var sliderPos = 0;
var sliderLength = 0;
var sliderPOn = '';

function sliderAnimate() {
  $('#projector_wrapper').animate({'left': '-'+(sliderPos*227)}, 100);
}

function sliderProgress() {
  var i;
  var imgs = $('#projector_progress img');
  for(i = 0;i < imgs.length;i++) {
    imgs[i].setAttribute('src', i >= sliderPos && i < (sliderPos + 4) ? sliderPOn : '/img/indicator_off.png');
  }
}

function sliderPrev() {
  if(sliderPos == 0) {
    return;
  }
  sliderPos--;
  sliderAnimate();
  sliderProgress();
}

function sliderNext() {
  if(sliderPos == (sliderLength - 4)) {
    return;
  }
  sliderPos++;
  sliderAnimate();
  sliderProgress();
}

$(document).ready(function() {
  sliderLength = $('#projector_wrapper .projector_unit').length;
  sliderPOn = $('#projector_progress img')[0].getAttribute('src');
  sliderProgress();
  $('.arrow_left').click(function() {
    sliderPrev();
  });
  $('.arrow_right').click(function() {
    sliderNext();
  });
});