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When enabled the particles' vorticity is calculated.
You have to activate the channel in the "Export" tab's "Particles cache (.rpc)" resource, otherwise the data will not be stored. The same applies to "Particles cache -Alembic- (.abc)" entry.
Normal
When enabled the particles' normals are calculated. Here we talk about the surface normal at the associated particle’s position.
You have to activate the channel in the "Export" tab's "Particles cache (.rpc)" resource, otherwise the data will not be stored. The same applies to "Particles cache -Alembic- (.abc)" entry.