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This node implements a normalConstraint. Each constraint has a set of targets that are connected under the target attribute, a single constrained object that is connected to the constraint* attributes, and possibly other information to help compute the correct results. In the case of the normalConstraint, the additional information is: aimVector, upVector, worldUpVector, worldUpMatrix, and worldUpType.

The normalConstraint node can have any number of target inputs. Each target is connected to attributes inside a single element of the target attribute. For example, the first target object would be connected elements of target[0], the second target object would be connected to elements of target[1], etc. The elements of each target are: targetGeometry and targetWeight.

The elements of each target are normally connected to the target objects as follows:

normalConstraint attribute connected to
targetGeometry worldSpace
targetWeight set to 1.0

The targetWeight attribute is not generally connected to the target object. Instead, it may be animated by other means to adjust the weighted average computation for the target orientation.

The constrained object is connected to the constraint* attributes. For a normalConstraint, the constraintTranslate, constraintRotatePivot, constraintRotateTranslate, and constraintParentInverseMatrix are inputs to the normalConstraint. The attribute constraintRotate is the only output..

The normalConstraint node uses the constraintTranslate, constraintRotatePivot, constraintRotateTranslate, constraintJointOrient, and constraintParentInverseMatrix attributes to compute the world space position of the pivot point of the constrained object. Then, for each target geometry, the closest point is found and the normal at that point is computed. Each normal is then added into a weighted average vector and the constrained object is oriented so that the aimVector (see below) matches the weighted average vector.

The additional normalConstraint inputs tell the constraint node how to aim the constrained object. The aimVector attribute defines a vector in the space of the constrained object that should be aligned with the weighted average vector computed by the constraint. The upVector, worldUpVector, worldUpMatrix, and worldUpType define how the constrained object is rotated about the aimVector.

The upVector defines a vector in the space of the constrained object, very much like the aimVector does. The constrained object is rotated so that the aimVector matches the weighted average vector and so that the upVector aligns as closely as possible with the computed world up vector. The world up vector is determined by the worldUpType, worldUpVector, and worldUpMatrix attributes.

The attribute worldUpType can have one of 5 values, which affects the calculation of the world up vector as shown in the following table.

Mnemonic Value Description
scene 0 The upVector is aligned with the up axis of the scene and worldUpVector and worldUpObject are ignored.
object 1 The upVector is aimed as closely as possible to the origin of the space of the worldUpObject and the worldUpVector is ignored.
objectrotation 2 The worldUpVector is interpreted as being in the coordinate space of the worldUpObject, transformed into world space and the upVector is aligned as closely as possible to the result.
vector 3 Default: The upVector is aligned with worldUpVector as closely as possible and worldUpMatrix is ignored.
none 4 No up vector is used in the computation of the orientation of the constrained object; only the aim vector and the target's position and surface normals are used. Specifying an up vector can cause flipping to occur when the constrained object's new orientation vector is close to the up vector. If the worldUpType is instead set to none, this flipping won't happen, at a loss of control over twisting.

While setAttr requires the numeric values for the worldUpType attribute, both numeric and mnemonic values are allowed by the normalConstraint command.

Although the all the constraint nodes inherit from transform, they do not actively use any of the attributes from transform.

Node nameParentsClassificationMFn typeCompatible function sets
normalConstraintconstraintanimationkNormalConstraintkBase
kNamedObject
kDependencyNode
kDagNode
kTransform
kConstraint
kNormalConstraint

## Attributes (47)

Long name (short name)TypeDefaultFlags
`target` (`tg`) compoundn/a
 Bundle of matrix, input position, and weight
`targetGeometry` (`tgm`) Genericn/a
 input geometry to which the object should be constrained
`targetWeight` (`tw`) double1.0
 Input weight for the position
`constraintParentInverseMatrix` (`cpim`) matrixidentity
 Input parent inverse matrix for the object
`aimVector` (`a`) double3
 Input aim vector (in local coordinates)
`aimVectorX` (`ax`) double1.0
 Aim vector X component
`aimVectorY` (`ay`) double0.0
 Aim vector Y component
`aimVectorZ` (`az`) double0.0
 Aim vector Z component
`upVector` (`u`) double3
 Input up vector (in local coordinates)
`upVectorX` (`ux`) double0.0
 Up vector X component
`upVectorY` (`uy`) double1.0
 Up vector Y component
`upVectorZ` (`uz`) double0.0
 up vector Z component
`worldUpVector` (`wu`) double3
 Input world up vector (in local coordinates)
`worldUpVectorX` (`wux`) double0.0
 World up vector X component
`worldUpVectorY` (`wuy`) double1.0
 World up vector Y component
`worldUpVectorZ` (`wuz`) double0.0
 World up vector Z component
`worldUpMatrix` (`wum`) matrixidentity
 Input world matrix for the up object
`worldUpType` (`wut`) enum3 vector
 Input behavior to resolve world up vector.
`constraintTranslate` (`ct`) double3
 Object translation (in local coordinates)
`constraintTranslateX` (`ctx`) distance (double)0.0cm
 Object X translation
`constraintTranslateY` (`cty`) distance (double)0.0cm
 Object Y translation
`constraintTranslateZ` (`ctz`) distance (double)0.0cm
 Object Z translation
`constraintRotatePivot` (`crp`) double3
 Object rotate pivot (in local coordinates)
`constraintRotatePivotX` (`crpx`) distance (double)0.0cm
 Object X rotate pivot
`constraintRotatePivotY` (`crpy`) distance (double)0.0cm
 Object Y rotate pivot
`constraintRotatePivotZ` (`crpz`) distance (double)0.0cm
 Object Z rotate pivot
`constraintRotateTranslate` (`crt`) double3
 Object rotate translate (in local coordinates)
`constraintRotateTranslateX` (`crtx`) distance (double)0.0cm
 Object X rotate translate
`constraintRotateTranslateY` (`crty`) distance (double)0.0cm
 Object Y rotate translate
`constraintRotateTranslateZ` (`crtz`) distance (double)0.0cm
 Object Z rotate translate
`constraintRotateOrder` (`cro`) enum0
 Input constrained object rotate order value.
`constraintJointOrient` (`cjo`) double3
 Input constrained object joint orient (if any).
`constraintJointOrientX` (`cjox`) angle (double)0.0deg
 Input constrained object joint orient X.
`constraintJointOrientY` (`cjoy`) angle (double)0.0deg
 Input constrained object joint orient Y.
`constraintJointOrientZ` (`cjoz`) angle (double)0.0deg
 Input constrained object joint orient Z.
`constraintRotate` (`cr`) double3
 Output orientation
`constraintRotateX` (`crx`) angle (double)0.0deg
 Output X orientation
`constraintRotateY` (`cry`) angle (double)0.0deg
 Output Y orientation
`constraintRotateZ` (`crz`) angle (double)0.0deg
 Output Z orientation
`constraintVector` (`cv`) double3
 Output vector from constrained object to target position
`constraintVectorX` (`cvx`) distance (double)0.0cm
 Output X vector from constrained object to target position
`constraintVectorY` (`cvy`) distance (double)0.0cm
 Output Y vector from constrained object to target position
`constraintVectorZ` (`cvz`) distance (double)0.0cm
 Output Z vector from constrained object to target position
`restRotate` (`rsrr`) double3
 Rest orientation. When enableRestPosition is enabled, and all the weights sum to zero, this is the output orientation of the constraint.
`restRotateX` (`rrx`) angle (double)0.0deg
 rest X orientation
`restRotateY` (`rry`) angle (double)0.0deg
 rest Y orientation
`restRotateZ` (`rrz`) angle (double)0.0deg
 rest Z orientation