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Areas for Review

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title	MaterialX Version Sync

What is the desired process to keep USD up to date with a given version of MaterialX.

Property	Description	USD level	USD/MTLX level	MTLX level	Status	Proposal(s)
API change handling	Some versions break API compatibility.		Y	Y	Need to discuss this. Jonathan Stone noted future versions need to be more careful about possible compatibility breaking changes (API, definition etc).	Individual fixes as they come (e.g. PR-1633)
Compile time version	Allow compile time version exposure.			Y		PR to know version of MTLX at compile time PR-704

1586

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title	Properties List

Property	Description	USD level	USD/MTLX level	MTLX level	Status	Proposal(s)
namespace	Helpful to qualify definitions with a given scope to avoid name clashes. e.g. there may be a Adobe vs ILM namespace.				Issue 1614 logged	Encode namespace as part of definition identifier (no consensus) (PR 1631)
colorspace	Color management tagging for inputs as well as color management system specification.	Y			Agreement to support as formal property. Needs scoping and definition. Issue 1532 logged for MTLX export. Internal issue: USD-6703 (old - pre-agreement)	"Follow what is going on with MaterialX". (vague)
ui value properties	Hints for UI. e.g. ui min, max, step etc.	Y			Separate proposal for this.
unit / dimension support	Support for a real world unit or dimension for an given shader input. The type of the unit may be dynamic / data driven.				Issue 1632 logged. Internal issue: USD-6928.
tokens	Import and resolving of token names used for geometric and file identifiers. Can include consistency of token delimiters		Y
fileprefx					Issue 974 logged. Admin: not closed	Resolved in PR 977.
version	Definition versioning				tbd

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title	Definition Handling

Property	Description	USD level	USD/MTLX level	MTLX level	Status	Proposal(s)
Support nodes with multiple outputs					issue 1581 logged. Internal issue: USD-6820

definition information association	Import does not capture the correct association between a definition and a nodegraph sometimes.				Issue 1629 logged	Specific code fix proposed for conversion to MaterialX
definition variations	Definitions may be specified in a variety of different ways. Not all appear to be consumable properly. Some deal with definition discovery.				issue 1636 logged	Refactor import discovery logic. This includes being more aligned with MaterialX Version 1.38.x (PR 1641)
definition search path	Related to definition discovery (definition not found in path)				Issue 1586 logged. Internal issue USD-6941	Two different (independent?) PRs. Suggestion: Should generalize the proposal here. consider USD search path env variable on read for mtlx (partial, no concensus) (PR 1628) runtime vs compile time constants for pathing: (PR-1610)
load / reload	Robustness / repeatability of loading documents				Issue 1504 logged. Internal issue: USD-6670 (data loss) Issue 1502 logged. Internal issue: USD-6669 (node missing)

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title	Code Generation

Property	Topic	Description	USD level	USD/MTLX level	MTLX level	Status	Proposal(s)
selection hilighting	Display feature	HdStorm has no selection highlighting for geomteric primitives with MaterialX materials applied.		Y		Issue 1614 logged	Modify GLSLFX shadergen to apply additional color overrides ? (PR-1647)
parameter update	Performance	Prevent compiles on parameter changes by changing GLSFX code generation to use templated code and parameter buffer updates.		Y	Y	USD Issue: MTX Issue: 710	MaterialX input parameters are no longer hardcoded in the shader but set from the parameter buffer Support float and integer types with sizes between 1 and 4. Make sure that all other types are still hardcoded, so that there are no gaps USD: PR-1664 ADSK MTLX PR: 1320.
Texture binding code injection	Binding code injection		Y				PR-1634 to address non-bindless texture issue Q: This addresses GLSLFX, but as MTLX code gen changes this may not be robust or is this a one-off ?

usdview slow on idel	Performance	Root cause not known yet.		Y		USD Issue: 1638

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