scrollText.lua

------------
-- Config --
------------

--Time in seconds between scroll updates
local updateSpeed = 0.1

--Text to scroll
local text = "This is a test!"

--Whether or not to scroll left-to-right
local scrollLeftToRight = false

---------------------------------
-- Dont edit past here, thanks --
---------------------------------

--Initial Variable Setup
local m = peripheral.find("monitor")
local mX,mY = m.getSize()
local cX = 0

if (scrollLeftToRight == true) then
    cX = -string.len(text)
end

--Function to run if scrollLeftToRight == false
function rtl()
    cX = cX+1; --Add one to the current X position of the text
    m.clear() --Clear the monitor
    m.setCursorPos(mX-cX,mY/2) --Set the cursor position of the monitor to the calculated coordinates
    m.write(text) --Write our text
    if (mX-cX < 0) then --If we are starting to lose text to the side of the screen...
        m.setCursorPos(mX-(cX-mX),mY/2) --Set the cursor pos to the end of the monitor, relative to where the main text is
        m.write(text) --Write the same text - this gives the illusion of it wrapping around.
    end
    if (cX-mX >= string.len(text)) then --If the text is all the way off the screen, reset the current position.
        cX = cX-mX
    end
end

--Function to run if scrollLeftToRight == true
--(Nearly identical to rtl(), comments show differences)
function ltr()
    cX = cX+1
    m.clear()
    m.setCursorPos(cX,mY/2) --Start from front of monitor instead of end
    m.write(text)
    if (cX > mX-string.len(text)) then
        m.setCursorPos(cX-mX,mY/2) --Start from front of monitor instead of end
        m.write(text)
    end
    if (cX-mX >= 0) then
        cX = cX-mX
    end
end

--Loop function. Simply chooses which direction to scroll in, based on config.
--  Technically this COULD be in the while loop instead of its own function, but meh.
function main()
    if scrollLeftToRight then
        ltr()
    else
        rtl()
    end
end

--Main loop. Not that interesting.
while true do
    main()
    sleep(updateSpeed)
end