ComputerCraft Wall Building Helpers

flood.lua

map = {}
x = 0
y = 0
h = 0

function reset()
  map = {}
  x = 0
  y = 0
end

function mapget(mx, my)
  if map[mx] == nil then return nil end
  return map[mx][my]
end

function mapset(mx, my, val)
  if map[mx] == nil then map[mx] = {} end
  map[mx][my] = val
end

function mapupdate(mx, my)
  move_to(mx, my)
  local val = turtle.detectDown()
  mapset(mx, my, val)
  return val
end

function right()
  turtle.turnRight()
  h = (h + 90) % 360
end

function left()
  turtle.turnLeft()
  h = (h + 270) % 360
end

turnmap = {
  [0]={[0]=0, [90]=1, [180]=1, [270]=-1},
  [90]={[0]=-1, [90]=0, [180]=1, [270]=1},
  [180]={[0]=1, [90]=-1, [180]=0, [270]=1},
  [270]={[0]=1, [90]=1, [180]=-1, [270]=0}
}
  
function heading(new_h)
  while true do
    local turn = turnmap[h][new_h]
    if turn < 0 then
      left()
    elseif turn > 0 then
      right()
    else
      break
    end
  end
end

function north() heading(0) end
function south() heading(180) end
function east() heading(90) end
function west() heading(270) end   

function distance(new_x, new_y, old_x, old_y)
  return math.abs(new_x - old_x) + math.abs(new_y - old_y)
end

function move_to(new_x, new_y)
  dist = distance(new_x, new_y, x, y)
  if dist > turtle.getFuelLevel() then
    error("Out of gas!")
  end
  while new_x < x do
    west()
    if not turtle.forward() then error("Obstructed!") end
    x = x - 1
  end
  while new_x > x do
    east()
    if not turtle.forward() then error("Obstructed!") end
    x = x + 1
  end
  while new_y < y do
    south()
    if not turtle.forward() then error("Obstructed!") end
    y = y - 1
  end
  while new_y > y do
    north()
    if not turtle.forward() then error("Obstructed!") end
    y = y + 1
  end
end

function ensure_item()
  for slot=1,16 do
    if turtle.getItemCount(slot) > 0 then
      turtle.select(slot)
      return
    end
  end
  error("Out of stuff!")
end

function test_trace()
  mapset(4, -1, true)
  mapset(1, 1, true)
  mapset(1, 2, false)
  mapset(2, 2, true)
  mapset(3, 0, true)
end

function trace()
  local q = { {x=x, y=y} }

  while true do
    sleep(0)
    n = table.remove(q)
    if n == nil then break end
    nv = mapget(n.x, n.y)
    if nv == nil then
      nv = mapupdate(n.x, n.y)
      if nv == true then
        print("Flood from "..n.x..","..n.y)
        table.insert(q, {x=n.x+1, y=n.y-1}) -- SE
        table.insert(q, {x=n.x-1, y=n.y-1}) -- SW
        table.insert(q, {x=n.x+1, y=n.y+1}) -- NE
        table.insert(q, {x=n.x-1, y=n.y+1}) -- NW
        table.insert(q, {x=n.x, y=n.y+1}) -- N
        table.insert(q, {x=n.x, y=n.y-1}) -- S
        table.insert(q, {x=n.x+1, y=n.y}) -- E
        table.insert(q, {x=n.x-1, y=n.y}) -- W
      end
    end
  end
end

function getpath()
  print("Finding optimal path...")
  local points = {}
  for ix,row in pairs(map) do
    for iy,exist in pairs(row) do
      if exist then
        table.insert(points, {x=ix,y=iy})
      end
    end
  end
  local path = {}
  local lx = x
  local ly = y
  while true do
    local ld = nil
    local closest
    for idx, point in pairs(points) do
      local td = distance(lx, ly, point.x, point.y)
      -- print(lx..","..ly.."-"..point.x..","..point.y.."="..td)
      if ld == nil or td < ld then
        closest = idx
        ld = td
      end
    end
    if closest == nil then break end
    -- print("Closest to "..lx..","..ly.." is "..points[closest].x..","..points[closest].y)
    path[#path+1] = points[closest]
    lx, ly = points[closest].x, points[closest].y
    points[closest] = nil
  end
  return path
end

function draw()
  local path = getpath()
  for idx, point in pairs(path) do
    print("Placing at "..point.x..","..point.y)
    ensure_item()
    move_to(point.x, point.y)
    turtle.placeDown()
  end
end

test.lua

os.loadAPI("flood")

turtle.refuel(8999)
flood.reset()
flood.trace()
for i=1,3 do
  turtle.up()
  flood.draw()
done
flood.move_to(0, 0)
flood.north()