Topdown camera focus with angle

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.

1. Use transform.forward of camera to get vector (Vector3 cameraDir) of direction your camera is looking at

2. Rotate by horizontal fov / 4 around y axis:

Vector3 cameraDirRotated = Quaternion.AngleAxis(hFov/4f, Vector3.up) * cameraDir;

3. -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().