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DanFor

DOPnet transform Q?

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Hi,

Currently transitioning to Houdini, and I would really appreciate if some kind soul would help me by explaining the following:

How does a Houdini DOP network deal with nested transforms?

I am currently simulating a sail using cloth. It works quite well, but I have noticed that if I move the sail geometry (by transforming the geometry node or the bundle containing it), the dopnet seems to ignore these transforms. This is visible since when stepping into the DOPnet, the dynamic object will shift in view.

So, I am currently confused regarding the right way to set up and transform a system that will be dependent on outside objects (in this case, the mast and rigging that will be moving),

 

Any explanation or advice would be most welcome. Many thanks in advance!

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Just to add my first findings:

- It seems that having a subnet with a geo node and a dopnet, and transforming the entire subnet will throw off the dopnet. Ie, it ignores the subnet world pos?

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..and I found some older posts where the conclusion seemed to be: Don't put sims in subnets.

Which prompts two follow-up questions:

- If I have a more complex scene with multiple simulations, how do I keep it organised on a scene level? I do not really want a bunch of separate dopnets on scene level.

- One solution I have seen in tutorials is to actually create the dopnet in the geo node (besides all the modelling stuff):

    1. Is this recommended?

    2. If so, how can I move an existing dopnet into a geo node? Copy/paste does not seem to work...

 

Again, many thanks for any help!

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Providing a file regarding your transform issue would be helpful as I'm not quite sure by your explanation what your trying to do exactly (apologies for my lack of understanding)

- But regarding multiple dop networks, I almost always especially with custom non shelf tool solutions put them within a geo node rather than having lots of dops at obj level like you said, and keep any other related geo/calculations in their too and then use network boxes inside the geo (obj level) node to keep it all organised.

Never particularly found any issues or limitations with doing that either, and is quite common practice I believe

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Thanks for the reply!

I would really like to keep the sim networks at least one level down (in their respective geo nodes) to keep the project from getting cluttered.

However, I now have them on scene level and can't seem to move them into a geo node... Any idea how to achieve that? (As mentioned, I can't get cut/paste to work...).

 

Regarding the transform issues it appears to be a common issue and it's quite easy to test:

1. Quickly create a cloth object with the shelf tools.

2. Move the geo node around, drop into dop level = no problem, scene view as expected.

3. Create a subnet containing the geo and dop nodes. 

4. Head down into the subnet and into the dop nodes = the simulated object shifts position.

Which is a bit strange... :)

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