So, here is what I am trying to do in Unity 5 (using C#). I want to draw a a 2D circle at the background of a 3D scene and apply a texture/image to fill it.
Just like it would be if the circle was in the GUI, but now being always behind everything else instead of always in front (think of a moon in the sky of a piloting game, or a distant planet in a space game, etc).
What would be the fastest way to draw such a circle and, of course, update its radius depending on the camera distance? Of course, I don't want to use a sphere, I want to learn how to that with a simple circle that gets bigger or smaller depending on the distance of the viewer.