feat: Implement inventory logic for dropping items

src/callbacks.cob

@@ -367,3 +367,45 @@ PROCEDURE DIVISION USING LK-WINDOW-TYPE LK-CB-PTR.
     GOBACK.
 
 END PROGRAM GetCallback-WindowSetSlot.
+
+*> --- SetCallback-WindowDrop ---
+IDENTIFICATION DIVISION.
+PROGRAM-ID. SetCallback-WindowDrop.
+
+DATA DIVISION.
+WORKING-STORAGE SECTION.
+    COPY DD-CALLBACKS.
+LINKAGE SECTION.
+    01 LK-WINDOW-TYPE               BINARY-LONG.
+    01 LK-CB-PTR                    PROGRAM-POINTER.
+
+PROCEDURE DIVISION USING LK-WINDOW-TYPE LK-CB-PTR.
+    IF LK-WINDOW-TYPE < 0
+        MOVE LK-CB-PTR TO CB-PTR-DROP-PLAYER
+        GOBACK
+    END-IF
+    MOVE LK-CB-PTR TO CB-PTR-DROP(LK-WINDOW-TYPE + 1)
+    GOBACK.
+
+END PROGRAM SetCallback-WindowDrop.
+
+*> --- GetCallback-WindowDrop ---
+IDENTIFICATION DIVISION.
+PROGRAM-ID. GetCallback-WindowDrop.
+
+DATA DIVISION.
+WORKING-STORAGE SECTION.
+    COPY DD-CALLBACKS.
+LINKAGE SECTION.
+    01 LK-WINDOW-TYPE               BINARY-LONG.
+    01 LK-CB-PTR                    PROGRAM-POINTER.
+
+PROCEDURE DIVISION USING LK-WINDOW-TYPE LK-CB-PTR.
+    IF LK-WINDOW-TYPE < 0
+        MOVE CB-PTR-DROP-PLAYER TO LK-CB-PTR
+        GOBACK
+    END-IF
+    MOVE CB-PTR-DROP(LK-WINDOW-TYPE + 1) TO LK-CB-PTR
+    GOBACK.
+
+END PROGRAM GetCallback-WindowDrop.

src/copybooks/DD-CALLBACK-WINDOW-DROP.cpy

@@ -0,0 +1,8 @@
+*> --- Copybook: callback parameters for dropping the item in a window-specific slot ---
+
+01 LK-PLAYER                BINARY-LONG.
+01 LK-INDEX                 BINARY-SHORT.
+*> whether to drop the entire stack, vs. just one item
+01 LK-STACK                 BINARY-CHAR UNSIGNED.
+*> whether dropping from the slot affected other slots (e.g. crafting output)
+01 LK-SYNC-REQUIRED         BINARY-CHAR UNSIGNED.

src/copybooks/DD-CALLBACKS.cpy

@@ -26,7 +26,9 @@
         03 CB-PTR-SYNC USAGE PROGRAM-POINTER.
         03 CB-PTR-CLOSE USAGE PROGRAM-POINTER.
         03 CB-PTR-SET-SLOT USAGE PROGRAM-POINTER.
+        03 CB-PTR-DROP USAGE PROGRAM-POINTER.
     02 PLAYER-INVENTORY-CALLBACKS.
         03 CB-PTR-SYNC-PLAYER USAGE PROGRAM-POINTER.
         03 CB-PTR-CLOSE-PLAYER USAGE PROGRAM-POINTER.
         03 CB-PTR-SET-SLOT-PLAYER USAGE PROGRAM-POINTER.
+        03 CB-PTR-DROP-PLAYER USAGE PROGRAM-POINTER.

src/inventory/window-crafting.cob

@@ -8,6 +8,7 @@ WORKING-STORAGE SECTION.
     01 SYNC-PTR                     PROGRAM-POINTER.
     01 CLOSE-PTR                    PROGRAM-POINTER.
     01 SET-SLOT-PTR                 PROGRAM-POINTER.
+    01 DROP-PTR                     PROGRAM-POINTER.
 
