Keep 2 players on screen by moving camera back

Let's think back to our lessons from Geometry and Trig, eh?

Ok, so let's visualize that we have two identical right triangles, TriangleA and TriangleB. The Hypotenuse of triangle a runs from player 1 to the camera, and the hypotenuse of triangleb runs from player 2 to the camera.

We also know from those lessons ages ago that if we count a single point on the triangle as our alpha point, that the triangle then has a opposite and an adjacent line. We can deduce that the length of the opposite line will match the distance from either player to the mid point between the players.

So far, we only know one angle, and one line, right? Wrong, we actually already know a second angle. The camera can only see to a specific angle of view. Let's say that the camera can see a full 90 degree angle. Then we know that the angle between the opposite line and the hypotenuse is half of 90 degreees.

Now, we have enough information to work with using what we know of SohCahToa.

Sine = Opposite / Hypotenuse Cosine = adjacent / hypotenuse Tangent = opposite / adjacent

What's that you say? Oh yeah, we only know one of those lengths. But we know two angles, using those two angles we can determine the third angle, because all the angles in a triangle add up to 180.

so we can use one of those angles to figure out the length of the adjacent line, which would be the distance the camera would need to be from the scene for both players to still be on camera.

adjacent = tangent * opposite

That's an inversion of the tangent formula above, we just multiplied both sides by opposite. so lets say that the players are 100 points away from each other, so the mid point is 50 points. And as we mentioned before our camera can see 90 degrees, so the angle of the hypotenuse from the opposite is about 45 degrees then our formula should look like this:

adjacent = Mathf.Tan(45) * 50;

Theoretically that adjacent value is the distance from the scene that the camera will need to be. However at this point I do need to point out that you will have to do some radian to degree transformations in all this mess. I don't remember off the top of my head at what point or in which direction it needs to be. I'm feeling like you should multiply the resulting adjacent value by Mathf.Rad2Deg to get the real results, but as I'm not actively working this out in Unity, I very well could be wrong.