Partitioned PCG graph dependency propagation doesn't work properly after recent UE5 main update

Development World Creation
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1

Hello,

Recently, after merging changes up to Epic main CL 49673189, we started having issues with partitioned graphs properly propagating changes among themselves.

Our setup looks something like this:

  • Partitioned graph A samples Landscape
  • Partitioned graph B sources data from single graph A by the 'Get PCG Component Data’ node and samples points according to data from Graph A
  • Partitioned graph C sources data from multiple graphs B via the 'Get PCG Component Data’ node, does some operations on the data from Graphs B, and displays the data in the scene

The issue is that if we make changes to the landscape, only the graph that directly samples the Landscape data gets called properly 100% of the time. The rest of them(Graphs B and C) not so much, altough they should also be run again since their input data changed and their ouput is now invalid. We’ve noticed that the results are a little bit random from PC to PC, but overall, it doesn’t work properly 90% of the time.

Previously, when we were working at revision //UE5/main at CL 47892199, it used to work without any hitches.

On all of our Get PCG Component Data nodes, we are using the Always Requery Actors option.

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The only way we managed to get the system running again was by adding a Landscape dependency to the Get PCG Component Data - it doesn’t have to be plugged into the Get PCG Component Data node specifically(other places worked fine too), that was the most sensical place to put it for now, since it is used as a “Get Data” refresh trigger.

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Any ideas on how we could fix these issues with graphs not triggering/outputting data correctly, so we can get rid of the Landscape dependency?

Cheers,

Adam

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2

Hey Adam,

we did a pretty big refactor around the dependency tracking between those version ranges, so it’s quite possible that something could have broke during that.

If you could provide us a small repro project that still exhibits the issue that would help speeding things up, since the team has limited availability this week.

Otherwise I’ll likely have time on Friday to look into this more closely. I’ll let you know if I hear something earlier or in case we have further questions.

Cheers,

Sebastian

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3

Hey Sebastian,

I’ve been pretty backed up myself this week, so unfortunately, I didn’t have spare time create the repro project.

I can probably look into it next week if you still need it.

Thank you,

Adam

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4

No worries! We’ve managed to reproduce it locally and it’s definitely some fallout from the recent refactor.

We’re working on a fix, I’ll let you know once there is a CL.

This will definitely be fixed before 5.8 for the general users, and hopefully should be in main by next week.

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5

Good news,

We’ve submitted a fix for the dependency tracking in CL50908905 in UE5/Main.

This should solve the problems you’ve had, let us know if that’s not the case. Our repro is fixed, but there might be potentially other fallout from the refactor we’ve missed.

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