Coding Dojo: Lua with LÖVE http://www.meetup.com/Latvian-Developers-Network/events/104717652/

katakana.png

main.lua

local CHAR_START = 48
local CHAR_END = 94
local letters = {}
local font = nil

function love.load()
  love.graphics.setColor(0, 255, 0)
  font = love.graphics.newImageFont(
    'katakana.png',
    '0123456789:;<=>?' ..
    '@ABCDEFGHIJKLMNO' ..
    'PQRSTUVWXYZ[\\]^'
  )
  love.graphics.setFont(font)
  particle = love.graphics.newImage('particle.png')
  fillLetters()
end

function ps()
  local ps = love.graphics.newParticleSystem(particle, 60)
  ps:setDirection(-math.pi/2)
  ps:setEmissionRate(10)
  ps:setParticleLifetime(math.random(), 5*math.random()+1)
  ps:setSpeed(math.random(70)+10)
  ps:setSpread(0.1)
  ps:setColors(0,255,0,128,0,255,0,255)
  ps:setSizes(0.4,0)
  ps:start()
  ps:update(10)
  return ps
end

function createLetter()
  letter = {
    x = math.random(love.graphics.getWidth()),
    y = math.random(love.graphics.getHeight()),
    l = string.char(math.random(CHAR_START, CHAR_END)),
    alpha = 32,
    speed = 0.5 + 2*math.random()
  }
  letter.ps = {};
  for i=1,5 do
    table.insert(letter.ps,ps());
  end
  return letter
end

function fillLetters()
  for i=1,100 do
    --letters.insert(i,createLetter())
    table.insert(letters, createLetter())
  end
end

function love.update(dt) --delta!
  x, y = love.mouse.getPosition()
  for i,letter in ipairs(letters) do
    distance = math.sqrt(
                math.pow((x - letter.x), 2) +
                math.pow((y - letter.y), 2))
    letter.alpha = math.max(0,math.min(255,255-distance/500*255))
    letter.y = letter.y + letter.speed
    for i,ps in ipairs(letter.ps) do
      ps:setColors(0,255,0,letter.alpha/8,0,255,0,0)
      ps:update(dt)
    end
    if letter.y > love.graphics.getHeight()+100 then
      letter.y = -font:getHeight()
      letter.x = math.random(love.graphics.getWidth())
    end
  end
end

function love.draw()
  for i,letter in ipairs(letters) do
    love.graphics.setColor(0, 255, 0, letter.alpha)
    love.graphics.print(letter.l, letter.x-font:getHeight()/2, letter.y)
    for i,ps in ipairs(letter.ps) do
      love.graphics.draw(ps, letter.x-i*2+5, letter.y)
    end
  end
end

particle.png