Endresult can start to be seen at 2:00
In this example we create a custom force that sends particles back if they move outside a defined border. This border can be anything you define mathematically. For simplicity I use a box as that's a common aquarium situation.
You can use the padding and the return strength to control how quickly the particles turn back.
This setup is built for localspace particles, as that's easy to place in a level, but it can work with worldspace as well, as long as you offset the box boundary appropriately and claculate the return vector as normalize(Engine.Owner.Position - Particles.Position) instead of normalize(Particles.Position). The tricky part is that then you need to transform the base axises manually as well. Using localspace, handles all this for you.
#UE4 #Niagara #Tutorial
