5-12 Click To Put Item Into Slot

本章要來完成背包系統點擊物品的功能，按住Z鍵點擊物品時僅會取得一半的物品，按住Z鍵放置物品時則會一個一個的放進去。若直接點擊物品則能取得所有物品，也能直接放置物品，同時必須顧慮到物品的容量上限。

本次修改只有動到Slot.cs，而且程式碼解說已經寫在註解中了，請大家自己看看吧！如果不懂這次修改的內容，請記得將前幾篇相關的文章都看一下唷！

5-10 Click To Pickup Item
https://rpgcorecombat.blogspot.tw/2018/01/5-10-click-to-pickup-item.html

5-11 Play Scale Animation When Getting Item

https://rpgcorecombat.blogspot.tw/2018/01/5-11-play-scale-animation-when-getting.html

Slot.cs：

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.EventSystems;

namespace RPG.Inventory{
 public class Slot : MonoBehaviour, IPointerEnterHandler, IPointerExitHandler, IPointerDownHandler {

  [SerializeField] GameObject itemPrefab;

  public void StoreItem(Item item){
   // 若Slot底下沒有Item，則Instantiate一個
   if (transform.childCount == 0) {
    GameObject itemObject = Instantiate (itemPrefab, transform);
    itemObject.GetComponentInChildren ().SetItem (item);
   } else {
    // 已存在該Item，所以增加數量即可
    transform.GetComponentInChildren ().AddAmount ();
   }
  }

  public int GetItemID(){
   return transform.GetComponentInChildren ().Item.ID;
  }

  public bool IsFilled(){
   ItemUI itemUI = transform.GetComponentInChildren ();
   return itemUI.Amount >= itemUI.Item.Capacity;
  }

  public void OnPointerEnter(PointerEventData eventData){
   if (transform.childCount > 0) {
    Item item = GetComponentInChildren ().Item;
    GetComponentInParent ().ShowToolTip (item.GetToolTipText ());
   }
  }

  public void OnPointerExit(PointerEventData eventData){
   GetComponentInParent ().HideToolTip ();
  }

  public void OnPointerDown(PointerEventData eventData){
   InventorySystem invetorySystem = GetComponentInParent ();
   // Slot內是否已經有物體
   if (transform.childCount > 0) {
    // 取得目前滑鼠點擊Slot的ItemUI
    ItemUI clickedItemUI = GetComponentInChildren ();
    // 當滑鼠沒有Item時
    if (invetorySystem.isPickedItem == false) {
     if (Input.GetKey (KeyCode.Z)) {
      // 壓住Z鍵時，只會取出一半的數量
      PickupHalfOfSlotItem(clickedItemUI, invetorySystem);
     } else {
      // 取出全部
      PickupAllSlotItem (clickedItemUI, invetorySystem);
     }
    // 當滑鼠有Item時
    } else if (invetorySystem.isPickedItem == true) {
     if (clickedItemUI.Item.ID == invetorySystem.GetPickedItem ().Item.ID) {
      if (Input.GetKey (KeyCode.Z)) {
       // 壓住Z鍵時，只會一個一個的放入物體
       PutInOneItem (invetorySystem);
      } else {
       // 放入所有物體
       PutInAllItem (clickedItemUI, invetorySystem);
      }
     }
    }
   } else {
    if (invetorySystem.isPickedItem == true) {
     if (Input.GetKey (KeyCode.Z)) {
      // 壓住Z鍵時，只會一個一個的放入物體
      PutInOneItem (invetorySystem);
     } else {
      // 放入所有物體
      PutInAllItemToEmptySlot (invetorySystem);
     }
    }
   }
  }

  private void PickupHalfOfSlotItem(ItemUI clickedItemUI, InventorySystem invetorySystem){
   int amountToPick = (clickedItemUI.Amount + 1) / 2;
   int amountRemained = clickedItemUI.Amount - amountToPick;
   // 將PickedItem的ItemUI設置為目前滑鼠點中的ItemUI
   invetorySystem.PickupItem (clickedItemUI.Item, amountToPick);
   if (amountRemained == 0) {
    Destroy (clickedItemUI.gameObject);
   } else {
    clickedItemUI.SetAmount (amountRemained);
   }
  }

  private void PickupAllSlotItem(ItemUI clickedItemUI, InventorySystem invetorySystem){
   // 將PickedItem的ItemUI設置為目前滑鼠點中的ItemUI
   invetorySystem.PickupItem (clickedItemUI.Item, clickedItemUI.Amount);
   // 因為已經選中物體了，要將Slot內的ItemUI刪除
   Destroy (clickedItemUI.gameObject);
  }

  private void PutInOneItem(InventorySystem invetorySystem){
   this.StoreItem (invetorySystem.GetPickedItem ().Item);
   invetorySystem.ReducePickedItem (1);
  }

  private void PutInAllItem(ItemUI clickedItemUI, InventorySystem invetorySystem){
   if (clickedItemUI.Item.Capacity > clickedItemUI.Amount) {
    int slotRemained = clickedItemUI.Item.Capacity - clickedItemUI.Amount;

    if (slotRemained >= invetorySystem.GetPickedItem ().Amount) {
     // 若Slot內的空間足以放下滑鼠拿著的全部物體
     clickedItemUI.SetAmount (clickedItemUI.Amount + invetorySystem.GetPickedItem ().Amount);
     invetorySystem.ReducePickedItem (invetorySystem.GetPickedItem ().Amount);
    } else {
     // Slot內的空間不夠放，只能放下部分滑鼠拿著的物體
     clickedItemUI.SetAmount (clickedItemUI.Amount + slotRemained);
     invetorySystem.ReducePickedItem (slotRemained);
    }
   }
  }

  private void PutInAllItemToEmptySlot(InventorySystem invetorySystem){
   for (int i = 0; i < invetorySystem.GetPickedItem ().Amount; i++) {
    this.StoreItem (invetorySystem.GetPickedItem().Item);
   }
   invetorySystem.ReducePickedItem (invetorySystem.GetPickedItem().Amount);
  }
 }
}

撰寫完程式碼後，來執行遊戲看看吧，壓住Z鍵就可以取出部分物品了，而且可以在每個Slot各放一個物品。

也可以隨自己的喜好隨便放置物品。