Masa murakami

Hi, I have a question about a TOP Network process (please see the attached picture).
I want to run two steps when executing Dirty and Cook:

1 - Run a Python script that updates or sets a new cache path on a File Cache node.
2 - Then run the actual simulation using a ROP Fetch node.

The problem isn’t with the Python script itself, but rather that the Python Script node seems to execute in the background Houdini session used by TOPs, instead of the current local Houdini session. I want the script to apply changes to my local session, and then trigger the ROP Fetch simulation task.

I suspect that using a Python Script node isn’t the right approach here — I probably need another method to execute the script locally before running the ROP Fetch. Or maybe I could fix the python node by changing parameters like a Generate When parm or Evaluate scripting During parm, etc, not sure at all. 

Of course, I could just run the Python script manually and then Dirty & Cook the network, but I have multiple dependent simulation steps, and I don’t want to manually update the File Cache nodes every time.

So, is there a recommended way to achieve this?

Yes, I did, thanks. But it seems that instancer + retimeInstancer LOPs have some limitations/problems, and sidefx needs to develop more.

npetit
In your particular case, using a static frame offset is relatively simple and will allow you to (almost) scrub the timeline in realtime using the retime instances LOP. Here's an updated hip file that uses the frameoffset instead of the explicit frame method.

Using an explicit frame for retiming instances is notoriously slow as it will create new retimed references at every frame. If you don't care about having smoothly interpolated retimed prototypes, creating all the individual frames as prototypes and switching prototypes accordingly is definitely an option as Thomas suggested. You can submit an RFE for us to look at adding it as an option to the retime prototypes LOP.

Hi, could you update the sample file, instance_growth_v01.hipnc (2.2 MB) again? Downloading has been failed.
I have the exact same issue that retime instance crashes a lot, so would like to take a look, thank you!!