Unity-CameraBoundsChecker

CameraBoundsChecker.cs

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

public class CameraBoundsChecker : MonoBehaviour {

	public event System.Action<CameraBoundsChecker,bool> OnCameraVisibilityChanged;

	public Camera cameraTarget;
	public Vector3 extraOffset = Vector3.one;

	private Vector3 minPoint;
	private Vector3 maxPoint;
	private Vector3 cameraMinPoint;
	private Vector3 cameraMaxPoint;
	private List<Transform> cachedChildren;

	private bool visible = true;
	private bool Visible {
		get {
			return visible;
		}
		set {
			if (visible != value) {
				visible = value;
				if (OnCameraVisibilityChanged != null) {
					OnCameraVisibilityChanged(this, visible);
				}
			}
		}
	}


	void Awake()
	{
		CacheChildren();
	}


	void Update()
	{
		CheckVisibility();
	}


	void OnDrawGizmos()
	{
		CacheChildren();
		CheckVisibility();

		Gizmos.color = Visible ? Color.green : Color.red;
		Gizmos.DrawLine(minPoint, new Vector3(maxPoint.x, minPoint.y, minPoint.z));
		Gizmos.DrawLine(new Vector3(maxPoint.x, minPoint.y, minPoint.z), maxPoint);
		Gizmos.DrawLine(maxPoint, new Vector3(minPoint.x, maxPoint.y, maxPoint.z));
		Gizmos.DrawLine(new Vector3(minPoint.x, maxPoint.y, maxPoint.z), minPoint);
	}


	void CacheChildren()
	{
		minPoint = new Vector3(float.MaxValue, float.MinValue, float.MaxValue);
		maxPoint = new Vector3(float.MinValue, float.MaxValue, float.MinValue);

		cachedChildren = new List<Transform>(this.transform.childCount);
		foreach (Transform child in this.transform) {
			cachedChildren.Add(child);
			minPoint.x = Mathf.Min(child.transform.position.x, minPoint.x);
			minPoint.y = Mathf.Max(child.transform.position.y, minPoint.y);
			minPoint.z = Mathf.Min(child.transform.position.z, minPoint.z);

			maxPoint.x = Mathf.Max(child.transform.position.x, maxPoint.x);
			maxPoint.y = Mathf.Min(child.transform.position.y, maxPoint.y);
			maxPoint.z = Mathf.Max(child.transform.position.z, maxPoint.z);
		}

		minPoint += new Vector3(-extraOffset.x, extraOffset.y, extraOffset.z);
		maxPoint += new Vector3(extraOffset.x, -extraOffset.y, extraOffset.z);

		if (cameraTarget) {
			cameraMinPoint = cameraTarget.WorldToViewportPoint(minPoint);
			cameraMaxPoint = cameraTarget.WorldToViewportPoint(maxPoint);
		}
	}


	void CheckVisibility()
	{
		Visible = !(cameraMinPoint.x < 0.0f && cameraMaxPoint.x < 0.0f
			|| (cameraMinPoint.x > 1.0f && cameraMaxPoint.x > 1.0f)
			|| (cameraMinPoint.y < 0.0f && cameraMaxPoint.y < 0.0f)
			|| (cameraMinPoint.y > 1.0f && cameraMaxPoint.y > 1.0f)
			|| (cameraMinPoint.z < 0.0f && cameraMaxPoint.z < 0.0f)
			|| (cameraMinPoint.z > cameraTarget.farClipPlane && cameraMaxPoint.z > cameraTarget.farClipPlane)
		);
	}
}