Birth particles on shape surface?

[tyFlow]

The only way to do 2-way interactions like that is with PhysX. So you could use a Spawn operator in "random on shape surface" mode to generate particles on your shape, then send them out to another operator where they are bound back to that shape with a PhysX Bind operator. Make sure you have a PhysX Shape operator on your shape prior to the spawn operator, so all the resulting particles will be PhysX meshes.