I have a stream of particles directed towards a country (Spain) on a map. I want those particles to go inside Spain's boundaries and remain/circulate there while the stream continues.
I imagined that I should make a mask around the country's boundaries and set it as a Boundary in Particle Playground --> Wall. But there's nothing to select, only None. (the printscreen below shows only two layers in my project but there was another layer - a mask around the Spain boundaries, and I still couldn't select anything in Wall --> Boundary)
What should I do in order to create the effect I described above?
Masks need to be on the layer with Playground.