User-observed regression on commit d247aef: creature reaches melee
range and "just runs" instead of stopping to attack. Two independent
research subagents converged on the same root cause.
When ACE broadcasts a melee swing, it sends an mt=0 UpdateMotion with
ForwardCommand=AttackHigh1 (Action class, 0x10000062), motion_flags
=StickToObject, and a trailing 4-byte sticky-target guid — there is
NO preceding cmd=Ready. The swing UM IS the stop signal.
Retail's CMotionInterp::move_to_interpreted_state
(acclient_2013_pseudo_c.txt:305936-305992) bulk-copies forward_command
from the wire into InterpretedState UNCONDITIONALLY, regardless of
motion class. With forward_command=AttackHigh1, get_state_velocity
(:305172-305180) returns velocity.Y=0 because its gate is
RunForward||WalkForward — body stops moving forward. The animation
overlay (the swing) is appended on top of whatever cyclic tail is
active.
Acdream's overlay branch in GameWindow.OnLiveMotionUpdated routed
Action-class commands through PlayAction (animation overlay only) and
SKIPPED:
- ServerMoveToActive flag update — stale RunForward MoveTo state
persisted, the per-tick driver kept steering toward the prior
Origin and calling apply_current_movement.
- InterpretedState.ForwardCommand bulk-copy — even if the flag had
been cleared, the body's InterpretedState.ForwardCommand stayed
at RunForward from the prior MoveTo cycle, so
apply_current_movement kept producing forward velocity.
- MoveToPath capture — staleness-timeout band-aid masked this.
Fix: lift the _remoteDeadReckon state-update block out of the
substate-only `else` branch so it runs for both overlay and substate
paths. For non-MoveTo packets, write fullMotion + speedMod directly to
InterpretedState.ForwardCommand/ForwardSpeed (bypassing
ApplyMotionToInterpretedState, which is a heuristic helper that
silently no-ops for Action class — see MotionInterpreter.cs:941-970).
This matches retail's copy_movement_from
(acclient_2013_pseudo_c.txt:293301-293311) bulk-copy semantics.
Also corrected RemoteMoveToDriver arrival predicate to retail-faithful:
chase = dist <= DistanceToObject; flee = dist >= MinDistance. The
prior max(MinDistance, DistanceToObject) defensive port happened to
compute the right value for ACE's wire defaults but had wrong
semantics (would have failed for any retail config with MinDistance >
DistanceToObject).
Tests: 1414 → 1416. New parser test for the AttackHigh1 wire layout;
new driver tests for retail-faithful chase/flee arrival.
Defers: target-guid live resolution for type 6 packets (chase-lag
mitigation, symptom #3), StickToObject sticky-target guid trailing
field, full MoveToManager port (CheckProgressMade, pending_actions
queue, Sticky/StickTo, use_final_heading).
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Root-causing the user-reported "monsters disappearing some time +
laggy/jittery locomotion" via systematic-debugging Phase 1: our
UpdateMotion parser kept only speed/runRate/flags from a movementType
6/7 packet and discarded Origin (destination), targetGuid, and the
distance/walkRunThreshold/desiredHeading half of MovementParameters.
The integrator consequently held Body.Velocity at zero during MoveTo
("incomplete state" stabilizer 882a07c), so the body froze with legs
animating until UpdatePosition snap-teleported it — sometimes outside
the visible window (disappearing) — and constant-velocity drift along
the old heading between snaps produced jitter on every UP correction.
The 882a07c stabilizer was deliberately conservative because the state
WAS incomplete. Completing the data plumbing makes its restriction
moot: with the full MoveTo payload captured, the body solver has every
field retail's MoveToManager::HandleMoveToPosition (0x00529d80) reads.
Why: server re-emits MoveTo packets ~1 Hz with refreshed Origin while
chasing — verified in the live log (guid 0x800003B5 seq 0x01FE→0x0204
all show different cell/xyz floats). Those are heading updates we'd
been throwing away. With the full payload retained, the per-tick driver
steers body orientation toward Origin (±20° snap tolerance, π/2 rad/s
turn rate above tolerance) and lets apply_current_movement fill in
Velocity from the existing RunForward cycle — no new motion path,
just the right heading.
Scope is the minimum viable subset: target re-tracking, sticky/StickTo,
fail-distance progress detector, and sphere-cylinder distance are
server-side concerns we don't need (server's emit cadence handles all
of them). MoveToObject_Internal target-guid resolution is also skipped
— Origin is refreshed each packet, so the effective target tracks the
real entity even without a guid lookup.
