Drawing circles at the background of a 3D scene and updating their size

Question

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.

Answer 1

Ok, so just of the top of my head your going to want to make a new circle(2d) and apply a texture to this then write something along these lines (and attach it to the object)

Pseudo code:

private gameobject player
private float scale;

update{
face the player (using transform.lookat(player))
float distance = vector3.distance(transfrom.position,player.transform.position);
transform.scale = distance / scale;
}

The scale in this case changes as the player gets closer or further away using the global scale variable to change the sensitivity of it. Obviously i haven't tested it but in 5 min this would be my initial solution.

If you wanted to make it more efficient, then only face the player every few updates, possibly only make it call recursively every few seconds (depending how far away the player is/ how fast the player is).

An answer is better than none... :)

Answer 2

You probably need a skybox or a skydome. A skybox is a box around the camera, and is always centered around it. Basically a model, wich isn't get transformed by the view matrix.