2DegreeCameraTracker

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class TargetingCamera : MonoBehaviour
{
	[SerializeField] Transform m_Horizontal = null;
	[SerializeField] Transform m_Vertical	= null;
	[SerializeField] Transform m_Target		= null;

    void Start()
    {}
    
    void Update()
    {
     	// find vector to target
		Vector3	v3RootToTarget							= ( m_Target.position - transform.position );
		Vector3 v3DirectionToCameraTarget				= v3RootToTarget.normalized;

		// project onto current root plane (not orizontal pivot only rotates around Y so has same up vector
		Vector3		v3CameraDirectionLocal					= transform.InverseTransformDirection( v3DirectionToCameraTarget );
		Vector3		v3CameraDirectionLocalHorizontal		= Vector3.ProjectOnPlane( v3CameraDirectionLocal, Vector3.up );
		float		fSignedAngleAroundY						= Vector3.SignedAngle	( Vector3.forward,		v3CameraDirectionLocalHorizontal, Vector3.up );
		Quaternion	qHorizontalRotation						= Quaternion.AngleAxis	( fSignedAngleAroundY,	Vector3.up );
		m_Horizontal.localRotation							= qHorizontalRotation;		

		Debug.DrawRay( transform.position, v3RootToTarget,									Color.yellow );
		Debug.DrawRay( transform.position, ( transform.TransformDirection( v3CameraDirectionLocalHorizontal ) * 1.5f ),	Color.cyan );
		Debug.DrawRay( transform.position, m_Horizontal.right,								Color.red );
		Debug.DrawRay( transform.position, m_Horizontal.up,									Color.green );
		Debug.DrawRay( transform.position, m_Horizontal.forward,							Color.blue );

		//  
		Vector3		v3CameraDirectionInHorizVerticalPlane	= Vector3.ProjectOnPlane( v3DirectionToCameraTarget, m_Horizontal.right ).normalized;
		Vector3		V3CameraInVerticalPlaneLocal			= m_Horizontal.InverseTransformVector( v3CameraDirectionInHorizVerticalPlane );
		float		fSignedAngleAroundHorizX				= Vector3.SignedAngle( Vector3.forward, V3CameraInVerticalPlaneLocal, Vector3.right );
		Quaternion	qVerticalRotationLocal					= Quaternion.AngleAxis( fSignedAngleAroundHorizX, Vector3.right );
		m_Vertical.localRotation							= qVerticalRotationLocal;								 

		Debug.DrawRay( transform.position, ( v3CameraDirectionInHorizVerticalPlane * 2f ),	Color.magenta );
		Debug.DrawRay( transform.position, ( m_Vertical.forward * 2.5f ),					Color.cyan );

	}
}