badeend-go/Assets/CollectableDuckManager.cs

using System;
using System.Collections;
using System.Collections.Generic;
using Mapbox.CheapRulerCs;
using Mapbox.Unity.Map;
using UnityEngine;
using UnityEngine.Serialization;

public class CollectableDuckManager : MonoBehaviour
{
    [FormerlySerializedAs("CollectableDucks")] public List<CollectableDuckData> collectableDucks;

    Dictionary<CollectableDuckData, CollectableDuck> spawnedDucks = new Dictionary<CollectableDuckData, CollectableDuck>();
    
    public AbstractMap map;
    public Transform player;

    /// <summary>
    /// Spawn distance in meters (i.e. how close should the player be to a duck before it spawns on the map
    /// </summary>
    public float spawnDistance = 50;

    public CollectableDuck duckSpawnPrefab;
    
    private static CollectableDuckManager _instance;
    public static CollectableDuckManager Instance
    {
        get { return _instance;  }
        private set { _instance = value; }
    }

    public CollectableDuckManager()
    {
        Instance = this;
    }

    private void Update()
    {
        var ruler = new CheapRuler(map.CenterLatitudeLongitude.x, CheapRulerUnits.Meters);
        var playerPosition = map.WorldToGeoPosition(player.position).ToArray();
        for (int i = 0; i < collectableDucks.Count; i++)
        {
            var duck = collectableDucks[i];
            var duckCoord = duck.LatitudeLongitude;
            var dist = ruler.Distance(duckCoord.ToArray(), playerPosition);
//            Debug.Log("Distance to " + duck.name + ": " + dist);
            if (dist < spawnDistance)
            {
                if (!spawnedDucks.ContainsKey(duck))
                {
                    // Spawn the duck
                    var duckSpawn = Instantiate(duckSpawnPrefab, map.GeoToWorldPosition(duckCoord), Quaternion.identity,
                        transform);
                    var duckModel = Instantiate(duck.ModelPrefab, duckSpawn.transform);
                    duckModel.transform.localPosition = Vector3.zero;

                    spawnedDucks[duck] = duckSpawn;
                }
                else
                {
                    if (!spawnedDucks[duck].gameObject.activeSelf)
                    {
                        spawnedDucks[duck].gameObject.SetActive(true);
                    }
                }

            } else if (spawnedDucks.ContainsKey(duck))
            {
                if (spawnedDucks[duck].gameObject.activeSelf)
                {
                    spawnedDucks[duck].gameObject.SetActive(false);
                }
            }
        }
    }
}