MPxNode Class Reference
 
 
 

#include <MPxNode.h>


Class Description

Base class for user defined dependency nodes.

MPxNode is the the parent class for user defined dependency nodes. A dependency node is an object that resides in the dependency graph. It computes output attributes based on a set of input attributes. When an input changes, the compute method is called for each dependent output.

The dependency graph is made up of nodes that have connections between their attributes. When an attribute changes, recomputation propagates through the graph until all affected values have been updated.

When writing a dependency node, there is a very basic rule that should be observed. The outputs should be calculated only using the values of the inputs. All information about the world outside the node should come from input attributes. If this rule is not observed, then the results may be unpredictable.

All dependency nodes have four basic attributes. Documentation for them may be found with the documentation for the dependency nodes in Maya. Only one attribute requires special attention by node developers. Developers must decide whether to support the HasNoEffect setting of the state attribute. {HasNoEffect} means that a node should pass through all data without performing computations on it. For example, a deformer node will pass geometry through unmodified when state is set to HasNoEffect. It is up the the plug-in writer to observe the HasNoEffect mode if it is relevant to the type of node.

Examples:

AbcImport/AlembicNode.h, affectsNode/affectsNode.cpp, animCubeNode/animCubeNode.cpp, anisotropicShader/anisotropicShader.cpp, apiMeshShape/apiMeshCreator.h, arcLenNode/arcLenNode.cpp, AshliShader/GLSLShaderNode.cpp, backfillShader/backfillShader.cpp, blindDataShader/blindDataMesh.h, brickShader/brickShader.cpp, buildRotationNode/buildRotationNode.cpp, cellShader/cellShader.cpp, cgfxShaderNode.cpp, cgfxShaderNode.h, cgfxVector.h, checkerShader/checkerShader.cpp, circleNode/circleNode.cpp, clearcoat.cpp, closestPointOnCurve/closestPointOnCurveNode.h, compositingShader/compositingShader.cpp, contrastShader/contrastShader.cpp, cvColorShader/cvColorShader.cpp, depthShader/depthShader.cpp, displacementShader/displacementShader.cpp, dx11Shader/dx11ConeAngleToHotspotConverter.h, dx11Shader/dx11Shader.cpp, dx11Shader/dx11Shader.h, exampleRampAttribute/exampleMRampAttribute.cpp, fileTexture/fileTexture.cpp, flameShader/flameShader.cpp, fullLoftNode/fullLoftNode.cpp, gammaShader/gammaShader.cpp, genericAttributeNode/genericAttributeNode.cpp, geomShader/geomShader.cpp, GLSLShaderNode.h, gpuCache/gpuCacheCmd.cpp, gpuCache/gpuCacheShapeNode.cpp, gpuCache/gpuCacheShapeNode.h, hlslShader/hlslShader.cpp, hlslShader/hlslShader.h, interpShader/interpShader.cpp, jitterNode/jitterNode.cpp, lambertShader/lambertShader.cpp, latticeNoise/latticeNoise.h, lavaShader/lavaShader.cpp, lightShader/lightShader.cpp, meshOpCmd/polyModifierNode.h, MetadataSample/tweakMetadataNode.h, mixtureShader/mixtureShader.cpp, multiCurveNode/multiCurveNode.cpp, noiseShader/noiseShader.cpp, phongShader/phongShader.cpp, pointOnMeshInfo/pointOnMeshInfoNode.h, pointOnSubdNode/pointOnSubdNode.h, renderAccessNode/renderAccessNode.cpp, sceneAssembly/adskPrepareRenderGlobals.h, shadowMatteShader/shadowMatteShader.cpp, shellNode/shellNode.cpp, shiftNode/shiftNode.cpp, simpleLoftNode/simpleLoftNode.cpp, sineNode/sineNode.cpp, slopeShader/slopeShaderNode.h, solidCheckerShader/solidCheckerShader.cpp, splitUVCmd/polyModifierNode.h, stringFormatNode/stringFormatNode.cpp, testNobjectNode/testNobjectNode.h, testNpassiveNode/testNpassiveNode.h, testNsolverNode/testNsolverNode.h, testNucleusNode/testNucleusNode.h, transCircleNode/transCircleNode.cpp, volumeShader/volumeShader.cpp, and weightListNode/weightListNode.cpp.

Inheritance diagram for MPxNode:
MPxAssembly MPxCameraSet MPxConstraint MPxDeformerNode MPxEmitterNode MPxFieldNode MPxHardwareShader MPxHwShaderNode MPxIkSolverNode MPxImagePlane MPxLocatorNode MPxManipContainer MPxManipulatorNode MPxObjectSet MPxParticleAttributeMapperNode MPxPolyTrg MPxSpringNode MPxSurfaceShape MPxThreadedDeviceNode MPxTransform

List of all members.

Public Types

enum   Type {
  kDependNode, kLocatorNode, kDeformerNode, kManipContainer,
  kSurfaceShape, kFieldNode, kEmitterNode, kSpringNode,
  kIkSolverNode, kHardwareShader, kHwShaderNode, kTransformNode,
  kObjectSet, kFluidEmitterNode, kImagePlaneNode, kParticleAttributeMapperNode,
  kCameraSetNode, kConstraintNode, kManipulatorNode, kClientDeviceNode,
  kThreadedDeviceNode, kAssembly, kLast
}
  Defines the type of node. More...

