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.
-- }
-- ]]

local SQUARE_WIDTH = 10
local SQUARE_HEIGHT = 5

local SQUARE_X = 0
local SQUARE_Y = 0

local SQUARE_VX = 1
local SQUARE_VY = 1

local timer = os.clock()
local color = math.random(0xFFFFFF)

function draw()
	-- Rather than progressing the animation by frame, do it based on
	-- seconds, like from os.clock(). 
	if timer + 0.025 < os.clock() then
		ly.clear()
		SQUARE_X = SQUARE_X + SQUARE_VX
		SQUARE_Y = SQUARE_Y + SQUARE_VY
		for x = SQUARE_X, SQUARE_X + SQUARE_WIDTH do
			for y = SQUARE_Y, SQUARE_Y + SQUARE_HEIGHT do
				ly.putCell(string.byte(' '), 0, color, x, y)
			end
		end
		if SQUARE_X <= 0 then SQUARE_VX = 1; color = math.random(0xFFFFFF) end
		if SQUARE_X + SQUARE_WIDTH >= ly.width-1 then SQUARE_VX = -1; color = math.random(0xFFFFFF) end
		if SQUARE_Y <= 0 then SQUARE_VY = 1; color = math.random(0xFFFFFF) end
		if SQUARE_Y + SQUARE_HEIGHT >= ly.height-1 then SQUARE_VY = -1; color = math.random(0xFFFFFF) end
		timer = os.clock()
	end
end