Request Description

Not sure how much we want to deviate from vanilla, but when it comes to rendering against blocks with full sides, many inconsistencies are to be found. Here's some pictures:

In some cases, the sides are culled; in others, they're not.

IMO for opaque blocks, the faces should definitely be culled. For visually transparent blocks, the interior faces should use the "plain" texture which is visible from the outside when water is against glass, for example (https://bugs.mojang.com/browse/MC-271735).

Sodium previously did something much more extreme, which was obviously undesirable (#991). The ideal outcome is to find a middle ground which visually makes sense.

An inside overlay is shown depending on whether the block is marked as "transparent". This is decided by FluidRenderHandlerRegistry on fabric, and neoforge has a similar mechanism. I don't think we want to change this because this behavior is presumably relied on by mods because they can specifically configure it and I don't think there's a more reasonable classification of blocks to show overlays for.