MItDependencyGraph Class Reference
[OpenMaya - API module for common classes]

#include <MItDependencyGraph.h>

Collaboration diagram for MItDependencyGraph:

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List of all members.


Detailed Description

Dependency Graph Iterator.

Iterate over Dependency Graph (DG) Nodes or Plugs starting at a specified root Node or Plug.

Set and query the root of the iteration.

Set and query the direction (downstream or upstream), traversal priority (depth first or breadth first) and level of detail (Node level or Plug level) of the iteration.

Set and disable a filter to iterate over only speicifc types (MFn::Type) of Nodes.

Reset the root, filter, direction, traversal priority and level of detail of the iteration.

Prune branches of the graph from iteration.

In Maya, all geometry, animation and rendering information is implemented in nodes in the Dependency Graph (DG). The DG includes the Directed Acyclic Graph (DAG). Therefore, all DAG nodes are also DG nodes. The data on nodes is associated with Attributes. Attributes on nodes are connected to Attributes on other nodes via plugs on the Attributes. Plugs are, in effect the external intefaces of Attributes.

The DG Iterator Class (MItDependencyGraph) provides methods for iterating over either nodes or plugs, as well as methods for setting and querying the characteristics and behaviour of the iterator.

This iterator will traverse all attributes upstream or downstream from the root node of the traversal. For non root nodes, only attributes that are affected by the incoming attribute to that node will be traversed. Hence, only nodes to which data from the root node is flowing will be traversed.

The DG Iterator is used in conjunction with the Maya Object (MObject), plug (MPlug), Maya Object Array (MObjectArray) and plug Array (MPlugArray) classes.

It is also useful to use Function Sets specific to the nodes returned by the iterator to query and modify the nodes in the DG.

The DG itself can be modified using a DG Modifer (MDGModifier).

Additionally, nodes can be added to and retrieved from selection lists using the Selection List (MSelectionList) class and Selection List Iterator (MItSelectionList). This can be useful for obtaining the root node for an iteration.

Attributes on the nodes can be manipulated using the Attribute Function Set (MFnAttribute) and its derivations.

Examples:

cgfxAttrDef.cpp, cvColorShader.cpp, D3DViewportRenderer.cpp, findFileTexturesCmd.cpp, findTexturesPerPolygonCmd.cpp, and polyWriter.cpp.


Public Types

enum  Direction { kDownstream, kUpstream }
 Direction within the DG relative to root Node or Plug. More...
enum  Traversal { kDepthFirst, kBreadthFirst }
 Perform a depth first or breadth first traversal. More...
enum  Level { kNodeLevel, kPlugLevel }
 Level of detail of the iteration. More...

