anchor.diff:  So basically, a light source in game is a color, and optionally other parameters like direction, position, radius, etc… An image has color informations, and this color can be considered as a light source.
   
   For global Illumination light is coming from everywhere. So a good way to simulate GI with IBL is to consider an environment map as a light source.
  +
   === Reminder on environment maps :
   
   Most often, in-game environment maps are cube maps.
  
positive.code: 
  Here is what indirect specular alone, looks like, with a roughness of 0.1.
  
  image::jme3/advanced/IndirectSpeculra.png[IndirectSpeculra.png,with="320",height="250",align="center"]
  
  *So in the end :*
  
  
negative.code: 
  Technically, every pixel in the environment map is a light source, so a shaded point is lighten by a vast amount of pixels.
  
  image::irradiance.png[irradiance,with="320",height="250",align="center"]
  
  In this picture the orange area represent the light rays coming from the cube map to the shaded pixel, that we have to consider to properly compute the light color. So the idea would be, for each shaded pixel, to fetch all that texels and combine the colors.
  
  