I made a Loot and Item system earlier and thought it was brilliant so I decided to share it. Lets get into it.
We need a ItemDatabase class that holds data of all items. We have a basic Item class that contains data of a single item. Then we have a constructor that deep copies our item, so holding multiple same items would work and different same items would act as individual instead of being a shallow copies of the main one.
ItemDatabase has two static methods that returns you item based on name or id.
using UnityEngine;
using System.Collections;
using System.Collections.Generic;
public class ItemDatabase : MonoBehaviour
{
public List<Item> allItems;
public static List<Item> items;
[System.Serializable]
public class Item
{
public string itemName = "";
public int itemID = 0;
public int dmg = 0;
public int armor = 0;
public Sprite icon;
public enum Type
{
equipment,
other
}
public enum Rarity
{
common,
uncommon,
rare,
epic
}
public Type type;
public Rarity rarity;
public Item()
{
}
public Item(Item itemCopy)
{
itemID = itemCopy.itemID;
icon = itemCopy.icon;
itemName = itemCopy.itemName;
dmg = itemCopy.dmg;
armor = itemCopy.armor;
}
}
private void Awake()
{
InitItems ();
}
private void InitItems()
{
items = allItems;
}
public static Item GetItemByName(string itemName)
{
for( int i = 0;i<ItemDatabase.items.Count;i++ )
{
if(ItemDatabase.items[i].itemName == itemName)
{
return ItemDatabase.items[i];
}
}
return null;
}
public static Item GetItemById(int id)
{
for( int i = 0;i<ItemDatabase.items.Count;i++ )
{
if(ItemDatabase.items[i].itemID == id)
{
return ItemDatabase.items[i];
}
}
return null;
}
}
Then we have a Loot class. This is attached to anything that drops loot. Loot class spawns a loot prefab which holds the dropped item, so player can pick it up. In Loot class you can specify which drop % the items have and what items the enemy drops. When enemy dies we call DropItems method. In that method we basically roll a dice for every item drop possibility that the enemy has. Then we check on which gap the roll landed into.
For example we have a loot table like this:
Sword 25%
Staff 15%
Potion 45%
Nothing 55%
Total 140%
We first add all those drop percentages together and get a total value. The value of 140. Now we need to take all the % values from 140 and add them together to get the maximum value. So 25% from 140 is 35 then we add 15% to it which is 21 and so on, until we get the maximum value of 196.
25% 35
15% 21
45% 63
55% 77
140% 196
Now when we roll between 0 and maximum value, we can check if roll land between 0 and 35 if it does we give player a sword. Next item to check is a staff, if player rolled between 35 and 56 we give player a staff. Now if player rolls 145 for example we don’t give him anything as the roll landed between nothing gap etc.
using UnityEngine;
using System.Collections;
public class Loot : MonoBehaviour
{
private Transform m_transform;
private int m_amountToDrop;
public NewPickUp pickUpPrefab;
public int minAmountOfDrops, maxAmountOfDrops;
[System.Serializable]
public class DropItem
{
public bool empty;
public string itemName;
public int amount;
public bool randomizeAmount;
public int min,max;
public float dropChance;
}
public DropItem[] itemsToDrop;
private float maximumPropability;
private void Start()
{
m_transform = transform;
m_amountToDrop = Random.Range( minAmountOfDrops,maxAmountOfDrops );
InitItemChances ();
}
/// <summary>
/// Initializes drop chances
/// </summary>
private void InitItemChances()
{
for( int i = 0;i<itemsToDrop.Length;i++ )
{
if(i != 0)
{
itemsToDrop[i].dropChance += itemsToDrop[i - 1].dropChance;
}
}
maximumPropability = itemsToDrop[itemsToDrop.Length - 1].dropChance;
for( int i = 0;i<itemsToDrop.Length;i++ )
{
int temp = System.Convert.ToInt32(((maximumPropability / 100) * itemsToDrop[i].dropChance));
itemsToDrop[i].dropChance = (float)temp;
}
maximumPropability = itemsToDrop[itemsToDrop.Length - 1].dropChance;
}
/// <summary>
/// Drops the items.
/// </summary>
public void DropItems()
{
for( int i = 0;i<m_amountToDrop;i++ )
{
int rnd = Random.Range(0,(int)maximumPropability + 1);
DropItem droppedItem = ChooseItem(rnd);
if( !droppedItem.empty )
{
SpawnItem(droppedItem);
}
}
}
/// <summary>
/// Spawns item.
/// </summary>
/// <param name="droppedItem">Dropped item.</param>
public void SpawnItem(DropItem droppedItem)
{
NewPickUp temp = GameObject.Instantiate( pickUpPrefab,m_transform.position,Quaternion.identity ) as NewPickUp;
temp.itemName = droppedItem.itemName;
if(droppedItem.randomizeAmount)
temp.amount = Random.Range(droppedItem.min,droppedItem.max);
else
temp.amount = 1;
temp.SetUp();
}
/// <summary>
/// Choose item to drop by its drop chance
/// </summary>
/// <returns>The item.</returns>
/// <param name="rnd">Random.</param>
public DropItem ChooseItem(int rnd)
{
int maxVal = (int)itemsToDrop [itemsToDrop.Length - 1].dropChance;
if(rnd == maxVal)
rnd -= 1;
int index = 0;
while (itemsToDrop[index].dropChance <= rnd)
{
index++;
}
return itemsToDrop [index];
}
}
Here is the pickup class. This class is spawned into the world as a prefab. If player steps on it we take the item to our inventory if we have space.
using UnityEngine;
using System.Collections;
public class NewPickUp : MonoBehaviour
{
public string itemName;
public int amount;
private void Start()
{
SetUp();
}
public void SetUp()
{
Item item = ItemDatabase.GetItemByName( itemName );
if(item != null)
{
GetComponent<SpriteRenderer>().sprite = item.icon;
}
}
private void OnTriggerEnter2D(Collider2D col)
{
if (col.GetComponent<Inventory> ())
{
Inventory inv = col.GetComponent<Inventory> ();
//We need to create deep copy from the item, so we can have multiple same items.
ItemDatabase.Item newItem = new ItemDatabase.Item(item);
if(newItem != null)
{
for(int i = 0;i<amount;i++)
{
if(!inv.IsFull(newItem))
{
inv.AddItem(newItem);
amount--;
}
}
}
if(amount == 0)
{
Destroy(gameObject);
}
}
}
}
I didn’t include my Inventory class, because it’s mostly about how the Inventory UI works. It contains 2 lists of itemslots. One for equipped items and one for inventory itself. Then you just do some kind of equipping system and handle all the checks such as; if your high enough level for the item, add and remove stats etc etc.
Thanks for reading and hope this helps someone.
Ati Marin 