Public Member Functions

 MItDependencyGraph (MObject &rootNode, MFn::Type filter=MFn::kInvalid, Direction direction=kDownstream, Traversal traversal=kDepthFirst, Level level=kNodeLevel, MStatus *ReturnStatus=NULL)
 MItDependencyGraph (MPlug &rootPlug, MFn::Type filter=MFn::kInvalid, Direction direction=kDownstream, Traversal traversal=kDepthFirst, Level level=kPlugLevel, MStatus *ReturnStatus=NULL)
 MItDependencyGraph (MObject &rootNode, MPlug &rootPlug, MIteratorType &infoObject, Direction direction=kDownstream, Traversal traversal=kDepthFirst, Level level=kNodeLevel, MStatus *ReturnStatus=NULL)
 ~MItDependencyGraph ()
MStatus reset ()
MStatus resetTo (MObject &rootNode, MFn::Type filter=MFn::kInvalid, Direction direction=kDownstream, Traversal traversal=kDepthFirst, Level level=kNodeLevel)
MStatus resetTo (MPlug &rootPlug, MFn::Type filter=MFn::kInvalid, Direction direction=kDownstream, Traversal traversal=kDepthFirst, Level level=kPlugLevel)
MStatus resetTo (MObject *rootNode, MPlug *rootPlug, MIteratorType &infoObject, Direction direction=kDownstream, Traversal traversal=kDepthFirst, Level level=kPlugLevel)
MObject rootNode (MStatus *ReturnStatus=NULL)
MPlug rootPlug (MStatus *ReturnStatus=NULL)
MFn::Type currentFilter (MStatus *ReturnStatus=NULL)
MStatus setCurrentFilter (MFn::Type filter=MFn::kInvalid)
MStatus resetFilter ()
bool isPruningOnFilter (MStatus *ReturnStatus=NULL)
MStatus enablePruningOnFilter ()
MStatus disablePruningOnFilter ()
bool isDirectionDownStream (MStatus *ReturnStatus=NULL)
Direction currentDirection (MStatus *ReturnStatus=NULL)
MStatus toggleDirection ()
bool isTraversalDepthFirst (MStatus *ReturnStatus=NULL)
Traversal currentTraversal (MStatus *ReturnStatus=NULL)
MStatus toggleTraversal ()
bool atNodeLevel (MStatus *ReturnStatus=NULL)
Level currentLevel (MStatus *ReturnStatus=NULL)
MStatus toggleLevel ()
MStatus next ()
bool isDone (MStatus *ReturnStatus=NULL)
MStatus prune ()
MObject thisNode (MStatus *ReturnStatus=NULL)
 This method is obsolete.
MObject currentItem (MStatus *ReturnStatus=NULL)
bool thisNodeHasUnknownType (MStatus *ReturnStatus=NULL)
MPlug thisPlug (MStatus *ReturnStatus=NULL)
MPlug previousPlug (MStatus *ReturnStatus=NULL)
MStatus getNodesVisited (MObjectArray &nodesVisted) const
MStatus getPlugsVisited (MPlugArray &plugsVisted) const
MStatus getNodePath (MObjectArray &path) const
MStatus getPlugPath (MPlugArray &path) const

Member Enumeration Documentation

Direction within the DG relative to root Node or Plug.

Enumerator:
kDownstream  From source to destination.
kUpstream  From destination to source.

Perform a depth first or breadth first traversal.

Enumerator:
kDepthFirst  Away from root first.
kBreadthFirst  Equidistant from root first.

Level of detail of the iteration.

Enumerator:
kNodeLevel  Visit each Node at most once.
kPlugLevel  Visit each Plug at most once.


Constructor & Destructor Documentation

MItDependencyGraph::MItDependencyGraph ( MObject rootNode,
MFn::Type  filter = MFn::kInvalid,
Direction  direction = kDownstream,
Traversal  traversal = kDepthFirst,
Level  level = kNodeLevel,
MStatus ReturnStatus = NULL 
)

Constructor for a DG Iterator with a root node. If a valid filter is enabled, the iterator automatically advances to the next node after the root node that matches the filter. If no matching node is found the status is failure (MFn::kFailure).

Parameters:
[in] rootNode Root node
[in] filter Object type filter (see MFn::Type)
[in] direction Primary direction of iteration
[in] traversal Order of traversal
[in] level Level of detail of the iteration
[out] ReturnStatus Status Code (see below)
Status Codes:

MItDependencyGraph::MItDependencyGraph ( MPlug rootPlug,
MFn::Type  filter = MFn::kInvalid,
Direction  direction = kDownstream,
Traversal  traversal = kDepthFirst,
Level  level = kPlugLevel,
MStatus ReturnStatus = NULL 
)

Constructor for a DG Iterator with a root plug. The type of root and the level of the iteration are independent. If a valid filter is enabled, the iterator automatically advances to the next node after the root node that matches the filter. If no matching node is found the status is failure (MFn::kFailure).

Parameters:
[in] rootPlug Root plug
[in] filter Object type filter (see MFn::Type)
[in] direction Primary direction of iteration
[in] traversal Order of traversal
[in] level Level of detail of the iteration
[out] ReturnStatus Status Code (see below)
Status Codes:

MItDependencyGraph::MItDependencyGraph ( MObject rootNode,
MPlug rootPlug,
MIteratorType infoObject,
Direction  direction = kDownstream,
Traversal  traversal = kDepthFirst,
Level  level = kNodeLevel,
MStatus ReturnStatus = NULL 
)

Constructor for a DG Iterator with a root node or a root plug. If the root node is to be specified, then the root plug will be null. If root plug is non-null, then null should be passed on to root node. The type of root and the level of the iteration are independent. If a valid filter is enabled, the iterator automatically advances to the next node after the root node that matches one of the filter in the filter list, which is specified thro' MIteratorType object. no matching node is found the status is failure (MFn::kFailure).

