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# MFnAttribute Class Reference
OpenMaya - API module for common classes | FunctionSet classes

This reference page is linked to from the following overview topics: Complex Attributes, Anatomy of a shading node plug-in, Implementing a custom transform, Appendix C: Frequently asked questions.

Search for all occurrences

## Detailed Description

Dependency node attribute function set.

MFnAttribute is the function set for dependency node attributes.

An attribute of a dependency node describes a piece of data that belongs to nodes of that type. For example, a node that makes a sphere might have a radius attribute. A node's attributes describe connections sites on the node that can be used in the dependency graph.

Attributes typically belong to a class of nodes, rather than to an individual node. For example, all sphere nodes have a radius. Even though a single attribute may be shared by all nodes of a given type, each node will have its own value for the attribute.

Attributes are hierarchical. For example, the translate scale attribute of a transform has x, y, and z child attributes.

By default, attributes are:

- Readable.
- Writable.
- Connectable.
- Storable.
- Cached.
- Not arrays.
- Have indices that matter.
- Do not use an array builder.
- Not keyable.
- Not hidden.
- Not used as colors.
- Not indeterminant.
- Set to disconnect behavior kNothing.

Examples:

  animExportUtil.cpp, apiMeshShape.cpp, cgfxAttrDef.cpp, cgfxShaderNode.cpp, dagPoseInfoCmd.cpp, getAttrAffectsCmd.cpp, and maTranslator.cpp.

`#include <MFnAttribute.h>`

Inheritance diagram for MFnAttribute:
[legend]

List of all members.

## Public Types
enum | DisconnectBehavior { kDelete, kReset, kNothing }
| Attribute behaviour on disconnect. More...
## Public Member Functions
virtual MFn::Type | type () const
| Function set type.
virtual | ~MFnAttribute ()
| Destructor.
| MFnAttribute ()
| Default constructor.
| MFnAttribute (MObject &object, MStatus *ReturnStatus=NULL)
| Constructor.
bool | isReadable (MStatus *ReturnStatus=NULL) const
| Returns true if this attribute is readable.
bool | isWritable (MStatus *ReturnStatus=NULL) const
| Returns true if this attribute is writable.
bool | isConnectable (MStatus *ReturnStatus=NULL) const
| Returns true if this attribute accepts dependency graph connections.
bool | isStorable (MStatus *ReturnStatus=NULL) const
| Returns true if this attribute is to be stored when the node is saved to a file.
bool | isCached (MStatus *ReturnStatus=NULL) const
| Returns true if this attribute is cached locally in the node's data block.
bool | isArray (MStatus *ReturnStatus=NULL) const
| Returns true if this attribute supports an array of data.
bool | indexMatters (MStatus *ReturnStatus=NULL) const
| Determines whether the user must specify an index when connecting to this attribute, or whether the next available index can be used.
bool | isKeyable (MStatus *ReturnStatus=NULL) const
| Returns true if this attribute is keyable.
bool | isChannelBoxFlagSet (MStatus *ReturnStatus=NULL) const
| Returns true if this attribute has its channel box flag set.
bool | isHidden (MStatus *ReturnStatus=NULL) const
| Returns true if this attribute is to hidden from the UI.
bool | isUsedAsColor (MStatus *ReturnStatus=NULL) const
| Returns true if this attribute is to be presented as a color in the UI.
bool | isIndeterminant (MStatus *ReturnStatus=NULL) const
| Returns true if this attribute is indeterminant.
bool | isRenderSource (MStatus *ReturnStatus=NULL) const
| Returns true if this attribute is a render source.
bool | isDynamic (MStatus *ReturnStatus=NULL) const
| Returns true if this attribute is a dynamic attribute.
bool | isExtension (MStatus *ReturnStatus=NULL) const
| Returns true if this attribute is an extension attribute.
bool | isWorldSpace (MStatus *ReturnStatus=NULL) const
| Returns true if this attribute is worldspace.
bool | isAffectsWorldSpace (MStatus *ReturnStatus=NULL) const
| Returns true if this attribute affects worldspace.
bool | isUsedAsFilename (MStatus *ReturnStatus=NULL) const
| Returns true if this attribute is to be used as a filename.
bool | affectsAppearance (MStatus *ReturnStatus=NULL) const
| Returns true if this attribute affects the appearance of the object when rendering in the viewport.
DisconnectBehavior | disconnectBehavior (MStatus *ReturnStatus=NULL) const
| Returns the behavior of this attribute when it is disconnected.
bool | usesArrayDataBuilder (MStatus *ReturnStatus=NULL) const
| Returns true if this attribute uses an array data builder.
bool | internal (MStatus *ReturnStatus=NULL) const
| Returns true if a node has internal member data representing this attribute.
MStatus | setReadable (bool state)
| Sets whether this attribute should be readable.
MStatus | setWritable (bool state)
| Sets whether this attribute should be writable.
MStatus | setConnectable (bool state)
| Sets whether this attribute should allow dependency graph connections.
MStatus | setStorable (bool state)
| Sets whether this attribute should be storable.
MStatus | setCached (bool state)
| Sets whether the data for this attribute is cached locally in the node's data block.
MStatus | setArray (bool state)
| Sets whether this attribute should have an array of data.
MStatus | setIndexMatters (bool state)
| If the attribute is an array, then this method specifies whether to force the user to specify an index when connecting to this attribute, or to use the next available index.
MStatus | setKeyable (bool state)
| Sets whether this attribute should accept keyframe data.
MStatus | setChannelBox (bool state)
| Sets whether this attribute should appear in the channel box when the node is selected.
MStatus | setHidden (bool state)
| Sets whether this attribute should be hidden from the UI.
MStatus | setUsedAsColor (bool state)
| Sets whether this attribute should be presented as a color in the UI.
MStatus | setIndeterminant (bool state)
| Sets whether this attribute is indeterminant.
MStatus | setRenderSource (bool state)
| Sets whether this attribute should be used as a render source attribute.
MStatus | setWorldSpace (bool state)
| Sets whether this attribute should be treated as worldspace.
MStatus | setAffectsWorldSpace (bool state)
| Sets whether this attribute should affect worldspace.
MStatus | setUsedAsFilename (bool state)
| Sets whether this attribute should be presented as a filename in the UI.
MStatus | setAffectsAppearance (bool state)
| Sets whether this attribute affects the appearance of the object when rendering in the viewport.
MStatus | setDisconnectBehavior (DisconnectBehavior behavior)
| Sets the disconnection behavior for this attribute.
MStatus | setUsesArrayDataBuilder (bool state)
| Sets whether this attribute uses an array data builder.
MStatus | setInternal (bool state)
| The function controls an attribute's data storage.
MStatus | setNiceNameOverride (const MString &localizedName)
| Sets the localized string which should be used for this attribute in the UI.
bool | accepts (MFnData::Type type, MStatus *ReturnStatus=NULL) const
| Returns true if this attribute can accept a connection of the given type.
bool | accepts (const MTypeId &id, MStatus *ReturnStatus=NULL) const
| Returns true if this attribute can accept a connection of the given type.
MObject | parent (MStatus *ReturnStatus=NULL) const
| Get the parent of this attribute, if it has one.
MString | name (MStatus *ReturnStatus=NULL) const
| Returns the long name of the attribute.
MString | shortName (MStatus *ReturnStatus=NULL) const
| Returns the short name of the attribute.
MString | getAddAttrCmd (bool useLongName=false, MStatus *status=NULL) const
| Returns a string containing the addAttr command which would be required to recreate the attribute on a node.
MStatus | addToCategory (const MString &category)
| Add the attribute to the named category.
MStatus | removeFromCategory (const MString &category)
| Remove the attribute from the named category.
bool | hasCategory (const MString &category) const
| Check to see if the attribute belongs to the named category.
MStatus | getCategories (MStringArray &ReturnStatus) const
| Get all of the categories to which this attribute belongs.
| MFnAttribute (const MObject &object, MStatus *ReturnStatus=NULL)
| NO SCRIPT SUPPORT.
## Protected Member Functions
virtual const char * | className () const
| Class name.

