#!ruby -Ks
# -*- mode: ruby; encoding: sjis -*-
# Last updated: <2015/03/22 01:03:24 +0900>
#
# GIMP 1.x の「RGB交換」と似た感じでアニメーションしてみるテスト
#
# Ruby 1.9.3 + DXRuby 1.4.1

require 'dxruby'

SS_SAVE = false

FPS_V = 60
ANG_SPD = 360.0 / FPS_V
V_SPD = 255.0 / FPS_V
R_SPD_A = 2.0 / FPS_V
R_SPD_B = 20.0 / FPS_V

imgs = []
["r.png", "g.png", "b.png"].each do |fn|
  imgs.push(Image.load(fn))
end

Window.fps = FPS_V
Window.resize(640, 480)
rt = RenderTarget.new(Window.width, Window.height)
step = 0
ang = 0
v = 0
r = Window.width / 2
r_spd = 0
timer = 0
framecount = 0

Window.loop do
  break if Input.keyPush?(K_ESCAPE)
  case step
  when 0
    ang += ANG_SPD
    v += V_SPD
    v = 255 if v > 255
    r -= r * R_SPD_A
    if r <= 1
      v = 255
      r = 0
      step += 1
      timer = FPS_V * 3 / 4
    end

  when 1
    timer -= 1
    step += 1 if timer <= 0

  when 2
    ang += ANG_SPD
    v -= V_SPD
    v = 0 if v < 0
    r += r_spd
    r_spd += R_SPD_B
    if r >= Window.width / 2
      v = 0
      r_spd = 0
      timer = FPS_V / 2
      step += 1
    end

  when 3
    timer -= 1
    if timer <= 0
      if SS_SAVE
        break
      else
        step = 0
      end
    end
  end

  a = ang
  imgs.each do |img|
    x = r * Math.cos(a * Math::PI / 180.0) + Window.width / 3
    y = r * Math.sin(a * Math::PI / 180.0) + Window.height / 2
    rt.draw_ex(x, y, img, :offset_sync => true, :blend => :add, :alpha => v)
    a += 360 / 3
  end

  Window.draw(0, 0, rt)

  if SS_SAVE
    oimg = rt.to_image
    fn = sprintf("ss_%04d.png", framecount)
    oimg.save(fn, FORMAT_PNG)
  end

  framecount += 1
end