Cinemachine Camera Size Adjuster Extension (Aspect Ratio Based Width Scaling)

CinemachineCameraSizeAdjuster.cs

using Cinemachine;
using UnityEngine;

namespace Cinemachine
{
    [AddComponentMenu("")] // Hide in menu
    [SaveDuringPlay]
    [ExecuteAlways]
    [DisallowMultipleComponent]
    public class CinemachineCameraSizeAdjuster : CinemachineExtension
    {
        [SerializeField] Vector2Int _baseAspectRatio = new Vector2Int(9, 16);
        [SerializeField][Range(0, 179)] float _baseCameraFOV = 60;
        [SerializeField] float _baseCameraSize = 5;

        float baseAspectRatio => _baseAspectRatio.x / (float)_baseAspectRatio.y;

        protected override void PostPipelineStageCallback(
            CinemachineVirtualCameraBase vcam,
            CinemachineCore.Stage stage, ref CameraState state, float deltaTime)
        {
            if (stage == CinemachineCore.Stage.Body)
            {
                LensSettings lens = state.Lens;

                if (state.Lens.Orthographic)
                {
                    if (state.Lens.Aspect < baseAspectRatio)
                    {
                        // letterboxing
                        var baseHorizontalSize = _baseCameraSize * baseAspectRatio;
                        var verticalSize = baseHorizontalSize / state.Lens.Aspect;

                        lens.OrthographicSize = verticalSize;
                    }
                    else
                    {
                        // pillarboxing
                        lens.OrthographicSize = _baseCameraSize;
                    }
                }
                else
                {
                    if (state.Lens.Aspect < baseAspectRatio)
                    {
                        // letterboxing
                        var baseVerticalSize = Mathf.Tan(_baseCameraFOV * 0.5f * Mathf.Deg2Rad);
                        var baseHorizontalSize = baseVerticalSize * baseAspectRatio;
                        var verticalSize = baseHorizontalSize / state.Lens.Aspect;
                        var verticalFov = Mathf.Atan(verticalSize) * Mathf.Rad2Deg * 2;

                        lens.FieldOfView = verticalFov;
                    }
                    else
                    {
                        // pillarboxing
                        lens.FieldOfView = _baseCameraFOV;
                    }
                }

                state.Lens = lens;
            }
        }
    }
}