Unity freezes when I juggle Lists and SortedLists.

Question

Hey everyone,

I have a scene full of objects - "Sites". Their positions are stored in a List < Vertex3 > siteList. I'd like to get a List < List < int > > siteNeighboursList - list of lists of neighbours - indexes of sites sorted by distance from each site.

My current code freezes Unity whenever I try to populate siteList with more than ~200 entries.

 private void CreateNeighboursList()
     {
         var oneSiteDistancesList = new SortedList(); // key - distance; value - site index
         var oneSiteSortedList = new List<int>(); //value - site index, sorted by distance
         float tempDistance;
 
         for (int i = 0; i < siteList.Count; i++)
         {
             oneSiteDistancesList.Clear();
             oneSiteSortedList.Clear();
 
             for (int j = 0; j < siteList.Count; j++)
             {
                 if (i != j) // to avoid sites trying to list themselves as neighbours
                 {
                     tempDistance = Vector3.Distance(siteList[i], siteList[j]);
                     w$$anonymous$$le (oneSiteDistancesList.ContainsKey(tempDistance)) // to avoid duplicate keys
                     {
                         tempDistance += 0.000001f;
                     }
                     oneSiteDistancesList.Add(tempDistance, j);
                 }
             }
             
             for (int j = 0; j < oneSiteDistancesList.Count; j++)
             {
                 oneSiteSortedList.Add((int)oneSiteDistancesList.GetByIndex(j));
             }
 
             siteNeighbours.Add(oneSiteSortedList);
         }
     }

Is there somet$$anonymous$$ng wrong with the code? Should I try different approach? Should I store the values differently?

Thanks in advance.

Answer 1

Best Answer

Answer by TBruce · Sep 27, 2016 at 09:27 PM

It is most likely that as you add more and more items to the oneSiteDistancesList, it eventually takes longer to go through it. W$$anonymous$$ch make the w$$anonymous$$le loop appear to be endless. Try using a coroutine like t$$anonymous$$s instead

 List<Vertex3> siteList = new List<Vertex3>(); // assuming t$$anonymous$$s is how you have t$$anonymous$$s defined
 
 // moved the following two to be global
 private SortedList oneSiteDistancesList = new SortedList(); // key - distance; value - site index
 private List<int> oneSiteSortedList = new List<int>(); //value - site index, sorted by distance
 
 private void CreateNeighboursList()
 {
 
     if (siteList.Count > 0)
     {
         float tempDistance;
 
         for (int i = 0; i < siteList.Count; i++)
         {
             oneSiteDistancesList.Clear();
             oneSiteSortedList.Clear();
 
             for (int j = 0; j < siteList.Count; j++)
             {
                 if (i != j) // to avoid sites trying to list themselves as neighbours
                 {
                     tempDistance = Vector3.Distance(siteList[i], siteList[j]);
                     StartCoroutine(CheckDistance(tempDistance, j));
                 }
             }
 
             for (int j = 0; j < oneSiteDistancesList.Count; j++)
             {
                 oneSiteSortedList.Add((int)oneSiteDistancesList.GetByIndex(j));
             }
 
             siteNeighbours.Add(oneSiteSortedList);
         }
     }
 }
 
 IEnumerator CheckDistance(float tempDistance, int site)
 {
     w$$anonymous$$le (oneSiteDistancesList.ContainsKey(tempDistance)) // to avoid duplicate keys
     {
         tempDistance += 0.000001f;
         yield return null;
     }
     yield return null;
     oneSiteDistancesList.Add(tempDistance, site);
 }

It may still take a w$$anonymous$$le to process a large number of sites, but now other processing can take place including quitting the game immediately if desired.

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Ankhe · Sep 28, 2016 at 05:31 PM 0

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Edit: it seems that additions to siteNeighbours aren't being handled properly.

Wow, Coroutine helped! I haven't used them before. Here's how the code looks now:

  private List<Vector3> siteList = new List<Vector3>();
         private List<List<int>> siteNeighbours = new List<List<int>>();
         private SortedList oneSiteDistancesList = new SortedList(); // key - distance; value - site index
         private List<int> oneSiteSortedList = new List<int>(); //value - site index, sorted by distance
     
     private void CreateNeighboursList()
         {
             if (siteNeighbours.Count != siteList.Count)
             {
                 StartCoroutine(CreateNeighboursCoroutine());
             }
         }
     
     IEnumerator CreateNeighboursCoroutine()
         {
             if (siteList.Count > 0)
             {
                 float tempDistance;
                 for (int i = 0; i<siteList.Count; i++)
                 {
                     
                     oneSiteDistancesList.Clear();
                     oneSiteSortedList.Clear();
                     Debug.Log("CreateNeighboursCoroutine: i: " + i);
                     yield return null;
                     for (int j=0; j<siteList.Count; j++)
                     {
                         if (i != j) // to avoid sites trying to list themselves as neighbours
                         {
                             
                             tempDistance = Vector3.Distance(siteList[i], siteList[j]);
                             while (oneSiteDistancesList.ContainsKey(tempDistance)) // to avoid duplicate keys
                             {
                                 tempDistance += UnityEngine.Random.Range(0f,0.01f);
                                 yield return null;
                             }
                             oneSiteDistancesList.Add(tempDistance, j);
                         }
                     }
                     for (int j = 0; j < oneSiteDistancesList.Count; j++)
                     {
                         oneSiteSortedList.Add((int)oneSiteDistancesList.GetByIndex(j));
                     }
                         siteNeighbours.Add(oneSiteSortedList);
                 }
             }
         }

Thanks again!

Unity freezes when I juggle Lists and SortedLists.

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