code: function SimpleLightmapFilter(lightmapTexture, ambientColor, resolution) {
      PIXI.Filter.call(this,
          // vertex shader
          // vertex shader
          glslify('./simpleLightmap.vert'),
          // fragment shader
          glslify('./simpleLightmap.frag')
      );
      this.uniforms.u_lightmap = lightmapTexture;
      this.uniforms.resolution = new Float32Array(resolution || [1.0, 1.0]);
      this.uniforms.ambientColor =  new Float32Array(ambientColor);
  }
docs: SimpleLightmap, originally by Oza94
  http://www.html5gamedevs.com/topic/20027-pixijs-simple-lightmapping/
  http://codepen.io/Oza94/pen/EPoRxj
  
  @class
  @param lightmapTexture {PIXI.Texture} a texture where your lightmap is rendered
  @param ambientColor {Array} An RGBA array of the ambient color
  @param [resolution] {Array} An array for X/Y resolution
  
  @example
  var lightmapTex = new PIXI.RenderTexture(renderer, 400, 300);
  
  // ... render lightmap on lightmapTex
  
  stageContainer.filters = [
  new SimpleLightmapFilter(lightmapTex, [0.3, 0.3, 0.7, 0.5], [1.0, 1.0])
  ];