What is going on? I can't stop this ball completely after calling on AddForce(FVector) just once.

[TK-Master]

@Rama;276799

Lovely to hear from your ! Thank you for UE4 Physics!

**A Ball That Stops Itself Is Possible Right Now**

I have not had any issues with infinite roll and I have a project that is based around a rolling ball, I am able to set the Angular Damping just fine like this:



```


UPrimitiveComponent* Comp = GetYourComp
if(!Comp)
{
  return;
}

FBodyInstance* Body = Comp->GetBodyInstance();
if(!Body || !Body->IsValidBodyInstance())
{
  return;
}

Body->AngularDamping = your new value

Body->UpdateDampingProperties(); //<~~~


```




The result in my game is a controllable ball that moves with WASD and stops very quickly after I stop applying impulses.

I write this just to let you know that it is possible! I am using 4.7.5.

Skeletal Mesh Ball Using Physics Asset

The only distinction I can think of with my ball is that it is a skeletal mesh component, not a static mesh component.

Asperatology, can you try using a skeletal mesh with a physics asset?

That’s what I am doing and it works great

Good luck!

Rama

PS: In the test I did in my post above I used a static mesh rolling ball and setting the angular damping worked just great there too, so I am not sure why I am able to get it to work so easily and others are having issues with it.

I did experience the infinite roll issue on my skeletal mesh ball until I added the Angular Damping as shown in code above, but that immediately fixed the infinite roll for me!

Hey Rama I have a question for you, is there a reason why you update the damping in C++? I have not tried that yet but the problem doesn’t seem to be the damping
The damping is actually applied without any C++ just fine (I can clearly see the ball slowing down faster) but unless you put some crazy-high value, it never completely stops rolling, it keeps moving really slowly forever.

But the thing is that there is no point in having a sphere with that high damping! you might as well put a box collision on the sphere at that point lol

Also, skeletal or not it doesn’t make any difference, the spheres are the same.

@'[Epic

;276722’]Hi all,
just to update you on this:

There is a new project setting in 4.8 called enablePCM which changes the way physx generates contact points. This fixes the infinite roll issue.

https://github.com/EpicGames/UnrealEngine/commit/c8a733313af1aa39061afd92ea9ee3ca7662b790

This still doesn’t fix the problem where friction has little affect on the sphere. The problem here is that for a perfect sphere the contact patch is infinitely small. However, if you turn PCM on and use angular damping you should get reasonable results.

Hope this helps

That sounds promising but if it’s a project setting that means you are forced to choose one or the other… is it possible to at least be able to enable this per object? or this has to be a global setting?

Also about the friction… are there any future plans to implement it? or this has to be done by the Nvidia guys? (sigh)
A side project of mine heavily relies on sphere friction so I’m basically forced to reinvent the wheel if I’m ever going to get realistic results

I will try the PCM setting when I get the chance though… thanks for that!