The retimer uses the cache, which is saved at rate of one data chunk per frame, regardless of what your time step setting is. It is also linearly interpolated between frames, instead cubicly interpolated. Eventually it would be nice to do cubic interpolation, which would create smooth/curved particle paths between frames rather than straight paths between frames, but that's extremely far down the priority list at the moment.
For retimings with particles following simple trajectories and the overall retime not going to extrmely slow speeds it's fine....but ramping down to 800fps with non-linear particle motion will indeed introduce visual artifacts.
One potential alternative is to export your particles to objects with the Export Particles operator and then scale their keyframes. Since keyframe curves are bezier curves by default you'll then get smooth trajectories. Obviously this method won't be great if you have a huge number of particles though.
You can also adjust your sim force values to replicate how things would look at 800fps, and then use the retimer to speed things up instead of slow it down....basically do an inverse retime from an 800fps look to a 24fps look, rather than 24 to 800.
The time scale spinner doing nothing is troubling...perhaps there's a bug and it's not working correctly...I've made a note to look into it.
For retimings with particles following simple trajectories and the overall retime not going to extrmely slow speeds it's fine....but ramping down to 800fps with non-linear particle motion will indeed introduce visual artifacts.
One potential alternative is to export your particles to objects with the Export Particles operator and then scale their keyframes. Since keyframe curves are bezier curves by default you'll then get smooth trajectories. Obviously this method won't be great if you have a huge number of particles though.
You can also adjust your sim force values to replicate how things would look at 800fps, and then use the retimer to speed things up instead of slow it down....basically do an inverse retime from an 800fps look to a 24fps look, rather than 24 to 800.
The time scale spinner doing nothing is troubling...perhaps there's a bug and it's not working correctly...I've made a note to look into it.