TopLeft to Cartesian

local coords = {{math.random(-14,14),math.random(-9,9),2^math.random(1,14)},{math.random(-14,14),math.random(-9,9),2^math.random(1,14)},{math.random(-14,14),math.random(-9,9),2^math.random(1,14)},{math.random(-14,14),math.random(-9,9),2^math.random(1,14)},{math.random(-14,14),math.random(-9,9),2^math.random(1,14)},{math.random(-14,14),math.random(-9,9),2^math.random(1,14)},{math.random(-14,14),math.random(-9,9),2^math.random(1,14)},{math.random(-14,14),math.random(-9,9),2^math.random(1,14)},{math.random(-14,14),math.random(-9,9),2^math.random(1,14)},{math.random(-14,14),math.random(-9,9),2^math.random(1,14)},{math.random(-14,14),math.random(-9,9),2^math.random(1,14)},{math.random(-14,14),math.random(-9,9),2^math.random(1,14)},{math.random(-14,14),math.random(-9,9),2^math.random(1,14)},{math.random(-14,14),math.random(-9,9),2^math.random(1,14)},{math.random(-14,14),math.random(-9,9),2^math.random(1,14)},{math.random(-14,14),math.random(-9,9),2^math.random(1,14)},{math.random(-14,14),math.random(-9,9),2^math.random(1,14)},}
local map = window.create(term.native(),1,1,29,19)
local oldCursorPos = map.setCursorPos
local oldGetCP = map.getCursorPos
local maxX, maxY = map.getSize()
map.getCursorPos = function() local x,y = oldGetCP() return x-(math.ceil(maxX/2)),-(y-(math.ceil(maxY/2))) end
map.setCursorPos = function(x,y) oldCursorPos(x+(math.ceil(maxX/2)),-(y-(math.ceil(maxY/2)))) end
map.setBackgroundColor(colors.white)
map.clear()
map.setTextColor(colors.black)
local stage = 1
while true do
local event, key = os.pullEvent("key")
    if key == keys.right then
        stage = stage - 1
        if stage < 1 then
            stage = 4
        end
    elseif key == keys.left then
        stage = stage + 1
        if stage > 4 then
            stage = 1
        end
    end
    map.setBackgroundColor(colors.white)
    map.clear()
    map.setBackgroundColor(colors.yellow)
    map.setCursorPos(0,0)
    map.write("^")
    for i,v in pairs(coords) do
        map.setBackgroundColor(v[3])
        if stage == 1 then
            map.setCursorPos(v[1],v[2])
            map.write("X")
        elseif stage == 2 then
            map.setCursorPos(v[2],-v[1])
            map.write("X")
        elseif stage == 3 then
            map.setCursorPos(-v[1],-v[2])
            map.write("X")
        elseif stage == 4 then
            map.setCursorPos(-v[2],v[1])
            map.write("X")
        end
    end
end