MFnBlendShapeDeformer Class Reference

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Detailed Description

blend shape deformer function set

MFnBlendShapeDeformer is the function set for blend shape deformers. A blend shape deformer takes a base shape (polygonal surface, curve, surface, or lattice) and blends it with other target shapes based on weight values.

The blend shape deformer is actually a small network of dependency nodes in the dependency graph. This function set is provided to make manipulation of the network easier. The main deformer node should be given to this function set as its object.

There are three parts to a blend shape deformer. There are the base objects, the target objects, and the weight values.

The base objects are the shapes that are to be deformed. There must be at least one base object. The base objects will change form as the targets and deformation parameters are modified.

Each base object has a list of target objects that affect its shape. Each target is associated with one of the the deformer's weight values. When the weight value increases, the target has more influence on the base shape.

There is just one array of weight values between all of the base objects and targets. So, it is possible for targets of different base objects to share the same weight index. When the weight value changes, it will affect all of the base objects that have targets using that weight value.

It is also possible to chain together target shapes so that a base object will deform through each shape one at a time as the weight value increases. This is done by adding multiple targets to a base shape using the same weight index for all of them. When each target is added, a weight value is specified at which that target will be in full effect. Give each target a different full weight value.

For example, one could take a sphere and make it blend into a cone and then into a cylinder. One way to do this is to make sphere the base shape. Then, add the cone as a target for the sphere at weight index 0 with a full effect weight of 0.5. Next, add the cylinder as a second target for the sphere also at weight index 0, but with a full effect weight of 1.0. Now, as the weight goes from 0 to 1, the base shape will start as a sphere, morph into a cone, and then into a cylinder.

It is not necessary for the base shape and its targets to have identical vertex/CV counts, but the blend will be more effective if they do.

#include <MFnBlendShapeDeformer.h>

Inheritance diagram for MFnBlendShapeDeformer:

List of all members.

Public Types
enum	Origin { kLocalOrigin, kWorldOrigin }
	Specifies the space to use for the deformation origin. More...
enum	HistoryLocation { kFrontOfChain, kNormal }
	Specifies where in the shape's history to place the deformer. More...
Public Member Functions
virtual MFn::Type	type () const
	Function set type.
virtual	~MFnBlendShapeDeformer ()
	Destructor.
	MFnBlendShapeDeformer ()
	Default constructor.
	MFnBlendShapeDeformer (MObject &object, MStatus *ReturnStatus=NULL)
	Constructor.
MObject	create (MObject baseObject, Origin originSpace=kLocalOrigin, MStatus *ReturnStatus=NULL)
	Creates a new blend shape deformer in the dependency graph with the specified shape as the baseObject.
MObject	create (const MObjectArray &baseObjects, Origin originSpace=kLocalOrigin, HistoryLocation=kNormal, MStatus *ReturnStatus=NULL)
	Creates a new blend shape deformer in the dependency graph.
MStatus	addBaseObject (MObject &object)
	Adds a new base object to the deformer.
MStatus	getBaseObjects (MObjectArray &objects) const
	Get a list of all of the base objects for this deformer.
MStatus	addTarget (const MObject &baseObject, int weightIndex, const MObject &newTarget, double fullWeight)
	Adds a new target object for the given base object.
MStatus	removeTarget (const MObject &baseObject, int weightIndex, const MObject &target, double fullWeight)
	Remove a target object for the given base object.
MStatus	getTargets (MObject baseObject, int weightIndex, MObjectArray &targetObjects) const
	Get a list of all of the target objects for the given base object that affect it based on the given weight index.
unsigned int	numWeights (MStatus *ReturnStatus=NULL) const
	Return the number of weight values that this blend shape deformer has.
MStatus	weightIndexList (MIntArray &indexList) const
	Return the array index numbers corresponding to the targets.
MStatus	targetItemIndexList (unsigned int weightIndex, MObject baseObject, MIntArray &targetItemIndices) const
	A base object may have more than one target using the same element of the blendShape's 'weights' array.
float	weight (unsigned int index, MStatus *ReturnStatus=NULL) const
	Get the weight value at the given index.
MStatus	setWeight (unsigned int index, float weight)
	Set the weight value at the given index.
float	envelope (MStatus *ReturnStatus=NULL) const
	Gets the envelope value of the deformer.
MStatus	setEnvelope (float envelope)
	Sets the envelope value of the deformer.
Origin	origin (MStatus *ReturnStatus=NULL) const
	Gets the origin space.
MStatus	setOrigin (Origin space)
	Sets the origin space.
	MFnBlendShapeDeformer (const MObject &object, MStatus *ReturnStatus=NULL)
	Constructor.
Protected Member Functions
virtual const char *	className () const
	Class name. Search for all occurrences

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Member Enumeration Documentation

enum Origin

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Specifies the space to use for the deformation origin.

Enumerator:

kLocalOrigin	Search for all occurrences
kWorldOrigin	Search for all occurrences

enum HistoryLocation

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Specifies where in the shape's history to place the deformer.

