hi, I've been asked several times about this effect https://vimeo.com/61015448 so here is the hip file with some notes inside. trail_smoke_on_curve.hip Also I have a question to houdini gurus here please: Is it possible to align the containers along the path in DOPs? If I have the tangent and up vector of every cluster point how can I get the orientation of every point from SOP and align the corresponding container in DOP? I've tried Point Position DOP but can't get it to work. Thanks!