code: function GlowFilter(distance, outerStrength, innerStrength, color, quality) {
      PIXI.Filter.call(this,
          // vertex shader
          // vertex shader
          glslify('./glow.vert'),
          // fragment shader
          glslify('./glow.frag')
              .replace(/%QUALITY_DIST%/gi, '' + (1 / quality / distance).toFixed(7))
              .replace(/%DIST%/gi, '' + distance.toFixed(7))
      );
  
      this.uniforms.distance = distance;
      this.uniforms.glowColor = new Float32Array([0, 0, 0, 1]);
  
      quality = Math.pow(quality, 1/3);
      this.quality = quality;
  
      this.uniforms.distance.value *= quality;
  
      this.color = color;
      this.outerStrength = outerStrength;
      this.innerStrength = innerStrength;
  }
docs: GlowFilter, originally by mishaa
  http://www.html5gamedevs.com/topic/12756-glow-filter/?hl=mishaa#entry73578
  http://codepen.io/mishaa/pen/raKzrm
  
  @class
  @param distance {number} The distance of the glow. Make it 2 times more for resolution=2. It cant be changed after filter creation
  @param outerStrength {number} The strength of the glow outward from the edge of the sprite.
  @param innerStrength {number} The strength of the glow inward from the edge of the sprite.
  @param color {number} The color of the glow.
  @param quality {number} A number between 0 and 1 that describes the quality of the glow.
  
  @example
  someSprite.filters = [
  new GlowFilter(15, 2, 1, 0xFF0000, 0.5)
  ];