 PROCEDURE DIVISION.
     CALL "Registries-Get-EntryId" USING "minecraft:menu" "minecraft:crafting" WINDOW-TYPE
@@ -19,9 +20,12 @@ PROCEDURE DIVISION.
     SET SYNC-PTR TO ENTRY "Callback-Sync"
     SET CLOSE-PTR TO ENTRY "Callback-Close"
     SET SET-SLOT-PTR TO ENTRY "Callback-SetSlot"
+    SET DROP-PTR TO ENTRY "Callback-Drop"
+
     CALL "SetCallback-WindowSync" USING WINDOW-TYPE SYNC-PTR
     CALL "SetCallback-WindowClose" USING WINDOW-TYPE CLOSE-PTR
     CALL "SetCallback-WindowSetSlot" USING WINDOW-TYPE SET-SLOT-PTR
+    CALL "SetCallback-WindowDrop" USING WINDOW-TYPE DROP-PTR
 
     GOBACK.
 
@@ -74,15 +78,15 @@ PROCEDURE DIVISION.
         *> stash the mouse item
         CALL "Inventory-StoreItem" USING PLAYER-INVENTORY(LK-PLAYER) PLAYER-MOUSE-ITEM(LK-PLAYER)
         IF PLAYER-MOUSE-SLOT-COUNT(LK-PLAYER) > 0
-            *> TODO drop item
+            CALL "World-DropItem" USING PLAYER-POSITION(LK-PLAYER) PLAYER-MOUSE-ITEM(LK-PLAYER)
             MOVE 0 TO PLAYER-MOUSE-SLOT-COUNT(LK-PLAYER)
         END-IF
 
         *> stash crafting input
         PERFORM VARYING SLOT FROM 1 BY 1 UNTIL SLOT > 9
             CALL "Inventory-StoreItem" USING PLAYER-INVENTORY(LK-PLAYER) PLAYER-WINDOW-SLOT(LK-PLAYER, SLOT + 1)
             IF PLAYER-WINDOW-SLOT-COUNT(LK-PLAYER, SLOT + 1) > 0
-                *> TODO drop item
+                CALL "World-DropItem" USING PLAYER-POSITION(LK-PLAYER) PLAYER-WINDOW-SLOT(LK-PLAYER, SLOT + 1)
                 MOVE 0 TO PLAYER-WINDOW-SLOT-COUNT(LK-PLAYER, SLOT + 1)
             END-IF
         END-PERFORM
@@ -131,4 +135,75 @@ PROCEDURE DIVISION.
 
     END PROGRAM Callback-SetSlot.
 
