lib_machines

lib_machines is a mcfunction library that adds logic for placing and breaking custom blocks.

Terminology

Gamemode 4 primarily uses this library for machine blocks, but any mention of "machine" or "machine blocks" below refers to any custom block.

How to Use

There are 2 function tags to be used: one for placing machines (#gm4_machines:place_down) and one for breaking machines (#gm4_machines:destroy).

Placing Down Machines

Machine blocks must be player heads with the following NBT data:

{components:{"minecraft:custom_data":{gm4_machines:{id:"BLOCK_INDENTIFIER"}}}}

When placing down a player head with this NBT, the function tag #gm4_machines:place_down will run. This will run as the player who placed the block and at the center of the block that was placed. The following command should be used to verify the specific machine placed:

execute if score $placed_block gm4_machine_data matches 0 if data storage gm4_machines:temp {id:"BLOCK_INDENTIFIER"} run function MODULE_NAMESPACE:machine/create

The function MODULE_NAMESPACE:machine/create should have the following commands:

scoreboard players set $placed_block gm4_machine_data 1
summon marker ~ ~ ~ {Tags:["gm4_machine_marker","smithed.block","smithed.entity","smithed.strict","IDENTIFIER","ADD ANY EXTRA TAGS"],CustomName:'"PLEASE NAME YOUR MACHINE MARKERS"',<...>}

Each machine block has a marker entity located at the center of the block (align xyz positioned ~0.5 ~0.5 ~0.5) with the tag gm4_machine_marker.

The score $rotation gm4_machine_data stores the direction the player is facing and can be used in the create function:

1: up
2: down
3: north
4: east
5: south
6: west

This can be used to rotate blocks according to facing direction. Note that normally most rotated blocks (droppers, barrels, pistons, etc.) are placed with a facing direction opposite of the player's facing direction. E.g. if the player faces downwards, a placed dropper faces upwards.

The score $single_rotation gm4_machine_data stores the cardinal direction the player is facing and can be used in the create function:

1: north
2: east
3: south
4: west

This can be used to rotate blocks according to facing direction if the block doesn't have a vertical direction, such as furnaces.

The score $face_placement gm4_machine_data stores the face that the block was placed on and can be used in the create function:

1: north
2: east
3: south
4: west

This can be used to rotate blocks according to what face of the block it was placed on. Note that normally hoppers are placed with a facing direction opposite to the face that it was placed on. E.g. if a player places a hopper onto the south face of a block, it will point north, into the block it was placed on.

The scores $x_rotation and $y_rotation store the exact rotations of the player and can be used for more precise block placement than the three options outlined above.

Breaking Machines

Every tick, machine markers will check if it is in one of the following blocks:

air
moving_piston
lava
water

If it is in one of those blocks, it will activate a destruction function tag #gm4_machines:destroy. This runs as and at the marker entity. This function is run during the command block sub-tick, meaning you can kill/modify items before they can be picked up by hoppers and hopper minecarts.

E.g. if the base block of a machine is a dropper, when the machine marker detects it has been broken, the dropper item can be killed and/or replaced with a custom item (likely the player head used to place down the machine block).

The following command should be used to verify the specific machine destroyed:

execute if entity @s[tag=IDENTIFIER] run function MODULE_NAMESPACE:machine/destroy

License

This library, and the contents of the lib_machines directory on the [github repository](https://github.com/Gamemode4Dev/GM4_data packs), is licensed under the MIT License.