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Tag: callbacks

Pilot Season – Day 16 – Automatically loading callbacks on scene load

Published by Raffaele on 22 July, 2017

Day 16 of the stream, this is where we wrap callbacks for good and show how to automatically deploy one on the rig at scene load time through a Script Node

Closing the callback saga we finally wrap it all together, make the callback work with the UI when an attribute is slid and not just changed, and finally make sure it auto deploys on the rig whenever the scene is opened through the use of a Script Node.

As usual with scripting heavy sessions at the end of this post you will find the transcriptions of the final result, in this case the script to add to the Script Node that will deploy the callback on scene load events.

 

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from maya.api import OpenMaya as om2
from maya import cmds
import math
 
 
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 cb(msg, plug1, plug2, payload):
    fkik_attrName = 'FKIK_switch'
    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,
        'dirtyTracker': 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
 
    dirtyTrackerPlug = settingsAttrs.get('dirtyTracker')
    isDirty = dirtyTrackerPlug.asBool() != plug1.asBool()
    if isDirty:
        dirtyTrackerPlug.setBool(plug1.asBool())
    else:
        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)
 
 
 
# full scene DAG path to the object we're looking for, our settings panel
settingsStrPath = "unicycle|pedals_M_cmpnt|control|pedals_M_settings_ctrl"
# check for its existence
found = cmds.objExists(settingsStrPath)
 
if found: # act only if found
    # the following is A way to get an MObject from a name in OM2
    sel = om2.MSelectionList();
    sel.add(settingsStrPath)
    settingsMob = sel.getDependNode(0)
 
    # first we need to ensure the node isn't dirty by default
    #  by aligning the value of the switch the rig was save with
    #  into the dirty tracker
    mfn_dep = om2.MFnDependencyNode(settingsMob)
    fkikPlug = mfn_dep.findPlug('FKIK_switch', False)
    dirtyTracker = mfn_dep.findPlug('dirtyTracker', False)
    dirtyTracker.setBool(fkikPlug.asBool())
 
    # as this is on scene open only the following callback removal
    #  shouldn't be necessary since callbacks don't persist on scene save,
    #  but why not?
    removeCallbacksFromNode(settingsMob)
 
    # and we finally add the callback implementation to the settings node
    om2.MNodeMessage.addAttributeChangedCallback(settingsMob, cb)

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)

Pilot Season – Day 11 – Guidable Components and Maya Callbacks Demo

Published by Raffaele on 25 June, 2017

Day 11 of the stream, where we introduce guides to the components, a space switch to the pedals, and most offer a demo of Maya Callbacks and how they can be introduced and managed.

This was a very long stream, and it’s sort of divided in two parts. Unintentionally, but luckily, it’s split right down the middle of its duration.

Part 1 lasts until the end of the first hour and it’s about adding live guides to components:

We show how to re-purpose some items we already had sitting around to add a guide mode to the two components we had finalized before, as well as introduce a parent switch/blend to the pedals.

Part 2, from the one hour mark on, is about Maya Callbacks:

Maya Callbacks are a native facility of Maya to introduce cross-talk between nodes driven by events that isn’t dependent on the graph, nor affects it.
It’s extremely useful to establish behavior in a graph that would otherwise be cyclic if it was left to live evaluation all the time:

E.G. Object A drives object B, but object B also drives in a similar fashion object A

 

Script notes:

Towards the end of the stream someone asked if I could post the example code, which seems like a very good idea.
At the end of this post you will find a formatted and cleaned up version of the episode’s script that you can run on a selection of N objects, and will install a callback that matches the translation of any node immediately downstream of the message plug of the node with the callback. If this sounds convoluted, don’t worry, the stream should make it a lot clearer.

Usage wise all you need to do to make it work and demonstrate how it can affect objects reciprocally is to have a couple nodes selected when you run it that are also connected to each other cyclically by their message plug. Again, if it sounds hard to understand, don’t worry, by the end of the video that should also be pretty obvious.

The script posted here isn’t meant to be a commando typing exercise, nor to crash your Maya session, so the callback is expanded with a circuit breaker to compare the effect of the loop, which wasn’t present in the one we worked on during the stream. That part represents what I was talking about when I mentioned you can use callbacks to manage benign cycles by exiting early on a successful comparison.

Last but not least: It also turns out I was probably incorrect in answering about deploying callbacks. They still don’t seem to leave any record in the scene, and therefore need to be managed on scene open by “the pipeline”.
It seems to me that showing a simple callback manager and tracker might be in the future of this season if the programming component shown today for the first time is to people’s liking 🙂

On to the videos, and script will follow at the end of the page:

 

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from maya.api import OpenMaya as om2
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)
    for eachCB in cbs:
        om2.MMessage.removeCallback(eachCB)
    len(cbs)
 
 
def translationPlugsFromAnyPlug(plug):
    """
    :param plug: [MPlug] plug on a node to retrieve translation related plugs from
    :return: [tuple(MPlug)] tuple of compound translate plug,
                            and three axes translate plugs
    """
    node = plug.node()
    if not node.hasFn(om2.MFn.kTransform): # this should exclude nodes without translate plugs
        return
    mfn_dep = om2.MFnDependencyNode(node)
    pNames = ('translate', 'tx', 'ty', 'tz')
    return tuple([mfn_dep.findPlug(eachName, False) for eachName in pNames])
 
 
def msgConnectedPlugs(plug):
    """
    :param plug: [MPlug] plug on a node owning message plug
                         we wish to retrieve all destination plugs from
    :return: [tuple(MPlug)] all plugs on other nodes receiving a message connection
                            coming from the one owning the argument plug
    """
    mfn_dep = om2.MFnDependencyNode(plug.node())
    msgPlug = mfn_dep.findPlug('message', False)
    return tuple([om2.MPlug(otherP) for otherP in msgPlug.destinations()])
 
 
def almostEqual(a, b, rel_tol=1e-09, abs_tol=0.0):
    """
    Lifted from pre 3.5 isclose() implementation,
    floating point error tolerant comparison
    :param a: [float] first number in comparison
    :param b: [float] second number in comparison
    :param rel_tol:  [float] relative tolerance in comparison
    :param abs_tol:  [float] absolute tolerance in case of relative tolerance issues
    :return: [bool] args are equal or not
    """
    return abs(a-b) &lt;= max(rel_tol * max(abs(a), abs(b)), abs_tol)
 
 
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
 
    srcTranslationPlugs = translationPlugsFromAnyPlug(plug1)
    if not len(srcTranslationPlugs):
        return
 
    # trim out the first plug, the translate compound, and only work on the triplet xyz
    values = [p.asFloat() for p in srcTranslationPlugs[1:4]]
 
    for eachDestPlug in msgConnectedPlugs(plug1): # all receiving plugs
        destTranslationPlugs = translationPlugsFromAnyPlug(eachDestPlug)[1:4]
        for i, p in enumerate(destTranslationPlugs):
            if almostEqual(p.asFloat(), values[i]):
                continue
            p.setFloat(values[i])
 
 
for eachMob in iterSelection():
    removeCallbacksFromNode(eachMob)
    om2.MNodeMessage.addAttributeChangedCallback(eachMob, cb)