+    *> --- Callback-Drop ---
+    IDENTIFICATION DIVISION.
+    PROGRAM-ID. Callback-Drop.
+
+    DATA DIVISION.
+    WORKING-STORAGE SECTION.
+        COPY DD-PLAYERS.
+        01 DROP-SLOT.
+            COPY DD-INVENTORY-SLOT REPLACING LEADING ==PREFIX== BY ==DROP==.
+        01 SLOT-INDEX               BINARY-LONG UNSIGNED.
+        *> TODO deduplicate with Callback-SetSlot
+        01 WINDOW-INVENTORY-LENGTH  BINARY-LONG UNSIGNED        VALUE 46.
+        01 CRAFTING-GRID-SIZE       BINARY-LONG UNSIGNED        VALUE 9.
+        01 CRAFTING-GRID-START      BINARY-LONG UNSIGNED        VALUE 1.
+        01 CRAFTING-OUTPUT-SLOT     BINARY-LONG UNSIGNED        VALUE 0.
+    LINKAGE SECTION.
+        COPY DD-CALLBACK-WINDOW-DROP.
+
+    PROCEDURE DIVISION USING LK-PLAYER LK-INDEX LK-STACK LK-SYNC-REQUIRED.
+        EVALUATE LK-INDEX
+            WHEN 0 *> crafting output
+                *> TODO support dropping entire crafting output (LK-STACK = 1)
+                MOVE PLAYER-WINDOW-SLOT(LK-PLAYER, LK-INDEX + 1) TO DROP-SLOT
+                IF DROP-SLOT-COUNT > 0
+                    *> crafting output becomes empty, input is reduced by 1 each
+                    MOVE 0 TO PLAYER-WINDOW-SLOT-COUNT(LK-PLAYER, LK-INDEX + 1)
+                    PERFORM VARYING SLOT-INDEX FROM 1 BY 1 UNTIL SLOT-INDEX > 9
+                        IF PLAYER-WINDOW-SLOT-COUNT(LK-PLAYER, SLOT-INDEX + 1) > 0
+                            SUBTRACT 1 FROM PLAYER-WINDOW-SLOT-COUNT(LK-PLAYER, SLOT-INDEX + 1)
+                        END-IF
+                    END-PERFORM
+                    CALL "World-DropItem" USING PLAYER-POSITION(LK-PLAYER) DROP-SLOT
+                    PERFORM UpdateCrafting
+                END-IF
+
+            WHEN 1 THRU 9 *> crafting input
+                MOVE PLAYER-WINDOW-SLOT(LK-PLAYER, LK-INDEX + 1) TO DROP-SLOT
+                IF DROP-SLOT-COUNT > 0
+                    IF LK-STACK = 0
+                        MOVE 1 TO DROP-SLOT-COUNT
+                    END-IF
+                    SUBTRACT DROP-SLOT-COUNT FROM PLAYER-WINDOW-SLOT-COUNT(LK-PLAYER, LK-INDEX + 1)
+                    CALL "World-DropItem" USING PLAYER-POSITION(LK-PLAYER) DROP-SLOT
+                    PERFORM UpdateCrafting
+                END-IF
+
+            WHEN 10 THRU 45 *> player inventory
+                MOVE PLAYER-INVENTORY-SLOT(LK-PLAYER, LK-INDEX) TO DROP-SLOT
+                IF DROP-SLOT-COUNT > 0
+                    IF LK-STACK = 0
+                        MOVE 1 TO DROP-SLOT-COUNT
+                    END-IF
+                    SUBTRACT DROP-SLOT-COUNT FROM PLAYER-INVENTORY-SLOT-COUNT(LK-PLAYER, LK-INDEX)
+                    CALL "World-DropItem" USING PLAYER-POSITION(LK-PLAYER) DROP-SLOT
+                END-IF
+
+            WHEN OTHER
+                DISPLAY "Invalid slot number: " LK-INDEX
+        END-EVALUATE
+
+        GOBACK.
+
+    UpdateCrafting.
+        CALL "Inventory-UpdateCraftingOutput" USING WINDOW-INVENTORY-LENGTH PLAYER-WINDOW-SLOTS(LK-PLAYER)
+            CRAFTING-GRID-SIZE CRAFTING-GRID-START CRAFTING-OUTPUT-SLOT
+        *> TODO only set this when the output slot is actually changed
+        MOVE 1 TO LK-SYNC-REQUIRED
+        .
+
+    END PROGRAM Callback-Drop.
+
 END PROGRAM RegisterWindow-Crafting.

src/inventory/window-player.cob

@@ -9,14 +9,20 @@ WORKING-STORAGE SECTION.
     01 SYNC-PTR                     PROGRAM-POINTER.
     01 CLOSE-PTR                    PROGRAM-POINTER.
     01 SET-SLOT-PTR                 PROGRAM-POINTER.
+    01 DROP-PTR                     PROGRAM-POINTER.
 
 PROCEDURE DIVISION.
+
     SET SYNC-PTR TO ENTRY "Callback-Sync"
     SET CLOSE-PTR TO ENTRY "Callback-Close"
     SET SET-SLOT-PTR TO ENTRY "Callback-SetSlot"
+    SET DROP-PTR TO ENTRY "Callback-Drop"
+
     CALL "SetCallback-WindowSync" USING WINDOW-TYPE SYNC-PTR
     CALL "SetCallback-WindowClose" USING WINDOW-TYPE CLOSE-PTR
     CALL "SetCallback-WindowSetSlot" USING WINDOW-TYPE SET-SLOT-PTR
+    CALL "SetCallback-WindowDrop" USING WINDOW-TYPE DROP-PTR
+
     GOBACK.
 
