-- LUA Script - precede every function and global member with lowercase name of script + '_main'
local sprites = {}
local spriteImage = spriteImage or LoadImage( "scriptbank\\radar\\radar-white.png" ) 

local maxSprites = 5000
local minSize    = 4
local maxSize    = 10
local minAlpha   = 20
local maxAlpha   = 80
local minSpeed   = 0.2
local maxSpeed   = 0.33

function spritefun_init( e )
end

local rand = math.random
local modf = math.modf

local function randCol()
	return modf( rand( 0, 255 ) )
end

local function randVal( minVal, maxVal )
	return minVal + rand() * ( maxVal - minVal )
end

local function randomSprite()
	local spr  = CreateSprite( spriteImage )
	local size = randVal( minSize, maxSize )
	
	SetSpriteSize     ( spr, -1, size )	
	SetSpriteOffset   ( spr, -1, size / 2 )
	
	local x = randVal( -size / 2, 100 + size / 2 )
	local y = randVal( -size / 2, 100 + size / 2 )
 	SetSpritePosition ( spr, x, y )	
	SetSpriteDepth    ( spr, rand( 0, 100 ) )
	SetSpriteColor    ( spr, randCol(), randCol(), randCol(), rand( minAlpha, maxAlpha ) )
	
	local speed = randVal( minSpeed, maxSpeed )
	
	return { spr = spr, x = x, y = y, size = size, speed = speed }
end

local function updateSprites()
	for _, v in pairs( sprites ) do
		v.y = v.y + v.speed
		if v.y > 100 + v.size / 2 then
			v.y =  -v.size / 2
			v.x = randVal( -v.size / 2, 100 + v.size / 2 )
			SetSpriteColor ( v.spr, randCol(), randCol(), randCol(), rand( minAlpha, maxAlpha ) )
			v.speed = randVal( minSpeed, maxSpeed )
		end
		SetSpritePosition ( v.spr, v.x, v.y )
	end
end

function spritefun_main( e )
	if sprites[ 1 ] == nil then
		for i = 1, maxSprites do
			sprites[ i ] = randomSprite()
		end
		return
	end
	
	updateSprites()		
end