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Pilot Season – Day 14 – Working dynamic callback

Published by Raffaele on 9 July, 2017

Day 14 of the stream, we finally install a fully working callback for the FK <-> IK switch on the pedals.

 

Finishing the Maya Callbacks and OpenMaya stretch of the stream we finally have a fully working FK <-> IK switch for the pedals.
We only have the virtual slider case to fix, which is more  a matter of finding a good stepped signal to work off of than anything else, and then maybe ensuring callbacks are installed every time the scene is opened.

Exercise for home, if you’re inclined:
Look into making the callback work with virtual sliders.

Hint 1: not unlike the reciprocal behaviour added as a demo to the end of the Day 11 Stream it’s about comparing the result we get, with something that changes reliably and not depending on UI interaction

Hint 2: the angles we get from the separate IK and FK feed could be compared against the angle coming from the blend, which is graph dependent and not UI dependent, and comparison should provide the clean state switch we’re after.

As with all previous script heavy days you will find the commented transcription at the end of the page.
Enjoy:

 

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fkik_attrName = 'FKIK_switch'
 
from maya.api import _OpenMaya_py2 as om2
from maya import cmds
import math
 
def iterSelection():
    """
    generator style iterator over current Maya active selection
    :return: [MObject) an MObject for each item in the selection
    """
    sel = om2.MGlobal.getActiveSelectionList()
    for i in xrange(sel.length()):
        yield sel.getDependNode(i)
 
 
def removeCallbacksFromNode(node_mob):
    """
    :param node_mob: [MObject] the node to remove all node callbacks from
    :return: [int] number of callbacks removed
    """
    cbs = om2.MMessage.nodeCallbacks(node_mob)
    cbCount = len(cbs)
    for eachCB in cbs:
        om2.MMessage.removeCallback(eachCB)
    return cbCount
 
 
def removeCallbacksFromSel():
    """
    Will remove all callbacks from each node in the current selection
    :return: [(int, int)] total number of objects that had callbacks removed,
                            and total count of all callbacks removed across them
    """
    cbCount = 0
    mobCount = 0
    for eachMob in iterSelection():
        mobCount += 1
        cbCount += removeCallbacksFromNode(eachMob)
    return mobCount, cbCount
 
 
def cb(msg, plug1, plug2, payload):
    if msg != 2056: #check most common case first and return unless it's
        return      # an attribute edit type of callback
 
    if not plug1.partialName(includeNodeName=False, useAlias=False) == fkik_attrName:
        # We ensure if the attribute being changed is uninteresting we do nothing
        return
 
    isFK = plug1.asBool() == False # Switched To FK
    isIK = not isFK # Switched to IK
 
    settingsAttrs = { # all interesting attribute names in keys, respective plugs in values
                     'fkRotation': None,
                     'ikRotation': None,
                     'fk_ctrl_rotx': None,
                     'ik_ctrl_translate': None,
                     'ikPedalOffset': None,
                     }
 
    mfn_dep = om2.MFnDependencyNode(plug1.node())
    # We populate the dictionary of interesting attributes with their plugs
    for eachPName in settingsAttrs.iterkeys():
        plug = mfn_dep.findPlug(eachPName, False)
        settingsAttrs[eachPName] = plug
 
    for p in settingsAttrs.itervalues():
        # We will exit early and do nothing if a plug couldn't be initialised, the object
        #  is malformed, or we installed the callback on an object that is only
        #  conformant by accident and can't operate as we expect it to.
        if p is None:
            return
 
    angle = None # empty init
    if isFK:
        # Simplest case, if we switched to FK we copy the roation from IK
        #  to the FK control's X rotation value
        angle = -settingsAttrs.get("ikRotation").source().asDouble()
        fkSourcePlug = settingsAttrs.get("fk_ctrl_rotx").source()
        fkSourcePlug.setDouble(angle)
    elif isIK:
        # If instead we switched to IK we need to
        #  derive the translation of the IK control that produces the result
        #  of an equivalent rotation to the one coming from the FK control
        angle = settingsAttrs.get("fkRotation").source().asDouble()
        projectedLen = settingsAttrs.get("ikPedalOffset").source().asDouble()
 
        y = ( math.cos(angle) * projectedLen ) - projectedLen
        z = math.sin(angle) * projectedLen
 
        ikSourcePlug = settingsAttrs.get("ik_ctrl_translate").source()
        for i in xrange(ikSourcePlug.numChildren()):
            realName = ikSourcePlug.child(i).partialName(includeNodeName = False, useAlias = False)
            if realName == 'ty':
                ikSourcePlug.child(i).setDouble(y)
            elif realName == 'tz':
                ikSourcePlug.child(i).setDouble(z)
 
 
removeCallbacksFromSel()
for eachMob in iterSelection():
    om2.MNodeMessage.addAttributeChangedCallback(eachMob, cb)
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