About output object's transfrom from HDA

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36 posts
Joined: March 2016
I'm using Houdini Engine for Unity.
I found an incomprehensive behavior as shown below.

For the sake of simplicity, I use a simple HDA which outputs the input as it is.

Case 1
The input is a GameObject(empty) which has two children GameObjects.
Parent's position is (0, 0, 5).
Child 1's position is (0, 3, 3).
Child 2's position is (0, 3, -5).

Then the output becomes this.

This result seems fine as I expected.

But in next case, I can't understand why the HDA outputs like this.

Case 2
The input is a GameObject(empty) which has a child GameObject.
Parent's position is (0, 0, 5).
Child's position is (0, 5, 3).

Then the output geometry's position becomes this.

I expected this output's position not to be changed just like with Case 1, but it`s position did in fact change.

Is there any solution for this behavior?
Edited by aoi36e - Jan. 19, 2022 23:01:09

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100 posts
Joined: Dec. 2020
Sounds like you might have the "Keep world Transform" option on when you input your meshes? This is on by default. This retains the world position (in Unity) when we input it into Houdini. If you turn it off, I think that's what you're looking for.
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36 posts
Joined: March 2016
Thank you for your reply.

Yes, I checked "Keep world Transform" in both case.

Event if I didn't check "Keep world Transform", this problem is not changed.
When I check "Keep world Transform", this results became as shown below.
This time, I updated the HDA. The input is gray box. The Output is red box. And gray and red squares are these origins.
The square objects are not in input game object.

Case 1. (two children)

Case 2. (one child)

This is not that I expect neither.
The difference between Case 1 and Case 2 is these origins and offsets.
Case 1 keeps children's offset.
But Case 2 doesn't child's offset.

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