How to prevent prefab of custom editor inspector from overriding array size.

Questions & Answers
1

I created a custom editor for the inspector of one of my scripts. The issue is, when I create a prefab of an object with the script attached, the prefab’s array will override the array of every instance to be the same.

What causes this and how can I prevent it?

EDIT: I am running unity version 5.6.2f1

Editor Code:

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


 [CustomEditor(typeof(PointMovingPlatform))]
public class PointMovingPlatformEditor : Editor {

    PointMovingPlatform pmp;

    public void OnEnable()
    {
        pmp = (PointMovingPlatform)target;
    }

    public override void OnInspectorGUI()
    {
        ///////////////////////////////////////
        //Display speed 
        ///////////////////////////////////////
        pmp.speed = EditorGUILayout.FloatField("Speed", pmp.speed);
        GUILayout.Space(20);

        /////////////////////////////////////////
        //Display waypoints array
        // - Allow adding/removing of points
        /////////////////////////////////////////

        if (GUILayout.Button("Add Waypoint"))
        {
            AddWaypoint();
        }

        for (int i = 0; i < pmp.waypoints.Count; i++)
        {
            GUILayout.BeginHorizontal();

            GUILayout.Label("Waypoint " + i.ToString());
            GameObject old = pmp.waypoints*;*

pmp.waypoints = (GameObject)EditorGUILayout.ObjectField(pmp.waypoints*, typeof(GameObject), true);*
if(old != pmp.waypoints*)*
{
if(old.name == “Waypoint”)
DestroyImmediate(old);
}
if (GUILayout.Button(“[X]”))
{
RemoveWaypoint(i);
}

GUILayout.EndHorizontal();
}

//Display original for reference
GUILayout.Space(40);
GUILayout.Label(“ORIGINAL INSPECTOR”);
base.OnInspectorGUI();
}

void AddWaypoint()
{
GameObject newWP = new GameObject(“Waypoint”);
newWP.transform.position = new Vector3(pmp.platform.transform.position.x, pmp.platform.transform.position.y, pmp.platform.transform.position.z);
newWP.transform.parent = pmp.transform;
pmp.waypoints.Add(newWP);
}

void RemoveWaypoint(int index)
{
DestroyImmediate(pmp.waypoints[index].gameObject);
pmp.waypoints.RemoveAt(index);
}
}

Script:
using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class PointMovingPlatform : MonoBehaviour {

public float speed;

public GameObject platform;

public List waypoints;
//public Transform[] waypoints;

private Vector3 direction;
private Transform destination;

private int currentWaypoint = 0;

* void Start () {*
* if(waypoints.Count > 0)*
{
destination = waypoints[currentWaypoint].transform;
direction = (destination.position - platform.transform.position).normalized;
}
* }*

void Update()
{
platform.transform.Translate(direction * speed * Time.deltaTime);

float distance = Vector3.Distance(platform.transform.position, destination.position);
if (distance < speed * Time.deltaTime || distance < speed / 20f)
{
platform.transform.position = destination.transform.position;

NextDestination();

}
}

private void OnDrawGizmos()
{
for(int i = 0; i < waypoints.Count; i++)
{
Gizmos.color = Color.grey;
Gizmos.DrawWireCube(waypoints*.transform.position, platform.transform.localScale);*

Gizmos.color = Color.black;
if(i + 1 >= waypoints.Count)
{
Gizmos.DrawLine(waypoints[waypoints.Count - 1].transform.position, waypoints[0].transform.position);
} else
{
Gizmos.DrawLine(waypoints*.transform.position, waypoints[i + 1].transform.position);*
}

if(waypoints.Count > 0)
{
Gizmos.DrawLine(platform.transform.position, waypoints[currentWaypoint].transform.position);
}
}
}

void NextDestination()
{
if (waypoints.Count > 0)
{
currentWaypoint++;
if(currentWaypoint >= waypoints.Count)
{
currentWaypoint = 0;
}
destination = waypoints[currentWaypoint].transform;
direction = (destination.position - platform.transform.position).normalized;
}
}

}

I apologize for the large amount of code, but I just want to ensure there is enough content to determine why this issue arises. Thank you in advance.

2

After some very deep research I discovered that it is simply because I am not using SerializedProperty data type for handling things. SerializedProperty has plenty of self handling for issues such as Undo and Prefab.

Therefore, if I do something like this:

    SerializedProperty m_Speed;
    SerializedProperty m_Waypoints;

public void OnEnable()
    {
        m_Speed = this.serializedObject.FindProperty("speed");
        m_Waypoints = this.serializedObject.FindProperty("waypoints");
    }


    public override void OnInspectorGUI()
    {
        this.serializedObject.Update();

            EditorGUILayout.PropertyField(m_Speed);
            if(m_Speed.floatValue < 0)
            {
                m_Speed.floatValue = 0f;
            }

            GUILayout.Space(40);
            if(GUILayout.Button("Add Waypoint"))
            {
                AddWaypoint();
            }
            for(int i = 0; i < m_Waypoints.arraySize(); i++) {
                EditorGUILayout.PropertyField(m_Waypoints.GetArrayElementAtIndex(i));
            }

        this.serializedObject.ApplyModifiedProperties();
}

It functions perfectly fine when prefabbed.

////////////////////

// This resource was very useful in understanding how to use SerializedProperty with arrays

////////////////////

Also, for a question very similar with a valuable answer is here