Physics Constraints have no effect in Unreal 4.26

Development World Creation
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1

In Unreal 4.26.preview4 the physics constraints setting has no effect, while it is expected to behave like in 4.25.

constraints menu

Perhaps it is related to the announced usage of “Chaos” engine instead of PhysX.

Example project here: GitHub - adynathos/UnrealConstraintsBug: Reproduce a bug: physics constraints do not work in Unreal 4.26

Setup

The test scene contains 4 rigid-bodies falling onto a sloped plane.
They have the following constraint settings, from left to right:

  • None
  • YZPlane
  • Lock X position
  • PhysicsConstraintActor attached to this body, locking X movement and all rotations

The settings have been applied per-instance in the map.
The general intent of the constraints is to keep the body at X=0 and prevent it from sliding down the plane.

scene setup
scene setup1158×641 114 KB

Result in 4.25

We run this map in 4.25.3 and observe the constraints preventing the bodies from sliding down the plane.

result 4.25
result 4.251161×609 94.4 KB

Result in 4.26

The same map run in 4.26.preview4 shows all bodies sliding the same way. The constraints have no effect.

result 4.26
result 4.261370×673 109 KB

( I have submitted the report as well )

2

Hello,

We’ve made a switch to a new bug reporting method using a more structured form. Please visit the link below for more details and report the issue using the new Bug Submission Form. Feel free to continue to use this thread for community discussion around the issue.

https://epicsupport.force.com/unrealengine/s/

Thanks

Marinna

3

Hi, I don’t know if is the same problem but I have problems with physics constrains too on version 4.26.

The node “Set Linear Limit” or “Set Angular Limit” has change the “Constraint Type” to Free when I update the project to 4.26.

I just reset the “Constraint Type” to Limited (In my case) solve the problem.

4

I had the same problem. Updating the engine version for my project wiped our some configuration on some important blueprint nodes for physics constraint components, which caused bugs. Finding these nodes and restoring the configuration seems to have fixed the issues I was having.