anchor.diff:  This is an approximation again, and it has a cost in quality, but we’re all for approximation as long as it’s perform faster while still looking good, right?
   
   Here is what the result looks like
  +
   image::jme3/advanced/PrefilteredEnvMap.png[PrefilteredEnvMap.png,with="320",height="250",align="center"]
   The prefiltered environment map, with the different mip levels. notice how the blur increases through them.
   
  
positive.code: Indirect diffuse is cool, but we want “shiny”!! Shiny implies specular lighting.
  
  It’s important to understand what we want as a specular reflection. We want it to be very neat when the roughness is low and very blurry when it’s high.
  image::jme3/advanced/Roughness.png[Roughness.png,with="320",height="250",align="center"]
  As roughness increase the reflection gets more blurry.
  
  
negative.code: As you can image that’s not practical for a real time rendering pipeline. Even with a 128×128 env map that’s around 50k texture fetches per pixel.
  
  Fortunately, We can use something called an *Irradiance map*. An irradiance map is basically the afford mentioned computation…except that it’s precomputed and baked into a texture. In practice here is what it looks like.
  
  image::jme3/advanced/irradianceMap.png[irradianceMap.png,with="320",height="250",align="center"]
  On the left the original cube map, on the right, the pre computed irradiance map.
  
  