The correct way of making Texture Atlas

Hello.

I think i got the idea of the texture atlas, but now i think of 2 ways making this and i wanted to be sure, which one is correct, so i'll need your help :).

Let's say i have 4 different objects with 4 different textures. Below are the 2 ways that i think they can be setUp'd. Each texture is 512x512.

1: The first way i think of is: I keep each model's UV's at 0 to 1 UV space. I combine all the 4 textures into one file (1024 x 1024). Then in Unity i create one scrip and apply it to all these 4 models. The script is something like this:

 #pragma strict
 public var xTile        : float;
 public var yTile        : float;
 
 public var xOffset        : float;
 public var yOffset        : float;
 
 function Start()
 {
     renderer.material.mainTextureScale = Vector2(xTile, yTile);
     renderer.material.mainTextureOffset = Vector2(xOffset, yOffset);
 }

After that i just specify the Tile and Offset for each object, so it matches with the position of it's texture, in the big texture map. The dissadvantage of this method is, that every object (That have Atlas texture) will have to execute that small piece of code at start...

2: The second way is: I make one big texture (1024 x 1024) but this time, instead of keeping each model's UV's, to 0 to 1, i select them and scale them down, so all 4 objects, have their UV's combined into one 0 to 1 UV space. (1 - up left, 2 - up right, 3 - low left, 4 - low right). Then i simply apply the same material to each object in Unity and avoid using the script for adjusting the Tiling and the Offset...

thanks :)