Need some help with Random.value and Instantiating objects.

Question

Need some help with Instantiating Coin objects when the enemy dies . Here I've a Top-Down space shooter game where enemies die and drop coins from the array of Coins where I've 4 different Coin prefabs Copper ,silver , gold and Super coin each with certain value. What i wanted to implement is a percent wise drop rate for each coin.

  public void DropCoin()   /// called when enemy dies.
     {
 
         for (float i = 0; i < GetNoOfCoinsChance() ; i++)  
         {
             GameObject Coin = Instantiate(AllCoins[GetCoinType()], transform.position, transform.rotation) as GameObject;
             Coin.GetComponent<Rigidbody2D>().AddForce(new Vector2(Random.Range(-1f, 1f), Random.Range(-1f, -1.5f)), ForceMode2D.Impulse);
             Debug.Log(GetCoinType());
         }
     }
 
     public float GetNoOfCoinsChance()      // No. of coins to spawn chance
     {
         if (Random.value <= 0.8) { return 1; }
         if (Random.value <= 0.5) { return 2; }
         if (Random.value <= 0.3) { return 3; }
         if (Random.value <= 0.2) { return 4; }
         if (Random.value <= 0.1) { return 5; }
         else                     { return 0; }
     }
 
     public int GetCoinType()          // Type of coin to spawn
     {
         if (Random.value <= 0.8) { return 0; }
         if (Random.value <= 0.6) { return 1; }
         if (Random.value <= 0.4) { return 2; }
         if (Random.value <= 0.2) { return 3; }
         else                     { return 0; }
     }

Here the for loop describes the no. of coin chance to spawn when a enemy dies and GetCoinType() defines the type of coin to spawn , The GetNoOfCoinsChance() works perfectly, but for some reason the GetCoinType() doesn't work it just spawn the copper coin every time i.e AllCoins[0]; Please can someone help me out with this problem. Thanks in advance. :).

Answer 1

Best Answer

Answer by Hellium · Jun 11, 2019 at 02:53 PM

I don't know if the following will solve your problem, but there is a big problem with your GetNoOfCoinsChance and GetCoinType functions. You call Random.value multiple times, generating a new random value each time.... And you should do your checks from the lowest chance to highest chance.

You should do the following:

  public float GetNoOfCoinsChance()      // No. of coins to spawn chance
  {
      float r = Random.value;
      if (r <= 0.1f) { return 5; }
      if (r <= 0.2f) { return 4; }
      if (r <= 0.3f) { return 3; }
      if (r <= 0.5f) { return 2; }
      if (r <= 0.8f) { return 1; }
      else             { return 0; }
  }
 
  public int GetCoinType()          // Type of coin to spawn
  {
      float r = Random.value;
      if (r <= 0.2f) { return 3; }
      if (r <= 0.4f) { return 2; }
      if (r <= 0.6f) { return 1; }
      else               { return 0; }
  }

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Poi7ioN · Jun 11, 2019 at 03:38 PM 0

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Oh, So the problem was with the check ordering . Thanks a lot it worked like a charm after some tweaks with the values. Although it worked i was still wondering if there is some another better way to make it possible or should i go with this one.. I'm not sure if it's performance friendly or not so please some light on this issue will be appreciated..:)

Hellium Poi7ioN · Jun 11, 2019 at 03:47 PM 0

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I don't think you will face performance issues with this code, however, it's not very flexible if you want to make some changes to it. Supposing you want to add a new coin type, you will need to change more code than you should.

Poi7ioN Hellium · Jun 11, 2019 at 05:23 PM 0

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Thanks a lot for your support truly appreciate it :)

Need some help with Random.value and Instantiating objects.

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