New Renderer: The Mega Issue (Please share use cases here!)

[pathunstrom]

This is a place to have the big strategy discussion on what the new ppb Renderer needs to be.

We've got a wishlist, but need to actually figuring out what's genuinely critical and core, what's a thing we want to be able to support, and what's outside the purview of the project. (Can exist in the ecosystem, but we're not going to build it, though we might consider ways to make those extensions easier to write.)

What we need is to collect use cases. Please present them below and start with the heading

# Use Case:

so they can be easily searched.