Re-definition/Assets/Resources/System/AspectUtility.cs

using UnityEngine;

public class AspectUtility : MonoBehaviour {

    public float _wantedAspectRatio = 1.5f;
    public bool landscapeModeOnly = true;
    static public bool _landscapeModeOnly = true;
    static float wantedAspectRatio;
    public static Camera cam;
    public static Camera backgroundCam;

    void Awake() {
        _landscapeModeOnly = landscapeModeOnly;
        cam = Camera.allCameras[0];
        wantedAspectRatio = _wantedAspectRatio;
        SetCamera();
    }

    float resetTimer = 0f;
    private void Update() {
        resetTimer += Time.deltaTime;
        if (resetTimer > 5f) {
            resetTimer = 0f;
            SetCamera();
        }
    }

    public static void SetCamera() {
        float currentAspectRatio = 0.0f;
        if (Screen.orientation == ScreenOrientation.LandscapeRight ||
            Screen.orientation == ScreenOrientation.LandscapeLeft) {
            Debug.Log("Landscape detected...");
            currentAspectRatio = (float) Screen.width / Screen.height;
        } else {
            Debug.Log("Portrait detected...?");
            if (Screen.height  > Screen.width && _landscapeModeOnly) {
                currentAspectRatio = (float) Screen.height / Screen.width;
            } else {
                currentAspectRatio = (float) Screen.width / Screen.height;
            }
        }
        // If the current aspect ratio is already approximately equal to the desired aspect ratio,
        // use a full-screen Rect (in case it was set to something else previously)

        Debug.Log("currentAspectRatio = " + currentAspectRatio + ", wantedAspectRatio = " + wantedAspectRatio);

        if ((int) (currentAspectRatio * 100) / 100.0f == (int) (wantedAspectRatio * 100) / 100.0f) {
            cam.rect = new Rect(0.0f, 0.0f, 1.0f, 1.0f);
            if (backgroundCam) {
                Destroy(backgroundCam.gameObject);
            }
            return;
        }

        // Pillarbox
        if (currentAspectRatio > wantedAspectRatio) {
            float inset = 1.0f - wantedAspectRatio/currentAspectRatio;
            cam.rect = new Rect(inset/2, 0.0f, 1.0f-inset, 1.0f);
        }
        // Letterbox
        else {
            float inset = 1.0f - currentAspectRatio/wantedAspectRatio;
            cam.rect = new Rect(0.0f, inset/2, 1.0f, 1.0f-inset);
        }
        if (!backgroundCam) {
            // Make a new camera behind the normal camera which displays black; otherwise the unused space is undefined
            backgroundCam = new GameObject("BackgroundCam", typeof(Camera)).GetComponent<Camera>();
            backgroundCam.depth = int.MinValue;
            backgroundCam.clearFlags = CameraClearFlags.SolidColor;
            backgroundCam.backgroundColor = Color.black;
            backgroundCam.cullingMask = 0;
        }
    }

    public static int screenHeight {
        get {
            return (int) (Screen.height * cam.rect.height);
        }
    }

    public static int screenWidth {
        get {
            return (int) (Screen.width * cam.rect.width);
        }
    }

    public static int xOffset {
        get {
            return (int) (Screen.width * cam.rect.x);
        }
    }

    public static int yOffset {
        get {
            return (int) (Screen.height * cam.rect.y);
        }
    }

    public static Rect screenRect {
        get {
            return new Rect(cam.rect.x * Screen.width, cam.rect.y * Screen.height, cam.rect.width * Screen.width, cam.rect.height * Screen.height);
        }
    }

    public static Vector3 mousePosition {
        get {
            Vector3 mousePos = Input.mousePosition;
            mousePos.y -= (int) (cam.rect.y * Screen.height);
            mousePos.x -= (int) (cam.rect.x * Screen.width);
            return mousePos;
        }
    }

    public static Vector2 guiMousePosition {
        get {
            Vector2 mousePos = Event.current.mousePosition;
            mousePos.y = Mathf.Clamp(mousePos.y, cam.rect.y * Screen.height, cam.rect.y * Screen.height + cam.rect.height * Screen.height);
            mousePos.x = Mathf.Clamp(mousePos.x, cam.rect.x * Screen.width, cam.rect.x * Screen.width + cam.rect.width * Screen.width);
            return mousePos;
        }
    }
}