using UnityEngine;

/**
https://gamedev.stackexchange.com/questions/144575/how-to-force-keep-the-aspect-ratio-and-specific-resolution-without-stretching-th
*/

[RequireComponent(typeof(Camera))]
public class CameraCrop : MonoBehaviour {

    // Set this to your target aspect ratio, eg. (16, 9) or (4, 3).
    public Vector2 targetAspect = new Vector2(16, 9);
    Camera _camera;

    void Start () {
        _camera = GetComponent<Camera>();
        UpdateCrop();
    }

    // Call this method if your window size or target aspect change.
    public void UpdateCrop() {
        // Determine ratios of screen/window & target, respectively.
        float screenRatio = Screen.width / (float)Screen.height;
        float targetRatio = targetAspect.x / targetAspect.y;

        if(Mathf.Approximately(screenRatio, targetRatio)) {
            // Screen or window is the target aspect ratio: use the whole area.
            _camera.rect = new Rect(0, 0, 1, 1);
        }
        else if(screenRatio > targetRatio) {
            // Screen or window is wider than the target: pillarbox.
            float normalizedWidth = targetRatio / screenRatio;
            float barThickness = (1f - normalizedWidth)/2f;
            _camera.rect = new Rect(barThickness, 0, normalizedWidth, 1);
        }
        else {
            // Screen or window is narrower than the target: letterbox.
            float normalizedHeight = screenRatio / targetRatio;
            float barThickness = (1f - normalizedHeight) / 2f;
            _camera.rect = new Rect(0, barThickness, 1, normalizedHeight);
        }
    }
}