a non-generated chunk is now always represented by NULL. This forces the case of ungenerated chunks to be handled by all code, which is necessary because ungenerated chunks cannot be interacted with or modified in any meaningful way.
in cases like PopulationTask it makes more sense to store the coordinates separately where they can be stored more efficiently (once instead of 9 times)
In addition, PopulationTask shouldn't need to serialize an empty chunk just to copy coordinates.
I've made changes like this in other areas already in preparation for the day when chunks no longer contain their coordinates, so this brings us one step closer to that goal.
I think we should probably get rid of this considering the potential for inconsistencies within a chunk, but not retaining this is a bug nonetheless, even though it doesn't have any effect in PM itself since we always use BlockLegacyIds << 4 as the empty block ID.
so, this is only really aiding (ab)use cases which weren't intended anyway ...
this better describes the purpose, which is to identify air.
though, it might make more sense to make air just always have zero as air's runtime ID, since this parameter is apparently making plugin devs think that this is suitable to fill a chunk with a specific block ...
this produces a major performance improvement for large render distances, and reduces the impact of lighting calculation to zero on servers which have random blockupdates turned off.
it's useful to have an immutable stub around for the sake of feeding back dummy read values, but for write values it has to barf instead of being quiet.
There's still some issues with LightArray which I don't currently have a solution for, but I'm thinking about separating light storage from chunks anyway.
recalculateHeightMapColumn is stateless, so it can't make any assumptions about which subchunks to check for blocks. However, in most the average case (6 allocated subchunks), this causes 2500+ useless SubChunk->getHighestBlockAt() calls (10 per column). Since we're calculating in bulk, we can figure out which subchunks are empty one time and ignore them for all 256 columns.
In the average case, this produced a 50-60% performance improvement for heightmap calculation (~1.1 ms -> 0.5 ms).
In extreme cases where the height is extremely varied, this produces no observable performance benefit, but for most cases with flattish terrain, it's an improvement.
It can likely be further improved, but further performance improvements are outside the scope of this commit and will likely result in more complexity increases.
opcache preloading doesn't store non-class constants, but it does store class constants. Class constants that reference non-class constants are pre-resolved into values before storing in opcache SHM, so class constants are OK to use, but non-class constants will come back as undefined.
this was degraded whenever it was I decided to make chunks always be allocated. This commit uses a fast path for light filling in subchunks which are completely clear of the heightmap, which returns the performance back to its old fast levels.
in pretty much every case, these usages really wanted to read the tag's contents anyway, which can be combined with a getTag() and instanceof call for more concise and static analysis friendly code.
In the few cases where the tag contents wasn't needed, it still wanted to check the type, which, again, can be done in a more static analysis friendly way by just using getTag() and instanceof.