## Member Enumeration Documentation

enum DisconnectBehavior

Search for all occurrences

Attribute behaviour on disconnect.

Enumerator:

  kDelete | Delete array element (array attributes only). Search for all occurrences
  kReset | Reset the attribute to its default. Search for all occurrences
  kNothing | Do nothing to the attribute's value. Search for all occurrences

## Constructor & Destructor Documentation

MFnAttribute | ( | MObject & | object,
|  | MStatus * | ReturnStatus = `NULL`
| ) |  |

Constructor.

Class constructor that initializes the function set to the given MObject.

Parameters:

  [in] | object | The MObject to attach the function set to
  [out] | ReturnStatus | the return status

Status Codes:
  - MS::kSuccess if the function set is successfully attached
  - MS::kInvalidParameter if the MObject does not represent a valid Maya object or if the function set is not allowed to attach to this MObject

MFnAttribute | ( | const MObject & | object,
|  | MStatus * | ReturnStatus = `NULL`
| ) |  |

NO SCRIPT SUPPORT.

Class constructor that initializes the function set to the given MObject.

Constructor

Parameters:

  [in] | object | The MObject to attach the function set to
  [out] | ReturnStatus | the return status

Status Codes:
  - MS::kSuccess if the function set is successfully attached
  - MS::kInvalidParameter if the MObject does not represent a valid Maya object or if the function set is not allowed to attach to this MObject

## Member Function Documentation

MFn::Type type | ( |  | ) | const`[virtual]`

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Function set type.

Return the class type : MFn::kAttribute.

Reimplemented from MFnBase.

Reimplemented in MFnCompoundAttribute, MFnEnumAttribute, MFnGenericAttribute, MFnLightDataAttribute, MFnMatrixAttribute, MFnMessageAttribute, MFnNumericAttribute, MFnTypedAttribute, and MFnUnitAttribute.

const char * className | ( |  | ) | const`[protected, virtual]`

Search for all occurrences

Class name.

Return the class name : "MFnAttribute".

Reimplemented in MFnCompoundAttribute, MFnEnumAttribute, MFnGenericAttribute, MFnLightDataAttribute, MFnMatrixAttribute, MFnMessageAttribute, MFnNumericAttribute, MFnTypedAttribute, and MFnUnitAttribute.

bool isReadable | ( | MStatus * | ReturnStatus = `NULL` | ) | const

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Returns true if this attribute is readable.

If an attribute is readable, then it can be used as the source in a dependency graph connection.

Attributes are readable by default.

Parameters:

  [out] | ReturnStatus | return status

Returns:
  A boolean value indicating whether this attribute is readable

Status Codes:
  - MS::kSuccess operation successful
  - MS::kFailure this function set does not have a valid attribute object

bool isWritable | ( | MStatus * | ReturnStatus = `NULL` | ) | const

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Returns true if this attribute is writable.

If an attribute is writable, then it can be used as the destination in a dependency graph connection.

Attributes are writable by default.

Parameters:

  [out] | ReturnStatus | return status

Returns:
  A boolean value indicating whether this attribute is writable

Status Codes:
  - MS::kSuccess operation successful
  - MS::kFailure this function set does not have a valid attribute object

bool isConnectable | ( | MStatus * | ReturnStatus = `NULL` | ) | const

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Returns true if this attribute accepts dependency graph connections.

If it does, then the readable and writable methods will indicate what types of connections are accepted.

Attributes are connectable by default.

Parameters:

  [out] | ReturnStatus | return status

Returns:
  A boolean value indicating whether this attribute is connectable

Status Codes:
  - MS::kSuccess operation successful
  - MS::kFailure this function set does not have a valid attribute object

bool isStorable | ( | MStatus * | ReturnStatus = `NULL` | ) | const

Search for all occurrences

Returns true if this attribute is to be stored when the node is saved to a file.

Attributes are storable by default.

Parameters:

  [out] | ReturnStatus | return status

Returns:
  A boolean value indicating whether this attribute is storable

Status Codes:
  - kSuccess operation successful
  - kFailure this function set does not have a valid attribute object

bool isCached | ( | MStatus * | ReturnStatus = `NULL` | ) | const

Search for all occurrences

Returns true if this attribute is cached locally in the node's data block.

