Initial commit: Item Interaction Ecosystem plugin (UE5.7)

Server-authoritative, data-driven item/inventory/interaction/carry/equipment/
world-slot/placement/crafting framework. 8 modules, compiles against UE 5.7.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Source/ItemDatabase/Public/ItemPlacementRules.h

@@ -0,0 +1,69 @@
+// Copyright ExByte Studios. Item Interaction Ecosystem.
+
+#pragma once
+
+#include "CoreMinimal.h"
+#include "GameplayTagContainer.h"
+#include "ItemPlacementRules.generated.h"
+
+/** How a placeable item snaps when previewed/placed (section 13.3). */
+UENUM(BlueprintType)
+enum class EItemPlacementMode : uint8
+{
+	FreeSurface,
+	SnapToGrid,
+	SnapToSocket
+};
+
+/**
+ * Static placement constraints for a placeable item (section 13.3).
+ * Evaluated locally for the ghost preview and re-validated on the server.
+ */
+USTRUCT(BlueprintType)
+struct ITEMDATABASE_API FItemPlacementRules
+{
+	GENERATED_BODY()
+
+	UPROPERTY(EditAnywhere, BlueprintReadOnly, Category = "Placement")
+	EItemPlacementMode PlacementMode = EItemPlacementMode::FreeSurface;
+
+	UPROPERTY(EditAnywhere, BlueprintReadOnly, Category = "Placement")
+	float MaxDistance = 400.f;
+
+	UPROPERTY(EditAnywhere, BlueprintReadOnly, Category = "Placement")
+	bool bRequiresFlatSurface = false;
+
+	UPROPERTY(EditAnywhere, BlueprintReadOnly, Category = "Placement", meta = (ClampMin = "0", ClampMax = "90"))
+	float MaxSlopeAngle = 35.f;
+
+	UPROPERTY(EditAnywhere, BlueprintReadOnly, Category = "Placement")
+	FName CollisionProfile = FName("BlockAll");
+
+	UPROPERTY(EditAnywhere, BlueprintReadOnly, Category = "Placement")
+	FGameplayTagContainer AllowedSurfaceTags;
+
+	UPROPERTY(EditAnywhere, BlueprintReadOnly, Category = "Placement")
+	FGameplayTagContainer BlockedSurfaceTags;
+
+	UPROPERTY(EditAnywhere, BlueprintReadOnly, Category = "Placement")
+	float SnapToGrid = 0.f;
+
+	/** When PlacementMode == SnapToSocket, only sockets carrying this tag accept the item. */
+	UPROPERTY(EditAnywhere, BlueprintReadOnly, Category = "Placement")
+	FGameplayTag SnapToSocketTag;
+
+	UPROPERTY(EditAnywhere, BlueprintReadOnly, Category = "Placement")
+	float MinDistanceFromOtherSameItems = 0.f;
+
+	UPROPERTY(EditAnywhere, BlueprintReadOnly, Category = "Placement")
+	bool bCanPlaceInWater = false;
+
+	UPROPERTY(EditAnywhere, BlueprintReadOnly, Category = "Placement")
+	bool bCanPlaceOnVehicle = false;
+
+	UPROPERTY(EditAnywhere, BlueprintReadOnly, Category = "Placement")
+	bool bCanPlaceOnWall = false;
+
+	UPROPERTY(EditAnywhere, BlueprintReadOnly, Category = "Placement")
+	bool bCanPlaceOnGround = true;
+};