I know this topic should’ve been under the 2h, shield visibility and dual-handed weapons, but this topic got closed, so I’m forced to open a new question
I gave a friend of mine a rough demo of my game for him to test out, and the first thing he does, is (miraculously) catch a glitch I never would’ve figured out on my own, turning my face into this:
Anyway, the guy tried dragging and dropping my shield into the shield slot whilst he was holding a 2h weapon, and the shield did NOT disarm his 2h weapon, causing the whole shield visibility we had when clicking to equip to re-appear, and I couldn’t figure out why (but I’m tuning the ‘EquipmentSlotUI.AddItems()’ functions for that matter, my guess is that this is where the error is coming from).
I tried fixing it on my own by attempting a bit of coding, but I couldn’t exactly figure out what went wrong (mainly because I’m very rusty on how Drag and Drop works 
). If it helps, here is the NRE:
NullReferenceException: Object reference not set to an instance of an object
GameDevTV.Inventories.Equipment.AddItem (GameDevTV.Inventories.EquipLocation slot, GameDevTV.Inventories.EquipableItem item) (at Assets/GameDev.tv Assets/Scripts/Inventories/Equipment.cs:92)
GameDevTV.UI.Inventories.EquipmentSlotUI.CheckLeftHand () (at Assets/GameDev.tv Assets/Scripts/UI/Inventories/EquipmentSlotUI.cs:129)
GameDevTV.UI.Inventories.EquipmentSlotUI.AddItems (GameDevTV.Inventories.InventoryItem item, System.Int32 number) (at Assets/GameDev.tv Assets/Scripts/UI/Inventories/EquipmentSlotUI.cs:110)
GameDevTV.Core.UI.Dragging.DragItem`1[T].AttemptSimpleTransfer (GameDevTV.Core.UI.Dragging.IDragDestination`1[T] destination) (at Assets/GameDev.tv Assets/Scripts/Utils/UI/Dragging/DragItem.cs:173)
GameDevTV.Core.UI.Dragging.DragItem`1[T].DropItemIntoContainer (GameDevTV.Core.UI.Dragging.IDragDestination`1[T] destination) (at Assets/GameDev.tv Assets/Scripts/Utils/UI/Dragging/DragItem.cs:102)
GameDevTV.Core.UI.Dragging.DragItem`1[T].UnityEngine.EventSystems.IEndDragHandler.OnEndDrag (UnityEngine.EventSystems.PointerEventData eventData) (at Assets/GameDev.tv Assets/Scripts/Utils/UI/Dragging/DragItem.cs:73)
UnityEngine.EventSystems.ExecuteEvents.Execute (UnityEngine.EventSystems.IEndDragHandler handler, UnityEngine.EventSystems.BaseEventData eventData) (at Library/PackageCache/com.unity.ugui@1.0.0/Runtime/EventSystem/ExecuteEvents.cs:85)
UnityEngine.EventSystems.ExecuteEvents.Execute[T] (UnityEngine.GameObject target, UnityEngine.EventSystems.BaseEventData eventData, UnityEngine.EventSystems.ExecuteEvents+EventFunction`1[T1] functor) (at Library/PackageCache/com.unity.ugui@1.0.0/Runtime/EventSystem/ExecuteEvents.cs:272)
UnityEngine.EventSystems.EventSystem:Update() (at Library/PackageCache/com.unity.ugui@1.0.0/Runtime/EventSystem/EventSystem.cs:514)
And here is my current attempt at coding a solution for it (I labelled line 129 in ‘EquipmentSlotUI.cs’ through comments, where the NRE is coming from):
// Corner case: Add a condition in here that checks if the player is holding a 2h sword,
// and he's trying to equip (through drag and drop) a shield. If he is, disarm his 2h sword first,
// and then place the shield into the appropriate slot:
public void AddItems(InventoryItem item, int number)
{
CheckLeftHand();
playerEquipment.AddItem(equipLocation, (EquipableItem) item);
}
private void CheckLeftHand()
{
Equipment equipment = GameObject.FindGameObjectWithTag("Player").GetComponent<Equipment>();
WeaponConfig otherWeapon = (WeaponConfig)equipment.GetItemInSlot(EquipLocation.Weapon);
ShieldConfig otherShield = (ShieldConfig)equipment.GetItemInSlot(EquipLocation.Shield);
if (otherWeapon.IsTwoHanded || otherWeapon.IsLeftHanded)
{
if (!inventory.HasSpaceFor(equipment.GetWeaponAndShieldAsIEnumerable()))
{
// Add the weapon back into the inventory (still thinking this one through)
return;
}
equipment.RemoveItem(EquipLocation.Weapon);
equipment.AddItem(equipLocation, otherShield); // line 129, for the NRE
return;
}
}
(This was worth 2 hours of trying out, before my brain fried out). Unfortunately this solution caused not only my shield to permanently disappear, but also my weapon to vanish, like poof.
I want to try and solve this, but for drag and drop, is ‘AddItems()’ really where I should even begin trying to solve this issue from, or should I go to ‘Fighter.UpdateWeapon()’ and tune that function instead?
