[BUG] GPU Collisions not working properly 4.14

Development Platform & Builds
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1

So I made a new rain GPU particle system and it looked like the collisions weren’t working properly so I adjusted the location so that the particles were a lot closer together (looks like a waterfall) and discovered that sure enough, the collisions start to work, but then when I move my camera down, the particles break through the collision mesh for some weird reason. I migrated the particle system into a new clean project and the problem is still persisting.

I’ve packaged the project and uploaded it so you can see what’s happening
http://www.torquemod.com/ParticleTest.rar

All you have to do is click Play and then look down at your “feet” to see that the particles break through the blocking mesh.

2

I’m totally trying to steal all of your Bit Coins with my ultra hax0r Trojan! lol

Using scene depth and everything else required of a GPU particle that I’m aware of. As long as the bounds are visible though, they shouldn’t be going through the collision object.

3

Yea, this is a limitation of gpu particles/scene depth. due to optimizations and the likes.
If the camera cant see it, the depth wont be calculated.

a good tutorial/video about it can be found here: Particle Effect Collision | Live Training | Unreal Engine - YouTube

That said, take it from me… a proper waterfall wouldnt be just gpu particles. it would be mainly a mesh with a panning texture, and additionally smoke/splash sprites.

4

A video would be preferred over a project, most people here arent official ue4 devs, and for all we know your computer or that zipfile contains a weird trojanvirusbitcoinminer thing.

So without a video I cant really tell whats going on, but might it have anything to do with the fact you are not looking directly at the gpu particles and the collision? because that will make them go trough any collision.
Additionally, did you enable scene depth?

5

Wasn’t trying to make a waterfall, I just concentrated it into a smaller point to make it more obvious. It’s a rain effect… I was hoping that it would be blocked by objects in the world. How do they pull that effect off in games then as I know plenty who do it? Can you increase the camera’s occlusion to make sure you never see it happening?

6

I remember a document about how the rain in gtaV was approached but cant find it for the life of me.
There are plenty of high end games that still dont know how to properly render rain/particles though, Final Fantasy 15 comes to mind.

I dont know if you can increase the camera’s occlusion, thats beyond my technical knowledge.
Im sure there is some way where due to an overlapping volume or whatever the particles or their textures might get culled, or alternative ways for collision… but, again… waaay beyond my technical knowledge.

7

I’d love to hear from one of the Epic Team members on why this happens. If the bounds are visible the collisions should still work the same way that the particles are still visible.