Get Block

A tile has not one content but four layers. getblock asks about any of them

mediumYou need: What a world processor is, Number, object and text

steptick 0

Get Block0

layerfloorresultxy

Get Block1

layeroreresultxy

Get Block2

layerblockresultxy

Get Block3

layerblockresultxy

Get Block4

layerbuildingresultxy

Get Block5

layerblockresultxy

Get Block6

layeroreresultxy

Stop7

@counter0number

floornullnull

orenullnull

wallnullnull

blocknullnull

buildingnullnull

emptynullnull

noOrenullnull

getblock floor floor 6 4
getblock ore ore 9 4
getblock block wall 12 4
getblock building building 6 7

One instruction and four different questions to the map. On this map it answers: metal floor, copper ore, stone wall and a router.

The four layers of a tile

Layer	What it gives	What can be there
floor	the floor	sand, stone, metal floor, water
ore	the overlay	ore on top of the floor, or @air if there is none
block	what stands there	a building, a static wall or @air
building	the building as an object	the block itself, the kind sensor works with

The difference between block and building is subtle but important:

• block gives a type: @router, @copper-wall, @stone-wall. That is content, not a structure on the map — it has to be compared with block constants;
• building gives the structure itself: the same thing getlink gives. It can be asked for health, stock and team.

getblock building store 6 7
sensor copperLeft store @copper

Note

A natural wall — stone, dark stone, sandstone — is also a block but not a building. It has neither health nor a team: it is part of the map, not a structure. So getblock block sees it and getblock building gives emptiness.

An empty tile is @air

Silent failure

getblock has two kinds of emptiness, and they are different things.

@air means “the tile is empty”: the layer was read and there is nothing in it. That is what block and ore answer on plain sand.

Real emptiness (null) means “there is no such tile”: the coordinates went past the edge of the map. Comparing with @air is useless there — compare with null.

This is worth checking whenever the coordinates are computed rather than written as numbers: a program walking a strip of the map will certainly go past the edge one day.

Why read the map

A world processor reads tiles for the sake of a script:

• check whether the player built what was asked: getblock building on a given tile and a type comparison;
• watch territory: is the enemy wall still standing, has the core been demolished;
• find a spot to build on: is it empty, and is the floor suitable;
• give a “build here” objective: a marker on the map plus a tile check.

Remember

• getblock layer where x y reads a map tile; there are four layers.
• floor is the floor, ore the ore on top of it, block what stands there, building the structure as an object.
• An empty tile answers @air, and a tile past the map’s edge null.
• Natural walls are in block but not in building.

Task

Change getblock block wall 12 4 in the example to getblock building wall 12 4: the variable goes empty — a stone wall is not a structure.

Then put the coordinates 99 99 in any line: the answer is null, not @air — there is no such tile on the map at all.