Java Edition 15w34a

15w34a is the tenth snapshot for Java Edition 1.9, released on August 19, 2015.^[1]

NBT format

• Added the powered and conditional byte tags to Control tile entity for command blocks.
• Added the life (Integer) and power (List/Double) tags to FireballBase.
• Added the id string tag inside SpawnData for the MobSpawner tile entity.
• Added the powered byte tag to Music tile entity for note blocks.

Command blocks

• New textures that now vary depending on what direction they are placed from, similar to dispensers and pistons.
  • It consists of a front, a back and a side texture (looks like arrows), so the orientation can be easily determined.
  • The texture is animated - the colored "buttons" in the middle change color.
  • The middle panel texture has a black outline.
• 3 modes: impulse, chain, and repeat - color changes based on mode.
  • Impulse mode (orange): Command is run once on rising edge.
    • Same behavior and color as previous versions.
  • Chain mode (green): Command is run whenever another command block pointing into it executes, and the command block in question is powered.
    • The chain signal is forwarded until the blocks get out of loaded chunks.
    • The signal is independent of the powered state of any block in the chain, as well as the command (or lack thereof) inside.
  • Repeat mode (blue): Command is run every game tick while powered.
    • Like a minecart with command block but faster.
  • Each new mode has its own block id and is obtainable with /give and pick block.
• Power received is now a data tag, allowing command blocks to have such a state under control, independent of any nearby redstone signal.
• Command block contraptions from earlier versions still work.
• The "Done" button is now always available to press, even when the command line is empty.

Note blocks

• Their power state is controlled through a tag, and can, therefore, be controlled independently on any redstone signal.

Maps

• Now start at a wider zoom level (1:4 instead of 1:1).
• New recipe for zooming in on a map: shears and a map together in any shape.
  • Zooms in on the lower-right quadrant of the original map.
  • This causes the shears to lose durability.

Zombies and zombie pigmen

• Now lift their arms slightly when becoming hostile.

Minecarts with command blocks

• The "Done" button is now always available to press, even when the command line is empty.

NBT format

• EntityId for the MobSpawner block entity has been deprecated.

Combat

• New attack speed combat mechanic.
  • A meter shows up after switching items or attacking.
    • Damage done depends on the fullness of the meter.
    • Fills in 0.25s for non-weapons, 0.8s for swords, pickaxes, and shovels, and 1.2s for axes.
    • The meter can be displayed next to the hotbar (left or right based on the player's main hand), under the crosshair or turned off.
      • Looks like the icon for the Strength effect on the side of the hotbar, or like a dagger under the crosshair.
      • This is controlled in video settings.
• Delay when selecting a sword, pickaxe, axe or shovel into the main hand.

Optimizations

• Optimized mob AI, pathfinding and block ticking.
  • 15% tick speed increase on 16 render distance.

7 issues fixed

From released versions before 1.9

• MC-86152 – Records lose their custom name when placed in a record player.

From the 1.9 development versions

• MC-83471 – "CustomPotionEffects" Inoperable with splash/lingering potions.
• MC-84260 – Tipped arrows show no potion particles.
• MC-85115 – Dragon fireball doesn't have a name (entity.DragonFireball.name).
• MC-85592 – Default log4j2.xml is suboptimal.

From the previous development version

• MC-86137 – Crash when breaking heads.
• MC-86138 – Pick block on mob (dragon) head/structure block crashes the game.

• This version was previously removed from the launcher for some time, but was added back in September 2018.