hi

maybe this is a stupid question but I'm comming from Maya and try to locate some things in Houdini like point, look at and other constraints, set driven keys.
wrap is very nice substitued by inflate (greate tool for character anim)
Another one is that squash and strech of ik chains, how does it work?

thx

“Look at” is right there in the object params, transform tab. You can also do this on the SOP level with expressions if you wish. The other terms I'm not familiar with since I'm not a Maya user. I'll leave that for an ex-Maya user to answer.

Just a suggestion, but I wouldn't try to approach many large, conceptual things as if they were substitutions for Maya operations. There's definitely certain basics that can be mirrored over between the packages, but Maya's approach is very linear, and the proceduralism is only pseudo… You'll get the most out of Houdini if you go through the tutorials and open your mind to a different way of doing things.

Geez, I sound like a frickin' self-help book.

Cheers,

J.C.

ok, I found “look at”, silly me, it was in front of my eyes.
I'm a character animator and I was realy amazed when I saw some tools in houdini (inflate tool, paste, ray and many others)but I wanted to ask if thete is a pdf file or something like thouse “quick guide to migrate from X (3d software) to Y (another 3d software).
Maybe if I give you a short description of some tools you can point me in the right direction:
point constraint- you have 3 objects A,B and C. you want to point constrain object B to A and C. The result is that object B gets snaped in the middle of the line between A and C. Depending on the weight of objects A and C the object B will follow the translations of one or another but will sit in the line between them.
orient constraint- does the same as point but one will follow the rotations.

The most important is ”set driven key“ tool:
-you have 2 or more objects, let's say 2; A and B.
you have an initial or 0, relation between A and B (key) and by relations I mean any attributes of object A with any attributes of object B (ex. rotation of A with translate,rotate and blendshapes of B) Now you alter the attribute of A (rotate 30 degrees) you ”teach“ object B to alter his attributes (to translate 10 units, rotate 45 degrees and go to blendshape no.2). Now you set a key for all this.
To give you a further example let's say you have a null wich have an attribute ”fist“-float from 0 to 1, a slider. What I want is to have connected all the bones rotations from the fingers to ”fist" attribute and when the slider is in 1 status the bones will go in a fist position.

many thx for your help

the maya wrap deformer is the latticeSOP with points turned on.

the inflate is something different.

the BlendOP at object level is the “swiss army knife” of constraints. If you clear your mind and think about what it is doing you will see what it can do. Filter out rotations, etc…
You just have to be aware of the second input so things have the correct transformations. It will give you your 3pt constraint. and orientation.

Lookat funcionality is there as well, you can also use an upvector to control that as well. Currently that is a bit tricky as you just can't drop down an object you need to do some expression stuff in the vector field to allow for the upvector to work.

biggest thing with character tools in general….
noK is what people generally call FK.
FK in houdini is an IK solver per bone in a chain
IK is IK but over a number of bones.
IK with a twist is IK with a “pull vector”
IK with Constraints is IK with the rotational limits on the bones.
IK with Constraints with a Twist. over kill in my opinion.
Follow curve is what is sounds like.

set driven key…
a bit more work than in maya but you just need to master the chf function. in the textport type help chf to get the usage.
Basically it can allow you to look up values in another channel and apply them somewhere else.

other nice things to look at.
fit expressions in a sequenceBlend or a BlendSOP.


hope that helps

-k

You can get much of the Set Driven Key functionality with the LookUp CHOP, which uses one channel to lookup values from another.

Dragos

Salut Calin, mai stii si altii din Romania care tocmai exploreaza Houdini? Poate facem un club

many thx for clear it up for me “thekenny”. In the next days I'll try all that you told me and see how it works. You were right about clearing my mind a bit about the multiple functionality of some OP's.
can you also please explain a bit how this new features “ squash and strech of ik chains” works?

thx again
calin


ps. for Dragos: can you please write me an e-mail on: casian@mail.dnttm.ro for talking about Houdini and 3D graphics in Romania.

squash and stretch has always been there. now it just works a bit better.
there are few tricks to it…

every since they went to the pretransform bones they changed how the second bone finds it position at the end of the first bone chain. It used to be the negative bone length of the parent bone in the z axis. Since they are internalizing this now. you need to always use the +vtorigin(“”,“”)*0 expression at the end of the bone length channel. You can do a simple channel expression cubic()*themultiplierchannel+vtorigin(“”,“”)*0. it just stirs the matrix and the bones done fly off strangely.


try it and it works.


-k

You can achieve the set driven keys effect by right clicking and holding on a channel and selecting copy parameter from the list. Now right click in the channel you want the first channel to drive and select “paste copied references”. This will put a channel expression in there which basically says follow the values. You can edit it with mathematical expressions, for instance if your expression read as follows: ch(“/obj/geo1/tx”) you can multiply the effect like so: ch(“/obj/geo1/tx”)*30. So if this expression was in the tx channel of Geo2 than any value in Geo1's tx will be multiplied by 30 in Geo2's tx. You can have almost any channel power any other channel. And once you begin to understand CHOPS then the fun really begins.

I'm just self-teaching myself Maya now. I use Max and Houdini professionally but Maya is one to know for long form projects like what I wish to get into.

Ian

many thx. I've posted a complex arm setup at od. That is how I manage to do so far. I'm self learning Houdini now. Now I'm trying to model and rig a complet character and since I'm no TD your advise realy helps me.

see ya

I understand that through expressions and chops one can achieve forms of linking and control like maya's setdriven technology.

However I fail to see how one could achieve the same complex control that setdriven has.

Setting up multiple objects to go through various poses all hooked up to a single channel without great stress and fiddling.


With setdriven not only can you set up multiple relationships rather easily but you can also edit the transition and type of function curve that is used to blend between these varoius goals.

You are also not contstrained to a transition to a single goal in mind.

From 0 to 1 …… you could have as many poses as you would want to hit along the way. As an extreme example you could setdrive an entire walkcycle.

Can someone explain how you could achieve something like storing multipe poses for bones/objects for the sake of facial animation?

well, I must admit that was a little hard in the begining to setup a set driven key like in maya but after some time I manage to get it along, now. you can do pretty much more with the Houdini way but you won't get along without some expressions. It's only about the way of thinking and some math, here, in Houdini you must DESIGN the tool, in Maya someone from AW design it and you USE it. I think it's much better to be a designer and a user because than you won't see the tool like a black box. But than again I'm still at the very begining of learning Houdini but maybe the most important lesson was that I realise: I must be a designer too.

True a little more work and thought is required.

But the matter is not any clearer.

Does anyone suppose they could explain how they would achieve a setdriven setup with multiple poses?