[Sidefx-houdini-list] Caching fluid sims

jiversen jiversen at rhythm.com
Wed Feb 11 17:57:05 EST 2009

jlait at sidefx.com wrote:
> On Tue, Feb 10, 2009 at 01:26:25PM -0500, craigleehoffman at aol.com wrote:
>> I am caching out a fluid sim by appending a File SOP to the bottom
>> of the AutoDopNetwork (as is done in the tutorials), setting it to
>> "Write", and then setting it to "Read" when it is done.? But when I
>> change frames and expect a fairly quick update due to the "Read"
>> File SOP being activated, I get a lengthy wait with things like "DOP
>> Pre-Simulation Step" and "DOP Network Cook" over and over in the
>> lower left-hand corner of the interface like it is re-calculating,
>> and I end up cancelling because it is taking too long.
>> Any ideas what I am doing wrong?? The fluid sim data is out there on
>> disk just fine and took over an hour to calculate and write out, so
>> I assume it is good.
>     By default DOPs will reload in all the frames up to the current
> frame.  Loading 100 frames from disk can easily be as slow as the
> original sim.   One work around in 9.5 is to turn on the Timeless
> option on the Dop Network, this will then only cook the current frame
> letting you jump around the playbar only paying the load time once.

The Timeless option can help; but it's a very bad thing that it's at the 
DOPNet level as it renders caching useless along with other things. I 
would so much prefer to see a Timeless option on a DOP node level - with 
the File DOP having this default On when in Read mode - ie., a "Read As 
Timeless".   I will submit an RFE .

>     Still, loading a .sim can be slower than loading the corresponding
> volumes because it loads all the fields while with volumes you can
> extract just the subset you need.  The recommended output from a fluid
> sim is thus usually a .bgeo.gz sequence.

jason iversen
  fx supervisor


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