notes on usd adoption

usd-adoption.md

• on Windows, pip largely works for PySide2, but PySide2 is poorly supported and mostly broken under conda. Mixing and matching pip and conda is a bad practice.
• in a non-studio environment, Qt is problematic outside of the GPL3 environment.
• usdview is great, but if Python, or Qt, or PySide2 provide challenges, the onboarding process to USD involves a large effort
• no low-dependency usdview is available
• boost is a barrier to adoption due to well documented versioning issues (e.g., it is in vfxplatform as a configuration difficulty) and an onboarding-unfriendly build system
• tbb is a barrier outside of the DCC environment, as it is Yet Another threading system that may be at odds with either a developer's own tasking system, or a system native one such as Apple's Grand Central Dispatch. It is very easy to induces oversubscription problems with TBB in practice.
• lack of standard cookbooks. there are multiple community efforts, but no acknowledged best practice sources
• Python is highly adopted in Film CG, and Machine Learning, but less so in broader industry
• The easy interfaces for USD are the Python interfaces. The C++ interfaces often feel as if they are meant to facilitate the Python interfaces. An "easy" or "friendly" interface for C++ is necessary for onboarding.
• The toolset is a mix of native binaries and Python. See comments on Python. To use all the tools, Python needs to be in the global path, which is a barrier to a non-pythonic environment as there is little appetite to introduce a Python dependency to get a small number of tools such as usdcat.
• A standard recipe for using USD within Conda does not yet exist. The Film CG world is still on pip, but the ML community is on Conda, this is another fragmentation.
• Static initializers require compiler specific tricks, such as whole-archive flags, which have drawbacks, such as increasing the size of libraries.
• loading of plugins is problematic, and makes assumptions about installation which are tricky to navigate in embedded and bundling scenarios.
• non-static runtime initialization, such as programmatically telling USD to load plugins is not straight forward, and requires work arounds to avoid asserts related to static initialization