MineOS/Wallpapers/Snow.wlp/Main.lua

local screen = require("Screen")
local color = require("Color")
local filesystem = require("Filesystem")
local system = require("System")
local GUI = require("GUI")

--------------------------------------------------------------------------------

local configPath = filesystem.path(system.getCurrentScript()) .. "Config.cfg"

local config = {
	backgroundColor = 0x0F0F0F,
	snowflakeColor = 0xFFFFFF,
	snowflakeAmount = 20,
	maxStackHeight = 10,
	maxWind = 2
}

if filesystem.exists(configPath) then
	for key, value in pairs(filesystem.readTable(configPath)) do
		config[key] = value
	end
end

local function saveConfig()
	filesystem.writeTable(configPath, config)
end

--------------------------------------------------------------------------------

local
	mathRandom,
	mathFloor,
	tableInsert,
	tableRemove,
	colorTransition,
	screenDrawRectangle,
	screenSemiPixelSet,
	screenDrawSemiPixelRectangle =

	math.random,
	math.floor,
	table.insert,
	table.remove,
	color.transition,
	screen.drawRectangle,
	screen.semiPixelSet,
	screen.drawSemiPixelRectangle

local snowflakes = {}
local stacks = {}
local wind = 0

local lastUpdateTime = computer.uptime()

return {
	draw = function(wallpaper)
		-- Spawning snowflakes
		local distance

		for i = 1, config.snowflakeAmount - #snowflakes do
			distance = math.random()

			tableInsert(snowflakes, {
				x = mathRandom(1, wallpaper.width) - 1,
				y = 0,
				color = colorTransition(config.snowflakeColor, config.backgroundColor, .2 + .8 * distance),
				speed = 2 - 1.5 * distance,
				vx = 0
			})
		end

		-- Clearing the area
		screenDrawRectangle(wallpaper.x, wallpaper.y, wallpaper.width, wallpaper.height, config.backgroundColor, 0, " ")

		-- Rendering snowflakes
		local snowflake

		for i = 1, #snowflakes do
			snowflake = snowflakes[i]

			screenSemiPixelSet(
				mathFloor(wallpaper.x + snowflake.x),
				mathFloor(wallpaper.y + snowflake.y),
				snowflake.color
			)
		end
		
		-- Rendering stacks
		local stackHeight

		for x, stackHeight in pairs(stacks) do
			screenDrawSemiPixelRectangle(wallpaper.x + x, wallpaper.y + wallpaper.height * 2 - stackHeight + 1, 1, stackHeight, config.snowflakeColor)

			if stackHeight > config.maxStackHeight then
				stacks[x] = stackHeight - 2
			end
		end

		-- Updating snowflakes
		local currentTime = computer.uptime()
		local deltaTime = (currentTime - lastUpdateTime) * 20
		
		wind = wind + .1 * (2 * mathRandom() - 1) * deltaTime
		if wind >  config.maxWind then wind =  config.maxWind end
		if wind < -config.maxWind then wind = -config.maxWind end

		local doubleHeight = wallpaper.height * 2
		local x, y

		local i = 1
		while i <= #snowflakes do
			snowflake = snowflakes[i]

			snowflake.y = snowflake.y + deltaTime *         snowflake.speed 
			snowflake.x = snowflake.x + deltaTime * (wind * snowflake.speed + snowflake.vx)
			
			snowflake.vx = snowflake.vx + (mathRandom() * 2 - 1) * 0.1 * deltaTime
			
			if snowflake.vx > 1 then
				snowflake.vx = 1
			elseif snowflake.vx < -1 then
				snowflake.vx = -1
			end
			
			-- When snowflake moves out of wallpaper bounds - teleporting
			-- it to the opposite side
			if snowflake.x < 0 then
				snowflake.x = wallpaper.width - snowflake.x
			elseif snowflake.x >= wallpaper.width then
				snowflake.x = snowflake.x - wallpaper.width
			end
			
			x, y = mathFloor(snowflake.x), mathFloor(snowflake.y)
			stackHeight = stacks[x] or 0
			
			if y >= doubleHeight - stackHeight then
				stacks[x] = stackHeight + 1
				
				if x > 0 then
					local leftStackHeight = stacks[x-1] or 0
					if stacks[x] - leftStackHeight > 2 then
						stacks[x-1] = leftStackHeight + 1
						stacks[x] = stackHeight
					end
				end

				if x < wallpaper.width-1 then
					local rightStackHeight = stacks[x+1] or 0
					if stacks[x] - rightStackHeight > 2 then
						stacks[x+1] = rightStackHeight + 1
						stacks[x] = stackHeight
					end
				end

				tableRemove(snowflakes, i)
			else
				i = i + 1
			end
		end

		lastUpdateTime = currentTime
	end,

	configure = function(layout)
		layout:addChild(GUI.colorSelector(1, 1, 36, 3, config.backgroundColor, "Background color")).onColorSelected = function(_, object)
			config.backgroundColor = object.color
			saveConfig()
		end

		layout:addChild(GUI.colorSelector(1, 1, 36, 3, config.snowflakeColor, "Snowflake color")).onColorSelected = function(_, object)
			config.snowflakeColor = object.color
			saveConfig()
		end

		local snowflakeAmountSlider = layout:addChild(
			GUI.slider(
				1, 1, 
				36,
				0x66DB80, 
				0xE1E1E1, 
				0xFFFFFF, 
				0xA5A5A5, 
				5, 50, 
				config.snowflakeAmount, 
				false, 
				"Snowflake amount: "
			)
		)
		
		snowflakeAmountSlider.roundValues = true
		snowflakeAmountSlider.onValueChanged = function()
			config.snowflakeAmount = math.floor(snowflakeAmountSlider.value)
			saveConfig()
		end

		local maxStackHeightSlider = layout:addChild(
			GUI.slider(
				1, 1, 
				36,
				0x66DB80, 
				0xE1E1E1, 
				0xFFFFFF, 
				0xA5A5A5, 
				0, 50, 
				config.maxStackHeight, 
				false, 
				"Stack height limit: "
			)
		)

		maxStackHeightSlider.roundValues = true
		maxStackHeightSlider.onValueChanged = function()
			config.maxStackHeight = math.floor(maxStackHeightSlider.value)
			saveConfig()
		end
	end
}