P PassBasic Parameter
To add a gravitational force to particles, group the particles and use PPass to pass the group to a PGravity node.
This frequently-used node allows you to pass a group of particles to another node. PPass is used to control which particle groups have which effects applied to them.
For example, suppose you want to apply gravity to a particular group of particles. In this case you would first assign the group to a PPass node and then connect the PPass node’s Particle output to the Particle input of a PGravity node.