message: Adds alpha param to constructor of AlphaFilter
diff: @@ -22,13 +22,13 @@ import fragment from './alpha.frag';
  export default class AlphaFilter extends Filter
  {
  /**
  - *
  + * @param {number} [alpha=1] Amount of alpha from 0 to 1, where 0 is transparent
  */
  - constructor()
  + constructor(alpha = 1.0)
  {
  super(defaultVertex, fragment);
  - this.alpha = 1.0;
  + this.alpha = alpha;
  this.glShaderKey = 'alpha';
  }
  