# Dans cette version du programme, nous n'utilisons pas la
# classe Complex de Ruby.
# De ce fait, nous perdons en lisibilité mais gagnons en vitesse
# d'exécution

require 'sdl'

Taille=200
$amin=-1.25
$amax=1.25
$bmin=-1.25
$bmax=1.25

def convert(x,y)
  return [x*($amax-$amin)/Taille+$amin, y*($bmax-$bmin)/Taille+$bmin]
end

def iterations(m,c)
  u=m.clone
  for i in 1..100
    tmp=u[0]
    u[0]=u[0]*u[0]-u[1]*u[1]+c[0]
    u[1]=2*tmp*u[1]+c[1]
    return i if u[0]*u[0]+u[1]*u[1]>=4
  end
  return -1
end

def trace(screen,c)
  for i in 0...Taille
    for j in 0...Taille
      m=convert(i,j)
      n=iterations(m,c)
      if n==-1:  screen[i,j]=[0,0,0]
      else screen[i,j]=[(4*n)%256,2*n,(6*n)%256] end
    end
    screen.flip
  end 
end

def zoom(c0,f)
  l=($amax-$amin)*f
  h=($bmax-$bmin)*f
  $amin=c0[0]-l/2.0
  $bmin=c0[1]-h/2.0
  $amax=$amin+l
  $bmax=$bmin+h
end

SDL.init( SDL::INIT_VIDEO )
screen = SDL::Screen.open(Taille,Taille,16,SDL::SWSURFACE)
trace(screen,[-0.5,0.6])

while true
  event = SDL::Event.poll
  if event.class==SDL::Event::MouseButtonDown
    z0=convert(event.x,event.y)
    f=1
    f=0.5 if event.button==SDL::Mouse::BUTTON_LEFT
    f=2 if event.button==SDL::Mouse::BUTTON_RIGHT
    zoom(z0,f)
    trace(screen,[-0.5,0.6])
  end
end