Java Edition 20w45a

20w45a is the first snapshot for Java Edition 1.17, released on November 4, 2020, which adds the first Caves & Cliffs features.

Blocks

 * Amethyst Bud
 * Grows from budding amethyst, which is found in amethyst geodes.
 * Starts out small, but grows into medium after a while, large after even more time and eventually becomes an amethyst cluster.
 * Unlike crops, each growth stage is a separate block instead of a block state.
 * Drops nothing if broken in its premature stages, even with Silk Touch.


 * Amethyst Cluster
 * The final, mature stage of the amethyst bud, which grows from budding amethyst in amethyst geodes.
 * Drops amethyst shards if broken, in an amount affected by Fortune, but can also be picked up with Silk Touch.
 * Emits a light level of 5.


 * Block of Amethyst
 * A block found in amethyst geodes.
 * Unlike the Budding Amethyst, the Block of Amethyst can be obtained when mined.
 * Can also be crafted with 4 amethyst shards.


 * Budding Amethyst
 * Generates amethyst crystals on any of its sides (if next to a water source block or air, and if the side is not against another block), in a given time.
 * Cannot be obtained when mined, even with Silk Touch, and does not drop anything.
 * Breaks immediately if pushed by a piston or sticky piston.
 * Cannot be pulled by sticky pistons.
 * Generates in amethyst geodes.


 * Calcite
 * An off-white stone that generates in geodes, between tuff and amethyst.


 * Candle
 * Crafted with honeycomb and string.
 * Comes with 16 dyed types and a yellowish non-dyed type.
 * Can be lit by any item that produces fire.
 * Up to 4 can be placed in a single block, similar to sea pickles, for a maximum light level of 12.
 * Only candles of the same color can be placed on the same block.
 * Only one can be placed on an uneaten cake and lit.
 * If any of the cake is consumed the candle pops off.
 * Can be placed, but cannot be lit, underwater.


 * Copper Block
 * Can be crafted with 9 copper ingots, and can also be crafted back into 9 copper ingots.
 * Oxidises and changes texture to a turquoise-green over time.
 * Can be stopped from oxidizing by combining it with a honeycomb to create a Waxed Copper Block.
 * Can be crafted into cut copper.


 * Copper Ore
 * Generates randomly underground in small veins, but this has been confirmed to be a placeholder.
 * Has the same rarity as iron.
 * Generating starts at the same minimum level(s) as iron.
 * Can be smelted into a copper ingot.


 * Cut Copper
 * Can be made into stair and slab variants.
 * Oxidises and changes texture over time.
 * Can be stopped from oxidizing by combining it with a honeycomb to create Waxed Cut Copper.


 * Cut Copper Slab
 * Oxidises and changes texture over time.
 * Can be stopped from oxidizing by combining it with a honeycomb to create a Waxed Cut Copper Slab.


 * Cut Copper Stairs
 * Oxidises and changes texture over time.
 * Can be stopped from oxidizing by combining it with a honeycomb to create Waxed Cut Copper Stairs.


 * Lightning Rod
 * Can be crafted with 3 copper ingots.
 * Nearby lightning strikes within a 16 block radius get redirected to the lightning rod.
 * Gives off a redstone signal with a strength of 15 if hit by lightning.
 * Can be activated directly by throwing a trident with Channeling at it during a thunderstorm, though this does not produce a redstone signal.


 * Tinted Glass
 * A black variant of glass that does not let light pass through.
 * Can be crafted with 4 amethyst shards and a glass block.
 * Stained glass cannot be used to craft tinted glass.
 * Drops itself if mined without Silk Touch or even by hand, unlike glass.


 * Tuff
 * A grayish stone that composes the outer layer of amethyst geodes.

Items

 * Amethyst Shard
 * Obtained from breaking amethyst clusters.
 * The amount dropped can be increased with the Fortune enchantment.
 * Can be used to craft tinted glass, blocks of amethyst and a spyglass.


 * Bundle
 * Can be crafted with 2 string and 6 rabbit hide.
 * Used to store other items inside of it.
 * Can only hold a single stack of items, but is able to hold different types of items inside of it.
 * Items with smaller stacks, such as ender pearls, take up more room in a bundle.
 * One non-stackable item takes up the whole space.
 * The bundle's contents can be opened by pressing right-click while holding it.
 * Cannot hold shulker boxes.
 * Even though bundles are not stackable, bundles can be nested.
 * Can hold up to 16 bundles.
 * Only empty bundles can be placed in other bundles without using commands.
 * Note: Bundles can hold any amount of any item if added using commands.


 * Copper Ingot
 * Obtained by smelting copper ore.
 * Used to craft copper blocks, lightning rods and spyglasses.