Public Member Functions

  MPxNode ()
  Constructor.
virtual  ~MPxNode ()
  Destructor.
virtual void  postConstructor ()
  Post constructor.
virtual MStatus  compute (const MPlug &plug, MDataBlock &dataBlock)
  This method should be overridden in user defined nodes.
virtual bool  getInternalValueInContext (const MPlug &plug, MDataHandle &dataHandle, MDGContext &ctx)
  This method is overriden by nodes that store attribute data in some internal format.
virtual bool  setInternalValueInContext (const MPlug &plug, const MDataHandle &dataHandle, MDGContext &ctx)
  This method is overriden by nodes that store attribute data in some internal format.
virtual bool  getInternalValue (const MPlug &plug, MDataHandle &dataHandle)
  This method is obsolete.
virtual bool  setInternalValue (const MPlug &plug, const MDataHandle &dataHandle)
  This method is obsolete.
virtual int  internalArrayCount (const MPlug &plug, const MDGContext &ctx) const
  This method is overriden by nodes that have internal array attributes which are not stored in Maya's datablock.
virtual void  copyInternalData (MPxNode *)
  This method is overriden by nodes that store attribute data in some internal format.
virtual MStatus  legalConnection (const MPlug &plug, const MPlug &otherPlug, bool asSrc, bool &isLegal) const
  This method allows you to check for legal connections being made to attributes of this node.
virtual MStatus  legalDisconnection (const MPlug &plug, const MPlug &otherPlug, bool asSrc, bool &isLegal) const
  This method allows you to check for legal disconnections being made to attributes of this node.
virtual MStatus  setDependentsDirty (const MPlug &plug, MPlugArray &plugArray)
  This method can be overridden in user defined nodes to specify which plugs should be set dirty based upon an input plug {plugBeingDirtied} which Maya is marking dirty.
virtual MStatus  connectionMade (const MPlug &plug, const MPlug &otherPlug, bool asSrc)
  This method gets called when connections are made to attributes of this node.
virtual MStatus  connectionBroken (const MPlug &plug, const MPlug &otherPlug, bool asSrc)
  This method gets called when connections are broken with attributes of this node.
virtual bool  isPassiveOutput (const MPlug &plug) const
  This method may be overridden by the user defined node if it wants to provide output attributes which do not prevent value modifications to the destination attribute.
virtual MStatus  shouldSave (const MPlug &plug, bool &isSaving)
  This method may be overridden by the user defined node.
virtual MPlug  passThroughToOne (const MPlug &plug) const
  This method may be overriden by nodes that have a one-to-one relationship between an input attribute and a corresponding output attribute.
virtual bool  passThroughToMany (const MPlug &plug, MPlugArray &plugArray) const
  This method is overriden by nodes that want to control the traversal behavior of some Maya search algorithms which traverse the history/future of shape nodes looking for directly related nodes.
virtual Type  type () const
  Returns the type of node that this is.
virtual bool  isAbstractClass () const
  Override this class to return true if this node is an abstract node.
virtual MStringArray  getFilesToArchive (bool shortName=false, bool unresolvedName=false, bool markCouldBeImageSequence=false) const
  Use this method to return all external files used by this node.
virtual MTypeId  typeId () const
  Returns the TYPEID of this node.
virtual MString  typeName () const
  Returns the type name of this node.
virtual MString  name () const
  Returns the name of this particular instance of this class.
virtual MObject  thisMObject () const
  Returns the MObject associated with this user defined node.
virtual MStatus  setExistWithoutInConnections (bool flag)
  This method specifies whether or not the node can exist without input connections.
virtual bool  existWithoutInConnections (MStatus *ReturnStatus=NULL) const
  Determines whether or not this node can exist without input connections.
virtual MStatus  setExistWithoutOutConnections (bool flag)
  This method specifies whether or not the node can exist without output connections.
virtual bool  existWithoutOutConnections (MStatus *ReturnStatus=NULL) const
  Determines whether or not this node can exist without output connections.

Static Public Member Functions

static MStatus  addAttribute (const MObject &attr)
  This method adds a new attribute to a user defined node type during the type's initialization.
static MStatus  inheritAttributesFrom (const MString &parentClassName)
  This method allows a class of plugin node to inherit all of the attributes of a second class of plugin node.
static MStatus  attributeAffects (const MObject &whenChanges, const MObject &isAffected)
  This method specifies that a particular input attribute affects a specific output attribute.
static const char *  className ()
  Returns the name of this class.

Static Public Attributes

static MObject  message
  message attribute
static MObject  isHistoricallyInteresting
  is historically interesting attribute
static MObject  caching
  caching attribute
static MObject  state
  state attribute

Protected Member Functions

virtual MDataBlock  forceCache (MDGContext &ctx=MDGContext::fsNormal)
  USE _forceCache() IN SCRIPT.
virtual void  setMPSafe (bool flag)
  USE _setMPSafe() IN SCRIPT.
virtual MStatus  setDoNotWrite (bool flag)
  USE _setDoNotWrite() IN SCRIPT.
virtual bool  doNotWrite (MStatus *ReturnStatus=NULL) const
  USE _doNotWrite() IN SCRIPT.

Member Enumeration Documentation

enum Type

Defines the type of node.

