The "No Cache" simulation nodes option effectively changes the cache
to work in a "realtime mode" where there are only two states, the
current and previous frame. Whenever the current frame doesn't
increase, the previous state should reset. This didn't happen
properly, and it was hard to verify because the code was shared
with the regular "cache on" mode.
Instead, separate the caching more in the code, using a different
struct to store the two "realtime" states. Also clarify that we
don't support animation of the "No Cache" option by disabling
support for that in RNA.
Pull Request: https://projects.blender.org/blender/blender/pulls/109741
Hans Goudey
80f105e924