95 lines
2.5 KiB
C++
95 lines
2.5 KiB
C++
// Copyright 2025 https://yuewu.dev/en All Rights Reserved.
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#include "Drops/GIS_RandomItemDropperComponent.h"
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#include "GameFramework/Actor.h"
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#include "GIS_InventorySystemComponent.h"
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#include "GIS_ItemCollection.h"
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#include "GIS_LogChannels.h"
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#include UE_INLINE_GENERATED_CPP_BY_NAME(GIS_RandomItemDropperComponent)
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TArray<FGIS_ItemInfo> UGIS_RandomItemDropperComponent::GetItemsToDropInternal() const
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{
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TArray<FGIS_ItemInfo> Results;
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UGIS_InventorySystemComponent* Inventory = UGIS_InventorySystemComponent::FindInventorySystemComponent(GetOwner());
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if (Inventory == nullptr)
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{
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GIS_CLOG(Error, "requires inventory system component to drop items.")
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return Results;
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}
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UGIS_ItemCollection* Collection = Inventory->GetCollectionByTag(CollectionTag);
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if (Collection == nullptr)
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{
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GIS_CLOG(Error, " inventory missing collection with tag:%s'", *CollectionTag.ToString())
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return Results;
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}
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const TArray<FGIS_ItemStack>& ItemStacks = Collection->GetAllItemStacks();
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TArray<FGIS_ItemInfo> ItemInfos;
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ItemInfos.Reserve(ItemStacks.Num());
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int32 ProbabilitySum = 0;
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for (int32 i = 0; i < ItemStacks.Num(); ++i)
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{
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//加权
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ProbabilitySum += ItemStacks[i].Amount;
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ItemInfos[i] = FGIS_ItemInfo(ProbabilitySum, ItemStacks[i]);
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}
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int32 RandomAmount = FMath::RandRange(MinAmount, MaxAmount + 1);
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Results.Empty();
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for (int i = 0; i < RandomAmount; i++)
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{
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auto& selectedItemInfo = GetRandomItemInfo(ItemInfos, ProbabilitySum);
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bool foundMatch = false;
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//去重，多个栈可能指向同一个道具实例，若发现重复
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for (int j = 0; j < Results.Num(); j++)
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{
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if (Results[j].Item == selectedItemInfo.Item)
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{
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Results[j] = FGIS_ItemInfo(Results[j].Amount + 1, Results[j]);
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foundMatch = true;
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break;
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}
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}
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if (!foundMatch) { Results.Add(FGIS_ItemInfo(1, selectedItemInfo)); }
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}
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return Results;
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}
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const FGIS_ItemInfo& UGIS_RandomItemDropperComponent::GetRandomItemInfo(const TArray<FGIS_ItemInfo>& ItemInfos, int32 ProbabilitySum) const
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{
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int32 RandomProbabilityIdx = FMath::RandRange(0, ProbabilitySum);
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int32 min = 0;
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int32 max = ItemInfos.Num() - 1;
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int32 mid = 0;
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while (min <= max)
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{
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mid = (min + max) / 2;
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if (ItemInfos[mid].Amount == RandomProbabilityIdx)
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{
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++mid;
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break;
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}
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if (RandomProbabilityIdx < ItemInfos[mid].Amount
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&& (mid == 0 || RandomProbabilityIdx > ItemInfos[mid - 1].Amount)) { break; }
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if (RandomProbabilityIdx < ItemInfos[mid].Amount) { max = mid - 1; }
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else
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{
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min = mid + 1;
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}
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}
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return ItemInfos[mid];
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}
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