Hello,…new to using vellum and have been playing around with it based off examples from the recent tutorials by Entagma and Rohan to get some orientation with them since I have no experience with them and the related Houdini areas pre H17.

In the pic you can see I have set up a visibility node that shows some of the ‘hairs’ penetrate inside the pig head geometry, around the mouth.

I know what's happening is that the length of the hairs is longer than the ‘cavity’ space of the mouth.

Setting aside that thought for a moment, by adding the pig head to the third input of the vellum solver you get the expected collision results.

That is, as the animation is run the hairs won't cross over the boundary of the pig head and go inside.

Now, although I haven't tried it, I'm pretty sure I could probably doing something with a raysop or use vex and the intersect function and ‘trim’ those hairs down to a length so that they don't cross over the pig mouths boundary initially to begin with.

And as such I believe then no hairs will go inside because they were out to begin with.

Or even something similarly as a post-solver operation to cull or do ‘whatever’ with those particular hairs(that crossed over).

But although I don't need to do this, I am wondering is there some kind of typical workflow where one can keep the initial hair length but not have it cross over the boundary to begin with?;

Maybe like some kind of ‘pre-solve’ for the hair generation that keeps the length and maybe ‘bunches’ up(randomized directions?) inside the mouth instead of crossing over?