World-space system inheriting velocity of game object?

I'm making a moving object that should leave particles behind it as it moves. I've set the system to World, which causes it to leave the particles behind, but I haven't found a way for them to inherit the velocity of the VFX graph which is moving. Ideally it would inherit the velocity, but some drag would slow it down. I tried adding a block to inherit source velocity, but this doesn't seem to do anything.

I'm starting with a default "Swarm Particle System", and I have a simple script to move the VFX Graph game object. Can anyone suggest an approach to having particles inherit the velocity of the system at the moment they're initialized?

 

I'm having a similar problem with this and that doesn't seem to work either.



I'm just trying to get the particles shot out to use the weapon turret's current velocity (this exposed Vector3 is set by C# code prior to triggering the start event) and then add the random velocity locally.

 

The approach that JulienF mentioned worked fine for me. I similarly have a Vector3 property on the VFX graph, which I use just like you use, except that for mine it's set to world velocity, not local velocity as you have it:



Then I just the velocity in code:

Code (CSharp):

1. vfxSystem.SetVector3(VisualEffectConstants.PreRift.SystemVelocityParameter, Velocity);
2. vfxSystem.Play();
3.  

Seems to work fine for me. Make sure you're not having issues with Local vs World.

 

Thanks for that! I tried setting velocity in World as well as Local but neither seem to work OK. Perhaps it's the velocity vector I'm setting that's the issue. I had set it to the velocity vector of the weapon turret carrying the VFX graph in it so it made sense to me. Maybe it's also the fact that I'm adding a random local velocity to it. I don't know really.

 

If you're adding more velocity, that should be fine. But if you're ever "setting" the velocity, that will step over this, so you shouldn't be setting the velocity more than once.

 

Thanks, yeah, I understand that. I managed to get it working as expected. The particles were dragging behind too much for my liking but it was my fault - I had Drag values set too high. Turns out for my use-case, it looks better to just keep everything local anyway, but at least with this thread, I've learned how to sort this out for other use-cases. Thank you.

 

Hey, can you please tell me how you did to leave particles behind it as it moves? thanks!

 

It's subtle, but within the nodes of the graph you'll see a small button you can toggle between World and Local. Usually you just need to make sure the rendering is done in World, to prevent the particles from moving along with the moving system.

 

thanks!

 

Hey everyone!
Sorry for necro, but it's 2023 now and I wonder if anything has happened on this front? Couldn't find a node for inherit emitter velocity, but since documentation is still spotty, I thought I'd ask.

 

Thanks so much for the detailed answer, Orson!
I'll try it today and let people here know how it went or if questions arise. Just wanted to say, I love Unity Forums, you people are so helpful and saved my day more than once <3

 

Hi there! Reviving this as well...
I tried to use your approach, Orson, and it works somewhat. I have a weird issue where it seems to only work for some particle emissions. If I have a constant emission rate only some of the particles actually inherit the velocity, and if I instead use a burst only some bursts of particles inherit the velocity. For the burst either all particles of a burst inherit the velocity or none do, which is a bit weird. I've just used a burst in the gif below as it clearly illustrates how some of the burst inherit the velocity while others don't. I've also added an image of the graph as well as the editor in case something is set up incorrectly. Hope you can help, thanks in advance!

I can't really figure out how to add images to the post... So I'll just post them as attachments