The default for this is true. Caching a node locally causes a copy of the attribute value for the node to be cached with the node. This removes the need to traverse through the graph to get the value each time it is requested.

Caching the value locally gives a speed increase at the cost of more memory.

Attributes are cached by default.

Parameters:

  [out] | ReturnStatus | return status

Returns:
  A boolean value indicating whether this attribute is cached locally

Status Codes:
  - kSuccess operation successful
  - kFailure this function set does not have a valid attribute object

bool isArray | ( | MStatus * | ReturnStatus = `NULL` | ) | const

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Returns true if this attribute supports an array of data.

Attributes are single elements by default.

Parameters:

  [out] | ReturnStatus | return status

Returns:
  A boolean value indicating whether this attribute stores an array of data

Status Codes:
  - MS::kSuccess operation successful
  - MS::kFailure this function set does not have a valid attribute object

bool indexMatters | ( | MStatus * | ReturnStatus = `NULL` | ) | const

Search for all occurrences

Determines whether the user must specify an index when connecting to this attribute, or whether the next available index can be used.

This method only applies to array attributes which are non readable, i.e. destination attributes.

This corresponds with the connectAttr command's -na/nextAvailable flag. If the destination attribute has set the indexMatters to be false with this flag specified, a connection is made to the next available index. No index need be specified

The index matters to attributes by default.

Parameters:

  [out] | ReturnStatus | return status

Returns:
  - true The user must specify the index when connecting to this attribute using connectAttr
  - false The next available index can be used when connecting to this attribute using connectAttr -na

Status Codes:
  - MS::kSuccess operation successful
  - MS::kFailure this function set does not have a valid attribute object

bool isKeyable | ( | MStatus * | ReturnStatus = `NULL` | ) | const

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Returns true if this attribute is keyable.

Keyable attributes will be keyed by AutoKey and the Set Keyframe UI. Non-keyable attributes prevent the user from setting keys via the obvious UI provided for keying. Being non-keyable is not a hard block against adding keys to an attribute.

This method determines the default keyability of a plug. The keyability can be changed after it is created. Use the MPlug::isKeyable method to determine whether or not a specific plug is keyable.

Attributes are not keyable by default.

Parameters:

  [out] | ReturnStatus | return status

Returns:
  A boolean value indicating whether this attribute is keyable

Status Codes:
  - MS::kSuccess operation successful
  - MS::kFailure this function set does not have a valid attribute object

bool isChannelBoxFlagSet | ( | MStatus * | ReturnStatus = `NULL` | ) | const

Search for all occurrences

Returns true if this attribute has its channel box flag set.

Attributes will appear in the channel box if their channel box flag is set or if they are keyable.

This method returns the default channel box display state of a plug. The display can be changed after it is created. Use the MPlug::isChannelBox method to determine whether or not a specific plug is displayed in the channel box.

Attributes are not in the channel box by default.

Parameters:

  [out] | ReturnStatus | return status

Returns:
  A boolean value indicating the status of the channel box flag on this attribute

Status Codes:
  - MS::kSuccess operation successful
  - MS::kFailure this function set does not have a valid attribute object

bool isHidden | ( | MStatus * | ReturnStatus = `NULL` | ) | const

Search for all occurrences

Returns true if this attribute is to hidden from the UI.

The attribute will not show up in attribute editors.

Attributes are not hidden by default.

Parameters:

  [out] | ReturnStatus | return status

Returns:
  A boolean value indicating whether this attribute is hidden

Status Codes:
  - MS::kSuccess operation successful
  - MS::kFailure this function set does not have a valid attribute object

bool isUsedAsColor | ( | MStatus * | ReturnStatus = `NULL` | ) | const

Search for all occurrences

Returns true if this attribute is to be presented as a color in the UI.

Parameters:

  [out] | ReturnStatus | return status

Returns:
  A boolean value indicating whether this attribute is used as a color

Status Codes:
  - MS::kSuccess operation successful
  - MS::kFailure this function set does not have a valid attribute object

bool isIndeterminant | ( | MStatus * | ReturnStatus = `NULL` | ) | const

Search for all occurrences

Returns true if this attribute is indeterminant.

If an attribute may or may not be used during an evaluation then it is indeterminant. This attribute classification is mainly used on rendering nodes to indicate that some attributes are not always used.

Attributes are not indeterminant by default.

Parameters:

  [out] | ReturnStatus | return status

Returns:
  A boolean value indicating whether this attribute is indeterminant

Status Codes:
  - MS::kSuccess operation successful
  - MS::kFailure this function set does not have a valid attribute object

bool isRenderSource | ( | MStatus * | ReturnStatus = `NULL` | ) | const

Search for all occurrences

Returns true if this attribute is a render source.

This attribute is used on rendering nodes to override the rendering sampler info.

Attributes are not render source by default.

Parameters:

  [out] | ReturnStatus | return status

Returns:
  A boolean value indicating whether this attribute is render source

Status Codes:
  - MS::kSuccess operation successful
  - MS::kFailure this function set does not have a valid attribute object

bool isDynamic | ( | MStatus * | ReturnStatus = `NULL` | ) | const

Search for all occurrences

Returns true if this attribute is a dynamic attribute.

Parameters:

  [out] | ReturnStatus | return status

Returns:
  A boolean value indicating whether this attribute is dynamic

Status Codes:
  - MS::kSuccess operation successful
  - MS::kFailure this function set does not have a valid attribute object

bool isExtension | ( | MStatus * | ReturnStatus = `NULL` | ) | const

Search for all occurrences

Returns true if this attribute is an extension attribute.

An extension attribute is a class-level attribute which has been added dynamically to a node class. Because it is added at the class level, all nodes of that class will have the given attribute, and will only store the attribute's value if it differs from the default.

Parameters:

  [out] | ReturnStatus | return status

Returns:
  A boolean value indicating whether this attribute is an extension attribute

Status Codes:
  - MS::kSuccess operation successful
  - MS::kFailure this function set does not have a valid attribute object

bool isWorldSpace | ( | MStatus * | ReturnStatus = `NULL` | ) | const

Search for all occurrences

Returns true if this attribute is worldspace.