Enumerator:
kDependNode 

Custom node derived from MPxNode.

kLocatorNode 

Custom locator derived from MPxLocatorNode.

kDeformerNode 

Custom deformer derived from MPxDeformerNode.

kManipContainer 

Custom container derived from MPxManipContainer.

kSurfaceShape 

Custom shape derived from MPxSurfaceShape.

kFieldNode 

Custom field derived from MPxFieldNode.

kEmitterNode 

Custom emitter derived from MPxEmitterNode.

kSpringNode 

Custom spring derived from MPxSpringNode.

kIkSolverNode 

Custom IK solver derived from MPxIkSolverNode.

kHardwareShader 

Custom shader derived from MPxHardwareShader.

kHwShaderNode 

Custom shader derived from MPxHwShaderNode.

kTransformNode 

Custom transform derived from MPxTransform.

kObjectSet 

Custom set derived from MPxObjectSet.

kFluidEmitterNode 

Custom fluid emitter derived from MpxFluidEmitterNode.

kImagePlaneNode 

Custom image plane derived from MPxImagePlane.

kParticleAttributeMapperNode 

Custom particle attribute mapper derived from MPxParticleAttributeMapperNode.

kCameraSetNode 

Custom director derived from MPxCameraSet.

kConstraintNode 

Custom constraint derived from MPxConstraint.

kManipulatorNode 

Custom manipulator derived from MPxManipulatorNode.

kClientDeviceNode 

Custom threaded device derived from MPxThreadedDeviceNode.

kThreadedDeviceNode 

Custom threaded device node.

kAssembly 

Custom assembly derived from MPxAssembly.

kLast 

Last value, used for counting.


Constructor & Destructor Documentation

MPxNode ( )

Constructor.

The constructor should never call any methods from MPxNode or make any calls that require the existence of the MObject associated with the user defined node. The postConstructor method should be used to do any initialization of this kind.


Member Function Documentation

void postConstructor ( ) [virtual]

Post constructor.

Internally maya creates two objects when a user defined node is created, the internal MObject and the user derived object. The association between the these two objects is not made until after the MPxNode constructor is called. This implies that no MPxNode member function can be called from the MPxNode constructor. The postConstructor will get called immediately after the constructor when it is safe to call any MPxNode member function.

Reimplemented in MPxPolyTrg, and MPxTransform.

Examples:
anisotropicShader/anisotropicShader.cpp, apiMeshShape/apiMeshShape.h, backfillShader/backfillShader.cpp, brickShader/brickShader.cpp, cellShader/cellShader.cpp, cgfxShaderNode.h, checkerShader/checkerShader.cpp, clearcoat.cpp, compositingShader/compositingShader.cpp, contrastShader/contrastShader.cpp, curvedArrowsNode/curvedArrowsNode.cpp, cvColorShader/cvColorShader.cpp, depthShader/depthShader.cpp, displacementShader/displacementShader.cpp, dx11Shader/dx11ConeAngleToHotspotConverter.h, fileTexture/fileTexture.cpp, flameShader/flameShader.cpp, gameInputDevice/gameInputDevice.cpp, gammaShader/gammaShader.cpp, geometrySurfaceConstraint/geometrySurfaceConstraint.h, geomShader/geomShader.cpp, GLSLShaderNode.h, hlslShader/hlslShader.h, hwAnisotropicShader_NV20/hwAnisotropicShader_NV20.h, hwColorPerVertexShader/hwColorPerVertexShader.cpp, hwDecalBumpShader_NV20/hwDecalBumpShader_NV20.h, hwManagedTextureShader/hwManagedTextureShader.cpp, hwPhongShader/hwPhongShader.h, hwReflectBumpShader_NV20/hwReflectBumpShader_NV20.h, hwRefractReflectShader_NV20/hwRefractReflectShader_NV20.h, hwToonShader_NV20/hwToonShader_NV20.h, hwUnlitShader/hwUnlitShader.h, interpShader/interpShader.cpp, lambertShader/lambertShader.cpp, lavaShader/lavaShader.cpp, lightShader/lightShader.cpp, mixtureShader/mixtureShader.cpp, noiseShader/noiseShader.cpp, phongShader/phongShader.cpp, quadricShape/quadricShape.cpp, randomizerDevice/randomizerDevice.cpp, renderAccessNode/renderAccessNode.cpp, sceneAssembly/assemblyDefinition.h, shadowMatteShader/shadowMatteShader.cpp, slopeShader/slopeShaderNode.h, solidCheckerShader/solidCheckerShader.cpp, squareScaleManipContext/squareScaleManipContext.h, udpDevice/udpDevice.cpp, and volumeShader/volumeShader.cpp.
MStatus compute ( const MPlug plug,
MDataBlock block 
) [virtual]

This method should be overridden in user defined nodes.

Recompute the given output based on the nodes inputs. The plug represents the data value that needs to be recomputed, and the data block holds the storage for all of the node's attributes.

The MDataBlock will provide smart handles for reading and writing this node's attribute values. Only these values should be used when performing computations.

When evaluating the dependency graph, Maya will first call the compute method for this node. If the plug that is provided to the compute indicates that that the attribute was defined by the Maya parent node, the compute method should return MS::kUnknownParameter. When this occurs, Maya will call the internal Maya node from which the user-defined node is derived to compute the plug's value.

This means that a user defined node does not need to be concerned with computing inherited output attributes. However, if desired, these can be safely recomputed by this method to change the behaviour of the node.

Parameters:
[in] plug plug representing the attribute that needs to be recomputed
[in] block data block containing storage for the node's attributes
Returns:
Status code
Status Codes:

Reimplemented in MPxEmitterNode, MPxFieldNode, MPxFluidEmitterNode, MPxParticleAttributeMapperNode, MPxPolyTrg, and MPxTransform.