Parameters:
[in] rootNode Root node, to which the iterator has to be set to, This can be NULL if we are resetting the root to plug object.
[in] rootPlug Root plug, to which the iterator has to be set to, This can be NULL if we are resetting the root to node object.
[in] infoObject MIteratorType object, having info about the filter list.
[in] direction Primary direction of iteration
[in] traversal Order of traversal
[in] level Level of detail of the iteration
[out] ReturnStatus Status Code (see below)
Status Codes:

MItDependencyGraph::~MItDependencyGraph (  ) 

Class destructor.


Member Function Documentation

MStatus MItDependencyGraph::reset (  ) 

Clears iterator data and resets the iterator to the root node or plug. If a valid filter is enabled, the iterator automatically advances to the next node after the root node that matches the filter. If no matching node is found the status is failure (MFn::kFailure).

Returns:
Status Code
Status Codes:

MStatus MItDependencyGraph::resetTo ( MObject rootNode,
MFn::Type  filter = MFn::kInvalid,
Direction  direction = kDownstream,
Traversal  traversal = kDepthFirst,
Level  level = kNodeLevel 
)

Clears iterator data and re-initializes the iterator. If a valid filter is provided, the iterator automatically advances to the next node after the root node that matches the filter. If no matching node is found the status is failure (MFn::kFailure).

Parameters:
[in] rootNode Root node of the iteration
[in] filter Object type filter (see MFn::Type)
[in] direction Primary direction of iteration
[in] traversal Order of traversal
[in] level Level of detail of the iteration
Returns:
Status Code
Status Codes:
  • MS::kSuccess Iterator created
  • MS::kInvalidParameter Invalid parameter passed for direction, traversal, or level - default used, or Invalid parameter passed for root node - node does not exist or is not accesible
  • MS::kFailure Iterator not reset - iterator does not exist or is not accessible

MStatus MItDependencyGraph::resetTo ( MPlug rootPlug,
MFn::Type  filter = MFn::kInvalid,
Direction  direction = kDownstream,
Traversal  traversal = kDepthFirst,
Level  level = kPlugLevel 
)

Clears iterator data and re-initializes the iterator. If a valid filter is enabled, the iterator automatically advances to the next node after the root node that matches the filter. If no matching node is found the status is failure (MFn::kFailure).

Parameters:
[in] rootPlug Root plug of the iteration
[in] filter Object type filter (see MFn::Type)
[in] direction Primary direction of iteration
[in] traversal Order of traversal
[in] level Level of detail of the iteration
Returns:
Status Code
Status Codes:
  • MS::kSuccess Iterator created
  • MS::kInvalidParameter Invalid parameter passed for direction, traversal, or level - default used, or Invalid parameter passed for root node - node does not exist or is not accesible
  • MS::kFailure Iterator not reset - iterator does not exist or is not accessible

MStatus MItDependencyGraph::resetTo ( MObject rootNode,
MPlug rootPlug,
MIteratorType infoObject,
Direction  direction = kDownstream,
Traversal  traversal = kDepthFirst,
Level  level = kPlugLevel 
)

Clears iterator data and re-initializes the iterator. The filter list is reset to the new list specified thro' MIteratorType object. If a valid filter is enabled, the iterator automatically advances to the next node after the root node/plug that matches the filter. If no matching node is found the status is failure (MFn::kFailure).

Parameters:
[in] rootNode Root Node of the iteration. This can be null if the root has to be reset to plug.
[in] rootPlug Root plug of the iteration. This can be null if the root has to be reset to node.
[in] infoObject MIteratorType Object which has info about the filter list and the object type, the root will be reset to.
[in] direction Primary direction of iteration
[in] traversal Order of traversal
[in] level Level of detail of the iteration
Returns:
Status Code
Status Codes:
  • MS::kSuccess Iterator created
  • MS::kInvalidParameter Invalid parameter passed for direction, traversal, or level - default used, or Invalid parameter passed for root node - node does not exist or is not accesible
  • MS::kFailure Iterator not reset - iterator does not exist or is not accessible

MObject MItDependencyGraph::rootNode ( MStatus ReturnStatus = NULL  ) 

Retrieves the root node of the iteration.

