access 2nd input in a wrangle

point(1, "P", @ptnum);

probably posted something about this before... but the "1" here lets you access the 2nd input's data.

Quick note about Houdini hair

when using Houdini's toolbar hair tools, pay attention to the highest-level node's parameters.
The groom should take place on a static mesh (laydown a timeshift node), and the deform node will do the movement magic.

Exporting curves to Maya

When exporting curves to Maya as arnold ASS files, you can export "pscale" (this can remain a point value) for thickness. Note, it can be varied along the length of the curves, to create variation/tapering etc. A good way to preview the pscale is to add a "polywire" node. You might have to use pscale/2 for the polywire radius. (remember to blast most of your curves first if there are lots and lots of them!)

In the options for the Arnold archive output, make sure the "export Asstoc file" box is ticked. This creates the bounding box info for the curves.

u value tip

With lines, instead of calculating U values by dividing @ptnum by @numpt, you could - at the very start of the process -  add a float attribute (using Attribute Create), with the value set to @ptnum. Lines by default only have 2 points, so pt 0 will have a value of 0 and pt 1 will be set to 1.

You then could resample the lines once they've been copied onto points (eg for hairs), by minimum distance, so that they are divided more evenly. The U value will have been interpolated correctly.