Splash 3.0

--By xXxMoNkEyMaNxXx (Whitemambaa)
local arg={
        monitor=term,
        speed=14,
        length=6,
        rolloff=1.1,
        damping=6,
}
local argtypes={
        monitor="peripheral",
        speed="number",
        length="number",
        rolloff="number",
        damping="number",
}
for parameter,value in table.concat({...}," "):gmatch'%-([%w_]+) ([^ ]+)' do
        local argtype=argtypes[parameter]
        if argtype=="string" then
                arg[parameter]=tostring(value) or arg[parameter]
        elseif argtype=="number" then
                arg[parameter]=tonumber(value) or arg[parameter]
        elseif argtype=="boolean" then
                arg[parameter]=value=="true" or arg[parameter]
        elseif argtype=="peripheral" then
                arg[parameter]=peripheral.wrap(value) or arg[parameter]
        end
end

arg.monitor.setTextScale(0.5)

local next=next
local time=os.time
local tick=os.clock

local pi=math.pi
local max=math.max
local min=math.min
local sin=math.sin
local sqrt=math.sqrt
local ceil=math.ceil
local floor=math.floor

local match=string.match

local remove=table.remove

local pull=os.pullEvent
local setAlarm=os.setAlarm

local paint=arg.monitor.write
local setPos=arg.monitor.setCursorPos
local setBGC=arg.monitor.setBackgroundColour

--local palette={colours.lightBlue,colours.cyan,colours.blue,colours.black,colours.grey,colours.lightGrey,colours.white}
local palette={colours.white,colours.lightGrey,colours.grey,colours.black,colours.blue,colours.cyan,colours.lightBlue}

local size={arg.monitor.getSize()}
local gridsize={1.1,0.7}
local maxAge=(sqrt(size[1]*size[1]+size[2]*size[2])+arg.length)/arg.speed
local splashes={}

local damping=arg.damping
local rolloff=arg.rolloff

--[[
--wave function
local function wave(x)
        return sin(2*pi*x)--4*(x-x*x)*
end

--damping coefficient
local function damp(x)
        return damping^-x
end

--rolloff coefficient
local function fade(x)
        return rolloff^-x
end
--]]

local function draw(t)
        local radii={}
        for i=1,#splashes do
                radii[i]=(t-splashes[i].t)*arg.speed
        end
        for x=1,size[1] do
                for y=1,size[2] do
                        local sum=0.5
                        for i=1,#splashes do
                                local s=splashes[i]
                                local dx,dy=(s[1]-x)/gridsize[1],(s[2]-y)/gridsize[2]
                                local r=sqrt(dx*dx+dy*dy)
                                local d=(radii[i]-r)/arg.length
                                if d>=0 then
                                        sum=sum+sin(2*pi*x)*damping^-x*rolloff^-x--wave(d)*damp(d)*fade(r)
                                end
                        end
                        setPos(x,y)
                        setBGC(palette[max(1,min(#palette,ceil(#palette*sum)))])
                        paint' '
                end
        end
end

do
        arg.monitor.clear()
        local message="Click Anywhere!"
        setPos(floor((size[1]-#message)/2),floor(size[2]/2-0.5))
        paint(message)
end

local enabled=true
while enabled do
        local event={pull()}
        local now=tick()
        for i=#splashes,1,-1 do
                if now-splashes[i].t>=maxAge then
                        remove(splashes,i)
                end
        end
        if event[1]=="mouse_click" or event[1]=="monitor_touch" then
                if #splashes==0 then
                        setAlarm((time()+0.001)%24)
                end
                splashes[#splashes+1]={event[3],event[4],t=now}
        end
        if #splashes>0 then
                draw(now)
                if event[1]=="alarm" then
                        setAlarm((time()+0.001)%24)
                end
        end
end