Find Compound Array Attribute, by Name

[Marcus Ottosson]

Hi all,

I’m looking for how to query a compound plug within an array plug, by name.

With non-compound attributes, you can query plugs using the function set.

from maya.api import OpenMaya as om
node = fn.create("wtAddMatrix")
fn = om.MFnDependencyNode()
nodeState = fn.findPlug("nodeState", False)

Likewise, I can get to the compound plug and its first index like this..

mplug = fn.findPlug("wtMatrix", False)
assert mplug.name().rsplit(".", 1)[-1] == "wtMatrix"
assert mplug.isArray and mplug.isCompound
first = mplug.elementByLogicalIndex(0)
assert first.name().rsplit(".", 1)[-1] == "wtMatrix[0]"

And I can guess my way to the weightIn attribute, by grabbing it by an arbitrary index.

# wtAddMatrix
#   [0]
#      .matrixIn
#      .weightIn
#   [1]
#      .matrixIn
#      .weightIn
#    ..
weigthIn = first.child(1)
assert weigthIn.name().rsplit(".", 1)[-1] == "weightIn"

But how can I get to nested the wtAddMatrix.wtMatrix[0].weightIn attribute by name?

weightIn = ... # By name?

Seeing as it’s the function set of a node that enables findPlug(), I can’t figure out how to apply this to the MPlug itself.

For the moment, I’ve “hacked” it by iterating through children till I find a match.

for index in range(first.numChildren()):
  child = first.child(index)
  if child.name().rsplit(".", 1)[-1] == "weightIn":
    return child

But it doesn’t look right.

Any ideas?

Best,
Marcus

[Pedro Bellini]

Hey,

First there is nothing wrong with the way you got it to work.

Second, have you tried getting the plug straight from MSelectionList() ? it could work for you...

ie.

Yeah, maybe it works. If not, your way is fine too.

from maya.api import OpenMaya
from maya import cmds

pma = cmds.createNode('plusMinusAverage')
plug = OpenMaya.MSelectionList().add(pma+'.input3D[1].input3Dx').getPlug(0)

plug.name()
# Result: u'plusMinusAverage1.input3D[1].input3Dx' #
plug.asFloat()
# Result: 0.0 #

plug2 = OpenMaya.MSelectionList().add('persp.t').getPlug(0)

pcst = cmds.createNode('parentConstraint')
plug3 = OpenMaya.MSelectionList().add(pcst+'.target[0].targetOffsetTranslate').getPlug(0)
plug3.name()
# Result: u'parentConstraint1.target[0].targetOffsetTranslate' #
plug3.isCompound
# Result: True #

plug3b = OpenMaya.MSelectionList().add(pcst+'.target[0].targetOffsetTranslateX').getPlug(0)
plug3b.asFloat()
# Result: 0.0 #

# for some reason this does not work in a few of attributes (not sure why)
# rotatePivot
plugFail = OpenMaya.MSelectionList().add('persp.rotatePivot').getPlug(0)
# TypeError: item is not a plug #
cmds.objExists('persp.rotatePivot')
# Result: True #

# which makes me get it the other way you mentioned
fnDg = OpenMaya.MFnDependencyNode(OpenMaya.MSelectionList().add('persp').getDependNode(0))
plugRp = fnDg.findPlug('rotatePivot', False)
plugRp.isCompound
# Result: True #

plugRp.numChildren()
# Result: 3 #

Cheers.

[Marcus Ottosson]

Thanks for confirming, Pedro!

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