[ComputerCraft] Pipes Screensaver

local pullEventBackup = os.pullEvent
os.pullEvent = os.pullEventRaw
term.clear()

-- this program accepts 1 optional argument, being intensity. Intensity determines the likelihood of the line to turn. Default is 0.05, max is 0.5 (mostly turning) and min is 0 (straight lines)
local args = {...}
local intensity = tonumber(args[1]) or 0.05
if intensity > 0.5 then intensity = 0.5 end
if intensity < 0 then intensity = 0 end

local linego = false
local redraw = os.startTimer(0.05)
local startfrom = {["x"] = 0, ["y"] = 0, ["dir"] = 0}
local termx, termy = term.getSize()
-- directions: 0 - down; 1 - left; 2 - up; 3 - right

while true do

    e, p1, p2, p3 = os.pullEvent()
    if e == 'terminate' then
        term.setBackgroundColor(2^15)
        term.clear()
        term.setCursorPos(1,1)
        if term.isColor() then
            term.setTextColor(2^14)
        end
        print('Terminated')
        os.pullEvent = pullEventBackup
        break
    end

    if e == 'key' then
        if p1 == keys.q then
            term.setBackgroundColor(2^15)
            term.clear()
            term.setCursorPos(1,1)
            sleep(0.05)
            os.pullEvent = pullEventBackup
            break
        end
    end

    if e == 'timer' then

        if startfrom.x > termx or startfrom.x < 1 or startfrom.y > termy or startfrom.y < 1 then
            linego = false
        end

        if not linego then
            linego = true
            math.randomseed(os.time()*1000)
            term.setBackgroundColor(math.pow(2, ((math.log(term.getBackgroundColor())/math.log(2)) + (math.random(1,14)))%15))
            local perimeter = (termx*2) + (termx*2)
            local startnum = math.random(1,perimeter)
            if startnum > (termx*2) + termy then
                -- left
                startfrom.x = 1
                startfrom.y = startnum - ((termx*2) + termy)
                startfrom.dir = 3
            elseif startnum > termx + termy then
                -- bottom
                startfrom.y = termy
                startfrom.x = startnum - (termx + termy)
                startfrom.dir = 2
            elseif startnum > termx then
                -- right
                startfrom.x = termx
                startfrom.y = startnum - termx
                startfrom.dir = 1
            else
                -- top
                startfrom.y = 1
                startfrom.x = startnum
                startfrom.dir = 0
            end
        end

        term.setCursorPos(startfrom.x, startfrom.y)
        write(' ')

        local rnd = math.random()

        if rnd < intensity then
            startfrom.dir = (startfrom.dir - 1) % 4
        elseif rnd > (1 - intensity) then
            startfrom.dir = (startfrom.dir + 1) % 4
        end

        if startfrom.dir == 0 then
            startfrom.y = startfrom.y + 1
        elseif startfrom.dir == 1 then
            startfrom.x = startfrom.x - 1
        elseif startfrom.dir == 2 then
            startfrom.y = startfrom.y - 1
        else
            startfrom.x = startfrom.x + 1
        end

        redraw = os.startTimer(0.05)
    end

end