Parameters:
[out] ReturnStatus Status Code (see below)
Returns:
The root node
Status Codes:
  • MS::kSuccess Root node is valid
  • MS::kFailure Root node not retrieved - iterator does not exist or is not accessible, or root node does not exist or is not accessible

MPlug MItDependencyGraph::rootPlug ( MStatus ReturnStatus = NULL  ) 

Retrieves the root plug of the iteration.

Parameters:
[out] ReturnStatus Status Code (see below)
Returns:
The root plug
Status Codes:
  • MS::kSuccess Root plug is valid
  • MS::kFailure Root plug not retrieved - iterator does not exist or is not accessible, or root plug does not exist or is not accessible

MFn::Type MItDependencyGraph::currentFilter ( MStatus ReturnStatus = NULL  ) 

Retrieves the current node type filter.

Parameters:
[out] ReturnStatus Status Code (see below)
Returns:
The current node type filter
Status Codes:

MStatus MItDependencyGraph::setCurrentFilter ( MFn::Type  filter = MFn::kInvalid  ) 

Sets the node or plug filter. Plug filtering is based on the type of the corresponding Attribute. Defaults to disabled (MFn::kInvalid). If a valid filter is specified, the iterator automatically advances to the next node that matches the filter. If no matching node status is failure (MFn::kFailure).

Disables pruning on the new filter (default). Use enablePruningOnFilter() method to enable pruning. No other iterator data is changed. If new filter is the same as current filter, no action is taken.

Parameters:
[in] filter node or Attribute type filter (see MFn::Type)
Returns:
Status Code
Status Codes:

MStatus MItDependencyGraph::resetFilter (  ) 

Resets the node or plug filter to default, MFn::kInvalid (filter disabled). Disables pruning on the filter (default). Resets the iterator.

Returns:
Status Code
Status Codes:

bool MItDependencyGraph::isPruningOnFilter ( MStatus ReturnStatus = NULL  ) 

Tests whether or not the iteration path is pruned automatically at nodes or plugs which do not match the filter.

Parameters:
[in] ReturnStatus Status Code (see below)
Returns:
Bool: true if pruning is enabled, false otherwise.
Status Codes:
  • MS::kSuccess State is valid
  • MS::kFailure Pruning state not known (default returned) - iterator does not exist or is not accessible

MStatus MItDependencyGraph::enablePruningOnFilter (  ) 

Enables automatic pruning of iteration path at nodes or plugs which do not match the filter.

Returns:
Status Code
Status Codes:

MStatus MItDependencyGraph::disablePruningOnFilter (  ) 

Disables automatic pruning of iteration path at nodes or plugs which do not match the filter.

Returns:
Status Code
Status Codes:
Examples:

bool MItDependencyGraph::isDirectionDownStream ( MStatus ReturnStatus = NULL  ) 

Tests whether or not the iteration is moving downstream (in the direction of data flow) in the DG.

Parameters:
[out] ReturnStatus Status Code (see below)
Returns:
Status Codes:
  • MS::kSuccess Direction is valid
  • MS::kFailure Direction not known (default returned) - iterator does not exist or is not accessible

MItDependencyGraph::Direction MItDependencyGraph::currentDirection ( MStatus ReturnStatus = NULL  ) 

Reports the direction of the iteration through the graph.

Parameters:
[out] ReturnStatus Status Code (see below)
Returns:
Status Codes:
  • MS::kSuccess Direction is valid
  • MS::kFailure Direction not known (default returned) - iterator does not exist or is not accessible

MStatus MItDependencyGraph::toggleDirection (  ) 

Toggles the direction of the iteration. Resets the root of the iteration to the current node or plug depending on the level of iteration. Clears iterator path data. If a valid filter is enabled, the iterator automatically advances to the next node that matches the filter. If no matching node is found the status is failure (MFn::kFailure). No other iterator parameters are affected.

Returns:
Status Code
Status Codes:

bool MItDependencyGraph::isTraversalDepthFirst ( MStatus ReturnStatus = NULL  ) 

Tests whether or not the iteration is proceeding depth first (away from the root of the iteration) in the DG.

