Houdini Engine for Unreal
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PDG Asset Link

The PDG Asset Link allows cooking and importing results from PDG Graphs embedded in HDAs directly in Unreal.


The PDG Asset Link will be automatically created by the plugin after instantiating an HDA that contains a TOP Network.

It will display a list of all the TOP Networks available in the HDA, as well as a list of all the TOP Nodes available found in the currently selected TOP Network, and controls to dirty, cook them...



To avoid exposing every nodes in the current TOP Network, the PDG Asset Link uses a filter that specifies a prefix for the node names that controls whether or not they will be listed in the Asset Link UI. The default value for this filter is HE_, so only nodes that start with HE_ will be listed in the PDG Asset Link. (ie: HE_Terrain, HE_Trees, etc...)

In a similar way, another name prefix filter, the TOP Output filter, is used to identify the nodes that produce output BGEOs, and whose results should be processed and created in Unreal. By default, the filter is set to HE_OUT_, so the PDG Asset Link will only try to load Work Item Output files that are created by nodes that start with this prefix. (ie: HE_OUT_Trees, HE_OUT_Roads, HE_OUT_Buildings..._

Those filters can be modified or disabled in the PDG Asset Link UI.

Loading Work Item Results

When cooking the PDG Graph, the PDG Asset Link will automatically import Work Items geometry output files (bgeos) that have successfully cooked on the TOP Output Nodes. The results are loaded on actors that reproduce the PDG Graph's hierarchy:

    • TOP NODE
      • WorkItemOutput1
      • WorkItemOutput2
      • WorkItemOutput3

Despite not being attached to the HDA, it is important to note that "Cooked" PDG results are still considered temporary, like normal HDA outputs would. They are still owned by the Houdini Asset Actor until they are baked. This means that dirtying or changing the PDG asset can potentially destroy or update them, and they will also be destroyed when destroying the Houdini Asset Actor that owns them.

The PDG Asset Link has its own "bake" section, which allow fore more fine grain control in deciding what/how the PDG graph's results are baked. You can choose whether to bake all outputs, only the selected top network, or selected TOP node. You can decide if you want to replace existing assets and actors created from a previous bake or create new ones...

Asynchronous Importer

The PDG Asset Link has the ability to use an asynchronous importer commandlet to import Work Item outputs once they are ready. This reduce lock ups of unreal, and is especially usefull when processing a lot of large meshes.

Asynchronous import can be enabled/started/stopped via the Work Item Import Settings entry in the Houdini Engine menu. The PDG Asset Link will display the status of the async importer in its details UI when using it.

Once started, the commandlet communicates with the PDG Asset Link via a message bus, and automatically imports the BGEO files from output work items, creating their corresponding uassets. After a successful import, the commandlet then notifies the PDG asset link which will then instantiate the uasset in the level.