-- 逆ピラミッド

local num = 10
local r = 10

local lnum=0

turtle.select(1)

for i = 1,10 do
  turtle.up()
end

-- ここから

for k=-1*r + 2 ,r do

  turtle.up()

  -- num = r - math.abs(k)
  num = math.floor((r^2 - k^2)^0.5)

  -- 移動
  for j =1,num do
    turtle.back()
  end
  turtle.turnLeft()
  for j =1,num do
    turtle.forward()
  end
  turtle.turnRight()



  for j =-1*num ,num do
    for i = -1*num,num do

        placeFlag = 0

        if i >=0 and j >= 0 then
          if (num)^2 <= (j+0.5)^2 + (i+0.5)^2 then
            if (num)^2 >= (j-0.5)^2 + (i-0.5)^2 then
      			  placeFlag = 1
            end
          end
        elseif i < 0 and j >= 0 then
          if (num)^2 <= (j+0.5)^2 + (i-0.5)^2 then
            if (num)^2 >= (j-0.5)^2 + (i+0.5)^2 then
      			  placeFlag = 1
            end
          end
        elseif i >= 0 and j < 0 then
          if (num)^2 <= (j-0.5)^2 + (i+0.5)^2 then
            if (num)^2 >= (j+0.5)^2 + (i-0.5)^2 then
      			  placeFlag = 1
            end
          end
        else
          if (num)^2 <= (j-0.5)^2 + (i-0.5)^2 then
            if (num)^2 >= (j+0.5)^2 + (i+0.5)^2 then
      			  placeFlag = 1
            end
          end

        end

        if placeFlag == 1 then
    			if turtle.getItemCount() == 0 then
    				selectNum = turtle.getSelectedSlot()
    				if selectNum == 16 then
    					selectNum = 0
    				end
    				turtle.select(selectNum+1)
    			end
          turtle.placeDown()
        end


    turtle.forward()
    end

    for i = -1*num,num do
      turtle.back()
    end

    turtle.turnRight()
    turtle.forward()
    turtle.turnLeft()

  end

  turtle.turnLeft()
  for j =0,num do
    turtle.forward()
  end
  turtle.turnRight()
  for j =1,num do
    turtle.forward()
  end

end