Explore asset atlases

[Shockah]

Two possible approaches, with different and unfortunately mutually exclusive benefits:

1. Per-mod atlases, statically generated by ModBuildConfig: Much faster load times for mods.
2. Dynamic global atlases, generated by Nickel at runtime: Improved frame-by-frame performance.

[Shockah]

What if both approaches could be used at once, and the player could choose in settings? I think that's viable.

[Shockah]

In hindsight, dynamic global atlases wouldn't make sense, as rendering would often have to switch between the game's main atlas, and the global atlas (assuming there's only one; with enough mods, there may be more). Unless the game's atlas is put into the dynamic global atlas... but that sounds like way too much trouble.