Examples:
AbcImport/AlembicNode.h, affectsNode/affectsNode.cpp, animCubeNode/animCubeNode.cpp, anisotropicShader/anisotropicShader.cpp, apiMeshShape/apiMeshCreator.h, apiMeshShape/apiMeshShape.h, arcLenNode/arcLenNode.cpp, backfillShader/backfillShader.cpp, blindDataShader/blindDataMesh.h, blindDataShader/blindDataShader.h, brickShader/brickShader.cpp, buildRotationNode/buildRotationNode.cpp, cellShader/cellShader.cpp, cgfxShaderNode.h, cgfxVector.h, checkerShader/checkerShader.cpp, circleNode/circleNode.cpp, clearcoat.cpp, closestPointOnCurve/closestPointOnCurveNode.h, compositingShader/compositingShader.cpp, contrastShader/contrastShader.cpp, curvedArrowsNode/curvedArrowsNode.cpp, cvColorNode/cvColorNode.cpp, cvColorShader/cvColorShader.cpp, depthShader/depthShader.cpp, displacementShader/displacementShader.cpp, dx11Shader/dx11ConeAngleToHotspotConverter.h, exampleRampAttribute/exampleMRampAttribute.cpp, fileTexture/fileTexture.cpp, flameShader/flameShader.cpp, footPrintManip/footPrintManip.cpp, footPrintNode/footPrintNode.cpp, fullLoftNode/fullLoftNode.cpp, gameInputDevice/gameInputDevice.cpp, gammaShader/gammaShader.cpp, genericAttributeNode/genericAttributeNode.cpp, geometrySurfaceConstraint/geometrySurfaceConstraint.h, geomShader/geomShader.cpp, GLSLShaderNode.h, hwColorPerVertexShader/hwColorPerVertexShader.cpp, hwDecalBumpShader_NV20/hwDecalBumpShader_NV20.h, hwPhongShader/hwPhongShader.h, hwReflectBumpShader_NV20/hwReflectBumpShader_NV20.h, hwRefractReflectShader_NV20/hwRefractReflectShader_NV20.h, hwToonShader_NV20/hwToonShader_NV20.h, hwUnlitShader/hwUnlitShader.h, interpShader/interpShader.cpp, jitterNode/jitterNode.cpp, lambertShader/lambertShader.cpp, latticeNoise/latticeNoise.h, lavaShader/lavaShader.cpp, lightShader/lightShader.cpp, MetadataSample/tweakMetadataNode.h, mixtureShader/mixtureShader.cpp, multiCurveNode/multiCurveNode.cpp, noiseShader/noiseShader.cpp, phongShader/phongShader.cpp, pointOnMeshInfo/pointOnMeshInfoNode.h, pointOnSubdNode/pointOnSubdNode.h, quadricShape/quadricShape.cpp, randomizerDevice/randomizerDevice.cpp, renderAccessNode/renderAccessNode.cpp, shadowMatteShader/shadowMatteShader.cpp, shellNode/shellNode.cpp, shiftNode/shiftNode.cpp, simpleLoftNode/simpleLoftNode.cpp, simpleSpring/simpleSpring.h, sineNode/sineNode.cpp, slopeShader/slopeShaderNode.h, solidCheckerShader/solidCheckerShader.cpp, splatDeformer/splatDeformer.cpp, sseDeformer/sseDeformer.cpp, stringFormatNode/stringFormatNode.cpp, swissArmyManip/swissArmyManip.cpp, testNobjectNode/testNobjectNode.h, testNpassiveNode/testNpassiveNode.h, testNsolverNode/testNsolverNode.h, testNucleusNode/testNucleusNode.h, transCircleNode/transCircleNode.cpp, udpDevice/udpDevice.cpp, volumeShader/volumeShader.cpp, and weightListNode/weightListNode.cpp.
bool getInternalValueInContext ( const MPlug plug,
MDataHandle dataHandle,
MDGContext ctx 
) [virtual]

This method is overriden by nodes that store attribute data in some internal format.

The internal state of attributes can be set or queried using the setInternal and internal methods of MFnAttribute.

When internal attribute values are queried via getAttr or MPlug::getValue this method is called.

NOTE: the default behaviour of this method is to call MPxNode::getInternalValue( const MPlug&, const MDataHandle& ) if the context is normal.

Parameters:
[in] plug the attribute that is being queried
[out] dataHandle the dataHandle to store the attribute value
[in] ctx the context the method is being evaluated in
Returns:
  • true the attribute was place on the datablock
  • false could not handle the specified attribute, pass this request to the default handler
Examples:
cgfxShaderNode.h, customImagePlane/customImagePlane.cpp, dx11Shader/dx11Shader.cpp, dx11Shader/dx11Shader.h, GLSLShaderNode.h, gpuCache/gpuCacheShapeNode.cpp, hlslShader/hlslShader.h, hwColorPerVertexShader/hwColorPerVertexShader.cpp, and hwPhongShader/hwPhongShader.h.
bool setInternalValueInContext ( const MPlug plug,
const MDataHandle dataHandle,
MDGContext ctx 
) [virtual]

This method is overriden by nodes that store attribute data in some internal format.

The internal state of attributes can be set or queried using the setInternal and internal methods of MFnAttribute.

When internal attribute values are set via setAttr or MPlug::setValue this method is called.

Another use for this method is to impose attribute limits.

NOTE: the default behaviour of this method is to call MPxNode::setInternalValue( const MPlug&, const MDataHandle& ) if the context is normal.