     *> --- Callback-Sync ---
@@ -67,15 +73,15 @@ PROCEDURE DIVISION.
         *> stash the mouse item
         CALL "Inventory-StoreItem" USING PLAYER-INVENTORY(LK-PLAYER) PLAYER-MOUSE-ITEM(LK-PLAYER)
         IF PLAYER-MOUSE-SLOT-COUNT(LK-PLAYER) > 0
-            *> TODO drop item
+            CALL "World-DropItem" USING PLAYER-POSITION(LK-PLAYER) PLAYER-MOUSE-ITEM(LK-PLAYER)
             MOVE 0 TO PLAYER-MOUSE-SLOT-COUNT(LK-PLAYER)
         END-IF
 
         *> stash crafting input
         PERFORM VARYING SLOT FROM 1 BY 1 UNTIL SLOT > 4
             CALL "Inventory-StoreItem" USING PLAYER-INVENTORY(LK-PLAYER) PLAYER-INVENTORY-SLOT(LK-PLAYER, SLOT + 1)
             IF PLAYER-INVENTORY-SLOT-COUNT(LK-PLAYER, SLOT + 1) > 0
-                *> TODO drop item
+                CALL "World-DropItem" USING PLAYER-POSITION(LK-PLAYER) PLAYER-INVENTORY-SLOT(LK-PLAYER, SLOT + 1)
                 MOVE 0 TO PLAYER-INVENTORY-SLOT-COUNT(LK-PLAYER, SLOT + 1)
             END-IF
         END-PERFORM
@@ -127,4 +133,75 @@ PROCEDURE DIVISION.
 
     END PROGRAM Callback-SetSlot.
 
+    *> --- Callback-Drop ---
+    IDENTIFICATION DIVISION.
+    PROGRAM-ID. Callback-Drop.
+
+    DATA DIVISION.
+    WORKING-STORAGE SECTION.
+        COPY DD-PLAYERS.
+        01 DROP-SLOT.
+            COPY DD-INVENTORY-SLOT REPLACING LEADING ==PREFIX== BY ==DROP==.
+        01 SLOT-INDEX               BINARY-LONG UNSIGNED.
+        *> TODO deduplicate with Callback-SetSlot
+        01 WINDOW-INVENTORY-LENGTH  BINARY-LONG UNSIGNED        VALUE 46.
+        01 CRAFTING-GRID-SIZE       BINARY-LONG UNSIGNED        VALUE 4.
+        01 CRAFTING-GRID-START      BINARY-LONG UNSIGNED        VALUE 1.
+        01 CRAFTING-OUTPUT-SLOT     BINARY-LONG UNSIGNED        VALUE 0.
+    LINKAGE SECTION.
+        COPY DD-CALLBACK-WINDOW-DROP.
+
+    PROCEDURE DIVISION USING LK-PLAYER LK-INDEX LK-STACK LK-SYNC-REQUIRED.
+        EVALUATE LK-INDEX
+            WHEN 0 *> crafting output
+                *> TODO support dropping entire crafting output (LK-STACK = 1)
+                MOVE PLAYER-INVENTORY-SLOT(LK-PLAYER, LK-INDEX + 1) TO DROP-SLOT
+                IF DROP-SLOT-COUNT > 0
+                    *> crafting output becomes empty, input is reduced by 1 each
+                    MOVE 0 TO PLAYER-INVENTORY-SLOT-COUNT(LK-PLAYER, LK-INDEX + 1)
+                    PERFORM VARYING SLOT-INDEX FROM 1 BY 1 UNTIL SLOT-INDEX > 4
+                        IF PLAYER-INVENTORY-SLOT-COUNT(LK-PLAYER, SLOT-INDEX + 1) > 0
+                            SUBTRACT 1 FROM PLAYER-INVENTORY-SLOT-COUNT(LK-PLAYER, SLOT-INDEX + 1)
+                        END-IF
+                    END-PERFORM
+                    CALL "World-DropItem" USING PLAYER-POSITION(LK-PLAYER) DROP-SLOT
+                    PERFORM UpdateCrafting
+                END-IF
+
+            WHEN 1 THRU 4 *> crafting input
+                MOVE PLAYER-INVENTORY-SLOT(LK-PLAYER, LK-INDEX + 1) TO DROP-SLOT
+                IF DROP-SLOT-COUNT > 0
+                    IF LK-STACK = 0
+                        MOVE 1 TO DROP-SLOT-COUNT
+                    END-IF
+                    SUBTRACT DROP-SLOT-COUNT FROM PLAYER-INVENTORY-SLOT-COUNT(LK-PLAYER, LK-INDEX + 1)
+                    CALL "World-DropItem" USING PLAYER-POSITION(LK-PLAYER) DROP-SLOT
+                    PERFORM UpdateCrafting
+                END-IF
+
+            WHEN 5 THRU 45 *> armor, inventory, offhand
+                MOVE PLAYER-INVENTORY-SLOT(LK-PLAYER, LK-INDEX + 1) TO DROP-SLOT
+                IF DROP-SLOT-COUNT > 0
+                    IF LK-STACK = 0
+                        MOVE 1 TO DROP-SLOT-COUNT
+                    END-IF
+                    SUBTRACT DROP-SLOT-COUNT FROM PLAYER-INVENTORY-SLOT-COUNT(LK-PLAYER, LK-INDEX + 1)
+                    CALL "World-DropItem" USING PLAYER-POSITION(LK-PLAYER) DROP-SLOT
+                END-IF
+
+            WHEN OTHER
+                DISPLAY "Invalid slot number: " LK-INDEX
+        END-EVALUATE
+
+        GOBACK.
+
+    UpdateCrafting.
+        CALL "Inventory-UpdateCraftingOutput" USING WINDOW-INVENTORY-LENGTH PLAYER-WINDOW-SLOTS(LK-PLAYER)
+            CRAFTING-GRID-SIZE CRAFTING-GRID-START CRAFTING-OUTPUT-SLOT
+        *> TODO only set this when the output slot is actually changed
+        MOVE 1 TO LK-SYNC-REQUIRED
+        .
+
+    END PROGRAM Callback-Drop.
+
 END PROGRAM RegisterWindow-Player.

