3D avatar, update. If you only use the 2D skeleton, nothing here
changes for you: the 2D renderer was always correct and is untouched.

The 3D avatar was placing hands in the wrong place

Its hands sat near the hips and barely moved, whatever the sign was. Three
separate faults in the 3D path, none of them in the sign data itself:

• The forearm was positioned against the wrong reference, inheriting a rotation
  from the upper arm that had already been applied. Isolated on the rig, the
  upper arm was exact while the forearm came out 72 degrees off whenever the
  arm moved. The forearm carries the hand, so that alone decided where every
  hand went.
• Arms were aimed rather than solved. Pointing a bone along a captured direction
  takes the limb LENGTH from the avatar, so the hand could only reach as far as
  the avatar's own arm allowed, which is shorter than the captured one. The
  wrist is now solved to its target position, with the captured elbow deciding
  which way the arm bends.
• Two different definitions of where the torso ends were being mixed, which left
  every hand slightly high.

Measured against the 2D renderer over 818,904 solves from 500 signs, since 2D
plots the captured points directly and is the picture that was already right.
Median error dropped from 0.434 to 0.003 of torso length, and the worst tenth
from 0.737 to 0.010. Just as important, the hand now travels the same range as
the reference instead of sitting in a narrow band at hip height.

Fingerspelling improved as a side effect. The same fault compounded down each
finger, curling them; fingers now extend to 0.83 of their natural span rather
than 0.66.

The female avatar had never moved

Not in this release or any before it. Her rig names its bones with a different
prefix to the male one, and the code assumed a single prefix for both. Nothing
failed loudly: she loaded, reported herself ready, and stood still through every
sign. The prefix is now read from the avatar. Both now animate.

Unchanged

The 192 bundled signs are byte for byte identical to v0.4.0. Only the manifest
and the 3D renderer differ.

Install

Download signlytic-extension.zip, unzip, open chrome://extensions, enable
Developer Mode, and Load Unpacked on the unzipped folder. If v0.4.0 is already
loaded, remove it first.

Attribution

Signlytic AI, by Oke Iyanuoluwa Enoch. If you use, fork or build on this project,
please credit the project and link back to this repository.