clearCube.lua

local depth, width, height = ...
if not (width and depth and height) then
    error("Not enough arguments; should be depth, width, height")
end
width = tonumber(width)
depth = tonumber(depth)
height = tonumber(height)

abs = math.abs
floor = math.floor
local heading = 0
local x, y, z = 0, 0, 0

local normalPasses = floor(height/3)
local remainingLayers = height % 3
local layers = 3

function isOdd(num)
    if num % 2 == 0 then
        return false
    else
        return true
    end
end

function changeHeading(amount)
    heading = (heading + amount) % 4
end

function turnRight()
    turtle.turnRight()
    changeHeading(1)
end

function turnLeft()
    turtle.turnLeft()
    changeHeading(-1)
end

function xIncrement(heading)
    if heading == 1 or heading == 3 then
        return 0
    elseif heading == 0 then
        return 1
    else return -1
    end
end

function zIncrement(heading)
    if heading == 0 or heading == 2 then
        return 0
    elseif heading == 1 then
        return 1
    else return -1
    end
end

function turnTo(newHeading)
    local rightTurns = (newHeading-heading)%4
    if rightTurns <= 2 then
        for i = 1, rightTurns do
            turnRight()
        end
    elseif rightTurns == 3 then
        turnLeft()
    end
end

function up()
    turtle.up()
    y = y+1
end

function down()
    turtle.down()
    y = y-1
end

function moveVert(signedDist)
    if signedDist < 0 then
        for i = signedDist, -1 do
            down()
        end
    else
        for i = 1, signedDist do
            up()
        end
    end
end

function moveHor(distance, direction)
    turnTo(direction)
    for i = 1, distance do
        forw()
    end
end

oddWidth = isOdd(width)
oddDepth = isOdd(depth)
oddHeight = isOdd(height)

function checkRefuel()
    if turtle.getFuelLevel() < 10 then
        turtle.refuel()
    end
end

function moveTo(destX, destZ, destY)
    if destY then
        moveVert(destY-y)
    end
    if destZ then
        local diffZ = destZ-z
        local distZ = abs(diffZ)
        moveHor(distZ, diffZ>0 and 1 or 3)
    end
    if destX then
        local diffX = destX-x
        local distX = abs(diffX)
        moveHor(distX, diffX>0 and 0 or 2)
    end
end

function forw()
    turtle.forward()
    x = x + xIncrement(heading)
    z = z + zIncrement(heading)
    --print("x"..x)
    --print("z"..z)
end

function fullDig()
    turtle.dig()
    if layers > 2 then turtle.digDown() end
    if layers > 1 then turtle.digUp() end
end

function moveX()
    fullDig()
    forw()
end

function moveZ()
    checkRefuel()
    if isOdd(z) then
        while x > 0 do
            moveX()
        end
    else
        while x < depth-1 do
            moveX()
        end
    end
    print("ferdigz "..z)
end

function moveY()
    while z < width-1 do
       moveZ()
       if not isOdd(z) then
           turnRight()
           fullDig()
           forw()
           turnRight()
       else
           turnLeft()
           fullDig()
           forw()
           turnLeft()
       end
    end
    moveZ()
    if layers > 1 then turtle.digUp() end
    if layers > 2 then turtle.digDown() end
end

function clearCube()
    turtle.dig()
    turtle.forward()
    while y < height-1 do
        moveY()
        moveTo(0,0,nil)
        turtle.digUp()
        up()
        turnTo(0)
    end
    moveY()
    moveTo(-1,0,0)
end

--clearCube()

function clearCubeEfficient()
    turtle.dig()
    turtle.forward()
    for pass = 1, normalPasses do
        if pass > 1 then
            turtle.digUp()
            up()
            turtle.digUp()
            up()
        end
        turtle.digUp()
        up()

        moveY()
        moveTo(0, 0, nil)
        turnTo(0)
    end
    layers = remainingLayers
    if remainingLayers > 0 then
        turtle.digUp()
        up()
        turtle.digUp()
        up()
        moveY()
    end
    moveTo(-1, 0, 0)
end

clearCubeEfficient()