src/packets/serverbound/play/container-click.cob

@@ -10,6 +10,7 @@ WORKING-STORAGE SECTION.
     01 STATE-ID                 BINARY-LONG.
     01 SYNC-PTR                 PROGRAM-POINTER.
     01 SET-SLOT-PTR             PROGRAM-POINTER.
+    01 DROP-PTR                 PROGRAM-POINTER.
     01 SLOT-SYNC-REQUIRED       BINARY-CHAR UNSIGNED.
     01 SYNC-REQUIRED            BINARY-CHAR UNSIGNED.
     01 SLOT                     BINARY-SHORT.
@@ -49,7 +50,8 @@ PROCEDURE DIVISION USING LK-CLIENT LK-BUFFER LK-OFFSET.
 
     CALL "GetCallback-WindowSync" USING PLAYER-WINDOW-TYPE(PLAYER-ID) SYNC-PTR
     CALL "GetCallback-WindowSetSlot" USING PLAYER-WINDOW-TYPE(PLAYER-ID) SET-SLOT-PTR
-    IF SYNC-PTR = NULL OR SET-SLOT-PTR = NULL
+    CALL "GetCallback-WindowDrop" USING PLAYER-WINDOW-TYPE(PLAYER-ID) DROP-PTR
+    IF SYNC-PTR = NULL OR SET-SLOT-PTR = NULL OR DROP-PTR = NULL
         DISPLAY "RecvPacket-ContainerClick: Unable to handle window type " PLAYER-WINDOW-TYPE(PLAYER-ID)
         PERFORM AbortEarly
     END-IF
@@ -60,18 +62,32 @@ PROCEDURE DIVISION USING LK-CLIENT LK-BUFFER LK-OFFSET.
         PERFORM AbortEarly
     END-IF
 
-    *> TODO support dropping items
-    IF (MODE-ENUM = 0 AND SLOT = -999) OR (MODE-ENUM = 4)
-        CALL SYNC-PTR USING PLAYER-ID
-        PERFORM AbortEarly
-    END-IF
-
     *> TODO handle offhand swap key (F) in containers
     If WINDOW-ID > 0 AND MODE-ENUM = 2 AND BUTTON = 40
         CALL "Inventory-SyncPlayerInventory" USING PLAYER-ID
         PERFORM AbortEarly
     END-IF
 
+    IF MODE-ENUM = 0 AND SLOT = -999 AND PLAYER-MOUSE-SLOT-COUNT(PLAYER-ID) > 0
+        *> click outside inventory; button 0: drop stack, button 1: drop single item
+        MOVE PLAYER-MOUSE-ITEM(PLAYER-ID) TO CLIENT-SLOT
+        IF BUTTON = 0
+            MOVE 0 TO PLAYER-MOUSE-SLOT-COUNT(PLAYER-ID)
+        ELSE
+            MOVE 1 TO CLIENT-SLOT-COUNT
+            SUBTRACT 1 FROM PLAYER-MOUSE-SLOT-COUNT(PLAYER-ID)
+        END-IF
+        CALL "World-DropItem" USING PLAYER-POSITION(PLAYER-ID) CLIENT-SLOT
+    END-IF
+
+    IF MODE-ENUM = 4
+        *> drop specific slot
+        IF SLOT = -999
+            PERFORM AbortEarly
+        END-IF
+        CALL DROP-PTR USING PLAYER-ID SLOT BUTTON SYNC-REQUIRED
+    END-IF
+
     *> TODO implement painting properly
     *> For now we ignore all but the end event, assuming the client will send the changed slots with the end event.
     IF MODE-ENUM = 5 AND NOT (BUTTON = 2 OR 6 OR 10)

src/packets/serverbound/play/player-action.cob

@@ -24,6 +24,9 @@ WORKING-STORAGE SECTION.
     01 BLOCK-HARDNESS           FLOAT-SHORT.
     01 CALLBACK-PTR             PROGRAM-POINTER.
     01 OTHER-CLIENT             BINARY-LONG UNSIGNED.
+    01 SLOT-INDEX               BINARY-LONG UNSIGNED.
+    01 DROP-SLOT.
+        COPY DD-INVENTORY-SLOT REPLACING LEADING ==PREFIX== BY ==DROP==.
 LINKAGE SECTION.
     01 LK-CLIENT                BINARY-LONG UNSIGNED.
     01 LK-BUFFER                PIC X ANY LENGTH.
@@ -45,6 +48,10 @@ PROCEDURE DIVISION USING LK-CLIENT LK-BUFFER LK-OFFSET.
             PERFORM CancelledDigging
         WHEN ACTION-ENUM = 2
             PERFORM FinishedDigging
+        WHEN ACTION-ENUM = 3
+            PERFORM DropItemStack
+        WHEN ACTION-ENUM = 4
+            PERFORM DropItem
         WHEN OTHER
             *> TODO The following is a workaround to reset the player's inventory until we support all actions fully
             CALL "Inventory-SyncPlayerInventory" USING PLAYER-ID
@@ -132,4 +139,23 @@ ResetBlockBreaking.
     END-PERFORM
     .
 
+DropItemStack.
+    COMPUTE SLOT-INDEX = 36 + PLAYER-HOTBAR(PLAYER-ID)
+    MOVE PLAYER-INVENTORY-SLOT(PLAYER-ID, SLOT-INDEX + 1) TO DROP-SLOT
+    IF DROP-SLOT-COUNT > 0
+        MOVE 0 TO PLAYER-INVENTORY-SLOT-COUNT(PLAYER-ID, SLOT-INDEX + 1)
+        CALL "World-DropItem" USING PLAYER-POSITION(PLAYER-ID) DROP-SLOT
+    END-IF
+    .
+
+DropItem.
+    COMPUTE SLOT-INDEX = 36 + PLAYER-HOTBAR(PLAYER-ID)
+    MOVE PLAYER-INVENTORY-SLOT(PLAYER-ID, SLOT-INDEX + 1) TO DROP-SLOT
+    IF DROP-SLOT-COUNT > 0
+        MOVE 1 TO DROP-SLOT-COUNT
+        SUBTRACT 1 FROM PLAYER-INVENTORY-SLOT-COUNT(PLAYER-ID, SLOT-INDEX + 1)
+        CALL "World-DropItem" USING PLAYER-POSITION(PLAYER-ID) DROP-SLOT
+    END-IF
+    .
+
 END PROGRAM RecvPacket-PlayerAction.