Realistic blowing debris, litter, etc

Hi guys
Trying to create a realistic effect of debris, litter, dust, etc blowing along the ground.
Any tips or suggestions?

Should I bother spending time in the Marketplace?

To save on performance doesn’t have to entirely physically accurate in terms of collision.

Vector fields in Cascade, or similar in Niagara. Use mesh emitters for larger objects, and add physics to things like crumpled paper / wrappers and dust so if it collides with other things, then it becomes temporarily trapped until a wind current going diagonal up or comes from the side moves it.

Depnds on what the debris needs to do.

niagar does allow collision now, and it is a lot easier to affect an emitter with wind.

The hard way is blueprints that move about. And it’s not hard just a pain because of costs.

In .25 (pre chaos, and assuming chaos works maybe this won’t be needed anymore) something as simple as a flag you can also collide with objects requires an extensive setup to get the PHAT asset to move with the wind.

The hardest part is that there is no built in function you can access to get the wind from outside of cpp. Even with cpp that’s a lot of digging you need to do to get wind actor information.

The baseline is you have to sum winds up yourself based on their settings.
This can require a bit of recrsiveness since there can be limitless wind actors in a scene.
each actor will cause more load on the calculations obviously.

Because of the nature of the wind actor your final BP that has to move needs to check proximity to other wind actors and do this math in order to determine the directionally of the wind local to it.
obviously on tick, so rather expensive to start, and gradually more expensive as more wind actors come into range.

Now, as far as I understand it the same is true for niagara. You need to pass wind to it in .25 via a variable / its not affected by the wind actor on its own - last time i tried it anyway. Could also be i missed a setting or something.
Since I needed the blueprint way I didn’t look into why the particles weren’t affected properly.

Either way, I’m hoping chaos in .26 will correct some if not all of that. Maybe eventually by .27… :stuck_out_tongue: