I've just started using Houdini with the starving artist license, and I've successfully applied fur to a horse, combed it, textured it, etc.

But I am struggling to give it a mane and a tail. I extracted a bit of geometry from the top of the horse's neck to generate some new fur for the mane, and I added dynamics to it using the very straightforward “Add Dynamics” tool. But of course it just falls right through my horse because it doesn't know it should collide with it.

I am struggling to find any kind of tutorial that gives me an example of how to add the horse as a collision object for the dynamic hair.

I can handle some high level instruction for this, as I've been using other 3D software for nearly a decade now, and I do a lot of scripting in my professional work. Just point me in the right direction please!!

lisae
I am struggling to find any kind of tutorial that gives me an example of how to add the horse as a collision object for the dynamic hair.

Use the “Static Object” tool (on the “Rigid Bodies” shelf tab) to bring the horse into the dynamics simulation as an object to collide against. If your horse is animated, you will also need to turn on the “Use Deforming Geometry” option on the Static Object node created by the shelf tool.

Keep in mind this will really slow your simulation time. Depending on how detailed your collision geometry is (and how many frames you want to simulate) you may want to parent a simple sphere to your horse rig and collide with that.

in most cases it's best to object merge out the horse into another object > delete the parts that will not collide with the hair then write this out as geometry to disc…then bring it into your sim…and remember to delete ALL groups and attibutes that you don't need form this geometry before writing it to disc - you'll save tons of ram etc

I'm sorry I don't have anything to contribute to your solution. I think derrick, sounds right (he should be ), but would it be possible to show your results with your Fur. I would love to see it.

-andrew

Thank you all! There is plenty of information here.

I already had a lower poly version of the horse for collisions, but deleting the geometry that won't be used makes even more sense.

I will definitely post the results

OK, I've been fooling around with hair and fur on this horse ever since my last post. I haven't quite got it where I want it, but it's all generally working.

So now I'm getting impatient to rig up the horse and start animating it. I watched the quadruped autorig tutorials, and it seems straight forward enough (much like using XSI's rigs, really).

But unfortunately, when I click the quadruped autorig button, the rig comes in at 90 degrees to my model.

It seems that I can't rotate the autorig, so I tried rotating all the bits of my horse. Unfortunately, when I do that it ruins all my combing work as well as the mane and tail simulations. It seems simple enough to re-do the mane and tail simulations in the new position, but I don't want to have to re-comb all the body fur! It has taken hours of work just to get it looking half as good as I want.

I think the issue is that I haven't added any dynamics to the body fur, but I didn't think I would have to. From reading the docs (Animating With Fur), it seems that it at least needs a Rest SOP and a Transform SOP. But I can't see where they are supposed to go in the network that the fur tool from the shelf creates. It doesn't look the same as the one in the docs. And anyway, that page says you can use the add dynamics tool as a shortcut… but I don't want full dynamics on the body fur. I don't think it needs gravity or collisions applied to it, does it? I just want it to move with the horse's skin.

So what do I have to do to this fur so that I can a) rotate my horse model 90 degrees without having to re-comb it all, and b) have it move with the skin when it's animated (which I assume it's not going to do if I can't even rotate the model without messing it up)?

i assume you are trying to rotate it at the SOP level with transform SOP
connect Rest Position node before your transform SOP in your horse object

Problem is, tamte, I don't have a “horse object” - I have a whole collection of objects that make up the horse, including collision geometry and other bits of geometry that have the mane and tail fur attached to them.

Well, I've managed to turn the horse around using the old traditional method of parenting everything to a null and turning that. It took me a few tries to work out which components should be parented and which shouldn't.

But now when I try to re-simulate the mane and tail in the new position, something is going wrong. It seems like the tail hair is colliding with something that isn't there. I don't know, it's messed up.

Anyway, here is my last render of my poor little Mongolian horse. It's still in need of a lot of hair/fur and texturing work, but I would really like to be able to animate him. Maybe one day he will have a Mongol on top of him.

Edited to add: Sorry, I scaled it down a bit now.