Physics need change or improve

Please fix that:

  • There are a lot of problems with the physics and are semi impossible make a game with gameplay physics based.
  • Please add support to Bullet physics or migrate to Bullet physics and add support to a Havok plugin or something.
  • There don’t are PhysX games with physics in the gameplay.
  • The true uses of PhysX always are for non gameplay things like effects, details, smoke, and other list of non gameplay things (only toy cars), you cannot create something like Gmod or Half Life 2 as you can see in the video…
  • Bullet physics work better than this.
  • Bullet physics are in all 3D apps Blender, Maya…
  • Bullet Physics use MIT license and all code is open…

As far as I know Arma 3 uses PhysX for their whole vehicle physics.

Yeah the only thing you going to see effects and vehicles, but look at the Arma 3 vehicles or Planetside 2 Vehicles are like toys.
*The game with more things using PhysX is the Watch Dogs and have problems + don’t have like the examples i say, the best example of physics is the Source engine, you can place boxes or models and jump over (more than 10 years old engine), check the video in UE4…

Hi everyone,

This conversation is already taking place on the forums. Please continue the conversation here:

we don’t need conversation we need fix))))) and why we don’t see future fix in UE roadmap?


anyone from Epic care to give their views or any information on this subject?


Vehicles are known to have problems (in both UE and physx), please see my post on the other thread.

The surfing bug you show in the video was introduced in 4.8, but is fixed in 4.9 - This still sucks though (Sorry!)

We don’t have plans to switch physics engines any time soon. While there are advantages/disadvantages to different engines, I don’t think switching is feasible or would solve most of the issues people encounter. The majority of bugs are actually the result of complex interaction of systems at the unreal level.

We are of course trying to improve this and posts by the community really help. I know it’s annoying, but posting a simple project that reproduces the problem goes a long way on our end to fixing the bug.

There are games out there that rely heavily on PhysX for gameplay - see Kerbal Space Programm.
There are just no games with UE4 + PhysX out there.

I also think switching physics engines is wrong. PhysX works well, not as reliable and robust as Havox, but then it is for free. Robustness is what you would pay for with Havok.
But it works well, see Unity3D. It is just that Epic needs to work more on a solid integration (and multi-threading PhysX like in Unity)

PhysX has been multi-threaded in UE4 since UE4 launched. I am not sure where this misconception came from, but my guess is that it’s related to the new function names in 4.8 which explicitly state whether a lock has been obtained.

Thanks for replies Ori, well as you can see this is about all physics not only the vehicles. Nice to know the 4.9 fixes.
For example i got there another problem this is fixed too in the 4.9 ?

This seems like more of a physx stability issue. I’ve sent this page to NVIDIA support to see if they have any thoughts.

Is it easy to repro? Just add sheets of simulated cubes in 1st person template?

Yes as you can see are the 3D model from starter content Floor400x400 x6 one over other turn in physics with gravity.

I did something vey similar without problems. If you want, you can share the stripped down project and I can take a look. Difficult to pin down what is wrong without a project file.
All the usual stuff is on, right? (sub-stepping, CCD, no huge mass ratios, generate hit events = OFF (in 4.8), velocity/position solver high,…)

Please Epic, when you do physics in 4.9, move careful. Or better: tell your developers to move careful. It was a trip to hell and back to retune physics in my project when I switched from 4.7.4 to 4.8.
You say now that a bug has been introduced in 4.8.
This renders all the ‘advice’ to always stay with one version during development useless, regardless of how many updates there are.
I could faint when I read that physics in 4.9 gets another overhaul.
At some point you guys really have to move slower, introduce less features and instead do solid work.
You are running to fast with rather short legs. You do not have that many people in your company but want to create output like you had 5x the employees.
It is not going to work.
Do it for your users, move slower!

This looks like a problem with our contact offset code. I’ve been able to fix it locally, but I need to verify some stuff with the original author.

Thanks for the info

thanks for the replies Ori

would this also explain a very similar looking problem when a character stands on top of a physics enabled object or a vehicle?

Do you mean the bug where you can surf the simulated object? That bug was because of something else which has been fixed in 4.9 - The commit in code can be found here:

thanks Ori
if that is the same bug im very glad to hear its been fixed.
with any luck ue4 will actually be useable sooner rather than later, cant wait :slight_smile:

I’m added a post about some question about why is missing things in the engine but is moved to content creation Vehicles change friction and friction per material? - Asset Creation - Unreal Engine Forums

You can set the friction of a Physical Material in the physical material properties, and PhysX will use that at runtime to calculate friction between two surfaces.

You set the physical material of a material shader here (which is right at the top btw…)

Additionally, you can change that Physical Material at runtime.


Thanks you for the friction clarification and the example, and is a way to change the friction from the tires/wheels in runtime ?