Houdini Fur advanced grooming techniques

[alfo@gmx.com]

Hi ,

im quite new to the houdini world, and thanks to the forum and lots of free video tutorial im getting quite excited about it.

I was wondering if you can point me out to the right direction on understanding better the way Fur grooming works in houdini .

For example what kind of techniques should i use to add custom guides to a groom, how would i go into modeling or comb the length of the existing guides ( for example if i want to create an Elvis looking spline/guides),

Should i model the Guides splines or the Clumps ones (i know Guides are for dynamics but in other softwares are also for the look, what about clumps?) ?

From the fur preset i can only enter the guides/clumps as a whole, can i separate them to act on a one by one? or at least is there an easy way to get to one curve only components at time?

How can i set a rest/goal pose for the dynamic curves guides, can i act on indivudual guides aswell???

Do you think would be possible to paint in view port a curve, moving the mouse around on a view plane/surface (with the paint tool?), and tell the surrounding guides to follow that painted curve?

Or is there a way of selecting few exact guides and make them follow a poligonal surface ( i tought maybe modeling out a modified poly cilinder and making the surrounding guides to snap on the cilinder lenght )?

The brush comb that houdini uses at the moment, are only working from the bottom of the guides i think they are nice but when it comes to a more advanced/specific type of creature/groom, i find them hard to use.

I come from a maya background, and im trying to get my head around houdini, i simply fell in love with mantra and im trying to switch my fur/render pipeline from maya to houdini.

thanks

[goldleaf]

Indeed, right now there aren't fur tools to comb the hairs themselves like in most other grooming tools. They only paint surface attributes.

However, you can use any tools you like to shape, deform, and manipulate the curves; and if you search around on odForce and the SideFX forums, there are threads on how to do volume sculpting of fur/hair.

Also, the advanced fur tutorial that comes in the docs is really well done; you should check it out: http://www.sidefx.com/docs/current/fur/advancedfur (if you launch the help from your local Houdini, I think the pictures will probably work; not sure why they don't in the online docs)

[alfo@gmx.com]

Hi Chris, thank you so much for the reply, as you suggested im now studying the help and all the example provided, and im wondering about another question :

The fur wire are following the clump wires that are following the guides wire, but it seems theres no way to tell (or at least i couldn't find a way..) the clumps wire to be exactly matching the Guides wires ?? In quantity position and shape? is this possible?

Edited May 3, 2013 by alfo@gmx.com

[goldleaf]

Certainly you can. Just merge the Guide curves from the object1_fur/guides into object1_fur/clumps (and make sure the display flag is set to the merged guide curves), and that should do it.

It's sort of daunting at first, but after poking around inside the fur object you get from the shelf tool, and reading the advanced help like you're doing, it all makes sense and you get to see what goes where and how to tweak and change it. Playing with fur led me to learning the wire solver a bit, and I made this as a learning exercise (and with lots of help of course!):

So much fun to learn stuff

Edited May 3, 2013 by goldleaf

[alfo@gmx.com]

Thank you again for the quick reply! And yes , the more i dig into it the more i like it!

Your test looks great i like the dynamic between plugsgeo to pugsgeo, it makes it look very realistic.

are those "guides" wires symulation? they do have hair to hair dynamics built in?

thats one of the reasons why i wanted to merge my clumps on top of my guides, so when it comes to dynamics the guides are bouncing off eachothers without intersecting? (its all a supposition at the moment..)

[goldleaf]

Thanks for the kind words!

By default, the guides don't sim. There is a shelf tool that does that sets it all up for you though; it's almost all the way to the right, on the fur shelf. You can even control some sim parameters on the fur object, in the physical tab.

You'd have to turn on self intersections on the wire solver itself, it's not on by default, because its pretty slow. And honestly, most of the time you can't tell. But you can when you need it.

[alfo@gmx.com]

Here i am with few more questions..:

Is there a way to precisely comb the hair direction to follow a custom axis/ vector that i want ?

Ideally what i would like to do is to select some guide or vertices, and tell the guide curves to comb / follow one direction, unfortunately using the comb brush, it is very VERY hard to make all the hair to go straight follow one direction.. if i make one set of hair the way i like, than rotating the view to fix the rest of the hair, will screw up the one i just fixed and goes on in an infinite loop of unsatisfaction..

And, is there a way to do the same thing, but with the Bend?

i think those are more of modelling techniques maybe than hair related tools, but in maya for example, i could simply apply a bend or a rotation on the spline curves itself, based on a custom pivot, than move the bend modifier pivot where i need it to be, and bend the SELECTED curves by that pivot.. ?..

i not intend to do it the same way i do it in maya , but i think is a pretty basic thing that i can't seem to figure out how to solve.

[alfo@gmx.com]

Little update :

i managed to "solve " the first point about a FurGlobal comb dir, using an attribcreate placed between add_furdirection and comb1, i basically created a type vector that connects to furdirection, and using the values i can give the fur an initial global direction.

I don't quite know yet if it is the correct way of doing it..but so far seems to work, and i can still comb the direction afterwards..

any ideas for the other points? For the Bend the same tecnique doesn't work..maybe im missing something..

one other thing, when i paint the Bend attribute, it seems that the guides of fur bends in random directions..? Painting the Twist also doesnt seem to have a precise controll on which guides i want to bend which way... am i missing something?

[woodenduck]

For something like a quiff, you can use a few selectively placed clump hairs with the tightness ramped up. You can use any curves you like and you can use the same curves as guides, you just need to make sure they have the correct attributes, clumporigin/clumpshape for the clumps and guide origin for the guides. If you are going to simulate then it would be nice to have the klinear and kangular on those guides too.

Here's a simple quiff -

WD

quiff.hip

[alfo@gmx.com]

Thank you very much for the example, this is a pretty cool styling way!!

The only thing im trying to understand is that on rendertime the hairs in your example are all following the only clump 1 hair that is visible and is pointing to the side, thou instead in the viewport the hair clumps are all following the curve you created?

Question : Is there a more effective way to get the curve/s number/name instead of having to group/select all the points that are creating that one/multiple curves?

-a