Parameters:
[out] ReturnStatus Status Code (see below)
Returns:
Status Codes:
  • MS::kSuccess Traversal is valid
  • MS::kFailure Traversal not known (default returned) - iterator does not exist or is not accessible

MItDependencyGraph::Traversal MItDependencyGraph::currentTraversal ( MStatus ReturnStatus = NULL  ) 

Reports the traversal mode of the iteration through the graph.

Parameters:
[out] ReturnStatus Status Code (see below)
Returns:
Status Codes:
  • MS::kSuccess Traversal is valid
  • MS::kFailure Traversal not known (default returned) - iterator does not exist or is not accessible

MStatus MItDependencyGraph::toggleTraversal (  ) 

Toggles the traversal of the iteration. Resets the root of the iteration to the current node or plug depending on the level of iteration. Clears iterator path data. If a valid filter is enabled, the iterator automatically advances to the next node that matches the filter. If no matching node is found the status is failure (MFn::kFailure). No other iterator parameters are affected.

Returns:
Status Code
Status Codes:

bool MItDependencyGraph::atNodeLevel ( MStatus ReturnStatus = NULL  ) 

Tests whether or not the iteration is at the node level of detail (every node is visited only once) in the DG.

Parameters:
[out] ReturnStatus Status Code (see below)
Returns:
Status Codes:
  • MS::kSuccess Level is valid
  • MS::kFailure Level not known (default returned) - iterator does not exist or is not accessible

MItDependencyGraph::Level MItDependencyGraph::currentLevel ( MStatus ReturnStatus = NULL  ) 

Reports the level of the iteration through the graph.

Parameters:
[out] ReturnStatus Status Code (see below)
Returns:
Status Codes:
  • MS::kSuccess Level is valid
  • MS::kFailure Level not known (default returned) - iterator does not exist or is not accessible

MStatus MItDependencyGraph::toggleLevel (  ) 

Toggles the level of the iteration. Resets the root of the iteration to the current node or plug depending on the level of iteration. Clears iterator path data. If a valid filter is enabled, the iterator automatically advances to the next node that matches the filter. If no matching node is found the status is failure (MFn::kFailure). No other iterator parameters are affected.

Returns:
Status Code
Status Codes:

MStatus MItDependencyGraph::next (  ) 

Iterates to the next node or plug in accordance with the direction, traversal, level and filter. If a valid filter is set, the iterator only visits those nodes that match the filter. When filtering is enabled nodes that have unknown type are treated as non-matching nodes. With filtering disabled, iteration to a node with an unknown type is treated as a failure. An attempt to iterate when there is nothing left to iterate over results in failure.

Returns:
Status Code
Status Codes:
  • MS::kSuccess Iteration successful
  • MS::kFailure Could not iterate - nothing left to iterate over, or iterator does not exist or is not accessible, or node has unrecognized type, or Attribute of plug is inaccessible, or could not update plug path length.
Examples:

bool MItDependencyGraph::isDone ( MStatus ReturnStatus = NULL  ) 

Indicates whether or not all nodes or plugs have been iterated over in accordance with the direction, traversal, level and filter. If a valid filter is set, the iterator only visits those nodes that match the filter.

Parameters:
[out] ReturnStatus Status Code (see below)
Returns:
  • true Iteration is done
  • false Iteration is not done
Status Codes:
Examples:

MStatus MItDependencyGraph::prune (  ) 

Prunes the search path at the current plug. Iterator will not visit any of the plugs connected to the pruned plug.

Returns:
Status Code
Status Codes:
  • MS::kSuccess Path pruned.
  • MS::kFailure Could not prune path - iterator does not exist or is not accessible, or iteration is done

MObject MItDependencyGraph::thisNode ( MStatus ReturnStatus = NULL  ) 

This method is obsolete.

Deprecated:
Use the MItDependencyGraph::currentItem method instead.
Retrieves the current node of the iteration. Results in a null object on failure or if the node is of a unrecognized type.

