Hi!

I'm trying to make a building generator (I'm probably the first to try this...). If I didn't use Unreal, I would simply have my first HDA output the hires main parts of the building and also (output #2) the simplified, box version that could conect to another HDA for the creation of stairs/ladders/balconies/etc. It would basically be a chain of HDAs, each adding an element to the building.

This method is easy in Houdini, but in Unreal, is it possible that:
A) an HDA would have 2 geo ouputs (hires and lowres)
B) use that lowres as an input for another HDA?

If I can't do that, it means I would have to make one uber/super HDA containing absolutely all the building elements. I'd like to avoid that workflow.

-Olivier

... so, there's no way that an HDA ouputs a geo that would be the input for another HDA?

For example, I'd have an HDA that creates a star shaped geo and another HDA that would scatter tiny cubes on the star?

Hi,

You can use "Asset inputs" for that.
Assuming you have two HDAs in Unreal, you can set the "tiny_cube_scatterer" HDA to Asset input, and select the "Star" HDA.

This will effectively connects the two HDAs directly in Houdini, unlike for example, using a World input, which would send the unreal output of one HDA to the other.

See:
https://www.sidefx.com/docs/unreal/_inputs.html#InputsAsset [www.sidefx.com]

The one caveat to that, is that you cant select which output of the HDA is connect to your second HDA's input.

Ah, ok, I just found out each time I rebuild my first HDA (Star geo), it saves a copy of the geo in content browser: HoudiniEngine - Temp - StarGenerator. So, I can click-and-drag that geo into my second HDA as an input.

EDIT: Oh, I saw your post after I wrote this one. Can you give me more info about "set the "tiny_cube_scatterer" HDA to Asset input," ? Not sure I follow.

I see a tab for Houdini Outputs but I don't see one for Inputs...

AHHH!! This is sick! Thanks a lot! Here's an image to show how this works (for anyone else). In my second HDA (scatter_on_Geo), I scroll down to the Houdini Parameters. I changed the the "Geometry Input" (is like that by default) to Asset Input. Below that, you'll see a list where you can pick another HDA as the input. That way, any time I modify HDA01, HDA02 updates automatically!