Parameters:
[in] plug the attribute that is being set
[in] dataHandle the dataHandle containing the value to set
[in] ctx the context the method is being evaluated in
Returns:
  • true the attribute was set
  • false could not handle the specified attribute, pass this request to the default handler
Examples:
cgfxShaderNode.h, customImagePlane/customImagePlane.cpp, dx11Shader/dx11Shader.cpp, dx11Shader/dx11Shader.h, GLSLShaderNode.h, gpuCache/gpuCacheShapeNode.cpp, hlslShader/hlslShader.h, hwColorPerVertexShader/hwColorPerVertexShader.cpp, and hwPhongShader/hwPhongShader.h.
bool getInternalValue ( const MPlug plug,
MDataHandle dataHandle 
) [virtual]
bool setInternalValue ( const MPlug plug,
const MDataHandle dataHandle 
) [virtual]
int internalArrayCount ( const MPlug plug,
const MDGContext ctx 
) const [virtual]

This method is overriden by nodes that have internal array attributes which are not stored in Maya's datablock.

This method is used by Maya to determine the non-sparse count of array elements during file io. If the internal array is stored sparsely, you should return the maximum index of the array plus one. If the internal array is non-sparse then return the length of the array.

This method does not need to be implemented for attributes that are stored in the datablock since Maya will use the datablock size.

If this method is overriden, it should return -1 for attributes which it does not handle. Maya will use the datablock size to determine the array length when -1 is returned.

Parameters:
[in] plug the array plug
[in] ctx the context
void copyInternalData ( MPxNode node ) [virtual]

This method is overriden by nodes that store attribute data in some internal format.

On duplication this method is called on the duplicated node with the node being duplicated passed as the parameter. Overriding this method gives your node a chance to duplicate any internal data you've been storing and manipulating outside of normal attribute data.

Parameters:
[in] node the node that is being duplicated

Reimplemented in MPxTransform.

Examples:
cgfxShaderNode.h, dx11Shader/dx11Shader.cpp, dx11Shader/dx11Shader.h, GLSLShaderNode.h, and hlslShader/hlslShader.h.
MStatus legalConnection ( const MPlug plug,
const MPlug otherPlug,
bool  asSrc,
bool &  isLegal 
) const [virtual]

This method allows you to check for legal connections being made to attributes of this node.

You should return kUnknownParameter to specify that maya should handle this connection if you are unable to determine if it is legal.

Parameters:
[in] plug attribute on this node
[in] otherPlug attribute on other node
[in] asSrc is this plug a source of the connection
[in] isLegal set this to true if the connection is legal, false otherwise
Returns:
Status code
Status Codes:
MStatus legalDisconnection ( const MPlug plug,
const MPlug otherPlug,
bool  asSrc,
bool &  isLegal 
) const [virtual]

This method allows you to check for legal disconnections being made to attributes of this node.

You should return kUnknownParameter to specify that maya should handle this disconnection if you are unable to determine if it is legal.

Parameters:
[in] plug attribute on this node
[in] otherPlug attribute on other node
[in] asSrc is this plug a source of the connection
[out] isLegal set this to true if the disconnection is legal, false otherwise
Returns:
Status code
Status Codes:
MStatus setDependentsDirty ( const MPlug plugBeingDirtied,
MPlugArray affectedPlugs 
) [virtual]

This method can be overridden in user defined nodes to specify which plugs should be set dirty based upon an input plug {plugBeingDirtied} which Maya is marking dirty.

The list of plugs for Maya to mark dirty is returned by the plug array {affectedPlugs}. This method handles both dynamic as well as non-dynamic plugs and is useful in the following ways:

  • Allows attributeAffects-style relationships to be handled for dynamically-added attributes. Since MPxNode::attributeAffects can only be used with non-dynamic attributes, use of this method allows a way for all attributes of a node to affect one another, both dynamic and non-dynamic.
  • Provides more flexible relationships than what is available with MPxNode::attributeAffects. For example, you may wish to not dirty plugs when the current frame is one. However, as the routine is called during dirty propagation, there are restrictions on what can be done within the routine, most importantly you must not cause any dependency graph computation. For details, see the IMPORTANT NOTE below.

This method is designed to work harmoniously with MPxNode::attributeAffects on the same node. Alternately, you can do all affects relationships within a yourNode::setDependentsDirty() implementation.

The body of a user-implemented setDependentsDirty() implementation might look like the following example, which causes the plug called "B" to be set dirty whever plug "A" is changed, i.e. A affects B.

    const   MString exampleNode::A( "A" );  // Dynamic attribute "A"
    MObject exampleNode::attrB;     // Non-dynamic attribute "B"

    MStatus exampleNode::setDependentsDirty(
            const MPlug &plugBeingDirtied,
            MPlugArray &affectedPlugs )
    {
        // This example shows a dynamic attribute (A) affecting a
        // non-dynamic attribute (B). For an example of a dynamic
        // affecting a dynamic, please the the developer's toolkit
        // example plug-in, affectsNode.cpp.
        //
        if ( plugBeingDirtied.partialName() == A ) {
            // "A" is being dirtied. We want "A" to affect "B", so we
            // add "B" to the list of plugs for Maya to dirty. Once again,
            // please see the IMPORTANT NOTE about what you can and
            // cannot do within a setDependentsDirty() routine.
            //
            MObject thisNode = thisMObject();
            MPlug pB( thisNode, exampleNode::attrB );
            affectedPlugs.append( pB );
        }
        return( MS::kSuccess );
    }

In the above example, whenever plugBeingDirtied is A, we add B to affectedPlugs so that Maya will dirty B and also any plugs which depend upon B.

For cases where multi compound attributes are dirtied, it is the programmer's responsibility to define ALL affects relationships. Dirtying the parent plug of a multi does not imply that all of its children will be marked dirty. Likewise, dirtying a child attribute does not imply the parent of the multi is dirty. This must be explicitly defined using the affected plug array. The following example demonstrates how one would dirty both the element affected and the parent plug.

