Two related AnimationSequencer fixes for visible animation glitches at
motion-cycle boundaries.
1. Link-tail blend hold (closes#61). BuildBlendedFrame was wrapping
nextIdx unconditionally to rangeLo at the high-frame boundary —
correct for looping cyclic nodes (idle/run/walk loops), wrong for
one-shot links and action overlays. During the ~30 ms fractional
tail before the sequencer transitions to the next queue node, the
blend mixed frame[end] with frame[0], producing a one-frame flash
through the anim's starting pose. Symptoms: door swing-open flap
(frame 0 = closed pose) and player run-stop twitch (frame 0 =
mid-stride). Fix: gate the wrap on curr.IsLooping; non-looping
nodes hold the boundary frame until AdvanceToNextAnimation fires.
2. Stop-anim direction fallback. Stopping from WalkBackward /
SideStepLeft / TurnLeft hit a null linkData from GetLink (the dat
authors a single forward/right stop link and reuses it for both
directions). SetCycle then enqueued only the Ready cycle, snapping
straight to idle with no leg-settle blend. Fix: when the primary
GetLink lookup is null, retry with the substate's low byte remapped
to its forward/right peer (0x06→0x05, 0x10→0x0F, 0x0E→0x0D).
Both fixes are pinned by new regression tests in
AnimationSequencerTests that fail against the prior code (Y=5.02 for
the link tail wrap → frame 0 blend; Y=0 for the backward stop snapping
to Ready cycle).
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
9f069e14c9