"Save Houdini scene (HIP)" in UE4 File menu generating empty .hip file

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Hi,

I have multiple multiple HDAs in a map in Unreal, and if I open the map and then select the “Save Houdini scene (HIP)” in the drop-down File menu, the .hip file it exports is missing all of the HDAs.

If I alter an HDA in the map or force it to recook, then it will be present in .hip files that are saved out afterwards, but for a large number of HDAs this can be a tedious process.

From this behaviour it seems to me that an HDA in an Unreal map needs to be “woken up” by getting it to cook before it will show up in a saved .hip file. Is there an easy way to save out a .hip file of the houdini scene from an Unreal map without recooking the HDAs first?

Thanks,
Francis.
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Hi,

This is exactly the way things are supposed to be working.

When you load a level in Unreal, none of the placed Houdini Assets are actually instantiated/cooked in Houdini, only their Unreal equivalent (Static meshes etc..) are loaded with the level.
Their houdini counterparts are created/updated only after you've used them, by changing parameters, or inputs..

If we didn't do things this way, loading a level with Houdini assets could take a very long time (since all the HDAs would need to be instantiated and cooked). This would also mean that a Houdini Engine license would be required for everyone loading a level that contains Houdini Assets, even if not using them, since this would be a part of the “loading a level” process.

The only way for all the HDAs to appear in the saved hip file is indeed to recook them all.
If you don't want to recook them all manually, then you can simply use the Houdini.CookAll command before saving the hip file.

Cheers
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I figured that this was likely to be the case, thanks for the prompt and thorough explanation!
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