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Category: Stream

Season 01 – Episode 01 – Set and Graph Theory Vocabulary

Published by Raffaele on 31 December, 2017

Welcome to a new season of Cult of Rig.

In the interest of building up vocabulary on math fundamentals for the rest of the season we introduce Set and Graph Theory.

Both the video description and a comment under it contain an Errata Corrige I have to make here as well:
While talking about the inverse function of sin, arcsin, I mention the co-domain of the function being -pi to +pi; that is incorrect, as the domain of arcsin spans the half circle, and therefore is -1/2pi to +1/2pi

Pilot Season – Day 17 – Maya Assets for Encapsulation

Published by Raffaele on 23 July, 2017

Day 17 of the stream, A.K.A. Season Finale, and also where we show a use of Maya Assets (Containers) to encapsulate and establish a publishing front for rig components

This wraps up the pilot season of the stream. Thanks everybody for following.

This episode is about an often overlooked feature of Maya, at least in rigging, assets.

Also, courtesy of a viewer there is an answer to my ramblings about proxy attributes that takes place towards the end, and while for now it’s a commands only thing, and it will alter your graph in potentially circular ways, it seems serviceable already.
The flag I show in the API also has a related command flag to establish an attribute as a proxy, and it’s pretty simple to use.

In its mel form:

addAttr -ln "proxyName" -proxy "sourceObject.attr" targetObject

And here’s the video, Enjoy:

 

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 15 – Events and Application loops

Published by Raffaele on 22 July, 2017

Day 15 of the stream, An introduction to Events and Application loops

We got blackboard heavy today, but understanding the basics of how interactive software works is important.

We spend a good hour going over how software simulates interactivity, how it tracks change, and at what points in those cycles you can insert your own operations.

Enjoy:

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)