Prevent flats clipping thru walls

[DunnyOfPenwick]

The problem is primarily with a small subset of monsters, like scorpions and spiders. The logic could be tailored for just those enemies, that would limit overall negatives.

[TacticalTrickery]

... and sometimes fail to display enemies under some conditions (seen thru small openings?), which is why I rejected that solution. But maybe it's not that bad, that's something to experiment with.

The problem is primarily with a small subset of monsters, like scorpions and spiders. The logic could be tailored for just those enemies, that would limit overall negatives.

This is a good idea. The limitation on negatives would be pretty high... it's not often you see a Spider/Scorp thru a small opening.