Since engine version: 5.3.3 OC
The value depends on the current angle of movement of the particle. Usually the factor-parameter can be left out, since the original purpose of this function is to be used for the rotation-property.
array PV_Direction(int factor);
- [opt] Factor to multiply the angle with. The factor of 1000 is equal to a real factor of 1.0.
See the particle documentation for further explanations of the particle system.