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	25	Note Block
Piston	33	Piston
Sticky Piston	29
Chest	54	Chest
Trapped Chest	146
Ender Chest	130	Ender Chest
Beacon	138	Beacon
Mob Spawner	52	Spawner
End Gateway	209	End Gateway
Anything else		Ignored

Note Block

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

Action IDs

The action ID is used to determine the instrument to play.

Type ID	Type Name
0	Harp (any material)
1	Bass Drum (stone)
2	Snare Drum (sand)
3	Clicks/Sticks (glass)
4	Bass guitar (wood)

Action param

The pitch of the note (between 0–24 inclusive where 0 is the lowest and 24 is the highest). 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.

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

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 yellow beam emitted by the end gateway when an entity passes through it.

Action param

Ignored.