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HDA doesn't cook the same way in Unity as it does in Houdini

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Varun_studentaccount
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I have a SciFi Stair Generator HDA that I made in H20.5 by following Simon Verstraete's H18.5 tutorial on the SideFX website. I was able to work out the outdated changes to get it working and it works perfectly in Houdini no matter what the parameters on the HDA are.

However, after bringing it to Unity, the HDA does not cook the same way for certain parameter values.
This happens in two ways:

1) Either the Geometry becomes wonky, folding in on itself and whatnot, with weird shading. This is unexpected because the same values work correctly within Houdini.
2) The Geometry cooks correctly, but the Shading is weird, turning it into a standard white Lit shader with only certain shaded spots.

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The workaround I have found for now is to play with the parameters until the Geometry is correct, then baking it and reapplying the same Unity Material on it manually that is defined inside the HDA. This fixes the weird Shading.

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I have attached the HDA with this post. It won't let me attach the whole Unity Project in RAR format, so I've only attached my Materials.
Image Not Found
Edited by Varun_studentaccount - Sept. 14, 2024 11:44:07

Attachments:
VEDA_SciFi_Stair_Generator.hdanc (60.4 KB)
M_Stairs.mat (4.0 KB)
Stairs_Trim_Texture.mat (10.0 KB)
Stairs_Trim_BaseColor.png (3.2 MB)
Stairs_Trim_Emissive.jpg (132.6 KB)
Stairs_Trim_MaskMap.png (4.6 MB)
Stairs_Trim_Normal.png (4.1 MB)

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Varun_studentaccount
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Screenshots of the problems and correctly baked outputs attached.

Wonky Shading:


Wonky Geometry:

For the same parameter and Curve positions as the above, it cooks correctly in Houdini:



Baked (fixed) Geometry with Material manually reassigned when Shading was wonky:
Edited by Varun_studentaccount - Sept. 14, 2024 11:34:25

Attachments:
HDA wonky shading.png (541.9 KB)
HDA impossible output weird geometry.png (422.8 KB)
HDA correct baked outputs.png (764.5 KB)
HDA correct cook in Houdini.png (1.2 MB)

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dpernuit
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Hi,

Tried on my end and I only get wonky geometry when using custom curves - both in H and Unity.
Likely the issue lies in the HDA - as I get the exact same result between Unity and H.

Have you tried using Session Sync to debug your asset?

In Unity: Houdini Engine > Session Sync.
Then in the session sync panel - disconnect (if you already had a session) then start Houdini.

You can then rebuild/recook your HDA - and it will show up in Houdini.

This likely will help you debug your HDA.
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Varun_studentaccount
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Okay, I will try and let you know, thank you!
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