Cross-references:
- docs/research/named-retail/acclient_2013_pseudo_c.txt — MoveToManager
+ MovementParameters::UnPackNet (0x0052ac50) + apply_run_to_command
(0x00527be0). 18,366 named PDB symbols make this the primary oracle.
- references/ACE/Source/ACE.Server/Physics/Animation/MoveToManager.cs
— port aid; flagged divergences (WalkRunThreshold default, set_heading
snap, inRange one-shot) called out in the new pseudocode doc.
- docs/research/2026-04-28-remote-moveto-pseudocode.md — pseudocode +
ACE divergence flags + out-of-scope list per CLAUDE.md mandatory
workflow (decompile → cross-reference → pseudocode → port).
Tests: 1404 → 1412 (parser type-7 path retention + type-6 target guid
retention; driver arrival, in-tolerance snap, beyond-tolerance step,
behind-target shortest-path turn, arrival preserves orientation,
Origin→world landblock-grid arithmetic).
Pending visual sign-off — handoff stabilizer 882a07c was the last
commit the user tested.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Retail MovementManager::PerformMovement (0x00524440) reads MoveTo speed and runRate from the packet, MovementParameters::UnPackNet (0x0052AC50) defines the layout, and CMotionInterp::apply_run_to_command (0x00527BE0) multiplies RunForward by runRate. Parse those fields for UpdateMotion/CreateObject, seed server-controlled MoveTo locomotion with the retail speed multiplier, and avoid overriding active monster MoveTo with sparse UpdatePosition-derived velocity.
Ports the retail client's client-side remote-entity motion pipeline
verbatim per the decompile research. Every remote now runs its own
PhysicsBody + MotionInterpreter + AnimationSequencer stack — retail has
no special "interpolator" for remotes, it runs the full motion state
machine on every entity. Now we do too.
## What changed
### Parser fixes (CreateObject, UpdateMotion)
Wire flag bits for InterpretedMotionState (per ACE MovementStateFlag enum):
CurrentStyle=0x01, ForwardCommand=0x02, ForwardSpeed=0x04,
SideStepCommand=0x08, SideStepSpeed=0x10, TurnCommand=0x20, TurnSpeed=0x40
Previously we only extracted CurrentStyle + ForwardCommand + ForwardSpeed
and SKIPPED the side/turn fields entirely. Result: we had zero rotation-
or strafe-intent data from the server — impossible to render turn or
sidestep animations. Now ServerMotionState carries all 7 fields and the
parser reads the bytes in ACE's write order (style, fwd, side, turn, then
fwdSpd, sideSpd, turnSpd).
### RemoteMotion (new per-remote struct in GameWindow)
Each remote gets its own PhysicsBody + MotionInterpreter + observed
angular velocity. Replaces the earlier shortcut RemoteInterpolator
(deleted — retail has no such thing).
On UpdateMotion:
- ForwardCommand flag absent → stop signal (reset to Ready) per
retail FUN_0051F260 bulk-copy semantics (absent = Invalid = default).
- Forward + sidestep + turn each route through DoInterpretedMotion,
exactly as retail FUN_00528F70 does.
- Animation cycle selection: forward wins if active, else sidestep,
else turn, else Ready. Matches the user's observation that retail
plays turn animation when only turning.
- Turn command seeds ObservedOmega = π/2 × turnSpeed (from Humanoid
MotionData.Omega.Z ≈ π/2 per decompile).
- Turn absent → ObservedOmega = 0 (stops rotation immediately).
On UpdatePosition:
- Hard-snap Body.Position + Body.Orientation per retail FUN_00514b90
set_frame (direct assignment, no slerp — retail does not soft-snap).
- HasVelocity + |v| < 0.2 → StopCompletely + SetCycle(Ready).
- ForwardSpeed=0 on wire is a VALID stop signal (ACE sends this when
alt releases W); previously we defaulted to 1.0, causing the "slow
walk that never stops" symptom.
Per-tick:
- apply_current_movement → Body.Velocity via get_state_velocity
(retail FUN_00528960: RunAnimSpeed × ForwardSpeed in body-local,
rotated by orientation).
- Manual omega integration: Orientation *= quat(ObservedOmega × dt).
Bypasses PhysicsBody.update_object's MinQuantum=1/30s gate that
was eating every-other-tick rotation updates at our 60fps render
rate — the cause of the persistent "rotation snaps every UP" bug.
- update_object still called for position integration and the motion
subsystem it drives.
### AnimationSequencer synthesis extension
Added omega synthesis for TurnRight/TurnLeft cycles (same pattern as
the earlier velocity synthesis): when the Humanoid dat leaves HasOmega
clear, SetCycle synthesizes CurrentOmega = ±π/2 × speedMod on Z so
dead-reckoning and stop detection can read a non-zero omega for turn
cycles.
