### Map control buttons

~~~ html
<div class="control tilt">
  <button class="dec">&#8601;</button>
  <button class="inc">&#8599;</button>
</div>

<div class="control rotation">
  <button class="inc">&#8630;</button>
  <button class="dec">&#8631;</button>
</div>

<div class="control zoom">
  <button class="dec">-</button>
  <button class="inc">+</button>
</div>
~~~

~~~ javascript
var controlButtons = document.querySelectorAll('.control button');

for (var i = 0; i < controlButtons.length; i++) {
  controlButtons[i].addEventListener('click', function(e) {
    var button = this;
    var parentClassList = button.parentNode.classList;
    var direction = button.classList.contains('inc') ? 1 : -1;
    var increment;
    var property;

    if (parentClassList.contains('tilt')) {
      property = 'Tilt';
      increment = direction*10;
    }
    if (parentClassList.contains('rotation')) {
      property = 'Rotation';
      increment = direction*10;
    }
    if (parentClassList.contains('zoom')) {
      property = 'Zoom';
      increment = direction*1;
    }
    if (property) {
      osmb['set'+ property](osmb['get'+ property]()+increment);
    }
  });
}
~~~