Parameters:
[out] ReturnStatus Status Code (see below)
Returns:
Current node
Status Codes:
  • MS::kSuccess node is valid
  • MS::kFailure node not retrieved. Iterator does not exist or is not accessible, or node does not exist or is not accessible, or node type is not recognized, or iteration is done (null Object returned)
Examples:

MObject MItDependencyGraph::currentItem ( MStatus ReturnStatus = NULL  ) 

Retrieves the current node of the iteration. Results in a null object on failure or if the node is of a unrecognized type.

Parameters:
[out] ReturnStatus Status Code (see below)
Returns:
Current node
Status Codes:
  • MS::kSuccess node is valid
  • MS::kFailure node not retrieved - iterator does not exist or is not accessible, or node does not exist or is not accessible, or node type is not recognized, or iteration is done (null Object returned)

bool MItDependencyGraph::thisNodeHasUnknownType ( MStatus ReturnStatus = NULL  ) 

Indicates whether or not the current node has an unrecognised type. This is useful if an unexpected failure is encountered in the next() or thisNode() methods.

Returns true only if node exists but is not a recognizable type.

Returns false if node exists and is recognizable. Also returns false on failure or if the iteration is done.

Parameters:
[out] ReturnStatus Status Code (see below)
Returns:
  • true Unknown type
  • false Type is known or iterator is done or failure encountered
Status Codes:
  • MS::kSuccess Return valid
  • MS::kFailure Return not valid - iterator does not exist or is not accessible, or node does not exist or is not accessible

MPlug MItDependencyGraph::thisPlug ( MStatus ReturnStatus = NULL  ) 

Retrieves the current plug of the iteration. Results in a null plug on failure.

Parameters:
[out] ReturnStatus Status Code (see below)
Returns:
Current plug
Status Codes:
  • MS::kSuccess plug is valid
  • MS::kFailure plug not retrieved - the iteration is done, iterator does not exist or is not accessible, or plug does not exist or is not accessible (null plug returned)

MPlug MItDependencyGraph::previousPlug ( MStatus ReturnStatus = NULL  ) 

Retrieves the previous plug of the iteration. Results in a null plug on failure. Null plug may also indicate that the current plug is the root plug.

Parameters:
[out] ReturnStatus Status Code (see below)
Returns:
  • Current plug
Status Codes:
  • MS::kSuccess plug is valid
  • MS::kFailure plug not retrieved - iterator does not exist or is not accessible, plug does not exist or is not accessible, or current plug may be root plug (null plug returned)

MStatus MItDependencyGraph::getNodesVisited ( MObjectArray nodes  )  const

Retrieves all nodes visited during the iteration. State of the provided array is undefined if this method fails.

Parameters:
[out] nodes Target array for retrieved nodes. On success contains all nodes visited
Returns:
Status Code
Status Codes:
  • MS::kSuccess
  • MS::kFailure Could not retrieve nodes - iterator does not exist or is not accessible, or list of nodes does not exist or is not accessible;

MStatus MItDependencyGraph::getPlugsVisited ( MPlugArray plugs  )  const

Retrieves all plugs visited during the iteration. State of the provided array is undefined if this method fails.

Parameters:
[out] plugs Target array for retrieved plugs. On success contains all plugs visited
Returns:
Status Code
Status Codes:
  • MS::kSuccess
  • MS::kFailure Could not retrieve plugs - iterator does not exist or is not accessible, or list of plugs does not exist or is not accessible;

MStatus MItDependencyGraph::getNodePath ( MObjectArray path  )  const

Retrieves the direct path from the current node to the root node. Path does not include the current node. State of the provided array is undefined if this method fails.

Parameters:
[out] path Target array for retrieved path. On success contains direct path from the current node to the root node
Returns:
Status Code
Status Codes:
  • MS::kSuccess
  • MS::kFailure Could not retrieve path - iterator does not exist or is not accessible, or path does not exist or is not accessible;
Examples:

MStatus MItDependencyGraph::getPlugPath ( MPlugArray path  )  const

Retrieves the direct path from the current plug to the root plug. Path does not include the current plug. State of the provided array is undefined if this method fails.

Parameters:
[out] path Target array for retrieved path. On success contains direct path from the current plug to the root plug
Returns:
Status Code
Status Codes:
  • MS::kSuccess
  • MS::kFailure Could not retrieve path - iterator does not exist or is not accessible, or path does not exist or is not accessible;


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