Motion-Physics Sync Engine

Motion-Physics Sync Engine

Module: Animation · Category: Physics · Tool ID: MotionPhysicsSyncEngine

A targeted fix for a specific bug: when an actor uses both Motion Matching (which ticks in PreCMC) and a Physics Control component, the competing tick group ordering can snap bones to the world origin every frame. This tool walks the level, finds every actor with the conflict, and shifts the conflicting component’s tick group to Pre-Physics to restore correct evaluation order.

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When to use it

• Bones snap to (0,0,0) every frame on a character that uses Motion Matching + Physics Control
• After enabling Physics Control on an existing Motion Matching character — usually triggers the issue
• Pre-shipping check on any character using both subsystems
• Onboarding a new project where this combination is part of the character setup

When not to use it

• Don’t use this on characters without Motion Matching or Physics Control — there’s nothing to fix
• Don’t use this as a generic tick group debugger — it’s specific to this exact MM+PC interaction

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Opening the tool

1. Open the EQLabs Hub and search for Motion-Physics or Tick Group (or browse to Animation → Physics)
2. Click the tool card
3. Make sure the level you want to scan is open

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Interface tour

Section	What it does
Scan World button	Walks every actor in the active level looking for MM+PC tick conflicts
Fix All button	Shifts every conflicting component’s tick group to Pre-Physics. Undoable.
Summary	Total actors scanned, conflicts found, conflicts fixed
Conflicts list	Per-actor row: actor name, two component names, both component tick groups, fix description, fix flag

What gets flagged

A row is added when an actor has both:

• A component using Motion Matching (typically ticking in PreCMC)
• A Physics Control component (typically ticking in a default group)

…and the relative tick order causes the known bone-snap symptom.

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Workflow

Step 1 — Open the level

The tool operates on the active editor world. Load the level that contains the affected characters.

Step 2 — Scan

Click Scan World. The conflicts list populates. If empty: no MM+PC conflicts in this level — you’re fine.

Step 3 — Review the proposed fixes

Each row tells you exactly which component will have its tick group shifted. Read them — the fix is conservative but worth a sanity check.

Step 4 — Fix in batch

Click Fix All. Every flagged component is shifted to Pre-Physics. Wrapped in a single transaction — Ctrl+Z reverses the lot.

Step 5 — Save

Save the affected actors / Blueprints so the fix persists.

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Settings reference

This tool has no persisted settings — it’s a single-purpose scan and fix.

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Output

• In-place modification — Fix All modifies component tick group properties on the affected actors
• Undo — wrapped in ScopedTransaction. Ctrl+Z reverses.
• Save — affected actors / Blueprints need to be saved to persist the change

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Tips & gotchas

• The fix is conservative — shifting tick group to Pre-Physics is the documented Epic resolution for this exact conflict. If your project has a more complex tick ordering scheme, review before applying.
• Single-click on a row selects the actor in the viewport.
• Re-scan after Fix All to confirm the conflicts list is empty.
• A persistent character template (Blueprint) may need to be edited at the source — fixing instances in the level is a level-only fix; for a permanent fix, edit the Blueprint class.

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Related tools

• Skeleton Inspector & Rig Shortcuts — when the underlying skeleton is part of the diagnosis
• Physics & Collision Studio (Modeling module) — for static mesh collision setup, related but different domain

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