Attributes are not worldspace by default.

Parameters:

  [out] | ReturnStatus | return status

Returns:
  A boolean value indicating whether this attribute is worldspace

Status Codes:
  - MS::kSuccess operation successful
  - MS::kFailure this function set does not have a valid attribute object

bool isAffectsWorldSpace | ( | MStatus * | ReturnStatus = `NULL` | ) | const

Search for all occurrences

Returns true if this attribute affects worldspace.

Attributes do not affect worldspace by default.

Parameters:

  [out] | ReturnStatus | return status

Returns:
  A boolean value indicating whether this attribute affects worldspace

Status Codes:
  - MS::kSuccess operation successful
  - MS::kFailure this function set does not have a valid attribute object

bool isUsedAsFilename | ( | MStatus * | ReturnStatus = `NULL` | ) | const

Search for all occurrences

Returns true if this attribute is to be used as a filename.

In the UI this attr will be presented as a file name.

Parameters:

  [out] | ReturnStatus | return status

Returns:
  A boolean value indicating whether this attribute is used as a filename

Status Codes:
  - MS::kSuccess operation successful
  - MS::kFailure this function set does not have a valid attribute object

bool affectsAppearance | ( | MStatus * | ReturnStatus = `NULL` | ) | const

Search for all occurrences

Returns true if this attribute affects the appearance of the object when rendering in the viewport.

Parameters:

  [out] | ReturnStatus | return status

Returns:
  A boolean value indicating whether this attribute affects the appearance of the object when rendering in the viewport.

Status Codes:
  - MS::kSuccess operation successful
  - MS::kFailure this function set does not have a valid attribute object

MFnAttribute::DisconnectBehavior disconnectBehavior | ( | MStatus * | ReturnStatus = `NULL` | ) | const

Search for all occurrences

Returns the behavior of this attribute when it is disconnected.

The possible settings are as follows:

- kDelete delete the element of the array that was connected. This is only used for array attributes
- kReset reset the attribute to its default value
- kNothing leave the attribute set to its last known value

Attributes have a default disconnect behavior of kNothing.

Parameters:

  [out] | ReturnStatus | return status

Returns:
  The disconnect behavior

Status Codes:
  - MS::kSuccess operation successful
  - MS::kFailure this function set does not have a valid attribute object

bool usesArrayDataBuilder | ( | MStatus * | ReturnStatus = `NULL` | ) | const

Search for all occurrences

Returns true if this attribute uses an array data builder.

If so, then the MArrayDataBuilder class may be used with this attribute.

By default array attributes do not use an array data builder.

Parameters:

  [out] | ReturnStatus | return status

Returns:
  A boolean value indicating whether this attribute uses an array data builder.

Status Codes:
  - MS::kSuccess operation successful
  - MS::kFailure this function set does not have a valid attribute object

bool internal | ( | MStatus * | ReturnStatus = `NULL` | ) | const

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Returns true if a node has internal member data representing this attribute.

Parameters:

  [out] | ReturnStatus | return status

Returns:
  A boolean value indicating whether this attribute uses internal data

Status Codes:
  - MS::kSuccess operation successful
  - MS::kFailure this function set does not have a valid attribute object

MStatus setReadable | ( | bool | state | ) |

Search for all occurrences

Sets whether this attribute should be readable.

If an attribute is readable, then it can be used as the source in a dependency graph connection.

Attributes are readable by default.

Parameters:

  [in] | state | whether the attribute is to be readable

Returns:
  Return status

Status Codes:
  - MS::kSuccess operation successful
  - MS::kFailure this function set does not have a valid attribute object

Examples:
  anisotropicShader.cpp, backfillShader.cpp, clearcoat.cpp, closestPointOnCurveNode.cpp, curvedArrowsNode.cpp, cvColorShader.cpp, displacementShader.cpp, dynExprField.cpp, geometrySurfaceConstraint.cpp, hwDecalBumpShader_NV20.cpp, hwReflectBumpShader_NV20.cpp, hwToonShader_NV20.cpp, interpShader.cpp, lambertShader.cpp, lightShader.cpp, multiCurveNode.cpp, phongShader.cpp, pointOnMeshInfoNode.cpp, pointOnSubdNode.cpp, shadowMatteShader.cpp, shiftNode.cpp, slopeShaderNode.cpp, stringFormatNode.cpp, volumeShader.cpp, and weightListNode.cpp.

MStatus setWritable | ( | bool | state | ) |

Search for all occurrences

Sets whether this attribute should be writable.

If an attribute is writable, then it can be used as the destination in a dependency graph connection. If an attribute is not writable then setAttr commands will fail to change the attribute.

If both keyable and writable for an attribute are set to true it will be displayed in the channel box when the node is selected.

Attributes are writable by default.

Parameters:

  [in] | state | whether the attribute is to be writable

Returns:
  Return status

Status Codes:
  - MS::kSuccess operation successful
  - MS::kFailure this function set does not have a valid attribute object

Examples:
  anisotropicShader.cpp, arcLenNode.cpp, backfillShader.cpp, cgfxVector.cpp, circleNode.cpp, clearcoat.cpp, closestPointOnCurveNode.cpp, curvedArrowsNode.cpp, cvColorShader.cpp, displacementShader.cpp, dynExprField.cpp, footPrintManip.cpp, genericAttributeNode.cpp, geometrySurfaceConstraint.cpp, hlslShader.cpp, hwDecalBumpShader_NV20.cpp, hwReflectBumpShader_NV20.cpp, hwToonShader_NV20.cpp, interpShader.cpp, jitterNode.cpp, lambertShader.cpp, latticeNoiseNode.cpp, lightShader.cpp, meshOpNode.cpp, multiCurveNode.cpp, particleAttrNode.cpp, phongShader.cpp, pointOnMeshInfoNode.cpp, pointOnSubdNode.cpp, renderAccessNode.cpp, shadowMatteShader.cpp, shellNode.cpp, shiftNode.cpp, sineNode.cpp, slopeShaderNode.cpp, splitUVNode.cpp, stringFormatNode.cpp, swissArmyManip.cpp, testNobjectNode.cpp, testNucleusNode.cpp, transCircleNode.cpp, and volumeShader.cpp.

