Compound array attribute with mesh data child issue

[David Lantos]

Hi guys,

I run into an issue, I created a compound array attribute with two children, an int array and mesh data attributes.

I copied here the part of the code, removed the unnecessary parts. I create a deformer and I connect the driver mesh into the "driverMesh" attribute.
The error I got this: # RuntimeError: (kFailure): Object does not exist //

@note: I found on internet other solutions to pull the data through plugs (it didn't work either). Because of performance I try to use only DataBlock to pull the mesh data and avoid reading the plugs.

Anybody has any ideas what I'm doing wrong?

@staticmethod
def initialize():
  tAttr = OpenMaya.MFnTypedAttribute()
  cAttr = OpenMaya.MFnCompoundAttribute()

  VertexSnap.aDriverMesh = tAttr.create('driverMesh', 'driverMesh', OpenMaya.MFnData.kMesh)

  VertexSnap.aDriverIndices = tAttr.create('driverIndices', 'driverIndices', OpenMaya.MFnData.kIntArray)

  VertexSnap.aDrivers = cAttr.create('drivers', 'drivers')
  cAttr.setArray(True)
  cAttr.addChild(VertexSnap.aDriverMesh)
  cAttr.addChild(VertexSnap.aDriverIndices)
  VertexSnap.addAttribute(VertexSnap.aDrivers)

  outputGeom = OpenMayaMPx.cvar.MPxGeometryFilter_outputGeom
  VertexSnap.attributeAffects(VertexSnap.aDriverMesh, outputGeom)
  VertexSnap.attributeAffects(VertexSnap.aDriverIndices, outputGeom)

def deform(self, data, geoIter, localToWorldMatrix, geoIndex):

  hDrivers = data.inputArrayValue(VertexSnap.aDrivers)
  numDrivers = hDrivers.elementCount()
  for driverIdx in range(numDrivers):
  hDrivers.jumpToElement(driverIdx)
  hDriver = hDrivers.inputValue()
  oDriverMesh = hDriver.child(VertexSnap.aDriverMesh).asMesh()

  if oDriverMesh.isNull():
  # No driver mesh
    return

  fnDriverMesh = OpenMaya.MFnMesh(oDriverMesh)
  print fnDriverMesh.name()
  # I got this: # RuntimeError: (kFailure): Object does not exist //

[David Lantos]

Sorry the identation went wrong, fixed here:

[David Lantos]

I got a solution from other forum. Since it's mesh data in the memory you can use only MDataHandle instead of MFnMesh.

hDrivers = data.inputArrayValue(MyDeformer.aDrivers)


for driverIdx in range(hDrivers.elementCount()):
    status = hDrivers.jumpToElement(driverIdx)
    if status:
        builder = hDrivers.builder()
        builder.addElement(driverIdx)
        hDrivers.setBuilder(builder)
        hDrivers.jumpToElement(driverIdx)


    hDriver = hDrivers.inputValue()
    hDriverMesh = hDriver.child(VertexSnap.aDriverMesh)


    geoIt = OpenMaya.MItGeometry(hDriverMesh)
    print geoIt.count()  # Result: 121