MPlugs: Connecting Plugs

On 14 Sep, 2014 By Austin With 0 Comments

Connecting two MPlugs together is fairly simple and is accomplished with MDGModifier.connect(). Lets connect two polygon spheres together such that translating one on X will translate the other on Y.

sphere_connect

First create the spheres and get them as MObjects.

import maya.OpenMaya as OpenMaya
import maya.cmds as cmds

def getMObject( obj_name ):
    sel_list = OpenMaya.MSelectionList()
    try:
        sel_list.add( obj_name )
        obj = OpenMaya.MObject()
        sel_list.getDependNode( 0, obj )
        
        return obj

    except:
        pass

cmds.polySphere( name='plugTest' )
sphere_one = getMObject( 'plugTest' )

cmds.polySphere( name='plugTest2')
sphere_two = getMObject( 'plugTest2' )

import maya.OpenMaya as OpenMaya

import maya.cmds as cmds

def getMObject( obj_name ):

sel_list = OpenMaya.MSelectionList()

try:

sel_list.add( obj_name )

obj = OpenMaya.MObject()

sel_list.getDependNode( 0, obj )

return obj

except:

pass

cmds.polySphere( name='plugTest' )

sphere_one = getMObject( 'plugTest' )

cmds.polySphere( name='plugTest2')

sphere_two = getMObject( 'plugTest2' )

Now we can write a function that makes use of MDGModifier.connect() to hook the spheres together. Connect takes two inputs – source MPlug and destination MPlug. In a previous post I covered how to get an MPlug on a node which will come in handy here.

def getPlugByName( inObj, inPlugName ):
    """
    Gets a node's plug as an MPlug.
    
    @inObj: MObject. Node to get plug from.
    @inPlugName: String. Name of plug to get from node.
    @return: MPlug.
    @return: None.
    """
    depFn = OpenMaya.MFnDependencyNode( inObj )
    try:
        plug = depFn.findPlug( inPlugName )
        return plug
    except:
        return None

def connectNodes( source_obj, source_plug_name, destination_obj, destination_plug_name ):
    '''
    @param source_obj: MObject. Source object.
    @param source_plug_name: String. Name of plug on parent node.
    @param destination_obj: MObject. Destination object.
    @param destination_plug_name: String. Name of plug on child node.
    '''
    source_plug = getPlugByName( source_obj, source_plug_name )
    destination_plug = getPlugByName( destination_obj, destination_plug_name )
    MDGMod = OpenMaya.MDGModifier()
    MDGMod.connect( source_plug, destination_plug )
    MDGMod.doIt()

def getPlugByName( inObj, inPlugName ):

"""

Gets a node's plug as an MPlug.

@inObj: MObject. Node to get plug from.

@inPlugName: String. Name of plug to get from node.

@return: MPlug.

@return: None.

"""

depFn = OpenMaya.MFnDependencyNode( inObj )

try:

plug = depFn.findPlug( inPlugName )

return plug

except:

return None

def connectNodes( source_obj, source_plug_name, destination_obj, destination_plug_name ):

'''

@param source_obj: MObject. Source object.

@param source_plug_name: String. Name of plug on parent node.

@param destination_obj: MObject. Destination object.

@param destination_plug_name: String. Name of plug on child node.

'''

source_plug = getPlugByName( source_obj, source_plug_name )

destination_plug = getPlugByName( destination_obj, destination_plug_name )

MDGMod = OpenMaya.MDGModifier()

MDGMod.connect( source_plug, destination_plug )

MDGMod.doIt()

Here’s everything together.

import maya.OpenMaya as OpenMaya
import maya.cmds as cmds

def getPlugByName( inObj, inPlugName ):
    """
    Gets a node's plug as an MPlug.
    
    @inObj: MObject. Node to get plug from.
    @inPlugName: String. Name of plug to get from node.
    @return: MPlug.
    @return: None.
    """
    depFn = OpenMaya.MFnDependencyNode( inObj )
    try:
        plug = depFn.findPlug( inPlugName )
        return plug
    except:
        return None

def connectNodes( source_obj, source_plug_name, destination_obj, destination_plug_name ):
    '''
    @param source_obj: MObject. Source object.
    @param source_plug_name: String. Name of plug on parent node.
    @param destination_obj: MObject. Destination object.
    @param destination_plug_name: String. Name of plug on child node.
    '''
    source_plug = getPlugByName( source_obj, source_plug_name )
    destination_plug = getPlugByName( destination_obj, destination_plug_name )
    MDGMod = OpenMaya.MDGModifier()
    MDGMod.connect( source_plug, destination_plug )
    MDGMod.doIt()
    
def getMObject( obj_name ):
    sel_list = OpenMaya.MSelectionList()
    try:
        sel_list.add( obj_name )
        obj = OpenMaya.MObject()
        sel_list.getDependNode( 0, obj )
        
        return obj

    except:
        pass

cmds.polySphere( name='plugTest' )
sphere_one = getMObject( 'plugTest' )

cmds.polySphere( name='plugTest2')
sphere_two = getMObject( 'plugTest2' )

connectNodes( sphere_one, 'translateX', sphere_two, 'translateY' )

import maya.OpenMaya as OpenMaya

import maya.cmds as cmds

def getPlugByName( inObj, inPlugName ):

"""

Gets a node's plug as an MPlug.

@inObj: MObject. Node to get plug from.

@inPlugName: String. Name of plug to get from node.

@return: MPlug.

@return: None.

"""

depFn = OpenMaya.MFnDependencyNode( inObj )

try:

plug = depFn.findPlug( inPlugName )

return plug

except:

return None

def connectNodes( source_obj, source_plug_name, destination_obj, destination_plug_name ):

'''

@param source_obj: MObject. Source object.

@param source_plug_name: String. Name of plug on parent node.

@param destination_obj: MObject. Destination object.

@param destination_plug_name: String. Name of plug on child node.

'''

source_plug = getPlugByName( source_obj, source_plug_name )

destination_plug = getPlugByName( destination_obj, destination_plug_name )

MDGMod = OpenMaya.MDGModifier()

MDGMod.connect( source_plug, destination_plug )

MDGMod.doIt()

def getMObject( obj_name ):

sel_list = OpenMaya.MSelectionList()

try:

sel_list.add( obj_name )

obj = OpenMaya.MObject()

sel_list.getDependNode( 0, obj )

return obj

except:

pass

cmds.polySphere( name='plugTest' )

sphere_one = getMObject( 'plugTest' )

cmds.polySphere( name='plugTest2')

sphere_two = getMObject( 'plugTest2' )

connectNodes( sphere_one, 'translateX', sphere_two, 'translateY' )

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