Grounded player remotes were showing a ~5 Hz Z staircase when running
up/down slopes — the rate of server UpdatePositions. Body Z stayed flat
between UPs, then ramped over ~100ms during the queue-active chase to
each new server position, then went flat again until the next UP.
Diagnosis (no diagnostic needed — the math is unambiguous):
PositionManager.ComputeOffset has two modes via
InterpolationManager.AdjustOffset:
- Queue active (body chasing a waypoint): returns
`(head − body) / dist × min(catchUpSpeed × dt, dist)`. 3D direction,
Z follows server's reported Z naturally.
- Queue empty / head-reached (within DESIRED_DISTANCE = 0.05m of the
most recent UP): returns Vector3.Zero. ComputeOffset falls back to
`seqVel × dt rotated into world` — pure animation root motion. Every
locomotion cycle bakes Z=0 in body-local, so the world result has
Z=0 too. XY advances at the running pace; Z stays at the last UP.
For a runner at maxSpeed ≈ 4 m/s with catchUpSpeed = 2× = 8 m/s and
server UPs at ~5 Hz, body covers ~0.8m per UP, chases for ~100ms
(queue-active 3D path, Z ramps), then sits in seqVel-only mode for
~100ms (Z flat) until the next UP. Visible as a 5 Hz Z staircase.
Fix mirrors retail's CTransition::adjust_offset contact-plane projection
(named-retail acclient_2013_pseudo_c.txt:272296-272346) for grounded
motion, applied at the queue-empty boundary instead of inside the sweep:
PositionManager.ComputeOffset gains an optional Vector3? terrainNormal.
When the seqVel-only fallback runs AND a non-trivial terrain normal is
supplied, project rootMotionWorld onto the plane:
result = rootMotionWorld − N × dot(rootMotionWorld, N)
Anim XY motion gains a corresponding Z component proportional to slope
angle × forward speed, so body Z follows the terrain mesh between UPs.
No-op on flat ground (N ≈ +Z, dot ≈ 0); cannot regress L.3 M2's
flat-ground verification.
GameWindow.TickAnimations grounded-remote path samples
PhysicsEngine.SampleTerrainNormal at the body's current XY each tick
and passes it to ComputeOffset. SampleTerrainNormal is a thin public
wrapper over the existing internal SampleTerrainWalkable that returns
just the plane normal (no need to expose the internal sample shape).
Diagnostic: ACDREAM_SLOPE_DIAG=1 prints a per-tick [SLOPE] line with
guid, body Z before/after, offset, queue active flag, and the sampled
plane Nz so we can grep before/after the fix and confirm Z changes
continuously between UPs on slopes.
Tests: PositionManagerTests gains two cases:
- slope projection: 30° east-tilted plane, body running due east at
4 m/s for 1s → expect (3.0, 0, −1.732) (descends along slope, not
flat). Math: dot(seqVel, N) = 2.0 → result = (4,0,0) − (0.5,0,0.866)
× 2.0 = (3.0, 0, −1.732).
- flat-ground no-op: N = +Z, expect identical Y-only motion as the
pre-fix behavior.
Build green. 357 pass / 6 pre-existing fail (same set as ec59a08;
verified by stashing this change). The pre-existing
`ComputeOffset_BothActive_Combined` failure reflects an outdated
additive-design test docstring; the M2 commit (40d88b9) deliberately
changed the implementation to REPLACE semantics to fix the prior
3×-server-pace overshoot.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Multi-bug fix for the env-var-gated retail-faithful remote tick path
(ACDREAM_INTERP_MANAGER=1). Combines four previously-stacked defects
into one coherent rewrite:
1. PositionManager.ComputeOffset was additive (rootMotion + correction).
Retail's PositionManager::adjust_offset (acclient @ 0x00555190 →
InterpolationManager::adjust_offset @ 0x00555d30) REPLACES the
offset frame via Frame::operator=(arg2, &__return) when catch-up
engages — it does NOT add to the rootOffset that CPartArray::Update
wrote. Switched to "correction overrides root motion" semantics.
2. MotionInterpreter.GetMaxSpeed was returning RunAnimSpeed × rate
(~11.7 m/s for run skill 200). The retail decomp at
acclient_2013_pseudo_c.txt:305127 shows get_max_speed returns the
bare run rate (~2.94) — the function's float return rides the x87
FPU stack, which Binary Ninja shows as void. Caller multiplies by
2.0 to get the catch-up speed. With the wrong return our catch-up
was 23.5 m/s instead of retail's 5.88 m/s — the queue would walk
the body 4× too aggressively.
3. The env-var TickAnimations branch was DOUBLE-COUNTING forward
translation: it applied seqVel × dt via PositionManager.ComputeOffset
AND let UpdatePhysicsInternal advance body.Position += body.Velocity
× dt. Both were ~11.7 m/s for run, so body raced at 23.4 m/s —
"way too fast" per the user. Pass seqVel=Vector3.Zero to
ComputeOffset; let body.Velocity (refreshed per tick by
apply_current_movement) drive the bulk translation alone.
4. Body orientation only applied sequencer.CurrentOmega per tick. For
the running-in-circles case ACE broadcasts ForwardCommand=RunForward
AND TurnCommand=TurnLeft on the same UpdateMotion; the sequencer
picks the RunForward cycle whose synthesized CurrentOmega is zero,
so body never rotated between UPs and body.Velocity stayed in an
out-of-date world direction — the visible "rectangle when running
circles" effect. Prefer ObservedOmega (set explicitly in
OnLiveMotionUpdated from the wire's TurnCommand + signed TurnSpeed)
when present; fall back to seqOmega for standalone turn cycles.
Also adds:
- Sequencer-reset call in the env-var landing-fallback so the legs
un-fold from Falling on land (mirrors the legacy K-fix17 path).
- LastServerZ now only updates on IsGrounded UPs, so the per-tick
landing-fallback floor doesn't drift up to the player's airborne
peak Z and force-land mid-arc — fixes the user-reported "small
landing in the air before landing on the ground" when jumping
while moving.
- VEL_DIAG now samples at UP arrival with overlapping windows, plus
TURN_WIRE / OMEGA_DIAG / FWD_WIRE diagnostics gated on
ACDREAM_REMOTE_VEL_DIAG=1 used to trace these bugs to ground truth.
Verified via live retail-driven character observation 2026-05-03:
turn-left now rotates left (was animating right with snap), running
in circles is much smoother, jumping lands on ground (no mid-air
pause). Residual ~20% steady-state overshoot for walk remains —
WalkAnimSpeed=3.12 (decompiled retail constant) doesn't match ACE's
actual broadcast walk pace (~2.6 m/s). Tracked separately.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
