Rotations are initiated from the friction generated between the particles and the collision object. You can control the nParticle object's tendency to rotate during collision by adjusting the Rotation Friction and Rotation Damp attributes. The Friction value of the collision objects can also affect the tendency of particles to rotate. Rotation Friction does not change how Friction affects nParticle motion during collision.
When on, nParticles rotate on a per-particle basis after they collide or self-collide. Compute Rotation also creates Rotation PP and Angular Velocity PP per-particle attributes on the nParticleShape node.
When on, Compute Rotation adds Rotation PP (rotationPP) and Angular Velocity PP (angularVelocityPP) per-particle attributes on the nParticleShape node. You can use Rotation PP to rotate instanced geometry on a per-particle basis. See Rotate instanced geometry in the Dynamics guide.
Rotation PP (rotationPP) and Angular Velocity PP can be used with expressions to add and control per-particle rotations. Rotation PP is the current rotation of the particle and Angular Velocity PP sets the rotational velocity of the object about its origin.
If Compute Rotation is turned off, you can create an expression that checks for collisions during the current frame, and then initializes angularVelocityPP for particles that collide. Also, for all particles, you can update the rotationPP using an expression that adds angularVelocityPP, multiplied by the frame length in seconds, to the current rotationPP value. Be aware that if you use Rotation PP (rotationPP) or Angular Velocity PP (angularVelocityPP) in an expression while Compute Rotation is on, the Nucleus solver updates any Rotation PP and Angular Velocity PP values set by the expression.
You can use Rotation PP to rotate instanced geometry on a per-particle basis. Rotation PP and Angular Velocity PP can be used with an expression to add and control per-particle rotations.
Sets the amount of friction that is applied to particles during collision or self-collision. Increasing Rotation Friction increases the tendency of particles to rotate. When set to 0, particles do not rotate.
You can add Rotation Friction PP as a dynamic attribute and use it to control rotations in an expression.
Specifies the amount of damping applied to the nParticle's rotational velocity. Increasing Rotation Damp causes particle rotation to slow down after collision or self collision. When set to 0, no damping is applied to the rotation, causing the particles to rotate forever if no collisions or self collisions occur.
You can add Rotation Damp PP as a dynamic attribute and use is to control rotations in an expression.