Set Physical Material Override seems broken in UE5. Chaos bug?

Development World Creation
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Swapping Physical Material with “Set Physical Material Override” during runtime is not working well in UE5 compared to UE4.

Case:
A sphere with a Low Friction Physical Material swaps to a High Friction Physical Material when moving. User press B to flip-flop between Physical Materials.

AVS_PM_BP
AVS_PM_BP1344×599 156 KB

In UE4:
https://youtu.be/s3j6T5Drdfo

The new High Friction PM will take effect right away. In the video, the high friction takes effect right away.

In UE5:
https://youtu.be/FezM6cuWgWA

The High Friction PM will only take effect when the sphere hits a different static mesh/surface/objects/hit proxies/etc. Unlike UE4, the High Friction only takes effect when the sphere is hitting something different, it is like it needs to be refresh. Is it asleep?

I really don’t know why it is not working like in UE4, has it is supposed to be…?!

Is this only my UE5? Did anyone else notice this bug as well?

Any tips would be very helpful, thank you

1 Like
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Same here, using 5.1.1, but still no change…

It says:
image
Friction was the only thing I wanted to change, but it´s not happening…

Tried it with sending them to sleep and wake up, but doesn´t help.
Same with disable and enable “simulate physics” again.

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I encountered similar issues when trying to update the Restitution on the PhysicalMaterial dynamically at runtime.

There is a solution available in code, via the public static FChaosEngineInterface::UpdateMaterial function.

After creating and assigning the PhysMaterialOverride on the BodyInstance, the properties such as Friction and Restitution can be changed and updated like this:

void Example_UpdatePhysicalMaterial(UPrimitiveComponent* BodyComponent, double InFriction, double InRestitution)
{
	UPhysicalMaterial* PhysMat = BodyComponent->BodyInstance.GetSimplePhysicalMaterial();
	if (PhysMat->Friction != InFriction || PhysMat->Restitution != InRestitution)
	{
		PhysMat->Friction = InFriction;
		PhysMat->Restitution = InRestitution;
		FChaosEngineInterface::UpdateMaterial(*PhysMat->MaterialHandle, PhysMat);
	}
}

I’m using this method (not the exact code above) and it works.