Custom editor for Unity to make it easier to edit collision layer interactions.

!Collision Matrix.md

Just download the script and put it in a "Editor" folder.

CollisionMatrixEditor.cs

/// Written by @cortvi
using UnityEngine;
using UnityEditor;
using System.Collections.Generic;

public class CollisionMatrixEditor : EditorWindow
{
	#region DATA
	private const string winTitle = "Collision Matrix";
	private const bool isUtility = false;

	private bool[] folds = new bool[32];
	private Vector2 scrollPos = Vector2.zero;
	#endregion

	[MenuItem ("Window/" + winTitle)]
	static void Init () 
	{
		/// Get existing open window or if none, make a new one:
		var window = GetWindow<CollisionMatrixEditor> (isUtility, winTitle);
		window.Show ();
	}

	void OnGUI ()
	{
		/// Actual GUI
		scrollPos = GUILayout.BeginScrollView (scrollPos);
		for (int one=0; one!=32; one++)
		{
			/// Get layer Name (un-named layers are unused)
			string name1 = LayerMask.LayerToName (one);
			if (string.IsNullOrEmpty (name1)) continue;

			/// Separate each layer with a horizontal bar
			EditorGUILayout.LabelField ("", GUI.skin.horizontalSlider);
			GUILayout.Space (5);

			/// Display a Foldout for each layer
			folds[one] = EditorGUILayout.Foldout (folds[one], name1);

			/// Group in categories
			if (folds[one])
			{
				/// Hacked For-loop to make current Layer1 be the first
				int layersRead = 0;
				for (int two=one; layersRead!=32; /*Loop is manually manipulated*/)
				{
					string name2 = LayerMask.LayerToName (two);
					if (!string.IsNullOrEmpty(name2))
					{
						/// Matching layer in the matrix is put first
						/// and re-named "self"
						if (two == one) name2 = "Self";

						GUILayout.BeginHorizontal ();
						GUILayout.Space (20);

						/// Get collision value, and change it if needed
						/// Values are inverted because fuck Unity -.-
						var value = !Physics.GetIgnoreLayerCollision (one, two);
						var newValue = EditorGUILayout.ToggleLeft (name2, value);
						if (value != newValue) Physics.IgnoreLayerCollision (one, two, !newValue);

						GUILayout.EndHorizontal ();
					}

					/// Manually continue For-loop
					layersRead++;
					if (two==31) two=0;
					else two++;
				}
			}

			/// Add some space before next layer
			GUILayout.Space (5);
		}
		GUILayout.EndScrollView ();
	}
}

Changelog:

• Now matching layers are renamed "self" and put in first place
• Code is overall optimized