Minecraft Turtle: Circle

    --[[
    2015 (c) psychedelixx
    Minecraft Turtle: Circle
    2015-01-08

    Builds a circle

    Robust API:
    http://computercraft.info/wiki/Robust_Turtle_API

    Usage:
    - use turtle and type "label set <name>"
    (to give your turtle an unique name so it remembers its programs)
    - type "pastebin get wgFfCNUq circle"
    - place blocks in turtle inventory
    - type "circle <radius>"
    ]]


-------------------------------------------------------------------------------------
-- INIT -----------------------------------------------------------------------------
-------------------------------------------------------------------------------------
slot = 1
posX = 0
posY = 0
posH = 0

height = 1
debug = 0
x = {}
y = {}

local args = { ... }
if #args < 1 or #args > 3 then
    print("")
    print("circle <radius> [<height>] [<debug {0|1}>]")
    print("place items in inventory")
    print("")

    error()
end

radius = tonumber(args[1])

if radius > 100 or radius < 1 then
    print("")
    print("Are you mad? I won't do this...")
    print("")
    error()
end

if #args == 2 then
    height = tonumber(args[2])
end

if #args == 3 then
    debug = tonumber(args[2])
end

-------------------------------------------------------------------------------------
-- ROUND ----------------------------------------------------------------------------
-------------------------------------------------------------------------------------

function round(num, idp)
  local mult = 10^(idp or 0)
  return math.floor(num * mult + 0.5) / mult
end

-------------------------------------------------------------------------------------
-- CALC CIRCLE ----------------------------------------------------------------------
-------------------------------------------------------------------------------------

function calcCircle()
    d_ = -radius
    x_ = radius
    y_ = 0

    -- 1/8 -------------------
    while y_ <= x_ do
        table.insert(x, x_)
        table.insert(y, y_)

        d_ = d_ + 2 * x_ * y_ + 1;
        y_ = y_ + 1;

        if d_ > 0 then
            d_ = d_ - 2 * x_ * x_ + 2;
            x_ = x_ - 1;
        end
    end

    length = table.getn(x)

    -- 2/8 -------------------
    for i = length, 1, -1 do
        table.insert(x, y[i])
        table.insert(y, x[i])
    end

    -- 3/8 -------------------
    for i = 1, length, 1 do
        table.insert(x, -y[i])
        table.insert(y, x[i])
    end

    -- 4/8 -------------------
    for i = length, 1, -1 do
        table.insert(x, -x[i])
        table.insert(y, y[i])
    end

    -- 5/8 -------------------
    for i = 1, length, 1 do
        table.insert(x, -x[i])
        table.insert(y, -y[i])
    end

    -- 6/8 -------------------
    for i = length, 1, -1 do
        table.insert(x, -y[i])
        table.insert(y, -x[i])
    end

    -- 7/8 -------------------
    for i = 1, length, 1 do
        table.insert(x, y[i])
        table.insert(y, -x[i])
    end

    -- 8/8 -------------------
    for i = length, 1, -1 do
        table.insert(x, x[i])
        table.insert(y, -y[i])
    end
end

-------------------------------------------------------------------------------------
-- CALC RESOURCES -------------------------------------------------------------------
-------------------------------------------------------------------------------------

function calcResources()
    count = 0
    for i=2, table.getn(x) do
        if not (x[i] == x[i-1] and y[i] == y[i-1]) then
            count = count + 1
        end
    end
    return count
end

-------------------------------------------------------------------------------------
-- CHECK RESOURCES ------------------------------------------------------------------
-------------------------------------------------------------------------------------

function checkResources()
    repeat
        overwrite = 0
        sumItems = 0
        for i=1, 16, 1 do
            sumItems = sumItems + turtle.getItemCount(i)
        end

        if sumItems < calcResources() then
            print("Not enough Resources for this layer")
            print("I need " .. (calcResources() - sumItems) .. " more blocks (" .. calcResources() .. " total)")
            print()
            print("Fill up and press enter")
            print("or type in '1' to start anyway")
            overwrite = read()
        end

        if overwrite == '1' then
            break
        end
    until sumItems >= calcResources()
end

