Do copper blocks oxidize indoors?
Does Minecraft 1.17.1 do any check to see if a copper block is sheltered before oxidizing it?
If so, what are the requirements for the shelter? Does it have to be enclosed, or just have a roof?
The short answer, yes, there are requirements for oxidation of copper blocks, and yes, they do oxidize indoors. It won't matter if you enclose it, or put a roof over it. The only way to prevent oxidation, is to add wax to the block.
To elaborate on this by summarizing the wiki, copper has four stages of oxidation, including its initial state. Oxidation relies on random ticks and is unaffected by things like weather:
Rain or water does not accelerate oxidation, and covering copper blocks with other blocks does not prevent oxidation.
It is described, that in minecraft-java-edition, when a random tick is given, there is a ~5.69% chance that a copper block will enter it's pre-oxidation state:
In Java Edition, when a random tick is given, a copper block has a 64⁄1125 chance to enter a state called pre-oxidation. This means a copper block enters pre-oxidation after approximately 20 minutes.
Note: I'm unsure if this works the same in minecraft-bedrock-edition.
During pre-oxidation, copper blocks search nearby, unwaxed, copper blocks to determine if pre-oxidation should end:
In pre-oxidation, the copper block searches its nearby unwaxed copper blocks for a distance of 4 blocks Manhattan distance. If there is any copper block that has a lower oxidation level, then the pre-oxidation ends, meaning that this copper block does not weather.
The wiki also defines the probability of oxidation quite clearly:
Let a be the number of all nearby unwaxed copper blocks, and b be the number of nearby unwaxed copper blocks that have a higher oxidation level. We derive the value of c from this equation:
c = b + 1⁄a + 1We also let the modifying factor m be 0.75 if the copper block has no oxidation level, or 1 if the copper block is exposed or weathered. Then the oxidation probability is mc2.
Yes, it does, only way to stop it from oxidizing is using honeycomb to wax it.