Another snapshot is going out, and this one introduces the Sculk. They're a bit creepy, but don't let that put you off. Pick up some good vibrations!

New Features in 20w49a

Added Dripstone Caves biome
Added Sculk Sensors

Dripstone Caves biome

This biome doesn't generate naturally yet, since it is designed for the upcoming larger caves. However, if you want to see the biome in the current caves you can create a single-biome world with dripstone caves.

Contains plenty of Pointed Dripstone on the floors and ceilings, and small pools of water
In some places you'll find larger stalagmites, stalactites, and columns built from Dripstone Blocks.

Sculk Sensors

Introducing the bizarre, tendril-filled world of Sculk - prepare for Sculk Sensors to creep you out with their unique ability to detect vibrations nearby.
A vibration is anything that causes physical motion; if you are careful, there are some motions that are undetectable to sensors by sneaking.
- These sneak-friendly vibrations currently include walking, falling to the ground or throwing/shooting projectiles.
Sculk Sensors will not listen to vibrations that are directly created by other Sculk sources.
When a vibration is detected, a signal is sent from the source location to the sensor at a speed of 1 game tick per block.
- Other vibrations cannot be detected by a sensor when a signal is already travelling to it.
- When the signal has arrived, the sensor will be activated for 40 game ticks (approximately 2 seconds).
- While activated, the sensor cannot detect other vibrations.
Sculk Sensors can detect vibrations in an 8 block radius around it.
The efficient tool to mine Sculk Sensors is the Hoe.
They can be waterlogged.

Redstone Emission

Sculk Sensors emit a redstone signal when they are activated.
The strength of the redstone signal is inversely proportional to the distance the vibration signal travelled.
- This means that the closer the vibration is, the stronger the redstone signal is.
- The output is also scaled based on the Sculk Sensor's radius, so it can reach the max redstone signal strength when the vibration is 0 distance away (directly on top of the sensor).

Vibration Frequencies

Sculk Sensors have a unique interaction with comparators.
Each vibration in the game falls under a certain frequency value, and this value can be measured with a comparator.
With the right contraption, this allows you to detect when a certain action has occured nearby.

Vibration Type	Frequency Value
Step	1
Flap	2
Swim	3
Elytra Free Fall	4
Hit Ground	5
Splash	6
Wolf Shaking	6
Projectile Shoot	7
Projectile Land	8
Start Eating	7
Finish Eating	8
Hit Entity	9
Add Item To Armor Stand	9
Open Block	11
Close Block	10
Switch Block	11
Unswitch Block	10
Press Block	11
Unpress Block	10
Attach Block	11
Detach Block	10
Open Container	11
Close Container	10
Dispense Failed	10
Use Flint And Steel	12
Place Block	12
Destroy Block	13
Place Fluid	12
Pickup Fluid	13
Cast Fishing Rod	15
Reel-In Fishing Rod	14
Extend Piston	15
Contract Piston	14
Explosion	15
Lightning Strike	15

Wool Occlusion

Wool has a special interaction with Sculk Sensors.
If a wool block is in the way of a vibration source, the sensor will not be able to detect it.

Technical Tidbits

Sculk Sensors have a cooldown period of 1 tick after being placed or after deactivating.
During this short cooldown period, it cannot detect vibrations. This is to prevent it from activating itself when a contraption it is powering is being unpowered. Feedback is welcome on this point!

Changes in 20w49a

The Fullness of a bundle now shows up regardless of whether Advanced Tooltips are on or off
Stalactites and stalagmites merge if the tips are next to each other, unless you press shift while placing

Technical Changes in 20w49a

A new game event system has been implemented to support Sculk Sensors detecting vibrations.
World height related values are now exposed for customized worlds
Removed the max-build-height server setting
Added occludes_vibration_signals block tag. Anything in this tag will occlude vibrations, and inherits wool tag entries by default
New particle types: vibration and dust_color_transition
A new game event system has been implemented to support Sculk Sensors detecting vibrations.

Game Events

This system has been developed to identify when certain in-world actions are happening in nearby chunks, particularly so the new Sculk Sensor can detect these events as vibrations.

The following is a list of the initial game events:

minecraft:step
minecraft:swim
minecraft:flap
minecraft:elytra_free_fall
minecraft:hit_ground
minecraft:splash
minecraft:projectile_shoot
minecraft:projectile_land
minecraft:entity_hit
minecraft:block_place
minecraft:block_destroy
minecraft:fluid_place
minecraft:fluid_pickup
minecraft:block_open
minecraft:block_close
minecraft:block_switch
minecraft:block_unswitch
minecraft:block_attach
minecraft:block_detach
minecraft:block_press
minecraft:block_unpress
minecraft:container_open
minecraft:container_close
minecraft:explode
minecraft:armor_stand_add_item
minecraft:wolf_shaking
minecraft:dispense_fail
minecraft:fishing_rod_cast
minecraft:fishing_rod_reel_in
minecraft:piston_extend
minecraft:piston_contract
minecraft:flint_and_steel_use
minecraft:eating_start
minecraft:eating_finish
minecraft:lightning_strike

Fixed bugs in 20w49a

MC-18880 The Absorption effect has no texture for poison/wither hearts (appears empty instead)
MC-201840 Optional function tags sometimes don't run even when the tag exists
MC-203797 Placing or removing a block over the void causes a DecoderException on servers
MC-204314 Double copper slabs only drop a single slab when mined
MC-205043 Absorption hearts appear broken when taking freezing damage
MC-205096 Hardcore hearts lose all color when player is taking freeze damage
MC-205391 Waxing cut copper doesn’t prevent it from oxidising
MC-205629 Unused sign cache when rendering signs
MC-206553 Pointed Dripstone creates water particles in the Nether
MC-206563 Pointed dripstone is not connected to the player's hand
MC-206578 Large pillars of stalactites don't fall when the block above is removed
MC-206583 Cauldrons below stalactites at least 2 blocks tall won't fill up
MC-206591 Setting any floating block to a pointed dripstone, causes the replaced block to drop as an item
MC-206594 Large stalactites falling occasionally don't drop all of their pointed dripstone items
MC-206599 Pointed dripstone can be placed atop each other, even if a player would be inside the hitbox of the lower dripstone
MC-206606 Frustum stage of stalactites negates fall damage
MC-206613 Pointed Dripstone duplicates when the block it was attached to is removed
MC-206615 Pointed dripstone's hitbox can extend further than a block, causing nearby stalactites to not be able to fall
MC-206642 Stalactites destroy items they fall on, however stalagmites don't
MC-206643 When a dripstone's hitbox extends into the space of another block, the area that extends into said block cannot be targeted
MC-206669 Inconsistency between dripstone and non-mob entities
MC-206682 Floating dripstone tips are sometimes left behind from large dripstone pillars
MC-206691 Pointed dripstone replaces items with pointed dripstone items
MC-206711 Coding error at net.minecraft.world.entity.Entity.resetPos()
MC-206790 Waterlogged dripstone does not update
MC-206878 Pointed dripstone attached to a piston is not removed as the piston extends

Minecraft Snapshot 20w49a