docs: function BlurXFilter()
  {
      core.AbstractFilter.call(this,
          // vertex shader
          fs.readFileSync(__dirname + '/blurX.vert', 'utf8'),
          // fragment shader
          fs.readFileSync(__dirname + '/blur.frag', 'utf8'),
          // set the uniforms
          {
              strength: { type: '1f', value: 1 }
          }
      );
  
      /**
       * Sets the number of passes for blur. More passes means higher quaility bluring.
       *
       * @member {number}
       * @memberof BlurXFilter#
       * @default 1
       */
      this.passes = 1;
  
      this.strength = 4;
  }