Topdown camera focus with angle - unity3d

Question

I'm making a topdown game with the camera at 40 degree angle. What I want to do is when i click an gameobject, It will move the camera and position the object at the left side from the center of the camera view regardless of its rotation. So that I can place a menu at the right side. How do I get the offset of the angled camera so that the object is in the middle left side of the camera view?
Right now i use lerp but it overshoots the target because of the cameras angle. Sorry for the noob question I'm new to unity3d.
transform.position = Vector3.Lerp(transform.position, new Vector3(target.transform.position.x, transform.position.y, target.transform.position.z), 0.1f);

Answer 1

First of all you should start by finding point that your camera will move/lerp to.
In your case in can be simplified to 2D-Space:
It shouldnt be tough to find that one.
Use transform.forward of camera to get vector (Vector3 cameraDir) of direction your camera is looking at
Rotate by horizontal fov / 4 around y axis:
Vector3 cameraDirRotated = Quaternion.AngleAxis(hFov/4f, Vector3.up) * cameraDir;
-cameraDirRotated will be vector from Cube To point P you're looking for, u can also scale it:
Vector3 PtoMoveTo = cube.transform.position - cameraDirRotated.normalized * 5f;
Full:
Vector3 FindCameraTarget(Transform targetObj, float hFov)
{
Vector3 cameraDir = transform.forward;
Vector3 cameraDirRotated = Quaternion.AngleAxis(hFov / 4f, Vector3.up) * cameraDir;
Vector3 target = targetObj.transform.position - cameraDirRotated.normalized * 5f;
return target;
}
Then:
transform.position = Vector3.Lerp(transform.position, FindCameraTarget(target, 90f) , 2f * Time.deltaTime);
For performance u can save that target vector once if Cube is not moving. Search web how to precisely count horizontal fov. Multiply speed by Time.timeDelta if u lerp in Update().