Marco Melantonio

I found a way.

It doesn't show on the viewport like when using polygons, but the attribute still there.
The only thing you have to do is to connect a "UserDataColor" (will depend of your render engine) on Hypershape on Maya and type the custom attribute name exported from Houdini.

Note: The attribute must be a vertex attribute.

Hey guys! I dig up this topic cause I've a related doubt.

What if, for example, my particles are a fish cluster swimming aligned to its velocity, who stops at some point and we'd like them to point at a specific direction?

I'm not sure if I'm doing rigth, but bellow is how I'm trying to blend the velocity orientation (p@vel_orient) with the target orientation (p@target_orient).

//Blend from velocity orientarion to target orientation
@orient = lerp(p@vel_orient, p@target_orient, chf(“blend”));

The target is working fine, but I'm stucked in how to replicate the same align to velocity behaviour to save under the p@vel_orient attribute in order to work with the interpolation?

Or, if there is a better way, please let me know. Thanks!

UPDATED BELLOW

I found this other discussion answered by Matt (tokeru)
https://forums.odforce.net/topic/27316-rotateorientalignmentquaternionsetc/ [forums.odforce.net]

The code bellow does the trick, but the orientation gets crazy when the speed gets closer to zero.

p@vel_orient = dihedral({0,0,1} ,@v);

A blur in the velocity make it better but don't fix all the problem.
Now I'm trying to fix that.

Any suggestions are welcome.
Thanks!

chrisgreb
You can set your ‘Cache Mode’ parm to ‘Read’ or ‘Automatic’ and re-cook your node. It should pick up the expected output and all your items as cooked right away.

What if we are using ROP Alembic? Like when we have a heavy mesh been exported in a single file, where some frames are failing?

A workaround would be to export an alembic sequence… But I've no sure if there is a way to merge them together later or if we have to create another task just for this.