m.cs

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

#if UNITY_EDITOR
using UnityEditor;
#endif

[ExecuteInEditMode]
public class DistanceMetrics : MonoBehaviour
{

#if UNITY_EDITOR
	[CustomEditor(typeof(DistanceMetrics))]
	[CanEditMultipleObjects]
	public class DistanceMetricsEditor : Editor
	{
		public override void OnInspectorGUI()
		{
			base.DrawDefaultInspector();
			if (GUILayout.Button("Update distance"))
			{
				foreach (var x in this.targets.Cast<DistanceMetrics>().Where(x => x != null))
					x.UpdateDistance();
			}

		}
	}
#endif

	public float avgValue;
	public float minValue;
	public float maxValue;

	private Texture2D reader; 

	private void Awake()
	{
		avgValue = 0;
		minValue = 0;
		maxValue = 0;
	}

	void UpdateDistance()
	{
		Debug.Log("UpdateDistance");

		var cam = this.GetComponent<Camera>();
		cam.Render();

		var rt = cam.targetTexture;

		if (reader == null || reader.width != rt.width || reader.height != rt.height)
		{
			reader = new Texture2D(rt.width, rt.height, TextureFormat.R16, false);
		}

		var prev_active = RenderTexture.active;
		try
		{
			RenderTexture.active = rt;
			reader.ReadPixels(new Rect(0, 0, rt.width, rt.height), 0, 0);
			reader.Apply();
		}
		finally
		{
			RenderTexture.active = prev_active;
		}

		double avg = 0;
		float min = float.MaxValue, max = float.MinValue;
		var c = 0;

		foreach (var color in reader.GetPixels(0, 0, reader.width, reader.height))
		{
			var v = color.r;
			min = Mathf.Min(min, v);
			max = Mathf.Max(max, v);
			avg += v;
			++c;
		}

		avgValue = (float) (avg / c);
		minValue = min;
		maxValue = max;

	}

}