MStatus setConnectable | ( | bool | state | ) |

Search for all occurrences

Sets whether this attribute should allow dependency graph connections.

This should only get called in the initialize call of your node creator.

Attributes are connectable by default.

Parameters:

  [in] | state | whether the attribute is to be connectable

Returns:
  Return status

Status Codes:
  - MS::kSuccess operation successful
  - MS::kFailure this function set does not have a valid attribute object

Examples:
  buildRotationNode.cpp, cgfxShaderNode.cpp, and offsetNode.cpp.

MStatus setStorable | ( | bool | state | ) |

Search for all occurrences

Sets whether this attribute should be storable.

If an attribute is storable, then it will be writen out when the node is stored to a file. This should only get called in the initialize call of your node creator.

Attributes are storable by default.

NOTE: Typed attributes of setting MFnData::kDynArrayAttrs are not storable.

Parameters:

  [in] | state | whether the attribute is to be storable

Returns:
  Return status

Status Codes:
  - MS::kSuccess operation successful
  - MS::kFailure this function set does not have a valid attribute object

Examples:
  animCubeNode.cpp, anisotropicShader.cpp, backfillShader.cpp, blindDataMesh.cpp, buildRotationNode.cpp, cgfxVector.cpp, circleNode.cpp, clearcoat.cpp, closestPointOnCurveNode.cpp, curvedArrowsNode.cpp, customImagePlane.cpp, cvColorShader.cpp, displacementShader.cpp, dynExprField.cpp, footPrintManip.cpp, fullLoftNode.cpp, genericAttributeNode.cpp, geomShader.cpp, hlslShader.cpp, hwAnisotropicShader_NV20.cpp, hwColorPerVertexShader.cpp, hwDecalBumpShader_NV20.cpp, hwPhongShader.cpp, hwReflectBumpShader_NV20.cpp, hwRefractReflectShader_NV20.cpp, hwToonShader_NV20.cpp, hwUnlitShader.cpp, interpShader.cpp, jitterNode.cpp, lambertShader.cpp, lightShader.cpp, meshOpNode.cpp, offsetNode.cpp, particleAttrNode.cpp, phongShader.cpp, pnTrianglesNode.cpp, pointOnMeshInfoNode.cpp, pointOnSubdNode.cpp, renderAccessNode.cpp, shadowMatteShader.cpp, shellNode.cpp, shiftNode.cpp, simpleLoftNode.cpp, sineNode.cpp, slopeShaderNode.cpp, splitUVNode.cpp, stringFormatNode.cpp, swissArmyManip.cpp, testNobjectNode.cpp, testNucleusNode.cpp, transCircleNode.cpp, and volumeShader.cpp.

MStatus setCached | ( | bool | state | ) |

Search for all occurrences

Sets whether the data for this attribute is cached locally in the node's data block.

The default for this is true. Caching a node locally causes a copy of the attribute value for the node to be cached with the node. This removes the need to traverse through the graph to get the value each time it is requested. This should only get called in the initialize call of your node creator.

Caching the value locally gives a speed increase at the cost of more memory.

Attributes are cached by default.

Parameters:

  [in] | state | whether the attribute is to be cached locally

Returns:
  Return status

Status Codes:
  - MS::kSuccess operation successful
  - MS::kFailure this function set does not have a valid attribute object

Examples:
  closestPointOnCurveNode.cpp, hwColorPerVertexShader.cpp, hwPhongShader.cpp, pointOnMeshInfoNode.cpp, pointOnSubdNode.cpp, and shellNode.cpp.

MStatus setArray | ( | bool | state | ) |

Search for all occurrences

Sets whether this attribute should have an array of data.

This should be set to true if the attribute needs to accept multiple incoming connections.

Attributes are single elements by default.

Parameters:

  [in] | state | whether the attribute is to have an array of data

Returns:
  Return status

Status Codes:
  - MS::kSuccess operation successful
  - MS::kFailure this function set does not have a valid attribute object

Examples:
  anisotropicShader.cpp, backfillShader.cpp, cgfxShaderNode.cpp, fullLoftNode.cpp, geometrySurfaceConstraint.cpp, lambertShader.cpp, multiCurveNode.cpp, phongShader.cpp, shadowMatteShader.cpp, slopeShaderNode.cpp, stringFormatNode.cpp, testNucleusNode.cpp, and weightListNode.cpp.

MStatus setIndexMatters | ( | bool | state | ) |

Search for all occurrences

If the attribute is an array, then this method specifies whether to force the user to specify an index when connecting to this attribute, or to use the next available index.

This corresponds with the connectAttr command's -na/nextAvailable flag. If the destination attribute has set the indexMatters to be false with this flag specified, a connection is made to the next available index. No index need be specified

This method will only affect array attributes with setReadable set to false, i.e. destination attributes.

The index matters to attributes by default.

Parameters:

  [in] | state | whether the attribute's index must be specified when connecting to this attribute using the connectAttr command

Returns:
  Return status

Status Codes:
  - MS::kSuccess operation successful
  - MS::kInvalidParameter attribute is readable
  - MS::kFailure this function set does not have a valid attribute object

Examples:
  slopeShaderNode.cpp, and stringFormatNode.cpp.

MStatus setKeyable | ( | bool | state | ) |

Search for all occurrences

Sets whether this attribute should accept keyframe data.

This should only get called in the initialize call of your node creator. Keyable attributes will be keyed by AutoKey and the Set Keyframe UI. Non-keyable attributes prevent the user from setting keys via the obvious UI provided for keying. Being non-keyable is not a hard block against adding keys to an attribute.

This method changes the default state of a plug. The keyability of a specific plug can be changed using the MPlug::setKeyable method.

If both keyable and writable for an attribute are set to true it will be displayed in the channel box when the node is selected.

Attributes are not keyable by default.

