Pixels

The colours of everything a stage has drawn, one number per pixel.

Reached through stage.getPixels():

int[] colours = this.getPixels().main();

These layers live on the graphics card, and reading them back is both slow and only possible while the stage is drawing. Asking from somewhere else - a sprite's run(), say - gives an empty array. Treat this as a low-level hook for drawing tricks rather than as a way to sense colours: a Scratch-style "touching colour" check would have to read the whole screen back every frame, which is far too slow for the machines this library is meant to run on.