The Algorithmist posted an AS3 character rigging class library. The kit includes some really specific classes for building characters and is quite well done.
The library includes all you need to rig up characters in flash and includes the source, samples for flex and what the hell more could you ask for?
The Algorithmist calls it the Singularity Package and it contains:
Singularity Package Contents (character rigging classes)
All rigging classes are in the Singularity package, which must be added to your path when building a new Flex project. The current package organization for the rigging classes is as follows,
Arm – 2-link bone chain representing right or left arm in a humanoid biped.
BaseBone – Base class encapsulating functionality common to Bones and Connectors.
Biped – Used to create and animate humaniod biped characters.
Bone – Represents a single bone with support for fast propagation of FK transformations in bone chains. The Bone class is optimized for linking bones together in chains.
Chain – Manager class for a single chain of bones.
Clavicle – 1-link connector representing right or left clavicle in a humanoid biped.
Connector – Optimized container for multiple single-bone chains with a single input and multiple terminators. Chains or additional connectors linked forward at each terminator.
Foot – 1-link connector representing right or left foot in a humanoid biped.
Hand – Multi-link connector representing right or left hand in a humanoid biped.
Head – 1-link connector representing a humanoid biped head.
IBone – Bone interface – represents all functionality a bone must implement.
IChain – Chain interface – represents all functionality a bone chain must implement. Chains and Connectors implement IChain and are considered interchangeable when propagating FK.
Leg – 2-link bone chain representing right or left leg in a humanoid biped.
Neck – 1-link connector representing the neck of a humanoid biped.
Pelvis – Multi-link connector representing the pelvis of a humanoid biped.
SimpleSpine – 1-link connector providing the simplest representation of a humanoid biped spine. Used for very simple (but fast) game characters.
Template – Templates are used to skin (or draw bones) for segmented characters. Refer to SimpleSkinTest for examples.
When developing physics and character based animation rigging can help to really speed things along in 3d and here in this case in 2d flash. This allows the developer/animator more freedom to work on the animation and not about redrawing. It also helps to create characters that can be animated from the beginning rather than an afterthought which usually leads to less troublesome issues.
The AS3 rigging classes are used for skelton rigging and skinning of 2D characters. The rigging class library is organized around the development of highly specific articulated rigs. The current focus is on humaniod bipedal characters. In a 3D animation package or game engine, a bone hierarchy would normally be represented as a tree structure. In this class library, bones and chains are organized in a structure that is easier to deconstruct and understand by OOP programmers. This structure has some performance advantages, particularly when propagating FK in a 2D rig.
The only drawback to this kit is it is not fully open source and commercial use must be approved.
The Singularity AS3 parametric curve library requires the Flash 9 player and a development environment supporting Actionscript 3. All demonstration programs were created with FlexBuilder 2. The AS 3 character rigging classes are copyrighted and licensed for personal, experimental usage. Please contact me to obtain authorization for commercial use. The download includes the entire Singularity package (which includes the parametric curve library).
Download library (.zip) here. Before running any example programs, place the Singularity package in your build path.