 * Spyglass
 * Crafted with 2 copper ingots and an amethyst shard.
 * When used, it zooms in on wherever the player is looking, but limits their view to a small circle.
 * The overlay that limits the view can be removed with a resource pack or by pressing.
 * There is a unique animation for using the spyglass, which is visible in third person perspective.

World generation

 * Amethyst Geodes
 * A new feature found uncommonly underground (can rarely appear exposed to the surface close to sea level).
 * Contains blocks of amethyst and budding amethyst blocks, which are encased in a shell of calcite and tuff.
 * Also generates with a small air pocket nearby which may open into the geode.
 * Generally generates at or below sea level (y = 63).
 * Most commonly generates at lower levels (y = 0 to y = 40)
 * Overrides standard caves and ravines, but is overridden by abandoned mineshafts.
 * Currently has a high generation rate, presumably for testing purposes which was also done with ruined portals before.

General

 * Loot tables
 * New functions:
 * Sets tags needed for banner patterns. Parameters:
 * patterns - list of pattern objects:
 * pattern - name of pattern (square_bottom_left, bricks, etc.)
 * color - name of color (light_gray, etc.)
 * append - if true, new elements will be appended to existing ones instead of replacing


 * Tags
 * Added the block tag.
 * Contains all 17 types of candle cake.
 * If the player puts a candle on a cake, and keeps clicking the candle on the cake, the candle will be duplicated.
 * Blocks in this tag are considered candle cakes and can be lit, if they have the block states set to false.
 * Added the block and item tags.
 * Contains all 17 types of candles.
 * Blocks in this tag are considered candles and can be lit, if they have the block states and both are false.
 * Cakes use this tag to determine if a candle item can be placed on it or not.
 * Added the block tag.
 * Contains cauldrons, water cauldrons, and lava cauldrons.
 * This tag is used in certain pathfinding processes.
 * Added the block tag.
 * Contains amethyst blocks and budding amethyst.
 * Blocks in this tag play play the "amethyst block chime" sound repeatedly for a short amount of time after being stepped on, gradually decreasing in volume.
 * Added the item tag.
 * Contains leather.
 * Baby piglins do not attempt to pick up items in this tag. Adult piglins are unaffected. Baby piglins still follow the other rules adult piglins follow.
 * If an item is in this tag while simultaneously being recognized as a wanted item by piglins, this tag takes precedence.
 * Added the item tag.
 * Contains raw and cooked porkchop.
 * Piglins can eat items in this tag.
 * Eating refers to the piglin seeking out and picking up an item without appearing in its inventory, thus vanishing.

Blocks

 * Cauldrons
 * Can now be filled with lava.
 * Lava filled cauldrons can damage players and mobs inside of it.
 * Lava filled cauldrons give off a redstone comparator signal of strength 1.
 * Have been split into normal, water and lava cauldrons.


 * Grass Path
 * Renamed to "Dirt Path", as per Bedrock Edition.
 * The block ID has also been changed to.
 * Can now be made with dirt, coarse dirt, mycelium, and podzol.


 * Pistons
 * Particles now appear if a block is broken by a piston.
 * Sounds, however, do not.


 * All rails
 * Are now able to be waterlogged.
 * No longer break when contacted by water.


 * Water
 * Flowing water no longer breaks rails.


 * Shulker boxes
 * Now mimics the opening and closing of a shulker.
 * Unlike its mob counterpart, it does not elevate the player when they are standing on it.

Items

 * Firework Rockets
 * Simple firework rockets with one gunpowder can now be crafted using the recipe book.

Mobs

 * Shulkers
 * If a shulker is hit by another shulker's projectile, it now has a chance of spawning a new shulker.
 * Shulkers are more likely to spawn new shulkers when there are fewer other shulkers nearby.

Non-mob entities

 * Experience Orbs
 * Now sometimes merge when in large quantities, to improve performance.
 * Merging does not affect the amount of experience gathered from collecting the merged orbs.
 * No longer follow dead players.


 * Minecarts
 * Can now move in water, but move considerably slower than they do on land.

General

 * Data and Resource Packs
 * Changed the  number in   from 6 to 7.
 * Split the  number into separate resource and data pack versions; the data pack version remains at 6.


 * Dedicated servers
 * A dedicated server can enforce custom resource packs by setting in . When this option is used, players will be prompted for a response and will be disconnected if they decline the required pack.


 * Entity storage
 * Entities have been extracted from main (terrain) chunks and are now stored in separate directory (similar to POI storage). Those new files are still region files with NBT.


 * Libraries
 * The game now uses javabridge 1.1.23 instead of 1.0.22.

Video
Video made by slicedlime: