ofxSpriteSheetRenderer arguments ?

Hi there,
ofxSpriteSheetRenderer is very nice.
I played and modified the example in order to test it and I’m really happy with it.

ofxSpriteSheetRenderer() takes 4 arguments:

  • number of layer
  • number of tiles per layer
  • default layer
  • tile size

I’m okay with all parameters except the layer.
what is a layer exactly ?