Once you think about it some more, it's not that different from any other quine. A quine is a program whose output is bytes that are shown as text to the viewer

Once you think about it some more, it's not that different from any other quine. A quine is a program whose output is bytes that are shown as text to the viewer. GLSL doesn't have text rendering capabilities, but all that means is that you have to embed a text renderer in your quine, i.e. a fixed string. Once you can build a quine, embedding any random fixed string in it is more or less trivial. Not that it's not super neat, but the more interesting achievement for me is the compact text renderer, not the act of embedding a text renderer in a quine.