ly/res/example.lua

-- [[
-- This is an example of using LuaJIT to create a custom animation in Ly, in this case a
-- bouncing square that changes colors.
--
-- You are given the following `ly` table:
-- {
--	height: number -- The height of the terminal
--	width: number -- The width of the terminal
--	frame_delay: number -- The amount of frames to delay an update to the animation
--	putCell(byte, fg, bg, x, y) -- Put the cell a buffer. This buffer will be drawn
--                                 on screen after draw() is called. It will not clear
--                                 itself automatically, see `ly.clear()`.
--                                 All arguments to this function are numbers, and 
--                                 must be in the unsigned 32-bit integer range: 0 to 2^32-1.
--  clear() -- Clear the buffer.
-- }
--
-- A function named `draw()` must be declared in the script. This is ran every frame.
-- 
-- ]]

local SQUARE_WIDTH = 10
local SQUARE_HEIGHT = 5

local SQUARE_COUNT = 25

local FPS = 120

local squares = {}

for i = 0, SQUARE_COUNT-1 do
	local vx = 1
	local vy = 1
	if math.random(1, 2) == 2 then vx = -vx end
	if math.random(1, 2) == 2 then vy = -vy end
	squares[#squares+1] = {
		x = math.random(1, ly.width - SQUARE_WIDTH),
		y = math.random(1, ly.height - SQUARE_HEIGHT),
		vx = vx,
		vy = vy,
		color = math.random(0xFFFFFF)
	}
end

local timer = os.clock()

function draw()
	-- Rather than progressing the animation by frame, do it based on
	-- seconds, like from os.clock(). 
	if timer + (1/FPS) < os.clock() then
		ly.clear()
		for i, v in ipairs(squares) do
			v.x = v.x + v.vx
			v.y = v.y + v.vy
			for x = v.x, v.x + SQUARE_WIDTH do
				for y = v.y, v.y + SQUARE_HEIGHT do
					ly.putCell(string.byte(' '), 0, v.color, x, y)
				end
			end
			if v.x <= 0 then v.vx = 1; v.color = math.random(0xFFFFFF) end
			if v.x + SQUARE_WIDTH >= ly.width-1 then v.vx = -1; v.color = math.random(0xFFFFFF) end
			if v.y <= 0 then v.vy = 1; v.color = math.random(0xFFFFFF) end
			if v.y + SQUARE_HEIGHT >= ly.height-1 then v.vy = -1; v.color = math.random(0xFFFFFF) end
		end
		timer = os.clock()
	end
end