Enumerator:

kFrontOfChain	Search for all occurrences
kNormal	Search for all occurrences

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Constructor & Destructor Documentation

MFnBlendShapeDeformer	(	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

MFnBlendShapeDeformer	(	const 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

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Member Function Documentation

MFn::Type type

(

)

const [virtual]

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Function set type.

Return the class type : MFn::kBlendShape.

Reimplemented from MFnDependencyNode.

MObject create	(	MObject	baseObject,
		Origin	originSpace = kLocalOrigin,
		MStatus *	ReturnStatus = NULL
	)

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Creates a new blend shape deformer in the dependency graph with the specified shape as the baseObject.

Parameters:

[in]	baseObject	a base object for the deformer
[in]	originSpace	origin about which to deform
[out]	ReturnStatus	return status

Returns:

A handle to the new deformer

Status Codes:

• MS::kSuccess operation successful
• MS::kInvalidParameter base object is null or is not of the correct type
• MS::kLicenseFailure application not licensed for attempted operation
• MS::kInsufficientMemory out of memory
• MS::kFailure unexpected failure

MObject create	(	const MObjectArray &	baseObjects,
		Origin	originSpace = kLocalOrigin,
		HistoryLocation	historyLoc = kNormal,
		MStatus *	ReturnStatus = NULL
	)

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Creates a new blend shape deformer in the dependency graph.

This method differs from the other MFnBlendShapeDeformer::create in that it allows multiple base shapes to be supplied at create time and it allows the use of the front-of-chain history location, which puts the blendShape ahead of other deformers such as skinning deformers.

Parameters:

[in]	baseObjects	base object(s) for the deformer
[in]	originSpace	origin about which to deform
[in]	historyLoc	where in the shape's history to place the deformer
[out]	ReturnStatus	return status

Returns:

A handle to the new deformer

Status Codes:

• MS::kSuccess operation successful
• MS::kInvalidParameter base object is not of the correct type
• MS::kLicenseFailure application not licensed for attempted operation
• MS::kInsufficientMemory out of memory
• MS::kFailure unexpected failure

MStatus addBaseObject

(

MObject &

object

)

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Adds a new base object to the deformer.

This object will be deformed as targets are added for it and the deformation parameters change.

Parameters:

[in]

object

new base object

Returns:

Return status

Status Codes:

• MS::kSuccess operation successful
• MS::kInvalidParameter base object is null or is not of the correct type
• MS::kInsufficientMemory out of memory
• MS::kFailure this function set does not have a valid attribute object

MStatus getBaseObjects

(

MObjectArray &

objects

)

const

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Get a list of all of the base objects for this deformer.

The objects returned will be the deformed versions of the base objects.

Parameters:

[out]

objects

storage for the array of base objects

Returns:

Return status

Status Codes:

• MS::kSuccess operation successful
• MS::kInvalidParameter base object is null or is not of the correct type
• MS::kInsufficientMemory out of memory
• MS::kFailure this function set does not have a valid attribute object

MStatus addTarget	(	const MObject &	baseObject,
		int	weightIndex,
		const MObject &	newTarget,
		double	fullWeight
	)

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Adds a new target object for the given base object.

The weight index says which of the deformer's weight values will control this target's affects on the base object. The full weight argument determines at what weight the target is in full effect. If a base object has no other targets and the weight is set to the 'full weight', then the base object will look just like the target object.

Parameters:

[in]	baseObject	base object for the target
[in]	weightIndex	weight index to use for target's effect
[in]	newTarget	new target object for the given base
[in]	fullWeight	weight value at which the target is in full effect

Returns:

Return status

Status Codes:

• MS::kSuccess operation successful
• MS::kInvalidParameter base object or target object is null or is not of the correct type
• MS::kInsufficientMemory out of memory
• MS::kFailure this function set does not have a valid attribute object

MStatus removeTarget	(	const MObject &	baseObject,
		int	weightIndex,
		const MObject &	target,
		double	fullWeight
	)

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Remove a target object for the given base object.

The weight index specifies the index at which target is connected. The full weight argument specifies at what weight the target is in full effect.

Parameters:

[in]	baseObject	base object for the target
[in]	weightIndex	weight index corresponding to the target
[in]	target	target object for the given base to be removed
[in]	fullWeight	weight value at which the target is in full effect

Returns:

Return status

Status Codes:

• MS::kSuccess operation successful
• MS::kInvalidParameter base object or target object is null or is not of the correct type
• MS::kInsufficientMemory out of memory
• MS::kFailure this function set does not have a valid attribute object

MStatus getTargets	(	MObject	baseObject,
		int	weightIndex,
		MObjectArray &	targetObjects
	)		const

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Get a list of all of the target objects for the given base object that affect it based on the given weight index.

Parameters:

[in]	baseObject	The base shape of interest.
[in]	weightIndex	The index of the weight attribute. Since the weight indices may be sparse, the weightIndexList method should be used to find the weight indices used by a given blendShape.
[out]	targetObjects	Storage for the returned array of target objects.

