Knowing which are right required making the function non-static, so the shadow manager had to become a singleton as the results of passing it around to where it's needed were hellish.
I'm seeing a bunch of OpenGL errors when actually using this, so I'll investigate whether they're happening on master.
I'm hesitant to look into it too much, though, as I'm affected by https://gitlab.com/OpenMW/openmw/-/issues/7811, and also have the Windows setting enabled that turns driver timeouts into a BSOD so a kernel dump is collected that I can send to AMD.
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