RFD 1115: VRM animation playback, one mixer, normalized bones
kimodoMotionLoader.js, vrmMixamoPlaybackGuard.js, viewportExpressionVrm.js, studioAnimations.js
Problem
A Mixamo FBX preset and a Kimodo motion clip both drive the same VRM, through retargeted humanoid bone tracks. Two failure modes kept recurring: an orphan FBX mixer layering under the VRM mixer, and a mixer track written against a raw skeleton bone name instead of a normalized humanoid one. The second failure is silent: the mixer time advances, the console logs a loaded clip, and the avatar stays frozen, since humanoid.update() never sees a bone it does not recognize.
Decision
An AnimationMixer track targets a normalized humanoid bone name, through resolveVrmBoneTrackName, never a raw skeleton bone name. Every frame, after mixer.update(delta), call humanoid.update(), then vrm.update(delta). The mixer root stays vrm.scene.
When primaryAnimationVrm is set, _getActiveAnimationControls() returns VRM controls only. _silenceOrphanFbxMixer() stops any leftover FBX mixer, on every preset swap and every Kimodo apply. A preset swap sets weightIn=1 and weightOut=0 on the primary VRM, never cross-fade-stacked. A VRM0 upload gets the standard axis flip on every bone, legs, shoulders, and arms alike. Skipping the shoulder tracks alone twists the arms.
See DETAILS.md for the forbidden-change list, the protected files, and the pre-merge test commands.