Parameters:

  [in] | state | whether the attribute is to be keyable

Returns:
  Return status

Status Codes:
  - MS::kSuccess operation successful
  - MS::kFailure this function set does not have a valid attribute object

Examples:
  apiMeshCreator.cpp, cgfxAttrDef.cpp, cgfxShaderNode.cpp, cgfxVector.cpp, closestPointOnCurveNode.cpp, curvedArrowsNode.cpp, customImagePlane.cpp, displacementShader.cpp, dynExprField.cpp, genericAttributeNode.cpp, geometrySurfaceConstraint.cpp, hlslShader.cpp, hwAnisotropicShader_NV20.cpp, hwColorPerVertexShader.cpp, hwDecalBumpShader_NV20.cpp, hwPhongShader.cpp, hwReflectBumpShader_NV20.cpp, hwRefractReflectShader_NV20.cpp, hwToonShader_NV20.cpp, hwUnlitShader.cpp, interpShader.cpp, lambertShader.cpp, lightShader.cpp, meshOpNode.cpp, multiCurveNode.cpp, pnTrianglesNode.cpp, pointOnMeshInfoNode.cpp, pointOnSubdNode.cpp, quadricShape.cpp, rockingTransform.cpp, shadowMatteShader.cpp, shellNode.cpp, simpleSpring.cpp, slopeShaderNode.cpp, stringFormatNode.cpp, torusField.cpp, volumeShader.cpp, weightListNode.cpp, and yTwistNode.cpp.

MStatus setChannelBox | ( | bool | state | ) |

Search for all occurrences

Sets whether this attribute should appear in the channel box when the node is selected.

This should only get called in the initialize call of your node creator. Keyable attributes are always shown in the channel box so this flag is ignored on keyable attributes. It is for intended for use on non-keyable attributes which you want to appear in the channel box.

This method changes the default state of a plug. Channel box visibility for a specific plug can be changed using the MPlug::setChannelBox method.

Attributes are not in the channel box by default unless they are keyable.

Parameters:

  [in] | state | whether the attribute is to appear in the channel box

Returns:
  Return status

Status Codes:
  - MS::kSuccess operation successful
  - MS::kFailure this function set does not have a valid attribute object

MStatus setHidden | ( | bool | state | ) |

Search for all occurrences

Sets whether this attribute should be hidden from the UI.

This is useful if the attribute is being used for blind data, or if it is being used as scratch space for a geometry calculation (should also be marked non-connectable in that case).

Attributes are not hidden by default.

Parameters:

  [in] | state | whether the attribute is to be hidden

Returns:
  Return status

Status Codes:
  - MS::kSuccess operation successful
  - MS::kFailure this function set does not have a valid attribute object

Examples:
  anisotropicShader.cpp, apiMeshCreator.cpp, backfillShader.cpp, brickShader.cpp, cellShader.cpp, cgfxShaderNode.cpp, checkerShader.cpp, clearcoat.cpp, cvColorShader.cpp, depthShader.cpp, displacementShader.cpp, flameShader.cpp, geomShader.cpp, hwDecalBumpShader_NV20.cpp, hwReflectBumpShader_NV20.cpp, hwToonShader_NV20.cpp, interpShader.cpp, lambertShader.cpp, lavaShader.cpp, lightShader.cpp, meshOpNode.cpp, noiseShader.cpp, phongShader.cpp, quadricShape.cpp, shadowMatteShader.cpp, shiftNode.cpp, slopeShaderNode.cpp, solidCheckerShader.cpp, testNobjectNode.cpp, testNucleusNode.cpp, and volumeShader.cpp.

MStatus setUsedAsColor | ( | bool | state | ) |

Search for all occurrences

Sets whether this attribute should be presented as a color in the UI.

Parameters:

  [in] | state | whether the attribute is to be presented as a color

Returns:
  Return status

Status Codes:
  - MS::kSuccess operation successful
  - MS::kFailure this function set does not have a valid attribute object

Examples:
  cgfxAttrDef.cpp, hwAnisotropicShader_NV20.cpp, hwDecalBumpShader_NV20.cpp, hwReflectBumpShader_NV20.cpp, hwRefractReflectShader_NV20.cpp, hwToonShader_NV20.cpp, hwUnlitShader.cpp, interpShader.cpp, lambertShader.cpp, and slopeShaderNode.cpp.

MStatus setIndeterminant | ( | bool | state | ) |

Search for all occurrences

Sets whether this attribute is indeterminant.

If an attribute may or may not be used during an evaluation then it is indeterminant. This attribute classification is mainly used on rendering nodes to indicate that some attributes are not always used.

Attributes are not indeterminant by default.

Parameters:

  [in] | state | whether the attribute indeterminant

Returns:
  Return status

Status Codes:
  - MS::kSuccess operation successful
  - MS::kFailure this function set does not have a valid attribute object

MStatus setRenderSource | ( | bool | state | ) |

Search for all occurrences

Sets whether this attribute should be used as a render source attribute.

When writing shader plug-ins, it is sometimes useful to be able to modify the sampler info, so upstream shading network can be re- evaluated with different sampler info values.

For example, if a shading node takes a 2D texture as input, the result color of the 2D texture is evaluated at the current sample's UV coordinates. Initializing uvCoords attributes as render source and modifing the U and V values, then setting it as output will modify the sampler info. Re-evaluating the input plug will cause the 2D texture to re-evaluate with the new U and V values, and return a different color to the shading node.

Only valid Maya rendering attributes can be set to render source.

