Forces tab menu.
Check this box to enable particle forces.
If enabled, connections will only be made between particles in the same group.
This value represents the number of particles any one particle can affect by its forces of attraction and repulsion.
The more particles, the longer it takes and the more iterations are needed to complete the solution.
xpConstraints_Forces_Forces Limit_v01.mp4
Animation to demonstrate the effect of the Forces Limit parameter, with the value raised from 1 to 30.
This setting alters the influence each constraint type provides to the overall solution.
Particles will attract one another, but only if the distance between them is less than the Radius value.