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juaneche

Liquid mix export to Maya-Arnold

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Greetings.

I am the filthiest of noobs and i found a problem i havent been able to solve.

I made a very beautiful flip fluid simulation in which two liquid sources mix together. (lots of tuts out there so it wasnt hard for me to do it)...... Both sources have different color attributes and density attributes  and they mix flawlessly..... I was successfuly able to do the simulation YAAY!.

The problem comes when our pipeline DEMANDS to render in Maya Arnold........ 

I export the VDB poligon soup via a Rop alembic output node...... and create an alembic file (it exports, it imports into Maya, no problem)

BUT..... when i have it in Maya, I havent found a way to mask the fluids, so an AI mix shader lets me use two AI shaders as the two liquids and lets me mix them as they were in Houdini....... I understand there are "Weight attributes" that come with the alembic and they should be the ones helping me mask the fluids, but i really dont know how to do it...... Im a noob both in Houdini and in Maya.

If anyone could help me showing me the workaround  , i would deeply appreciate it.

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To be able to access alembic point data exported from Houdini in Maya with Arnold, you must export the attributes as vertex color data. The trick here is that it MUST be a color type attribute in houdini, a regular vector will not work, and it MUST be a vertex class attribute. So if you were to create a color node and use one of the RGB channels as your "weight", and then promote it to a vertex attribute it would export properly.

In order to access this data in Maya with Arnold, you need to check the "Export Vertex Colors" box under the Arnold tab on the alembic shape node. Then you can use the "aiUserDataColor" node in a shader network to put your weight attribute to work using a ramp or something.

Also, you can get motion blur data from alembic files with changing topology this way as well. Export your velocity vector as a vertex color and then use the "motion vector source" attribute on the shape node to access the velocity data.

 

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Thank you very much for your swift answer..... i will try some things taking into account your recommendations.

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