Points from hda are only displayed when at frame 1

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Hi,

I create points in houdini which create particles in Maya. Although the houdini_engine node is connected to the time and only updates it's output when the current frame is set to 1. any other values prevent the node from updating the output.

Can you tell me how to fix this issue? Is this a wanted behaviour and I just need to set a property in the hda output parameters?

Cheers,
Georg
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Hi Georg,

I'm unable to reproduced your issue. To test, I created a simple HDA that consisted of a box plugged into a mountain SOP, which was then connected into a scatter SOP with the offsets set to $F/100. Maya loaded this without issue, and the points update over time.

Would you be able to attach an HDA that replicates the issue?

Thanks.
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Okay thanks for your example.
So you example works as well. What I found out:
Only when I add $F and the node gets the clock symbol on it, Maya updates the particles.
If I don't have any $F inside of my nodes, they output is not generated. But I think this should be also updated at least when I click “Sync Asset” (although also changing parameters should update it). If you are working in a scene with a timeline range e.g. 500-700 then you never have the chance to get the points updated.

If you remove your $F from your node and make it non-timeable and plugin a parameter from you hda you will see that in maya the points only get updated when you are at frame 1.
When you combine both
$F * ch("../numpoints")
in the Force Total Count parameter you will see that points update when changing the timeline in Maya, but if you change the parameter numpoints on the houdini asset in maya, all points get lost and it will output: “No geometry generated”. Going back to frame one and sync the asset and the points show upagain!

Sorry, I have no permissions in my browser to upload files to the internet .

I'm using:
Maya 2018.4.6
Houdini Engine 17.5.293

Best regards,
Georg.
Edited by msearl001 - Dec. 8, 2019 19:33:14
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Hi Georg,

I think I understand now. To confirm, if you expose the “Force Total Count” parm to the hda interface, bring the hda into Maya, and try to change that parm, it will only update on the first frame of the time slider, correct?
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Hi John,

Exactly.

My guess is that it even tries to update the particles, but as the hda is not timed (because no $F is used on any parameter) it does not find any output data that responds to that frame and therefore displays an empty particle node.

Best regards,
Georg
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Hi John,

do you have any news regarding this topic?

Cheers,
Georg
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Hi Georg,

I'm in talks with Autodesk regarding this - It's been a bit slow due to the holidays. Hopefully I'll have an update soon.

-John
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Awesome. Thanks for your fantastic support!

Do you might have an idea for a workaround to fake-enable a node to be time-driven so that it takes always the same values for every frame. This way I could make it work for now.

Cheers,
Georg
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Hi Georg,

You may be able to trick it by placing a $F * 0 expression into a parameter.
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Unfortunately the HDA only gets updated when the frame range is changed. So only the $F parameter causes a recook of that node. If I change my numpoints parameter, the HDA also doesn't update.

ch("../points_num") + ($F / 0)

Looks really like there something that needs a fundamental change.
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