    MObject exampleNode::inputAttr;     // Non-dynamic multi-input attribute.
    MObject exampleNode::outputAttr;    // Non-dynamic multi-output attribute.
    MStatus exampleNode::setDependentsDirty(MPlug const & inPlug,
                                            MPlugArray  & affectedPlugs)
    {
        if ( inPlug.attribute() != inputAttr ) {
            return MS::kSuccess;
        }

        MPlug outArrayPlug(thisMObject(),outputAttr);

        if (inPlug.isElement()) {
            // First dirty the output output element first.
            // Of course, dirty output element itself
            MPlug elemPlug = outArrayPlug.elementByLogicalIndex(
                                                inPlug.logicalIndex());
            affectedPlugs.append(elemPlug);

            // We also need to dirty the parent.
            //
            affectedPlugs.append(outArrayPlug);
        } else {
            // Mark the parent output plug as dirty.
            //
            affectedPlugs.append(outArrayPlug);

            // Also visit each element.
            //
            unsigned int i,n = outArrayPlug.numElements();
            for (i = 0; i < n; i++) {
                MPlug elemPlug = outArrayPlug.elementByPhysicalIndex(i);
                affectedPlugs.append(elemPlug);
            }
        }
        return MS::kSuccess;
    }

IMPORTANT NOTE: since the setDependentsDirty() method is called during dirty propagation, you must be careful not to perform any dependency graph computations from within the routine. Instead, if you want to know the value of a plug, use MDataBlock::outputValue() because it will not result in computation (and thus recursion). In general, the majority of {setDependentsDirty()} methods which users will implement should involve only fixed relationships. In the rare occurence where you need to look at plug values, please heed the warning with {MDataBlock::outputValue()} and use plugs which contain values which you know to be up to date prior to the start of dirty propagation.

Parameters:
[in] plugBeingDirtied plug which is being set dirty by Maya
[in] affectedPlugs the programmer should add any plugs which they want to set dirty to this list.
Returns:
Status code
Status Codes:
Examples:
affectsNode/affectsNode.cpp, apiMeshShape/apiMeshShape.h, dx11Shader/dx11Shader.cpp, dx11Shader/dx11Shader.h, and fileTexture/fileTexture.cpp.
MStatus connectionMade ( const MPlug plug,
const MPlug otherPlug,
bool  asSrc 
) [virtual]

This method gets called when connections are made to attributes of this node.

You should return kUnknownParameter to specify that maya should handle this connection or if you want maya to process the connection as well.

Parameters:
[in] plug attribute on this node
[in] otherPlug attribute on other node
[in] asSrc is this plug a source of the connection
Returns:
Status code
Status Codes:
Examples:
apiMeshShape/apiMeshShape.cpp, apiMeshShape/apiMeshShape.h, dx11Shader/dx11Shader.h, and GLSLShaderNode.h.
MStatus connectionBroken ( const MPlug plug,
const MPlug otherPlug,
bool  asSrc 
) [virtual]

This method gets called when connections are broken with attributes of this node.

You should return kUnknownParameter to specify that maya should handle this connection or if you want maya to process the connection as well.

Parameters:
[in] plug attribute on this node
[in] otherPlug attribute on other node
[in] asSrc is this plug a source of the connection
Returns:
Status code
Status Codes:
Examples:
apiMeshShape/apiMeshShape.cpp, apiMeshShape/apiMeshShape.h, and GLSLShaderNode.h.
bool isPassiveOutput ( const MPlug plug ) const [virtual]

This method may be overridden by the user defined node if it wants to provide output attributes which do not prevent value modifications to the destination attribute.

For example, output plugs on animation curve nodes are passive. This allows the attributes driven by the animation curves to be set to new values by the user.

Parameters:
[in] plug plug representing output in question
Returns:
true indicates passive
Examples:
AbcImport/AlembicNode.cpp, and AbcImport/AlembicNode.h.
MStatus shouldSave ( const MPlug plug,
bool &  isSaving 
) [virtual]

This method may be overridden by the user defined node.

It should only be required to override this on rare occasions.

This method determines whether a specific attribute of this node should be written out during a file save. The default behavior is to only write the value if it differs from the default and is not being supplied by a connection. This behavior should be sufficient in most cases. This method is not called for ramp attributes since they should always be written.

Parameters:
[in] plug plug representing the attribute to be saved
[in] isSaving boolean telling whether to save or not
Returns:
Status code
Status Codes:
Examples:
apiMeshShape/apiMeshShape.cpp, apiMeshShape/apiMeshShape.h, cgfxShaderNode.cpp, and cgfxShaderNode.h.
MPlug passThroughToOne ( const MPlug plug ) const [virtual]

This method may be overriden by nodes that have a one-to-one relationship between an input attribute and a corresponding output attribute.

This method is used by Maya to perform the following capabilities:

  • When this node is deleted, the delete command will rewire the source of the input attribute to the destination of the output attribute if the source and destination are connected to nodes that are not deleted.
  • History traversal algorithms such as the bakePartialHistory command use this method to direct its traversal through a shape's construction history.
  • The base class Maya implementation of passThroughToAll will call this method if passThroughToAll returns false.
Parameters:
[in] plug the plug
Returns:
The corresponding plug, or an empty plug if no corresponding plug exists
bool passThroughToMany ( const MPlug plug,
MPlugArray plugArray 
) const [virtual]

This method is overriden by nodes that want to control the traversal behavior of some Maya search algorithms which traverse the history/future of shape nodes looking for directly related nodes.