### Stop-detection heuristic removed
No more 300ms/2000ms/5000ms idle timers. Retail's stop signal is
explicit (UpdateMotion with ForwardCommand flag absent → Ready); we
handle it directly. Client-side timers were a source of flicker during
normal running.
## Confirmed working
- Walking (matches retail speed + leg cadence)
- Running (matches retail speed + leg cadence)
- Strafing (body moves sideways + strafe animation plays)
- Turning while stationary (body rotates smoothly + turn animation plays)
- Turning while running (body rotates + leg anim continues)
- Stopping (instant stop, no slow-walk tail)
All 717 tests green.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
UpdateMotion's InterpretedMotionState payload includes not just
ForwardCommand but a whole Commands[] list of MotionItem entries — each
carrying an Action (attack, portal, skill use), Modifier (jump,
stop-turn), or ChatEmote (Wave, BowDeep, Laugh) that should overlay the
current cycle. The old parser stopped reading after ForwardSpeed, so
emotes/attacks/deaths never reached the sequencer and NPCs just sat in
their idle cycle.
Three parts:
1. New MotionItem wire record in ServerMotionState — carries Command
(u16), PackedSequence (u16 with IsAutonomous bit + 15-bit stamp),
and Speed (f32). Mirrors ACE Network/Motion/MotionItem.cs.
2. Both UpdateMotion.TryParse and CreateObject.TryParseMovementData
now read the full InterpretedMotionState: all 7 flag fields
(CurrentStyle, ForwardCommand, SidestepCommand, TurnCommand,
ForwardSpeed, SidestepSpeed, TurnSpeed) plus the numCommands ×
MotionItem tail. The packed u32 encodes flags in low 7 bits and
command count in bits 7+ (see ACE InterpretedMotionState.cs:131).
3. New MotionCommandResolver — reconstructs the 32-bit MotionCommand
class byte from a 16-bit wire value via a reflection-built lookup
of DatReaderWriter.Enums.MotionCommand. Server serializes as u16
(ACE InterpretedMotionState.cs:139) and we need the class to route:
- 0x10xxxxxx Action / 0x20xxxxxx Modifier / 0x12,0x13 ChatEmote →
PlayAction (resolves from Modifiers or Links dict, overlays on
current cycle)
- 0x40xxxxxx SubState → SetCycle (cycle change)
4. OnLiveMotionUpdated in GameWindow dispatches each command:
- SubState class (0x40xxx) → SetCycle (treated same as
ForwardCommand)
- Action/Modifier/ChatEmote → PlayAction — the link animation
plays once then drops back to the current cycle naturally
(matches retail's action-queue pattern in CMotionInterp
DoInterpretedMotion, decompile FUN_00528F70).
Result: NPCs now animate attacks, waves, bows, death throes, and other
one-shots that ACE broadcasts via the Commands list rather than the
primary ForwardCommand field. Combined with the dead-reckoning + speed-
scaling from the prior commits, remote characters look visually correct
during the full motion spectrum (idle → walk → run → attack → death).
Tests: 2 new UpdateMotion wire-format tests (ForwardSpeed parse, full
Wave command list parse) + 19 new MotionCommandResolver reconstruction
tests covering SubState, Action, and ChatEmote classes. 654 tests green
(was 633).
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
The previous tests pinned the buggy 8-byte header assumption. Now they
match ACE's actual wire format: u16 movSeq + u16 srvSeq + u8 isAuto +
1 pad (via BinaryWriter.Align based on absolute stream length 15→16).
All 166 Core.Net tests now green again.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Server sends UpdateMotion whenever an entity's motion state changes:
NPCs starting a walk cycle, creatures switching to a combat stance,
doors opening, a player waving, etc. Phase 6.1-6.4 already handles
rendering different (stance, forward-command) pairs for the INITIAL
CreateObject, but without this message NPCs freeze in whatever pose
they spawned with and never transition to walking/fighting.
Added UpdateMotion.TryParse with the same ServerMotionState the
CreateObject path uses, reached via a slightly different outer
layout (guid + instance seq + header'd MovementData; the MovementData
starts with the 8-byte sequence/autonomous header this time rather
than being preceded by a length field). Only the (stance, forward-
command) pair is extracted — same subset CreateObject grabs.
WorldSession dispatches MotionUpdated(guid, state) when a 0xF74C
body parses successfully. The App-side wiring (guid→entity lookup
and AnimatedEntity cycle swap) is intentionally deferred to a
separate commit because it touches GameWindow which is currently
being edited by the Phase 9.1 translucent-pass work.
89 Core.Net tests (was 83, +6 for UpdateMotion coverage).
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
