Metadata allows you to better organize assets and scripts and provide flexibility in a rigging pipeline. These notes are from David Hunt's Modular Rigging lecture at GDC '09
Example Meta Node:
global proc string metaNode (string $metaParent, string $metaType)
node type: "network
Connect metaNodes to rig nodes with
stringAttr
messageAttr
Add standard attributes to all metaNodes
metaType (string)
version (int)
metaParent (message)
metaChildren (string)
-Later we will add more attrs to metaNode types as necessary
In other words, each normal Maya node in your rig (ie., ikHandle, joint, proxy mesh, etc.) has an attribute .metaparent that connects it to a metaNode (ie, metaRigFKIKChain_leftShoulder.ikChain), that contains information about the entire module.
In this way you have a metanetwork that runs alongside your normal node network for easy semantic traversal, and allows pieces to be plugged in to each other without having to hard code pieces of the actual code.
easy to maintain
scripts don't have to guess
allows you to build more complex rig behaviors
great for custom tool building
can also be used to make nonlinear editing animation tool w/in Maya (to switch between multiple cameras in the timeline
MetaRoot (the 'brain' of the rig):
All metaNodes connect "upward" to metaRoot
Directional graph like DAG in the DG
MetaRoot stores global object info (asset-centric)
global proc string metaRoot(string $rootJoint, string $objectType, string $objectTypeValue, string $objectId, string $sourceFilePath);
Semantic Traversal Functions
def listMetaParent(node):
crawl "up" the .metaParent connection
def listMetaChildren (metaNode):
crawl "down" to metaNodes connected to .metaChildren attribute
def listMetaRoot(node):
a reliable way to get metaRoot from any node on the rig
def listMetaChildOfType (metaNode, $metaType)
returns metaChildren of a given type
def listAllMetaChildren(metaNode):
returns all metaNodes "below" the input metaNode
def listMetaConnections (node):
returns a list of all metaNodes connected to the input node (nonhierarchical)
def listSingleConnections (node, attr):
gets a specific node connected to the input node.attribute plug
Object-Oriented Rigging in Skeleton Builder (H. Mackenzie)