In particular, the Artisan paint code uses this method when searching for paintable nodes, and the disk cache code uses this method when searching for upstream cacheFile nodes.

If this method is not implemented or returns false, the base class Maya implementation of this method calls passThroughToOne and returns the results of that call.

Parameters:
[in] plug the plug
[in] plugArray the corresponding plugs
Returns:
true if plug was handled, false to invoke base class implementation
MPxNode::Type type ( ) const [virtual]

Returns the type of node that this is.

This is used to differentiate user defined nodes that are derived off different MPx base classes.

It is not necessary to override this method.

Returns:
Type of the node

Reimplemented in MPxAssembly, MPxCameraSet, MPxClientDeviceNode, MPxDeformerNode, MPxEmitterNode, MPxFieldNode, MPxFluidEmitterNode, MPxHardwareShader, MPxHwShaderNode, MPxIkSolverNode, MPxImagePlane, MPxLocatorNode, MPxManipContainer, MPxObjectSet, MPxParticleAttributeMapperNode, MPxSpringNode, MPxSurfaceShape, MPxThreadedDeviceNode, and MPxTransform.

bool isAbstractClass ( ) const [virtual]

Override this class to return true if this node is an abstract node.

An abstract node can only be used as a base class. It cannot be created using the 'createNode' command.

It is not necessary to override this method.

Returns:
true if the node is abstract.

Reimplemented in MPxPolyTrg.

MStatus addAttribute ( const MObject attr ) [static]

This method adds a new attribute to a user defined node type during the type's initialization.

This method will only work during the static initialization method of the user defined node class. The initialization method is the one that is passed into MFnPlugin::registerNode. The attributes must first be created using one of the MFnAttribute classes, and can then be added using this method.

For compound attributes, the proper way to use this method is by calling it with the parent attribute. If a compound attribute is passed, this method will add all of its children. NOTE: A failure will occur if you attempt to call addAttribute() on the children of a compound attribute.

Parameters:
[in] attr new attribute to add
Returns:
Status code
Status Codes:
  • MS::kSuccess Operation successful
  • MS::kInvalidParameter Attribute is invalid or already added or child of a compound attribute is being added before the parent
  • MS::kFailure Method was not called during the node's initialize routine
Examples:
geometryReplicator/geometryReplicator.cpp, gpuCache/gpuCacheShapeNode.cpp, sceneAssembly/adskPrepareRenderGlobals.cpp, sceneAssembly/assemblyDefinition.cpp, sceneAssembly/assemblyReference.cpp, uiDrawManager/uiDrawManager.cpp, and xmlAssembly/XMLAssembly.cpp.
MStatus inheritAttributesFrom ( const MString parentClassName ) [static]

This method allows a class of plugin node to inherit all of the attributes of a second class of plugin node.

This method will only work during the static initialization method of the user defined node class and must be called before any other attributes have been added. The initialization method is the one that is passed into MFnPlugin::registerNode.

A plugin node may only inherit attributes from one other class of plugin node. Attempting to call this method multiple times within a node's initialization method will result in an error.

Both node classes must be registered using the same MPxNode::Type.

Parameters:
[in] parentClassName class of node to inherit attributes from
Returns:
Status code
Status Codes:
MStatus attributeAffects ( const MObject whenChanges,
const MObject isAffected 
) [static]

This method specifies that a particular input attribute affects a specific output attribute.

This is required to make evaluation efficient. When an input changes, only the affected outputs will be computed. Output attributes cannot be keyable - if they are keyable, this method will fail.

This method must be called for every attribute dependency when initializing the node's attributes. The attributes must first be added using the MPxNode::addAttribute method. Failing to call this method will cause the node not to update when its inputs change. If there are no calls to this method in a node's initialization, then the compute method will never be called.

This method will only work during the static initialization method of the user defined node class. The initialization method is the one that is passed into MFnPlugin::registerNode. As a result, it does not work with dynamic attributes. For an alternate solution which handles dynamic as well as non-dynamic attributes refer to MPxNode::setDependentsDirty.

Parameters:
[in] whenChanges input attribute - MObject that points to an input attribute that has already been added
[in] isAffected affected output attribute - MObject that points to an output attribute that has already been added
Returns:
Status code
Status Codes:
  • MS::kSuccess Operation successful
  • MS::kInvalidParameter At least one of the attributes is invalid or has not been added to this node using the addAttribute routine
  • MS::kFailure Method was not called during the node's initialize routine
MStringArray getFilesToArchive ( bool  shortName = false,
bool  unresolvedName = false,
bool  markCouldBeImageSequence = false 
) const [virtual]

Use this method to return all external files used by this node.

This file list will be used by the File > Archive zip feature, maya.exe -archive and the `file -q -list` mel command.

Only include files that exist.

If shortName is true, return just the filename portion of the path (can be obtained with MString::baseName()). Otherwise, return a full path.

If unresolvedName is true, return the path before any resolution has been done (i.e leave it as a relative path, include unexpanded environment variables, tildes, ".."s etc). Otherwise, resolve the file path and return an absolute path (to resolve with standard Maya path resolution, use MFileObject::resolvedFullName()).

Parameters:
[in] shortName If true, only add the filename of the path
[in] unresolvedName If true, add paths before any resolution, rather than absolute paths.
[in] markCouldBeImageSequence If true, append an asterisk after any file path that could be an image sequence (note: only used by maya.exe -archive)
Returns:
Array of file paths
Examples:
AbcImport/AlembicNode.h.
MTypeId typeId ( ) const [virtual]

Returns the TYPEID of this node.

