AL_USDMaya and pxrUSDMaya Feature Sets

This is heavily biased towards AL_USDMaya - someone with deeper knowledge of the Pixar plugin should add more detail here

Standalone Utility Libraries

Feature	Feature Detail	Notes	Future?
Utilities
	Event System	used heavily by USDMaya
MayaTest
	Test framework	used heavily by USDMaya	see docs
Maya Utilities			We could probably extract these to a new AL OSS Library? (need to think how this would work
	Common	macros for shortening the amount of boilerplate code we need
	CommandGuiHelper	Automatically generate a simple UI from MpxCommands
	DGNodeHelper	get/set types on DG Nodes
	FileTranslatorBase	macros and templates to help automate the boiler plate setup of Maya import/export plugins
	MenuBuilder	generate Menu entries for an entire Plugin
	NodeHelper	various utility functions for adding static/dynamic attributes to an MpxNode
USD Utilities			This lib is probably too small to exist on it's own
	DiffCore	diffing utilities
	SIMD
USD+Maya Utilities
	USD to Maya Diffing, Conversion, Attribute Manipulation

Import/Export to File

Feature	Feature Detail	AL_USD	PxrUSD	Notes	Future Support
Export to File					Priority #1 for ADSK plugin?
	Transforms	yes	yes
	Camera	yes	yes
	General
	Duplicate Instances	yes	yes	see AL_USDMaya docs
	Merging Transforms	yes	yes	see AL_USDMaya docs
	Time Samples	yes	needs investigation	pxr seems to have no compression flags
	Frame Samples / Sub-Frame Export	yes	yes	see AL_USDMaya docs
	Animated Visibility	yes	yes
	Instancing	yes	yes
	Dynamic Attributes	yes	yes
	Metadata / extra attrs	yes	yes
	Lights	no	yes	Pixar only supports RfM Lights. AL todo: Include Reference Translator for Maya Lights
	Mesh
	UVs	yes	needs investigation	pxr seems to have no compression flags
	Topology and Point Positions	yes	yes
	Varying Topology	no	yes
	Indexed UVs	yes	yes
	Color Sets (by default RGBA and faceVarying)	yes	yes	AL_USD requires colorSet to be called displayColor ( displayOpacity is also supported ). See AL_USDMaya docs. pxrUSD has the same displayColor set requirement, however it handled the missing 'flood data' elegantly. multiple colorSets have not been tested yet*
	Subdivision Edge and Vertex Creases	yes	yes
	NurbsSurface	no	yes
	NurbsCurve	yes	yes	Note: Not currently renderable in Hydra
	BasisCurve	no	no	Note: Renderable in Hydra
	Particles	no	yes	OriginalForce may be adding support in AL_USDMaya? (eoinm)
	Shaders	yes	yes (RfmShaders)	via ExtraData Plugin
	Skin/Joints	no	yes	PxrUsd has basic USDSkel support
Import from File					Priority #1 for ADSK plugin?
	Lights	yes	yes	PxrUsd only supports RfM Lights, AL_USD has reference DistantLight importer
	Supported Animation	yes	yes	through time1 connection
	"AlembicMaya" style Animated Geometry Cache	yes	yes	see docs
	Load Part of Stage	yes	yes	yes, each plug-in has it's own way of importing 'fast' (ie: proxyShape), then diving down into transforms to interact with / update the usd stage (visible in the viewport )
	Shaders	no	yes	PxrUsd only supports RfM Shaders
	Custom Shapes, Transforms	yes - enumerate special features	?

Extension Points

Feature	AL_USD	PxrUSD	Notes	Future Support
UsdAdaptor	no	yes	The rationale behind this was to make it easier to adapt an existing UsdSchema into and out of Maya. It's not something user-facing.. rather, if you're writing tools/scripts to work with data, this would help transfer data between Usd and Maya in a consistent manner.
Custom Blind Data	no	yes	If a maya node has some extra "user" attribute that we want to export, the "User Exported Attributes" interface helps with this. It lets users tag nodes and get them exporting to Usd. Users can choose to export as normal attributes, or primvars
Chasers	no	yes	This is similar to the "post-export" jobs that some other file format plugins have.
Extra Data Plugins	yes	no	see https://github.com/AnimalLogic/AL_USDMaya/blob/master/docs/extraDataTranslatorPlugins.md
Events	yes	no	https://github.com/AnimalLogic/AL_USDMaya/blob/master/docs/events.md to the existing events documentation

Interactive Workflows (Proxy Shape)

Feature Type	Feature Description	AL_USD	PxrUSD	Notes	Future Support
Hydra Integration
	Hydra GL Support	yes, via USDImaging	yes, via custom code Path (optimised for multiple shapes)		Consolidate
	Support other Hydra Render Delegates	yes	?
Selection
	Partial Stage Selection	yes	yes
	VP2 Selection of Stage	yes	no/ip	see AL_USDMaya PR
	UFE Selection	yes		see PR
	VP2 Selection from Stage to Outliner	yes	under investigation	AL_USD has extra selection management going on, and hooks into it's ProxyShapeImportTransforms command. PxrUSD selection ( back to native dag nodes of some form) might not be possible this is being investigated
Live/Interactive Workflows
	Constraint Based Workflows	yes	limited	AL_USD has bi-directional constraint support, including access to constrain to individual elements of the USD Stage. PxrUSD has limitations due to the Assembly node and not having 'connect to prim' capability (out-of-the-box, might be possible through scripting and such )
	Interface with Native USD	no*	no*	not natively, but through custom commands / plugins ( pxrUsdReferenceAssembly or AL_usdmaya_Transforms or a proxyShape node to each USD Stage )
	Variant Switching	yes	no	A
	Variant Switching of MayaReferences	yes	no	AL_USD has a schema for MayaReferences to allow to switch out to rig representations.
	Selective Translation USD to Maya	yes	no	Can select prim hierarchy in USD, translate to Maya
	Selective Translation Maya to USD	yes	no	Can select USD translated data in Maya, modify, Translate Back. This is a key feature, and very powerful. It does a diff of the converted maya data to work out what's changed, so "overs" can be generated
	"Live" Maya Nodes	yes	no	AL_USDMaya uses maya's "storage=internal" to allow creation Cameras, Lights and other MPxNodes which directly drive a USD equivalent, storing values in USD
Layer-based Workflows
	Layer Management	yes	no	AL_USD serializes 'live layer data' so when artist re-opens maya session it opens the usd stage, then your local edits. Once task is complete, layer can be saved out and merged back to the usd stage/file ). PxrUSD seems to require full import / export from usd -> maya nodes, which can impact Maya performance