Unexpected behavior when controlling emitter velocity in a callback.

[lukashof]

Hi 👋,

I am building a model including an emitter that changes its extrusion velocity during the simulation. I use the callback function to set the velocity before every iteration. The velocity should initially be zero and subsequently be determined by a separate simulation.

I have reduced my model to a minimal example (it's a .txt-file due to GitHub's restrictions). Here the velocity is initialized as zero and then simply set to a constant velocity in the callback.

Unfortunately, the emitter will only emit a single layer of particles and then stop. However, if I reset the simulation from the GUI, the emitter will work as expected afterward.

When the initial velocity is set to a small non-zero value (e.g., 0.1) a single layer of particles is emitted followed by the expected stream of particles. Again, after a reset the emitter returns to the expected behavior.

Am I missing something about the emitter or callback? I am looking forward to any input.

Best regards!