Block Actions

These block actions are used in the Block Action packet. Depending on the block, different action IDs mean different things:

Block	ID	Section
Note Block	minecraft:note_block	Note Block
Piston	minecraft:piston	Piston
Sticky Piston	minecraft:sticky_piston
Chest	minecraft:chest	Chest
Trapped Chest	minecraft:trapped_chest
Ender Chest	minecraft:ender_chest	Ender Chest
Beacon	minecraft:beacon	Beacon
Mob Spawner	minecraft:mob_spawner	Spawner
End Gateway	minecraft:end_gateway	End Gateway
Shulker Box	minecraft:shulker_box minecraft:<color>_shulker_box	Shulker Box
Anything else		Ignored

Note Block

Displays a colored note particle and plays the appropriate note sound effect.

In 1.13, the parameters are no longer used to determine what effect to use; instead, the information is obtained from the block state.

More information about how the pitch values correspond to notes in real life and how they correspond to pitch scaling on the sound effects can be found in the Note Block article on the Minecraft wiki.

Action IDs

Ignored, always 0.

Action param

Ignored, always 0.

Piston

Extends or retracts the piston. Always used on the piston base (either sticky or regular), never on the head. Also plays the extending/retracting sound.

	The following information needs to be added to this page:
	It's unclear what blocks and tile entities the client needs to create, and which ones the server creates. From a rough glance, it seems like the server changes the piston base block, but the client needs to create the piston head, create the block 36es, and create the piston moving tile entities. As such, the server needs to make the same assumptions as the client, or else ghost blocks may occur.

Action IDs

	The following information needs to be added to this page:
	This may have changed in 1.13; there is also a 2 state that seems to be used if a piston was canceled mid-push (maybe).

0 to extend the piston, 1 to retract it.

Action param

The direction the piston is facing (which is a metadata field on the piston). This is only used when the piston is retracting to generate the nearest block 36; all other parts appear ignore this parameter and use the piston's actual metadata field.

Direction ID	Direction
0	Down
1	Up
2	South
3	West
4	North
5	East

Chest

Action IDs

There is only one action, with ID 1. It is used to update the number of players who are looking in the chest, which in turn is used to update lid animation.

This value seems to be recalculated every 200 ticks, but isn't resent until a player closes/reopens.

Action param

When the action ID is 1, this is the number of players who have the chest open. If 0, then the chest is closed; if 1 or more the chest is open.

Ender chest

Action IDs

There is only one action, with ID 1. It is used to update the number of players who are looking in the ender chest, which in turn is used to update lid animation. This is recalculated and resent every 80 ticks (4 seconds), even if the value hasn't changed.

Action param

When the action ID is 1, this is the number of players who have the chest open. If 0, then the chest is closed; if 1 or more the chest is open.

Beacon

Action IDs

There is only one action, with ID 1. It is used to tell the client to recalculate the beacon beam. This happens whenever the beacon base receives a block update. Additionally, whenever a stained glass block or stained glass pane is placed above a beacon that can see the sky. The client goes through all blocks above the beacon, disabling/enabling the beam if it is covered and recoloring the beam if it passes through glass or stained glass.

Note that the beacon beam is also recomputed every 80 ticks (4 seconds), but no block action occurs when that happens. The block action allows placing of a beacon and recoloring of the beam to potentially be instant, but does not make all other changes to the beam instant.

Action param

Ignored.

Spawner

Action ID

There is only one action, with ID 1, which resets the delay in the spawner to the minimum spawn delay.

Action param

Ignored.

End gateway

Action ID

There is only one action, with ID 1, which triggers the magenta beam emitted by the end gateway when an entity passes through it.

Action param

Ignored.

Shulker Box

Animates the shulker box's shell opening.

Action IDs

There is only one action: 1, which updates the number of players who are looking in the shulker box.

Action param

If the action is 1, updates the number of players who have the shulker box open. If 0, the shulker box enters its closing animation; if 1, the shulker box enters its opening animation.