Question Set custom attribute in Spawn context?

I'm trying to tag a batch of particles with a Group ID, so that later I can read that attribute and do something different in rendering depending on the batch. I was hoping I could create a custom "Set SpawnEvent Attrbute" node, to set this value, but I don't see any way to do something like that. What I want to do is very similar to setting the Tex Index of a particle:



Is there any way to set some property of a particle within a Spawn context, so that I can tell which Spawn context the particle was generated from? Technically, I could hijack Tex Index here, since I'm not using a flipbook for this VFX, but that feels bad to me.

In short, I have a couple of different Spawn contexts in my graph all feeding into the same renderer, but I want one conditional branch in the system that does something different depending on which spawn context it came from. It seems there's a way to get/set custom attributes, but I don't see how to set it within a Spawn context.

 

It’s in the initialize step, but Vlad’s answer could help you: https://forum.unity.com/threads/sin...s-and-colors-from-script.855634/#post-5920883

 

I see. Thanks. I guess it's not what I need, though. Or, maybe I just don't know how to use it properly. My goal was that all particles spawned in a "batch" would have the same value for some custom property. But that would require setting the value within the SpawnEvent section. By the time I'm in Initialize Particle, I won't know which SpawnEvent the particle came from. Thanks for clearing up the usage, though.

 

I may have misunderstood. But Vlad's description sounded like it could help "here we set a Uint in Initialize (which you can populate with some data you send over an event)". Here's how you set atributes in an event on spawn which you can then catch in the initialize block: https://docs.unity3d.com/Packages/c....1/manual/Events.html#eventattribute-payloads

 

Oh, I'll take a closer look then. Maybe there's something about the Spawn block that lets me feed something into Initialize, from your reading of it. I'll see how it goes.

 

It sounds like it in his description and on the linked page: “EventAttribute Payloads are attributes that will implicitly travel through the graph from Events, through Spawn Systems, and that can be caught in Initialize Contexts using Get Source Attribute Operators and Inherit [Attribute] Blocks”.

 

I stumbled upon this same issue and I think setting custom attributes in the spawn event is a missing feature. You can have work arounds like feeding in values, but that is a solution I don't like very much.

My workaround for instance is, taking an existing attribute (in my case alpha) and using this instead. It can be overwritten in initialize if needed. That works, but isn't very pretty.