(UE4 V4.7.6)Why is physic behave different in PIE vs Standalone?

When I chose my skeletalmesh’s collision presets to PhysicActor, PIE and standalone has the same physical behavior.

When I chose me skeletalmesh’s collision presets to CharacterMesh, PIE and standalone has a drastic difference. In PIE, physic seems more “stable”, but in standalone game physic stutters a lot.

Is there anyway to make CharacterMesh collision preset behave like in PIE whn playing standalone game?

Try tweaking swing constraint, swing limit soft, linear dampening, angular dampening, but still can’t get standalone to behave like PIE.

I partially track down this issue, it seems the 'collision enable" option is causing this difference PIE vs standalone.

No Collision → PIE and Standalone are the same

No Physics Collision → PIE and Standalone behaves different

Collision Enabled → PIE and Standalone are the same

The Unreal Engine does not use a fixed timestep size, so the time step used by the physics engine will vary based on what the frame rate is.

What’s extra annoying about not using a fixed time step is that, if there is a framerate stutter, objects that are balancing may “jerk” and stop balancing, because the act of gravity/acceleration takes a longer time step.

You can make this somewhat better by enabling “substepping” and setting a substep size that’s something on the order of 0.005 to 0.009 seconds. But it’s not going to be great, and the cost of physics simulation will go up.

Hey thanks for the reply.

Interestingly I have the same skeletalmesh and the same physic setup in UDK, but didn’t encounter this problem before.

I’ll try tweaking the substep and report my result.

I tried substep, it sort of remedy the stutter like you said, but not good enough.

I think I’ll just stick to PhysicActor for the collion enable option for now.

Thanks again for the tip.