-------------------------------------------------------------------------------------
-- PLACE ----------------------------------------------------------------------------
-------------------------------------------------------------------------------------

function place()
    if posX == x[i] and posY == y[i] and not(x[i] == x[i-1] and y[i] == y[i-1]) then
        if debug == 1 then
            print(posH .. ' # ' .. i .. ' # ' .. x[i] .. ' # ' .. y[i] .. ' # ' .. x[i+1] .. ' # ' .. y[i+1] .. ' # ' .. posX .. ' # ' .. posY)
        else
            print(round(((posH*table.getn(x) + i)/table.getn(x)-1)/height*100, 1) .. " %")
        end
        while turtle.getItemCount(slot) == 0 and slot < 16 do
            slot = slot + 1
        end
        if turtle.getItemCount(slot) == 0 and slot == 16 then
            print('Please put items into slot 1 and press enter')
            read()
            slot = 1
        end
        turtle.select(slot)
        turtle.digDown()
        turtle.placeDown()
    end
end

-------------------------------------------------------------------------------------
-- MOVE -----------------------------------------------------------------------------
-------------------------------------------------------------------------------------

function move(var, op, turn)
    if turn == 'lr' then
        t.left()
        t.forward()
        t.right()
    elseif turn == 'rl' then
        t.right()
        t.forward()
        t.left()
    elseif turn == 'no' then
        t.forward()
    end

    if op == 'inc' then
        var = var + 1
    elseif op == 'dec' then
        var = var - 1
    end
    return var
end

-------------------------------------------------------------------------------------
-- MAIN -----------------------------------------------------------------------------
-------------------------------------------------------------------------------------

calcCircle()

if turtle.getFuelLevel() < calcResources()*height then
    print("I need " .. math.ceil(calcResources()*height - turtle.getFuelLevel()) .. " more fuel!")
else
    print("======== 2015 (c) psychedelixx ========")
    print("Let's go!")
    print("Building a circle...")
    print("")

    checkResources()
    t.forward(radius)
    posX = posX + radius
    t.left()

    while posH < height do

        if posH > 0 then
            checkResources()
        end

        posH = posH + 1

        t.up()
        i = 1

        print("Building layer " .. posH .. " of " .. height)

        -- 1/8 --------------------------------------------
        while y[i] < x[i] do
            place()

            if y[i] < y[i+1] then
                posY = move(posY, 'inc', 'no')
            end
            if x[i] > x[i+1] then
                posX = move(posX, 'dec', 'lr')
            end

            i = i+1
        end

        t.left()

        -- 2/8 --------------------------------------------
        while x[i] > 0 do
            place()

            if y[i] < y[i+1] then
                posY = move(posY, 'inc', 'rl')
            end
            if x[i] > x[i+1] then
                posX = move(posX, 'dec', 'no')
            end

            i = i+1
        end

        -- 3/8 --------------------------------------------
        while math.abs(x[i]) < y[i] do
            place()

            if y[i] > y[i+1] then
                posY = move(posY, 'dec', 'lr')
            end
            if x[i] > x[i+1] then
                posX = move(posX, 'dec', 'no')
            end

            i = i+1
        end

        t.left()

        -- 4/8 --------------------------------------------
        while y[i] > 0 do
            place()

            if y[i] > y[i+1] then
                posY = move(posY, 'dec', 'no')
            end
            if x[i] > x[i+1] then
                posX = move(posX, 'dec', 'rl')
            end

            i = i+1
        end

        -- 5/8 --------------------------------------------
        while y[i] < x[i] do
            place()

            if y[i] > y[i+1] then
                posY = move(posY, 'dec', 'no')
            end
            if x[i] < x[i+1] then
                posX = move(posX, 'inc', 'lr')
            end

            i = i+1
        end

        t.left()

        -- 6/8 --------------------------------------------
        while x[i] < 0 do
            place()

            if y[i] > y[i+1] then
                posY = move(posY, 'dec', 'rl')
            end
            if x[i] < x[i+1] then
                posX = move(posX, 'inc', 'no')
            end

            i = i+1
        end

        -- 7/8 --------------------------------------------
        while math.abs(y[i]) > x[i] do
            place()

            if y[i] < y[i+1] then
                posY = move(posY, 'inc', 'lr')
            end
            if x[i] < x[i+1] then
                posX = move(posX, 'inc', 'no')
            end

            i = i+1
        end

        t.left()

        -- 8/8 --------------------------------------------
        while y[i] < 0 do
            place()

            if y[i] < y[i+1] then
                posY = move(posY, 'inc', 'no')
            end
            if x[i] < x[i+1] then
                posX = move(posX, 'inc', 'rl')
            end

            i = i+1
        end
    end

    print("Finished")
end