Xpresso and rig building

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Old 10 October 2005   #1
Xpresso and rig building

Can anyone point me in the right direction to learning xpresso for rigging? Rigs contain express but there hard to figure out. I know about the global rotation and global position and such like that, but I am not really sure on how combine them in order to get a good rig. I am useing cd ik tools if that helps you. But I am just scratch your brains and hopeing to get some help with xpresso and rigging. I know how to set up the bones and such in CD IK but I don;t know how to set up good constraints so that my rigs will be working right. I know others are looking for this info too, so maybe if we can start a tips guide or such of useful xpresso set ups for others to add to there rigs that would be great.
 
Old 10 October 2005   #2
Howdy,

Well, when setting up constraints in Xpresso there are two important tips to remember: Exectution order and Priority. The execution order in the OM is top-down for objects and left-right for tags. If you're constraining an object high up in the list to one that's low down in the list, then it's trying to constrain to an object that hasn't been positioned yet. So, you'll get a delay or lag in the constraint. You can change the Xpresso tag's prority setting to a higher number so that its execution will be moved up in the prority list, or if it's possible, you can move the target object up above the constrained object in the OM. Which method you use depends on how your hierarchy has to be set up.

When it comes to rigging, you need to keep this in mind and set up your hierarchy to get the best performance from your constraints.

Adios,
Cactus Dan
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Old 10 October 2005   #3
Originally Posted by Cactus Dan: When it comes to rigging, you need to keep this in mind and set up your hierarchy to get the best performance from your constraints.

Adios,
Cactus Dan


Yea most xpresso you see on rigs right now is likely to be some sort of constraint as Dan said. Fortunatley there are two plugins that iwll cover msot of this for you, either Dan's constrain plugin, or Third Party's CAR tags plugin which has a constrainer tag. both systems can do most constraints quickly and easily and perform better then xpresso variations.

The Key thing with constraints is more in how you set up your hierarchies of both your skeletons and your controller, the constraint is typically going to serve one of two purposes, either ton connect seperate hiararchies together, or to a connection between a controller object and a bone there are a few other uses but most will be one of those two.
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Old 10 October 2005   #4
Talking

you can take a look at this rig i made with CD's Iktools. it may give u some kind of idea of what kinds of expresso to use and where to use it. this thing is Not perfect by any means. just think of it as a learning tool to grow from

http://webpages.charter.net/deolsons/GENcdik.c4d
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Old 10 October 2005   #5
Hey Guys,
I thought I would pipe in too. Although my rig doesnt use CDIKTools it does use a bit of expresso. What I set out to accomplish with my rigging tutorials was a basic rig that would complement any other toolset available.

In my experience to get a decent rig going you need (at least) an up vector function of some sort, a global rotation function, a target function and some sort of IK constraint system.

Putting those peices together into more functional hierarchies like spines , rotate plane solvers for arms and legs and global rotations for things like hands and feet can take a bit of experimentation. I think that it can be argued that more than a few examples of each are available.

Dan touched on something pretty important in that calculation order is something to be aware of. You may have all the right tags on the right objects but in the wrong order in the OM. Also thing slike spines can be problematic becasue their hierarchies can run pretty deep and their calculation order may have to be setup to work from th edeepest most object to be calculated first.

I dont know how well my rig plays with CDIKTools although I think that some CA functions should be fairly universal.

hope any of this helps
-Danny
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Old 10 October 2005   #6
Those are some good tips, can anyone point me in the right direction on seting up a good right with xpresso? I will check out your rigs you posted. Also has anyone done that mocca rig tutorial and tried it with cdik tools becasue I know they use xpresso, but can that same expresso be applied to other rigs with CD IK tools?
 
Old 10 October 2005   #7
Originally Posted by Stray: Hey Guys,
In my experience to get a decent rig going you need (at least) an up vector function of some sort, a global rotation function, a target function and some sort of IK constraint system.
-Danny


good list, and believe it or not everyone of those can be done entirely with xpresso, and
Chap here on cgtlak that I worked with on an HP commercial last month, actually managed to get an IK solution of sorts entirelyw ith xpresso no CDIK or MOCCA at all, and fairly stable though lack the upvectors but there are already a few xpresso upvector solutions out there.
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Kai Pedersen
 
Old 10 October 2005   #8
Howdy,
Originally Posted by backlashcs: Also has anyone done that mocca rig tutorial and tried it with cdik tools becasue I know they use xpresso, but can that same expresso be applied to other rigs with CD IK tools?

Yes, CD IK Tools is a set of Expression tags, so you can mix any other expressions with a rig built with CD IK Tools. The only thing to watch out for is that you don't try to have more than one expression trying to do the same thing to an object, so that they are fighting each other for control of the object. That goes with any expressions, whether they are two Xpresso tags fighting each other or an Xpresso tag fighting with a plugin expression tag.

The only real difference between an Xpresso expression tag and a compiled C++ expression tag is the execution speed, and of course the other functions that C++ has more access to in Cinema 4D.

Adios,
Cactus Dan
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Old 10 October 2005   #9
so therefor is xpresso really needed? or can I still build a stable good rig with only useing cdik?
 
Old 10 October 2005   #10
i use mocca with cdik tools for all my rigs. but yes to answer your question you can build any rig you want from cdiktools without xpresso,however if you need constraints you will have to use any of the 3 methods, id recommend one of the plugin ones as xpresso tends to slow down some.


Mike
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Old 10 October 2005   #11
Howdy,
Originally Posted by backlashcs: so therefor is xpresso really needed? or can I still build a stable good rig with only useing cdik?

Well, these days, I use my CD Constraints plugin when I need constraints, but I use Xpresso a lot for when I add User Data controllers to my rigs. CD IK Tools will give you a stable rig to begin with, but to add custom controller setups you need to add User Data controllers and tie them in with the rig through Xpresso.

Adios,
Cactus Dan
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Old 10 October 2005   #12
what do you mean when you say "user data controlers"? are you talking about the feature to add sliders and such to the hud?
 
Old 11 November 2005   #13
bump anymore advice on things I can read up on to get myself started in xpresso for rigs?
 
Old 11 November 2005   #14
Howdy,

Hey, this thread got moved.

Well, the two best sources for Xpresso techniques are Maxon's web site and Srek's web site: http://www.bonkers.de/

It's difficult to say "you need this Xpresso" or "you need that Xpresso" for a rig, because every rig is a bit different. For example, the elephant rig that I did is using an Xpresso setup similar to the "Follow the Leader" tutorial on Maxon's web site to set up the ears so that their movement lags a bit.
http://www.cactus3d.com/ElephantRig.mov

Adios,
Cactus Dan
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Old 11 November 2005   #15
you can build an animatable stable rig without any xpresso (well I might bite my tongue a little and say with CDIK you should be able to, mocca won't be totally stable without a little)

Thing is you'll be left with awkward aniamtion hierarchies andlimited controls. The idea behind using xpresso si tosimply things for the end user, the animator. A riggers job is not just to make a character movable, but make it as easy as possible to work with and perform as fast as possible. This is where rigging becomes more of an art then most people like to treat it.
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