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Cassidy van Dyk avatar image
Cassidy van Dyk asked ·

Read Cd attribute from Houdini splines in C4DtoA

Hi there,

I am trying to read a Cd attribute on alembic splines created in Houdini but can't seem to get it to work in C4DtoA. I have no problem reading the Cd attribute from Houdini particles...


Thanks

splines
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Peter Horvath avatar image
Peter Horvath answered ·

In theory all attributes, including Cd should be picked up by the Alembic procedural. We'll take a look if there's a bug somewhere. Meanwhile, do you have any errors or warnings in the console log?

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Cassidy van Dyk avatar image
Cassidy van Dyk answered ·

Sorry, newbie question — where can I check the console log? Also, would you recommend a user data shader to access the cd attribute? That’s what I have in my setup currently.

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Yes, a user data shader should do it.

For the Arnold log:

1623793700070.png

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1623793700070.png (333.6 KiB)
Cassidy van Dyk avatar image
Cassidy van Dyk answered ·

Thank you.

Here's what I'm seeing in the console:screen-shot-2021-06-16-at-12748-pm.png


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Looks like the data is not there or invalid. Have to take a look.
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Cassidy van Dyk avatar image
Cassidy van Dyk answered ·

Does that mean there’s an issue on the Arnold or Houdini side?

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Don't know yet, we have to investigate.
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Could we get a simple Houdini scene to see how Cd is being set on the splines?
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Cassidy van Dyk avatar image
Cassidy van Dyk answered ·

I'm getting an error when I try to attach the Houdini file to this thread...

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You can rename it to a ".txt" file
For example:

maya-arnold-usd-test.hip.txt

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Cassidy van Dyk avatar image
Cassidy van Dyk answered ·

Thank you. See the working file attached :)


Point_Painting_Basic.txt


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Stephen Blair avatar image
Stephen Blair answered ·

I don't have your texture, so I used a test UV grid texture.

It's picking up the colors, but there's no much variation, even in Houdini (so I wonder about the UVs?)

1624305599136.png


1624305599136.png (1.7 MiB)
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Cassidy van Dyk avatar image
Cassidy van Dyk answered ·

Hi Stephen,

Thanks for looking into it for me. I've attached an updated Houdini file as well as my original texture. There was quite a bit of variation between colors (see a screenshot of the Houdini file)... C4D / Arnold just doesn't seem to pick any of it up.


screen-shot-2021-06-22-at-92845-am.png

photo-1579009120005-df2fd9baf7e5.jpgPoint_Painting_Basic.txt



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Cassidy van Dyk avatar image
Cassidy van Dyk answered ·

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Stephen Blair avatar image
Stephen Blair answered ·

Cd is there, but even in Houdini I can't get anything except pale red if I render popnet or trial (see my previous post and screenshots).


1624318798555.png


If I export the ABC from attribfrommap, I get something in C4D too:

1624318865743.png


1624318798555.png (972.8 KiB)
1624318865743.png (1.5 MiB)
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