The following code example demonstrates how this is done:

initialize()

...

creates attributes for uvCoord and set them to be render source

u = nAttr.create( "uCoord", "u", MFnNumericData::kFloat, 0.0 ); nAttr.setStorable(false); nAttr.setWritable(true); nAttr.setRenderSource(true); v = nAttr.create( "vCoord", "v", MFnNumericData::kFloat, 0.0 ); nAttr.setStorable(false); nAttr.setWritable(true); nAttr.setRenderSource(true); uv = nAttr.create( "uvCoord", "uv", u, v ); nAttr.setStorable(false); nAttr.setWritable(true); nAttr.setRenderSource(true);

need to have the output uv affect the input uv because we want the new uv values we set to cause other inputs to this node to evaluate

attributeAffects ( uv, uv );

...

compute()

...

get uv coordinates from the sampler

MDataHandle uH = data.inputValue( u, &stat); MDataHandle vH = data.inputValue( v, &stat); float oldU = uH.asFloat(); float oldV = vH.asFloat();

get shading color input at the current sampler's uv coordinates

MDataHandle colorH = data.inputValue( inColor, &stat); MFloatVector color = colorH.asFloatVector(); // color at the sampled uv location

evaluate input color at a different uv location:

set output uv coordinates back to sampler this is only possible because we've set uv to be render source

MDataHandle outUV = data.outputValue( uv ); outUV.set( oldU-0.01, oldV-0.01 );

get newly evaluated inColor at uv(oldU-0.01, oldV-0.01)

any shading node connected to inColor will get uvCoord values as we've supplied. Calling data.inputValue( inColor, &stat) causes it to re-evaluate the network again with the new uvCoord values.

colorH = data.inputValue( inColor, &stat); // evaluate again color = colorH.asFloatVector(); // color at the new uv location

...

outUV.set( oldU, oldV ); // set the values back before we exit

...

Parameters:

  [in] | state | whether the attribute is to be a render source

Returns:
  Return status

Status Codes:
  - MS::kSuccess operation successful
  - MS::kFailure this function set does not have a valid attribute object

Examples:
  shiftNode.cpp.

MStatus setWorldSpace | ( | bool | state | ) |

Search for all occurrences

Sets whether this attribute should be treated as worldspace.

Being worldspace indicates the attribute is dependent on the worldSpace transformation of this node, and will be marked dirty by any attribute changes in the hierarchy that affects the worldSpace transformation. The attribute needs to be an array since during instancing there are multiple worldSpace paths to the node & Maya requires one array element per path for worldSpace attributes.

NOTES: 1. Can only be used on array attributes. 2. This property is ignored on non-dag nodes.

Parameters:

  [in] | state | whether the attribute is to be presented as worldspace

Returns:
  Return status

Status Codes:
  - MS::kSuccess operation successful
  - MS::kFailure this function set does not have a valid attribute object or the attribute is not an array

MStatus setAffectsWorldSpace | ( | bool | state | ) |

Search for all occurrences

Sets whether this attribute should affect worldspace.

NOTES: This property is ignored on non-dag nodes.

Parameters:

  [in] | state | whether the attribute should affect worldspace

Returns:
  Return status

Status Codes:
  - MS::kSuccess operation successful
  - MS::kFailure this function set does not have a valid attribute object

Examples:
  rockingTransform.cpp.

MStatus setUsedAsFilename | ( | bool | state | ) |

Search for all occurrences

Sets whether this attribute should be presented as a filename in the UI.

Parameters:

  [in] | state | whether the attribute is to be presented as a filename

Returns:
  Return status

Status Codes:
  - MS::kSuccess operation successful
  - MS::kFailure this function set does not have a valid attribute object

MStatus setAffectsAppearance | ( | bool | state | ) |

Search for all occurrences

Sets whether this attribute affects the appearance of the object when rendering in the viewport.

Parameters:

  [in] | state | whether the attribute affects the appearance of the object when rendering in the viewport.

Returns:
  Return status

Status Codes:
  - MS::kSuccess operation successful
  - MS::kFailure this function set does not have a valid attribute object

Examples:
  cgfxAttrDef.cpp, cgfxShaderNode.cpp, hwColorPerVertexShader.cpp, and hwPhongShader.cpp.

MStatus setDisconnectBehavior | ( | MFnAttribute::DisconnectBehavior | behavior | ) |

Search for all occurrences

Sets the disconnection behavior for this attribute.

This determines what happens when a connection to this attribute is deleted. This should only get called in the initialize call of your node creator.

The settings are as follows:

- kDelete delete the element of the array that was connected. This is only used for array attributes
- kReset reset the attribute to its default value
- kNothing leave the attribute set to its last known value

Attributes have a default disconnect behavior of kNothing.

If the kDelete behaviour is set on an array attribute which is a compound, that will only handle the case where the connection is to the parent attribute not to its children. So breaking a connection to an element of the parent (e.g. node.parent[3]) would cause that element to be removed, but breaking a connection to a child (e.g. node.parent[3].child) would leave the element intact, even if it was the last such connection.

To have the parent array element deleted when the last connection to a child is broken, you must set the kDelete behaviour on the connectable children as well.

Parameters:

  [in] | behavior | the new disconnect behavior

Returns:
  Return status

Status Codes:
  - MS::kSuccess operation successful
  - MS::kFailure this function set does not have a valid attribute object

Examples:
  cvColorShader.cpp, and geometrySurfaceConstraint.cpp.

MStatus setUsesArrayDataBuilder | ( | bool | state | ) |

Search for all occurrences

Sets whether this attribute uses an array data builder.

If true, then the MArrayDataBuilder class may be used with this attribute to generate its data. If false, MArrayDataHandle::builder will fail.

By default array attributes do not use an array data builder.

Parameters:

  [in] | state | whether the attribute uses an array data builder

Returns:
  Return status

Status Codes:
  - MS::kSuccess operation successful
  - MS::kFailure this function set does not have a valid attribute object

Examples:
  multiCurveNode.cpp, slopeShaderNode.cpp, and weightListNode.cpp.

MStatus setInternal | ( | bool | state | ) |

Search for all occurrences

The function controls an attribute's data storage.

When set to true, the virtual methods MPxNode::setInternalValueInContext() and MPxNode::getInternalValueInContext() are invoked whenever the attribute value is set or queried, respectively. By default, attributes are not internal.

There are two reasons to set an attribute as 'internal'. The first, and simplest, is when you want notification that the attribute has been set, or queried. This allows you to invoke some related action. In this case getInternalValueInContext() and setInternalValueInContext() should return false to indicate that Maya can store the attribute's value in the data block, instead of your own custom structure.

The second use of internal attributes is to store the data in a structure other than the datablock. When MPxNode::setInternalValueInContext() is called, the attribute's data can be transferred into your custom data structure. When getInternalValueInContext() is called, you can return your data. In this case getInternalValueInContext() and setInternalValueInContext() should return true to indicate that Maya should not store the attribute's value in the data block but use your own custom structure instead.

