title: Libgdx grain / noise effect
body: <p>I'm facing a problem achieving a cinema like grain effect for my background in the game (using libgdx). Something important on that: The grain or noise effect should be not static. </p>
  
  <p>I have had different ideas how to do that:<br>
  1. Just render another img with some noise / grain effect with less alpha over the first one.<br>
  That works actually nearly just as i wanted.   </p>
  
  <pre><code>// Draw level Background
  batch.disableBlending();
  batch.begin();
  batch.draw(lvlCreator.getBackgroundTexture(), 0, 0, lvlCreator.getBackgroundWidth() / 3, lvlCreator.getBackgroundHeight() / 3, 
              0, 0, 4144, 2000, false, false);
  batch.end();
  
  // Draw noise
  batch.enableBlending();
  batch.begin();
  Color c = batch.getColor();
  batch.setColor(c.r, c.g, c.b, .1f);
  batch.draw(Assets.noiseAnimation.getKeyFrame(stateTime, true), 0, 0, 0, 0, 400, 400, 1, 1, 0);
  </code></pre>
  
  <p>2.Using some sort of Shader. However my Shader knowledge is kinda poor. So my question here is if there are some build-in shaders i can use for that. Or do I have to implement my own shader?</p>
  
  <p>3.Since I'm working with libgdx I hoped to achieve that with some libs from it. But if someone knows another lib that could help me here I would love it.</p>
  
  <p>So just tell me whats best practise here and maybe an example if possible. :)</p>