nodes for falloff from driven at

oneChannelFalloff.py

def oneChannelFalloff( ctrlAt, targetAts, stepFactor = 1 ):
    '''
    @param ctrlAt: string, attribute driving the targets
    @param ctrlAt: string, attribute driven by stepped influence from ctrlAt
    @param stepFactor: float, how much influence should the effect have
    @param preval: float, optional starting value of control Attr to be normalized
    
    '''
    preval = mc.getAttr( ctrlAt )
    step = 1.0 / len( targetAts )   
    recip = 1.0 / preval 
    
    # normalize preexisting values from control attr
    ctrlMulti = mc.createNode( 'multDoubleLinear', n = ctrlAt.split( '.' )[0] + 'ctrl_mlt' )
    mc.setAttr( ctrlMulti + '.input1', recip )
    mc.connectAttr( ctrlAt , ctrlMulti + '.input2' )
    
    # apply factor for falloff nodes
    factorMulti = mc.createNode( 'multDoubleLinear', n = ctrlAt.split( '.' )[0] + 'factor_mlt' )
    mc.setAttr( factorMulti + '.input1', stepFactor )
    mc.connectAttr( ctrlMulti + '.output', factorMulti + '.input2' )
    factorAt = factorMulti + '.input1'
    
    # create nodes and connect to targetAts
    falloffNodes = []
    for idx, targetAt in enumerate( targetAts ):
        stepIdx = step * idx
        targetPrefix = targetAt.split( '.' )[0] 
        targetPreval = mc.getAttr( targetAt )
        falloffNode = mc.createNode( 'multDoubleLinear', n = targetPrefix + '_mlt' )
        mc.setAttr( falloffNode + '.input1', stepIdx )
        mc.connectAttr( factorMulti + '.output', falloffNode + '.input2' )
        
        if targetPreval:
            addNode = mc.createNode( 'addDoubleLinear', n = targetPrefix + '_add' )
            mc.setAttr( addNode + '.input1', targetPreval )
            mc.connectAttr( falloffNode + '.output', addNode + '.input2' )
            mc.connectAttr( addNode + '.output', targetAt )
        
        else:   
            mc.connectAttr( falloffNode + '.output' , targetAt )
       
        falloffNodes.append( falloffNode )
        
    return {
            'falloffNodes': falloffNodes,
            'factorAt': factorAt
            }