Duncan Brinsmead posts a look at creating spiral motions for particles using expressions in Maya, demonstrating two methods for doing so, with a displacement method and a method that uses a force.
This method propagates a local up vector for the curl so that the twist direction does not go through pole flipping as the particle changes direction
The displacement method preserves the particle’s normal trajectory and collision behavior by applying the curl as a displacement from the original particle path, making the curl as a post-dynamics displacement, separating it form the particle overall motion in the scene.
The force method actually applies the curling motion as a force that will affect the particle velocity instead of displacing the position. Duncan notes that this can be more of a challenge to control, but may actually provide more natural movement.
Check out the post for Duncan’s look at Curling Particle Trajectories in Maya here.
