From 45da02f14607da6f624bc44c00ebbd02bb36881c Mon Sep 17 00:00:00 2001
From: emilianavt <38952746+emilianavt@users.noreply.github.com>
Date: Sat, 24 Nov 2018 20:44:47 +0100
Subject: [PATCH] Allow first/third person layers to be named

The first person and third person layers used hard coded IDs. If these layers
are already in use in a Unity project, this use can lead to conflicts between
the layers used by UniVRM and those inside the project. This patch allows using
Unity's layer settings to assign layer IDs through names ("VRMFirstPersonOnly"
and "VRMThirdPersonOnly").

If no named layers are found, the predefined layer IDs will be used. Since the
layer IDs are accessed only during model setup, there should be no performance
impact from this change. The names of the fields storing the layer IDs have not
been changed to keep API compatibility.

This issue was originally noticed by @Deatrathias (Virtual_Deat on Twitter).
---
 Scripts/FirstPerson/VRMFirstPerson.cs | 21 +++++++++++++++++++--
 1 file changed, 19 insertions(+), 2 deletions(-)

diff --git a/Scripts/FirstPerson/VRMFirstPerson.cs b/Scripts/FirstPerson/VRMFirstPerson.cs
index 8eadb96cf..e4b0761ae 100644
--- a/Scripts/FirstPerson/VRMFirstPerson.cs
+++ b/Scripts/FirstPerson/VRMFirstPerson.cs
@@ -9,8 +9,11 @@ namespace VRM
 {
     public class VRMFirstPerson : MonoBehaviour
     {
-        public const int FIRSTPERSON_ONLY_LAYER = 9;
-        public const int THIRDPERSON_ONLY_LAYER = 10;
+        // If no layer names are set, use the default layer IDs.
+        // Otherwise use the two Unity layers called "VRMFirstPersonOnly" and "VRMThirdPersonOnly".
+        public static bool TriedSetupLayer = false;
+        public static int FIRSTPERSON_ONLY_LAYER = 9;
+        public static int THIRDPERSON_ONLY_LAYER = 10;
 
         [SerializeField]
         public Transform FirstPersonBone;
@@ -155,12 +158,24 @@ namespace VRM
 
             // ここには来ない
         }
+		
+        public static void SetupLayers()
+        {
+            if (!TriedSetupLayer) {
+                TriedSetupLayer = true;
+                int layer = LayerMask.NameToLayer("VRMFirstPersonOnly");
+                FIRSTPERSON_ONLY_LAYER = (layer == -1) ? FIRSTPERSON_ONLY_LAYER : layer;
+                layer = LayerMask.NameToLayer("VRMThirdPersonOnly");
+                THIRDPERSON_ONLY_LAYER = (layer == -1) ? THIRDPERSON_ONLY_LAYER : layer;
+            }
+        }
 
         private static void CreateHeadlessModelForMeshRenderer(MeshRenderer renderer, Transform eraseRoot)
         {
             if (renderer.transform.Ancestors().Any(x => x == eraseRoot))
             {
                 // 祖先に削除ボーンが居る
+                SetupLayers();
                 renderer.gameObject.layer = THIRDPERSON_ONLY_LAYER;
             }
             else
@@ -171,6 +186,7 @@ namespace VRM
 
         private static void CreateHeadlessModelForSkinnedMeshRenderer(SkinnedMeshRenderer renderer, Transform eraseRoot)
         {
+            SetupLayers();
             renderer.gameObject.layer = THIRDPERSON_ONLY_LAYER;
 
             var go = new GameObject("_headless_" + renderer.name);
@@ -220,6 +236,7 @@ namespace VRM
         /// </summary>
         public void Setup()
         {
+            SetupLayers();
             if (m_done) return;
             m_done = true;
             foreach (var x in Renderers)