Nicholas ButzkeandClaude Opus 5
2a6b321984
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]>
