Spatial layers are a PopcornFX feature that enables the power to issue data queries on volumes that store particle information.
To put most simply, it gives a particle the power to retrieve data from other particles, and enables the power to do a lot of different stuff with that data. Actually, anything you want!
Here’s an example of basic interaction: particles are traveling inside the nerves network, like neurons inside a brain. These neurons are inserted inside a query volume, so that nearby particles can constantly look for their current position. Based on that, particles forming the membrane are “push outwards” and change color to let the neurons flow through the network.