WaterSim

local width, height = term.getSize()
local llvls = {}

local damt = 8
local dskip = 0
local dmax = 45

local dith = 30
local dithd = damt
local function getDither()
    dith = dith + dithd
    if dith >= dmax then dithd = -(damt) end
    if dith <= -(dmax) then dithd = damt end
    if dith <= dskip and dith >= -(dskip) then
        if dithd == -(damt) then dith = -(dskip)-1
        elseif dithd == damt then dith = dskip+1 end
    end
    return dith/10
end

local stcmax = 90
local stcmin = 75
local stcamt = 2

local stc = stcmin
local stcd = stcamt
local function getStretch()
    stc = stc + stcd
    if stc >= stcmax then stcd = -(stcamt) end
    if stc <= stcmin then stcd = stcamt end
    return ( (stc/10) - 0.5 )
end

local offset = width

local function getOffset()
    return (offset%(width)) + width
end

local startLvl = nil
local function draw()
    offset = offset + 1
    local dither = getDither()
    local stretch = getStretch()
    for x=1,width do
        local lvl = math.max((math.sin((x-getOffset())/stretch)*(dither))-0.5) + math.floor(height/2)
        local llvl = llvls[x]
        if llvl == nil then llvl = 1 end
        for y=1,height do
            term.setCursorPos(x, y)
            if y >= lvl then term.setBackgroundColor(colors.lightBlue)
            else term.setBackgroundColor(colors.white) end
            if y >= llvl then
                term.setBackgroundColor(colors.blue)
            end
            term.write(" ")
        end
        llvls[x] = lvl
    end
    term.setCursorPos(1, 1)
    term.setBackgroundColor(colors.white)
    term.setTextColor(colors.black)
    --print(offset)
    --print(getOffset())
end

local pause = 0.05

local on = true
local timer = os.startTimer(pause)
while on do
    local event, p1 = os.pullEvent()
    if event == "timer" and p1 == timer then
        draw()
        timer = os.startTimer(pause)
    elseif event == "key" then
        if p1 == 29 then
            on = false
        end
    end
end