Returns:

Return status

Status Codes:

• MS::kSuccess operation successful
• MS::kInvalidParameter base object is null or is not of the correct type, or the weightIndex is invalid.
• MS::kInsufficientMemory out of memory
• MS::kFailure this function set does not have a valid attribute object

unsigned int numWeights

(

MStatus *

ReturnStatus = NULL

)

const

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Return the number of weight values that this blend shape deformer has.

The number of weight values is equal to the number of targets. Targets are either shapes in the dag or baked data on the blendShape node (when a target shape is deleted).

Parameters:

[out]

ReturnStatus

return status

Returns:

The number of weight indices

Status Codes:

• MS::kSuccess operation successful
• MS::kFailure function set does not have a valid object

MStatus weightIndexList

(

MIntArray &

indexList

)

const

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Return the array index numbers corresponding to the targets.

The resulting index list will be the length of MFnBlendShape::numWeights. This method exists because the indices of the targets can be sparse. For example, if a target has been removed using Deform -> Edit BlendShape -> Remove.

Parameters:

[out]

indexList

the array index numbers for the blendShape targets

Returns:

The return status

Status Codes:

• MS::kSuccess operation successful
• MS::kFailure function set does not have a valid object

MStatus targetItemIndexList	(	unsigned int	weightIndex,
		MObject	baseObject,
		MIntArray &	targetItemIndices
	)		const

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A base object may have more than one target using the same element of the blendShape's 'weights' array.

We refer to these as the base object's "target items" for that weight index.

Each target item should have a different 'fullWeight' value at which it takes full effect. As the value of the weights array element approaches the lowest of those 'fullWeight' values the associated target item has an increasing effect on the shape of the base object. As the value of the weights array element passes that first 'fullWeight' value and starts to approach the next higher 'fullWeight' value, the next target item starts to gain influence and the influence of the previous one drops off.

In this way, as the weight value increases, influence passes from one target item to another, allowing the target object to morph through a sequence of different target shapes.

Each target item is connected to an element of the blendShape deformer's 'inputTargetItem' array for that base object and weights array index. The inputTargetItem array index is calculated as follows: index = fullWeight * 1000 + 5000.

For example, if a base object has three different targetItems for a given weights array element, having fullWeight values of 0.5, 1.0 and 2.0, they will be connected to inputTargetItem array indices 5500, 6000 and 7000, respectively.

This method returns an array containing the inputTargetItem array indices of all the target items of a given base object which use the specified weight index.

Parameters:

[in]	weightIndex	'weights' array index.
[in]	baseObject	The deformed object of interest
[out]	targetItemIndices	'inputTargetItem' array indices of the requested target items.

Returns:

Return status

Status Codes:

• MS::kSuccess operation successful
• MS::kFailure function set does not have a valid object
• MS::kInvalidIndex no target exists at the specified target index

float weight	(	unsigned int	index,
		MStatus *	ReturnStatus = NULL
	)		const

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Get the weight value at the given index.

To be valid, a weight value should only be requested at index values returned by MFnBlendShapeDeformer::weightIndexList.

Parameters:

[in]	index	index of weight value
[out]	ReturnStatus	return status

Returns:

The weight value

Status Codes:

• MS::kSuccess operation successful
• MS::kInvalidParameter the weightIndex is invalid.
• MS::kFailure function set does not have a valid object

MStatus setWeight	(	unsigned int	index,
		float	weight
	)

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Set the weight value at the given index.

Parameters:

[in]	index	index of weight value
[in]	weight	new weight value

Returns:

Return status

Status Codes:

• MS::kSuccess operation successful
• MS::kInvalidParameter the weightIndex is invalid.
• MS::kFailure function set does not have a valid object

float envelope

(

MStatus *

ReturnStatus = NULL

)

const

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Gets the envelope value of the deformer.

The envelope is a global scale factor that is applied to all of the weight values in the deformer. The envelope can be used increase or decrease the effects of all of the targets at the same time.

Parameters:

[out]

ReturnStatus

return status

Returns:

Envelope value

Status Codes:

• MS::kSuccess operation successful
• MS::kFailure function set does not have a valid object

MStatus setEnvelope

(

float

envelope

)

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Sets the envelope value of the deformer.

The envelope is a global scale factor that is applied to all of the weight values in the deformer. The envelope can be used increase or decrease the effects of all of the targets at the same time.

Parameters:

[in]

envelope

envelope value

Returns:

Return status

Status Codes:

• MS::kSuccess operation successful
• MS::kFailure function set does not have a valid object

MFnBlendShapeDeformer::Origin origin

(

MStatus *

ReturnStatus = NULL

)

const

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Gets the origin space.

It defines the point around which the differences in the geometry are calculated.

Parameters:

[out]

ReturnStatus

return status

Returns:

The origin space

Status Codes:

• MS::kSuccess operation successful
• MS::kFailure function set does not have a valid object

MStatus setOrigin

(

Origin

space

)

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Sets the origin space.

It defines the point around which the differences in the geometry are calculated.

Parameters:

[in]

space

origin space

Returns:

The origin space

Status Codes:

• MS::kSuccess operation successful
• MS::kFailure function set does not have a valid object