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fabric-carpet/docs/scarpet/api/BlockIterations.md
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2020-06-17 13:08:34 -03:00

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# Iterating over larger areas of blocks
These functions help scan larger areas of blocks without using generic loop functions, like nested `loop`.
### `scan(center, range, lower_range?, expr)`
Evaluates expression over area of blocks defined by its center `center = (cx, cy, cz)`, expanded in all directions
by `range = (dx, dy, dz)` blocks, or optionally in negative with `range` coords, and `upper_range` coords in
positive values.
`center` can be defined either as three coordinates, a list of three coords, or a block value.
`range` and `lower_range` can have the same representations, just if its a block, it computes the distance to the center
as range instead of taking the values as is.
`expr` receives `_x, _y, _z` as coords of current analyzed block and `_`, which represents the block itself.
Returns number of successful evaluations of `expr` (with `true` boolean result) unless called in void context,
which would cause the expression not be evaluated for their boolean value.
`scan` also handles `continue` and `break` statements, using `continue`'s return value to use in place of expression
return value. `break` return value has no effect.
### `volume(from_pos, to_pos, expr)`
Evaluates expression for each block in the area, the same as the `scan` function, but using two opposite corners of
the rectangular cuboid. Any corners can be specified, its like you would do with `/fill` command.
You can use a position or three coordinates to specify, it doesn't matter.
For return value and handling `break` and `continue` statements, see `scan` function above.
### `neighbours(pos)`
Returns the list of 6 neighbouring blocks to the argument. Commonly used with other loop functions like `for`.
<pre>
for(neighbours(x,y,z),air(_)) => 4 // number of air blocks around a block
</pre>
### `rect(centre, range?, positive_range?)`
Returns an iterator, just like `range` function that iterates over a rectangular area of blocks. If only center
point is specified, it iterates over 27 blocks. If `range` arguments are specified, expands selection by the respective
number of blocks in each direction. If `positive_range` arguments are specified,
it uses `range` for negative offset, and `positive_range` for positive.
`centre` can be defined either as three coordinates, a list of three coords, or a block value.
`range` and `positive_range` can have the same representations, just if its a block, it computes the distance to the center
as range instead of taking the values as is.`
### `diamond(centre_pos, radius?, height?)`
Iterates over a diamond like area of blocks. With no radius and height, its 7 blocks centered around the middle
(block + neighbours). With a radius specified, it expands shape on x and z coords, and with a custom height, on y.
Any of these can be zero as well. radius of 0 makes a stick, height of 0 makes a diamond shape pad.