In UE5.5.4 the return value of ’Get Physics Linear Velocity at Point’ is wrong

Summary

In UE5.5.4 the return value of ’Get Physics Linear Velocity at Point’ is wrong

Please select what you are reporting on:

Creative

What Type of Bug are you experiencing?

Other

Steps to Reproduce

Calling [Get Physics Linear Velocity at Point] on an actor that is rotating always gives wrong results.

I created an actor blueprint to attach to the actor whose linear velocity is being detected. It gets its own linear velocity and the linear velocity at the target position and draws them as arrows. The red arrow is the linear velocity of using [Get Physics Linear Velocity at Point]; the green arrow is the linear velocity of the [attach actor root] component. Obviously, the speed of the red arrow is completely wrong.

Expected Result

I use [Get Physics Linear Velocity at Point] to get the linear velocity of a point on a rotating actor. It should be the same as the linear velocity of the attached actor at that point.

Observed Result

I’m using [Get Physics Linear Velocity at Point] to get the linear velocity of a point on a rotating actor. It doesn’t match the linear velocity of the attached actor at that point at all.

Platform(s)

Windows 11

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Additional Notes

I created an actor blueprint to attach to the actor whose linear velocity is being detected. It gets its own linear velocity and the linear velocity at the target position and draws them as arrows. The red arrow is the linear velocity of using [Get Physics Linear Velocity at Point]; the green arrow is the linear velocity of the [attach actor root] component. Obviously, the speed of the red arrow is completely wrong.

I may know what the problem is.

My self-spinning Actor offsets a cube component and then sets its rotation, which causes its center of rotation to be inconsistent with its model’s origin. Getting the linear velocity of a physics point seems to be calculated based on its model’s origin or center of mass.

If so, is there another way to get the linear velocity of a point on a self-spinning and moving Actor?