Maya 2022 API Update guide

The guide is based on What's New in the Maya Devkit in Maya 2022 with some extra info. Check the Maya documentation for the most up to date information.

Build environment:

The build environments have been upgraded. Mac still uses Mojave 10.14.x with Xcode 10.x, and Windows remains Windows 10 with an upgrade to VS2019. Linux has been updated to CentOS/RHEL 7.6 or above and DTS 9.1.

Platform	OS	Compiler
Windows	Windows 10 x64	Visual Studio 2019
Mac	Mojave 10.14.x	XCode 10.2.1
Linux	CentOS/RHEL 7.6+ and 8.2+ (8.0 and 8.1 are missing some system packages)	gcc 9.3.1 (DTS 9.1)

Developer resources

The Maya docs are being updated with API changes. You can find the most up to date information for the API in the What's New / What's Changed section.
For those who are part of the Feedback community, there is an additional resource to help determine if your plug-in needs to be recompiled for Maya 2022. The product team is posting API compatibility reports in the Feedback forum for every PR release so check it out.

Changes in Maya 2022 at a glance

Python 3 support - Python 3 support is now available for all OS. Python 2 is still supported on Linux and Windows only.
Changes to third party components - Qt and PySide updated to version 5.15.2. Updates made to Alembic and OpenEXR libraries. Qt Creator Tools will not be distributed in their entirety. The pysideuic module has been deprecated by QtC and replaced by the pyside2-uic script.
Unicode characters support in Script Editor - Scripts are now saved using UTF-8 encoding as prescibed by PEP-263.
New environment variables - Two new environment variables added to control what is the output to stderr and stdout: MAYA_BATCH_STDOUT_LOGGING_LEVEL and MAYA_BATCH_STDERR_LOGGING_LEVEL.
Opting out of analytics in batch mode - Analytics will run by default when Maya starts in batch mode. Set MAYA_DISABLE_ADP to 1 to opt out of analytics.
AutoLoadOnce added to PackageContent.xml - A new option, AutoLoadOnce has been added to PackageContents.xml that is used when distributing plug-ins using the App Store format.
API changes - New smart pointer, classes, methods, and attributes have been added along with some changes made to the API.
Changes to Devkit examples - Several examples have new node IDs. Python examples have been renamed and moved. New examples added to the Devkit and some have been updated.
Scripting changes - Some commands now accept UFE path strings. Two new commands: FBXExtPlugin and mimicManipulation. Several new flags and options were added along with changes to some.

Python Updates

Maya starts up in Python 3 by default

Note: Maya on Windows and Linux supports both Python 2 and Python 3. Maya on macOS only supports Python 3.

To ways to start Maya in Python 2 mode:

Start Maya from the command line with -pythonver 2. For example, run maya.exe -pythonver 2 on command window.
Set the environment variable MAYA_PYTHON_VERSION to 2. For example, set MAYA_PYTHON_VERSION to 2 in the command window, then start Maya from the same command window.

Render.exe and Render.sh can now run in either Python 2 or Python 3 mode

Python 2: Run Render.exe -pythonver 2 on Windows or ./Render -pythonver 2
Python 3: Run Render.exe -pythonver 3 on Windows or ./Render -pythonver 3.

New pip support

mayapy now supports installing Python 3 modules with pip. To use pip with mayapy, use the follow command:

