So I found a cave spider spawner in 1.14 that I would very much like to use for an XP farm due to me badly wanting the guud enchants, but there's a problem. The spawner spawned at Y level SEVEN. For a very obvious reason, I don't really have the Y-space to make any sort of usual XP farm setup that involves dropping the cave spiders down a bit.
Any ideas on how to make a cave spider XP farm that would coerce the spiders to climb up a ways?
Bedrock is a full block, which probably allows mobs to choose it as a pathfinding destination. That means you have a ton of potential pathfinding destinations too close to the mobs that you can't legitimately do anything about, so raw pathfinding logic won't work without severely stuttering the grinder. I dunno if bedrock is specially exempted from this, so you could clear out everything that isn't bedrock that is within 5 blocks of the cage. From there, you would use full blocks to build the path you want the mobs to take and every other part of the walls/floor/ceiling would be non-full blocks like stairs and slabs. If the spiders keep hanging around in the spawn area, then bedrock is a valid pathfinding destination and you should probably go looking for a better cage location.
That said, you could use aggro-based pathfinding. It's basically the same thing as regular pathfinding, except you're specifically aggroing the spiders and having them come attack you instead of randomly choosing a place to walk to. THAT is basically the same thing as what the really old designs do (from when spiders could see you through walls), except nowadays they actually do have to have line of sight on you.
Ofc I COULD go looking for a better cave location, but I honestly had to do a lot of searching before I bumbled into this one. I'd like to use every opportunity to make this one work first. I'll try to hollow out the appropriate area and see how they pathfind.
I was wrong on the specifics, but the correct information (assuming it hasn't changed regarding modern versions of Minecraft) is found in this video
Basically, mobs can wander to any block that has a solid, non-transparent block beneath them in a 21x by 15y by 21z cube centered on the mob (that's 7 blocks away vertically and 10 blocks away horizontally). It's basically the same condition that allows iron golems to spawn in water or with their feet in glass. Up to 10 attempts will be made to find a valid destination, and the wandering task can be triggered in 3 scenarios: when first spawning, when moving <32 blocks to the nearest player, and when moving >32 blocks away from the nearest player (in all three cases, the wandering can only happen within the first 5 seconds).
In Hex's pictures, the cave walls, floor, and ceiling are far too close and are putting tons of valid destination blocks in range. It's not surprising they aren't going where he wants them to, because they've got something like a thousand choices to choose from.
I hollowed out an 8w by 8l by 5h area around the spawner to work with. Don't mind the non vanilla look, i'm only using Jolicraft texture pack and some shaders. I'm gonna try and work out how to make the water flow in there.
I'll admit i'm not particularly skilled in how to make this work, especially for goading the cave spiders into climbing up a particular spot. Advice for this point onwards would be appreciated.
Bedrock definitely seems to be a valid destination.
There is absolutely a tendency to find solid blocks but some of the cave spiders take several minutes before running off to a solid block and I'm not sure they all eventually get there, I got tired of waiting.
I know that recent updates made it possible to create an upwards force in water using soul sand. Is there a clever way to use that to shoot the cave spiders upwards, perhaps?
I have a couple of vague ideas, but I lack the big brain power to actually make it happen due to me not having a particularly genius grasp of MC's water physics. I got most of the way using trapdoors and the like but i'm unsure how to use it to properly horizontally carry spiders forward after moving them up.