setair.lua

local args = {...}

function setair (values)
  if not dfhack.isMapLoaded() then
    dfhack.color (COLOR_RED)
    dfhack.print("Error: This script requires a Fortress Mode embark to be loaded.")
    dfhack.color(COLOR_RESET)
    dfhack.println()
    return
  end

  local max_x, max_y, max_z = dfhack.maps.getTileSize()
  local lastvalueindex = -1
  function lenTable (subject)
    local len = 0
    for iter in pairs(subject) do
      len = len + 1
    end
    return len
  end

  local lengthofArgs = lenTable(values)
  function getNextValue ()
    lastvalueindex  = lastvalueindex + 1
    return tonumber(values[1+(lastvalueindex % lengthofArgs)])
  end

  function Is_Air_Tile (x, y, z)
    local tile_type
    local block = dfhack.maps.getBlock (math.floor (x / 16), math.floor (y / 16), z)
    local region_offset = block.region_offset [block.designation [0][0].biome]
    local result = true

    for i = 0, 15 do
      for k = 0, 15 do
        if dfhack.maps.getTileBiomeRgn (x, y, max_z - 1 - z) ~= nil then
          tile_type = dfhack.maps.getTileType (x + k, y + i, z)
          if tile_type > df.tiletype.Void and
             tile_type ~= df.tiletype.OpenSpace and
             (tile_type < df.tiletype.BurningTreeTrunk or
              tile_type > df.tiletype.BurningTreeCapFloor) and
             (tile_type < df.tiletype.TreeRootSloping or
              tile_type > df.tiletype.TreeDeadTrunkInterior) and
             (tile_type < df.tiletype.ConstructedFloor or
              tile_type > df.tiletype.ConstructedRamp) and
             (tile_type < df.tiletype.ConstructedFloorTrackN or
              tile_type > df.tiletype.ConstructedFloorTrackNSEW) and
             (tile_type < df.tiletype.ConstructedRampTrackN or
              tile_type > df.tiletype.ConstructedRampTrackNSEW) then
              result = false
              break
          end
        end

        if region_offset ~= block.region_offset [block.designation [k][i].biome] then  --  Air tiles have uniform offsets (even when they are shears)
          result = false
          break
        end
      end

      if not result then
        break
      end
    end

    if result and region_offset ~= 0 then
      dfhack.println ("Shear at " .. tostring (x) .. ", " .. tostring (y) .. ", " .. tostring (z))
    end

    return result
  end

  local block
  local offsetbiome = 0
  for l = 0, max_z - 1 do
    for i = 0, math.floor (max_y - 1) / 16 do
      for k = 0, math.floor ((max_x - 1) / 16) do
        if i==0 and k==0 then
        end
        if not Is_Air_Tile (k * 16, i * 16, max_z - 1 - l) then
          break
        end

        block = dfhack.maps.getBlock (k, i, max_z - 1 - l)
        offsetbiome = getNextValue()
--      dfhack.println("offsetbiome is " .. tostring(offsetbiome))
        for m = 0, 15 do
          for n = 0, 15 do
            block.region_offset [block.designation [n][m].biome] = offsetbiome
          end
        end
      end
    end
  end
end

setair (args)