Linux and macOS: ./mayapy -m pip <command>
Windows: mayapy -m pip <command>

API Updates

New smart pointer - MSharedPtr<> has been added to Maya. They are used in the Maya API to make object ownership explicit.
New validator for decimal indicators - MayaQclocaleDoubleValidator was added to maya.internal.common.qt.doubleValidator to accomodate locales where decimal values use commas instead of periods.
New class in OpenMayaAnim module - MFalloffContext
New class added as part of the GPU deformer upgrades - MFnFloatVectorArrayData has been added to provide access to MFloatVectorArray.
New class and methods to perform MRenderItem-specific evaluations - MPxViewportComputeItem, MRenderItem::addViewportComputeItem(), and MRenderItem::viewportComputeItem().
New syntax for Python iterators - The newly-added syntax calls next with the iterator as the parameter: next(iterator).
Changed behavior for MGlobal::setActiveSelectionList() - MGlobal::setActiveSelectionList() will behave as expected: when it is called with an empty selection list, it will delete the list if ListAdjustment is set to kReplaceList, otherwise it will do nothing.
Deprecated method and changed behavior in MCacheSchema - The method reset() has been deprecated and attributes() is now a range over MObject rather than MPlug.
Changes to MItGeometry constructors - Two new constructors have been added for MItGeometry.
Changes to MRenderItem - Six new methods have been added to MRenderItem. Three methods have been deprecated.
New attribute and method added to MPxGeometryFilter - The componentTagExpression attribute has been added to MPxGeometryFilter in the OpenMayaAnim module.
New interface added to MRenderOverride in the OpenMayaRender module - New interface added to MRenderOverride to override the default Viewport 2.0 selection
New methods added to MSelectionInfo in the OpenMayaRender module - Two new methods were added to MSelectionInfo.
New methods and types added to MFnGeometryData to support component tags - Several new methods and types added to MFnGeometryData to support component tags
New methods and types added to MItDependencyGraph - Several new methods and types have been added to MItDependencyGraph to allow for traversing on graphs based on different relations.
New methods added to MFragmentManager - Two new methods were added to MFragmentManager to add and remove, respectively, a specific shader stage's input parameters. Three new methods were added to manage the mapping between parameter names and transient names.
New method added to MSelectionList - getPlug() have been added to MSelectionList.
New method added to MDGModifier - deleteNode() has been added to MDGModifier.
New methods added to MPxGPUDeformer - Two new methods have been added to MPxGPUDeformer.
New method added to MFnNurbsCurve - findParamFromLength() has been added to MFnNurbsCurve.
New methods added to MEvaluationNode - Two new methods have been added to MEvaluationNode. A new example, simpleSkipNode, has been added to demonstrate the use of these new methods.
New methods added to MPxCustomEvaluator - Two new methods have been added to MPxCustomEvaluator. A new example, evaluationPruningEvaluator, has been added to demonstrate the use of these new methods.
New methods added to MGPUDeformerRegistrationInfo - Four new methods have been added to MGPUDeformerRegistrationInfo.
Changes to MGPUDeformerBuffer - Two new methods added to MGPUDeformerBuffer, and the signature for MGPUDeformerBuffer() has been changed.
Signature changes in MGPUDeformerData and MPxGPUDeformer classes - The signature for MGPUDeformerData::getBuffer() and MPxGPUDeformer::evaluate() has changed.
New argument added to MPxCommand.setResult - A new argument, append, has been added to MPxCommand.setResult in Python API 2.0
Other new methods
Other deprecated methods

Devkit Updates

New node IDs for several examples - Changes were made to ensure that the node IDs used in all examples were unique. Examples with node ID changes will need to be recompiled.
Python examples have been moved and renamed - Python 1.0 examples have been renamed to have py1 prefix and Python 2.0 examples have py2 prefix. Python examples have been moved from scripting directory to python directory.
New examples - Six new examples added to the devkit: customComponentTagNode, exampleFalloff, basicMorphNode, simpleSkipNode, evaluationPruningEvaluator, and narrowPolyRenderOverride
Updated examples - Six examples have been updated: offsetNode, threadingLockTests, moveManip.py, blindDoubleDataCmd.py, glslShader, and manipOverride.
Alembic examples updated to only support Ogawa Alembic files - Maya no longer supports HDF5 variants of Alembic. These examples now only support Ogawa Alembic files: gpuCache, AbcBullet, AbcImport, AbcExport
Removed examples - Two examples removed from the devkit: exampleCameraSetView, narrowPolyViewer

Scripting Updates

UFE-aware commands - Some commands now accept UFE path strings. Commands that are UFE-aware will have different syntax than non-UFE-aware commands.
New plug-ins - Three new plug-ins: convertToComponentTags.py, snapTransform.py, and gameVertexCount
New commands - Two new commands: FBXExtPlugin, mimicManipulation
New flags and options New flags and options added to these commands: file, outlinerEditor, sets, deformerEvaluator, filterCurve, optVar, geometryAttrInfo, deformableShape, and ghosting
Changed flags and options - Changes made to: deformableShape, deleteAttr, affectedNet, dynExpression, and cutKey
Removed script - performSkinCluster.mel have been removed.