The TYPEID is a four byte identifier that uniquely identifies this type of node to the binary file format.

It is not necessary to override this method.

Returns:
Type id of the node

Reimplemented in MPxAssembly.

Examples:
dx11Shader/dx11ConeAngleToHotspotConverter.h, dx11Shader/dx11Shader.h, and gpuCache/gpuCacheShapeNode.cpp.
MString typeName ( ) const [virtual]

Returns the type name of this node.

The type name identifies the node type to the ASCII file format. It may also be used with the MEL command "createNode" to create a new node of this type.

It is not necessary to override this method.

Returns:
Type name of the node

Reimplemented in MPxAssembly.

Examples:
sceneAssembly/adskPrepareRenderGlobals.h.
MString name ( ) const [virtual]

Returns the name of this particular instance of this class.

Each object in the dependency graph has a name. This name will be used by the UI and by MEL.

It is not necessary to override this method.

Returns:
Type id of the node

Reimplemented in MPxAssembly.

MObject thisMObject ( ) const [virtual]

Returns the MObject associated with this user defined node.

This makes it possible to use MFnDependencyNode or to construct plugs to this node's attributes.

It is not necessary to override this method.

Returns:
MObject handle for this node

Reimplemented in MPxAssembly.

MStatus setExistWithoutInConnections ( bool  flag ) [virtual]

This method specifies whether or not the node can exist without input connections.

If a node connected to this node is deleted resulting in no more input connections and if this flag is false, then this node will be deleted.

Parameters:
[in] flag true if this node can exist without input connections, false otherwise
Status Codes:
  • MS::kSuccess operation successful
  • MS::kFailure this MPxNode has not been initialized properly. Make sure this method is not being called from the constructor.

Reimplemented in MPxAssembly.

bool existWithoutInConnections ( MStatus ReturnStatus = NULL ) const [virtual]

Determines whether or not this node can exist without input connections.

If a node connected to this node is deleted resulting in no more input connections and if this flag is false, then this node will be deleted.

Parameters:
[out] ReturnStatus Status code.
Returns:
true is this node can exist without input connections, false otherwise
Status Codes:
  • MS::kSuccess operation successful
  • MS::kFailure this MPxNode has not been initialized properly. Make sure this method is not being called from the constructor.

Reimplemented in MPxAssembly.

MStatus setExistWithoutOutConnections ( bool  flag ) [virtual]

This method specifies whether or not the node can exist without output connections.

If a node connected to this node is deleted resulting in no more output connections and if this flag is false, then this node will be deleted.

Parameters:
[in] flag true if this node can exist without output connections, false otherwise
Status Codes:
  • MS::kSuccess operation successful
  • MS::kFailure this MPxNode has not been initialized properly. Make sure this method is not being called from the constructor.

Reimplemented in MPxAssembly.

bool existWithoutOutConnections ( MStatus ReturnStatus = NULL ) const [virtual]

Determines whether or not this node can exist without output connections.

If a node connected to this node is deleted resulting in no more output connections and if this flag is false, then this node will be deleted.

Parameters:
[out] ReturnStatus Status code.
Returns:
true is this node can exist without output connections, false otherwise
Status Codes:
  • MS::kSuccess operation successful
  • MS::kFailure this MPxNode has not been initialized properly. Make sure this method is not being called from the constructor.

Reimplemented in MPxAssembly.

MDataBlock forceCache ( MDGContext context = MDGContext::fsNormal ) [protected, virtual]

USE _forceCache() IN SCRIPT.

Get the datablock for this node.

If there is no datablock then one will be created. NOTE: This should be used only in places where fast access to the datablock outside of a compute is critical such as the transformUsing method of MPxSurfaceShape.

Parameters:
[in] context The context in which the node will evaluate.
Returns:
The datablock

Reimplemented in MPxAssembly.

void setMPSafe ( bool  flag ) [protected, virtual]

USE _setMPSafe() IN SCRIPT.

Set a flag to specify if a user defined shading node is safe for multi-processor rendering.

For a shading node to be MP safe, it cannot access any shared global data and should only use attributes in the datablock to get input data and store output data.

This flag does NOT mark a node thread safe for parallel DG evaluation in Viewport 2.0. To mark a node thread safe for parallel DG evaluation see the setNodeTypeFlag mel command.

NOTE: This should be called from the postConstructor() method for shading node plug-ins only. If a shading node is non-safe, then it will only be useful during single processor rendering.

Parameters:
[in] flag True if user node is safe, false if non-safe.

Reimplemented in MPxAssembly.

MStatus setDoNotWrite ( bool  flag ) [protected, virtual]

USE _setDoNotWrite() IN SCRIPT.

Use this method to mark the "do not write" state of this proxy node.

If set, this node will not be saved when the Maya model is written out.

NOTES: 1. Plug-in "requires" information will be written out with the model when saved. But a subsequent reload and resave of the file will cause these to go away. 2. If this node is a DAG and has a parent or children, the "do not write" flag of the parent or children will not be set. It is the developer�s responsibility to ensure that the resulting scene file is capable of being read in without errors due to unwritten nodes.

Parameters:
[in] flag True if the user node should not be saved.

Reimplemented in MPxAssembly.

bool doNotWrite ( MStatus ReturnStatus = NULL ) const [protected, virtual]

USE _doNotWrite() IN SCRIPT.

Use this method to query the "do not write" state of this proxy node.

True is returned if this node will not be saved when the Maya model is written out.

Parameters:
[out] ReturnStatus

Reimplemented in MPxAssembly.


The documentation for this class was generated from the following files: