Скрипт инструмента перемещения с примагничиванием, для туториала https://youtu.be/2dsoFUtQ0ck

CustomSnappingTool.cs

using System;
using System.Collections;
using System.Collections.Generic;
using UnityEditor;
using UnityEditor.EditorTools;
using UnityEditor.Experimental.SceneManagement;
using UnityEngine;

[EditorTool("Custom Snap Move", typeof(CustomSnap))]
public class CustomSnappingTool : EditorTool
{
    public Texture2D ToolIcon;

    private Transform oldTarget;
    private CustomSnapPoint[] allPoints;
    private CustomSnapPoint[] targetPoints;

    private void OnEnable()
    {
        Debug.Log("Enabled");
    }

    public override GUIContent toolbarIcon
    {
        get
        {
            return new GUIContent
            {
                image = ToolIcon,
                text = "Custom Snap Move Tool",
                tooltip = "Custom Snap Move Tool - best tool ever"
            };
        }
    }

    public override void OnToolGUI(EditorWindow window)
    {
        Transform targetTransform = ((CustomSnap) target).transform;

        if (targetTransform != oldTarget)
        {
            PrefabStage prefabStage = PrefabStageUtility.GetPrefabStage(targetTransform.gameObject);

            if (prefabStage != null)
                allPoints = prefabStage.prefabContentsRoot.GetComponentsInChildren<CustomSnapPoint>();
            else
                allPoints = FindObjectsOfType<CustomSnapPoint>();
            
            targetPoints = targetTransform.GetComponentsInChildren<CustomSnapPoint>();

            oldTarget = targetTransform;
        }

        EditorGUI.BeginChangeCheck();
        Vector3 newPosition = Handles.PositionHandle(targetTransform.position, Quaternion.identity);

        if (EditorGUI.EndChangeCheck())
        {
            Undo.RecordObject(targetTransform, "Move with custom snap tool");

            if (((CustomSnap) target).IsGrounded) newPosition.y = 0;
            
            MoveWithSnapping(targetTransform, newPosition);
        }
    }

    private void MoveWithSnapping(Transform targetTransform, Vector3 newPosition)
    {
        Vector3 bestPosition = newPosition;
        float closestDistance = float.PositiveInfinity;

        foreach (CustomSnapPoint point in allPoints)
        {
            if (point.transform.parent == targetTransform) continue;

            foreach (CustomSnapPoint ownPoint in targetPoints)
            {
                if (ownPoint.Type != point.Type) continue;
                
                Vector3 targetPos = point.transform.position - (ownPoint.transform.position - targetTransform.position);
                float distance = Vector3.Distance(targetPos, newPosition);

                if (distance < closestDistance)
                {
                    closestDistance = distance;
                    bestPosition = targetPos;
                }
            }
        }

        if (closestDistance < 0.5f)
        {
            targetTransform.position = bestPosition;
        }
        else
        {
            targetTransform.position = newPosition;
        }
    }
}