Transmission
Note: This feature only works in Multi-Lit mode.
Transmission can be used to fake volumen by revealing a sprite when a Point or Spot Light shines behind the sprite. The NextGenSprites Webplayer illustrates well how this works!
This is the Sprite in the Sprite; so to speak.
Left: Transmission Sprite. Right: Result.
The density controls how much the transmission sprite gets revealed by a light source.