Developer Notes

From the dev - "The way that PhysX works is that it guarantees stability at the cost of accuracy. At low frame rates in particular, you may see different damping than at higher frame rates for example. The best solution is to use substepping to have a more consistent timestep for physics."

I tested this and it does help close the gap at different FPS.


Damping is handled differently at lower frame rates. Slight changes in damping at lower FPS (25) drastically effects objects and isn't applied in the same way as at higher FPS (60)

User Description:

TorqueTest sets the frame cap by command starting at 10 fps, rotating 4 times and then it rises the frame cap by one. It doesn't seem to be any different from going into 'Project settings//Engine//General Settings' and set the frame cap with the 'use fixed frame rate' option.

Steps to Reproduce

1. Open the attached test project
2. PIE
3. Scroll up on the Mouse-wheel to set the Damping to 31
4. Scroll down on the Mouse-wheel to set the Damping to 29
5. Toggle these to values to see the change in torque
6. Press the 2-key to set the FPS to 25
7. Repeat step 5

Results: The damping is handled completely different at 25 FPS than at 60 FPS

Expected: For the damping to be handled the same at both FPS rates


From QA-Game

1. Create an actor class BP & open it
2. Add a Static Mesh component
3. In the Details panel of the Static Mesh component, Enable Simulate Physics
4. Under Physics, Set Constraints to this: (E=Enabled D=Disabled)

Lock Position: X: e | Y: e | Z: e
Lock Rotation: X: e | Y: e | Z: d

5. Under Class Defaults > Input > Auto Receive Input > Set to Player 0
6. In the Event Graph, create the setup from screenshot #1
7. Compile & save
8. Back in the editor, PIE

Community References

Have Comments or More Details?

Head over to the existing Questions & Answers thread and let us know what's up.

Login to Vote

By Design
ComponentUE - Gameplay
Affects Versions4.12.54.14
CreatedAug 3, 2016
ResolvedAug 3, 2016
UpdatedJul 14, 2021