Parameters:

  [in] | state | whether the attribute uses internal data

Returns:
  Return status

Status Codes:
  - MS::kSuccess operation successful
  - MS::kFailure this function set does not have a valid attribute object

Examples:
  cgfxShaderNode.cpp, customImagePlane.cpp, hlslShader.cpp, hwColorPerVertexShader.cpp, hwPhongShader.cpp, and pnTrianglesNode.cpp.

MStatus setNiceNameOverride | ( | const MString & | localizedName | ) |

Search for all occurrences

Sets the localized string which should be used for this attribute in the UI.

The name given to an attribute when it is created is the name used to refer to it when the scene is written to a file. To ensure that the scene file is readable across all locales it is essential that the attribute have the same name in all locales. So if it's called 'keyLight' in an English locale then it must also be called 'keyLight' in French and Chinese locales.

The setNiceNameOverride() method provides a means for associating a more user-friendly name with the attribute, one which can change to accomodate the user's locale. If such a name is present then Maya will use it instead of the attribute's fixed name when displaying the attribute in various UI elements such as the Channel Box.

Parameters:

  [in] | localizedName | The name to use for the current locale.

Returns:
  Return status

Status Codes:
  - MS::kSuccess operation successful
  - MS::kFailure this function set does not have a valid attribute object

bool accepts | ( | MFnData::Type | type,
|  | MStatus * | ReturnStatus = `NULL`
| ) |  | const

Search for all occurrences

Returns true if this attribute can accept a connection of the given type.

Parameters:

  [in] | type | data type
  [out] | ReturnStatus | return status

Returns:
  A boolean value indicating whether a connection of that type is valid

Status Codes:
  - MS::kSuccess operation successful
  - MS::kFailure this function set does not have a valid attribute object

bool accepts | ( | const MTypeId & | id,
|  | MStatus * | ReturnStatus = `NULL`
| ) |  | const

Search for all occurrences

Returns true if this attribute can accept a connection of the given type.

Parameters:

  [in] | id | data type id
  [out] | ReturnStatus | return status

Returns:
  A boolean value indicating whether a connection of that type is valid

Status Codes:
  - MS::kSuccess operation successful
  - MS::kFailure this function set does not have a valid attribute object

MObject parent | ( | MStatus * | ReturnStatus = `NULL` | ) | const

Search for all occurrences

Get the parent of this attribute, if it has one.

Parameters:

  [out] | ReturnStatus | return status

Returns:
  The parent attribute

Status Codes:
  - MS::kSuccess operation successful
  - MS::kNotFound the attribute does not have a parent
  - MS::kFailure function set does not have a valid object

MString name | ( | MStatus * | ReturnStatus = `NULL` | ) | const

Search for all occurrences

Returns the long name of the attribute.

If the attribute has no long name then its short name is returned.

Parameters:

  [out] | ReturnStatus | The status of the resulting operation.

Returns:
  The name of the attribute.

Status Codes:
  - MS::kSuccess operation successful
  - MS::kFailure this function set does not have a valid attribute object

Examples:
  cgfxAttrDef.cpp, and getAttrAffectsCmd.cpp.

MString shortName | ( | MStatus * | ReturnStatus = `NULL` | ) | const

Search for all occurrences

Returns the short name of the attribute.

If the attribute has no short name then its long name is returned.

Parameters:

  [out] | ReturnStatus | The status of the resulting operation.

Returns:
  The name of the attribute.

Status Codes:
  - MS::kSuccess operation successful
  - MS::kFailure this function set does not have a valid attribute object

MString getAddAttrCmd | ( | bool | useLongName = `false`,
|  | MStatus * | status = `NULL`
| ) |  | const

Search for all occurrences

Returns a string containing the addAttr command which would be required to recreate the attribute on a node.

The command includes the terminating semicolon and is formatted as if for use with a selected node, meaning that it contains no node name.

To get the addAttr commands for a compound attribute and its children, use MFnCompoundAttribute::getAddAttrCmds.

Parameters:

  [in] | useLongName | if true, use the attribute's long name rather than its short name
  [in] | status | The status of the resulting operation. addAttr command

Returns:
  Return status

Status Codes:
  - MS::kSuccess operation successful
  - MS::kFailure operation failed
  - MS::kInvalidParameter function set is not bound to an attribute

MStatus addToCategory | ( | const MString & | category | ) |

Search for all occurrences

Add the attribute to the named category.

Attributes can be associated with different categories to facilitate grouping related concepts. For example, these categories could be queried at runtime to customize the UI.

Parameters:

  [in] | category | New category to which the attribute is to be added

Returns:
  Return status

Status Codes:
  - MS::kSuccess operation successful
  - MS::kFailure this function set does not have a valid attribute object

MStatus removeFromCategory | ( | const MString & | category | ) |

Search for all occurrences

Remove the attribute from the named category.

Presumes membership in the named category and fails if that's not true.

Parameters:

  [in] | category | Category from which the attribute is to be removed

Returns:
  Return status

Status Codes:
  - MS::kSuccess operation successful
  - MS::kNotFound attribute was not in category
  - MS::kFailure this function set does not have a valid attribute object

bool hasCategory | ( | const MString & | category | ) | const

Search for all occurrences

Check to see if the attribute belongs to the named category.

Matching is done solely on the string so multiple categories with the same name will not be unique.

Parameters:

  [in] | category | Category to check for attribute membership

Returns:
  True if the attribute belongs to that category

MStatus getCategories | ( | MStringArray & | categories | ) | const

Search for all occurrences

Get all of the categories to which this attribute belongs.

Parameters:

  [in] | categories | An MStringArray which will be overwritten with the categories associated with this attribute.

Returns:
  Return status

Status Codes:
  - MS::kSuccess operation successful
  - MS::kFailure this function set does not have a valid attribute object

MFnAttribute MFnAttribute MFnAttribute MFnAttribute MFnAttribute MFnAttribute MFnAttribute MFnAttribute MFnAttribute MFnAttribute
MFnAttribute MFnAttribute MFnAttribute MFnAttribute MFnAttribute MFnAttribute MFnAttribute MFnAttribute MFnAttribute MFnAttribute