Help particle like obiactor

[josemendez]

I have to use the renderablePosition or the "classic" one?

It depends on what you want to do. As the name implies, "renderablePositions" are used exclusively for rendering. Modifying them has no impact on the simulation, as they are reset to the (possibly interpolated, depending on your settings) regular positions right after simulation has finished each frame.

Regular "positions" are the ones used for the simulation.

To sum up:
If you want to physically move particles around, use positions.
If you're only interested in "post-processing" positions every frame, use renderablePositions.