Matrix [1.0.1]

--(c) 2013 Felix Maxwell
--License: CC BY-SA 3.0

local fps = 8 --Determines how long the system will wait between each update
local maxLifetime = 40 --Max lifetime of each char
local minLifetime = 8 --Min lifetime of each char
local maxSourcesPerTick = 5 --Maximum number of sources created each tick
local sourceWeight = 0 --Affects the chance that no sources will be generated
local greenWeight = 8 --Threshhold out of 10 that determines when characters will switch from lime to green
local grayWeight = 2 --Same as about, but from green to gray

function getMonitors()
    local monitors = {}
    if checkMonitorSide( "top" ) then table.insert( monitors, "top" ) end
    if checkMonitorSide( "bottom" ) then table.insert( monitors, "bottom" ) end
    if checkMonitorSide( "left" ) then table.insert( monitors, "left" ) end
    if checkMonitorSide( "right" ) then table.insert( monitors, "right" ) end
    if checkMonitorSide( "front" ) then table.insert( monitors, "front" ) end
    if checkMonitorSide( "back" ) then table.insert( monitors, "back" ) end
    return monitors
end
function checkMonitorSide( side )
    if peripheral.isPresent( side ) then
        if peripheral.getType(side) == "monitor" then
            return true
        end
    end
    return false
end
function printMonitorStats( side )
    local x, y = peripheral.call(side, "getSize")
    local color = "No"
    if peripheral.call(side, "isColor") then
        color = "Yes"
    end
    print("Side:"..side.." Size:("..x..", "..y..") Color?"..color)
end
function askMonitor()
    local monitors = getMonitors()
    if #monitors == 0 then
        print("No monitors found, add more!")
        return nill
    elseif #monitors == 1 then
        return monitors[1]
    else
        while true do
            print("Multiple monitors found, please pick one.")
            for i,v in ipairs(monitors) do
                write("["..(i).."] ")
                printMonitorStats( v )
            end
            write("Selection: ")
            local sel = tonumber(io.read())
            if sel < 1 or sel > #monitors then
                print("")
                print("Invalid number.")
            else
                return monitors[sel]
            end
        end
    end
end

function printCharAt( monitor, x, y, char )
    monitor.setCursorPos( x, y )
    monitor.write( char )
end
function printGrid( monitor, grid, color )
    for i=1,#grid do
        for o=1,#grid[i] do
            if color then monitor.setTextColor( grid[i][o]["color"] ) end
            printCharAt( monitor, i, o, grid[i][o]["char"] )
        end
    end
end

function colorLifetime( life, originalLifetime )
    local lifetimePart = originalLifetime/10
    if life < grayWeight*lifetimePart then
        return colors.gray
    elseif life < greenWeight*lifetimePart then
        return colors.green
    else
        return colors.lime
    end
end
function getRandomChar()
    local randTable = {"1","2","3","4","5","6","7","8","9","0","!","@","#","$","%","^","&","*","(",")","_","-","+","=","~","`",",","<",">",".","/","?",":","{","}","[","]","\\","\"","\'"}
    return randTable[math.random(1, #randTable)]
end
function tick( screen )

    --update lifetimes
    for x=1,#screen do
        for y=1,#screen[x] do
            screen[x][y]["curLife"] = screen[x][y]["curLife"] - 1
        end
    end

    --make the sources 'fall' and delete timed out chars
    for x=1,#screen do
        for y=1,#screen[x] do
            if screen[x][y]["type"] == "source" and screen[x][y]["curLife"] == 0 then
                screen[x][y]["type"] = "char"
                screen[x][y]["lifetime"] = math.random(minLifetime, maxLifetime)
                screen[x][y]["curLife"] = screen[x][y]["lifetime"]
                screen[x][y]["color"] = colors.lime

                if y < #screen[x] then
                    screen[x][y+1]["char"] = getRandomChar()
                    screen[x][y+1]["lifetime"] = 1
                    screen[x][y+1]["curLife"] = 1
                    screen[x][y+1]["type"] = "source"
                    screen[x][y+1]["color"] = colors.white
                end
            elseif screen[x][y]["curLife"] < 0 then
                screen[x][y]["char"] = " "
                screen[x][y]["lifetime"] = 0
                screen[x][y]["curLife"] = 0
                screen[x][y]["type"] = "blank"
                screen[x][y]["color"] = colors.black
            elseif screen[x][y]["type"] == "char" then
                screen[x][y]["color"] = colorLifetime( screen[x][y]["curLife"], screen[x][y]["lifetime"] )
            end
        end
    end

    --create new character sources
    local newSources = math.random( 0-sourceWeight, maxSourcesPerTick )
    for i=1,newSources do
        local col = math.random(1, #screen)
        screen[col][1]["char"] = getRandomChar()
        screen[col][1]["lifetime"] = 1
        screen[col][1]["curLife"] = 1
        screen[col][1]["type"] = "source"
        screen[col][1]["color"] = colors.white
    end

    return screen
end

function setup( w, h )
    local retTab = {}
    for x=1,w do
        retTab[x] = {}
        for y=1,h do
            retTab[x][y] = {}
            retTab[x][y]["char"] = " "
            retTab[x][y]["lifetime"] = 0
            retTab[x][y]["curLife"] = 0
            retTab[x][y]["type"] = "blank"
            retTab[x][y]["color"] = colors.black
        end
    end
    return retTab
end
function run()
    local monitor = peripheral.wrap( askMonitor() )
    local color = monitor.isColor()
    local w, h = monitor.getSize()
    local screen = setup( w, h )
    while true do
        screen = tick( screen )
        printGrid( monitor, screen, color )
        os.sleep(1/fps)
    end
end

run()