Implement showShieldWhenSwordInHand option (#2417)

api/src/main/java/us/myles/ViaVersion/api/ViaVersionConfig.java

@@ -79,10 +79,22 @@ public interface ViaVersionConfig {
     /**
      * Whether the player can block with the shield without a delay.
      *
+     * This option requires {@link #isShowShieldWhenSwordInHand()} to be disabled
+     *
      * @return {@code true} if non delayed shield blocking is enabled.
      */
     boolean isNoDelayShieldBlocking();
 
+    /**
+     * Puts the shield into the second hand when holding a sword.
+     * The shield will disappear when switching to another item.
+     *
+     * This option requires {@link #isShieldBlocking()} to be enabled
+     *
+     * @return {@code true} if the shield should appear when holding a sword
+     */
+    boolean isShowShieldWhenSwordInHand();
+
     /**
      * Get if armor stand positions are fixed so holograms show up at the correct height in 1.9 & 1.10
      *

common/src/main/java/us/myles/ViaVersion/AbstractViaConfig.java

@@ -33,6 +33,7 @@ public abstract class AbstractViaConfig extends Config implements ViaVersionConf
     private boolean suppressMetadataErrors;
     private boolean shieldBlocking;
     private boolean noDelayShieldBlocking;
+    private boolean showShieldWhenSwordInHand;
     private boolean hologramPatch;
     private boolean pistonAnimationPatch;
     private boolean bossbarPatch;
@@ -93,6 +94,7 @@ public abstract class AbstractViaConfig extends Config implements ViaVersionConf
         suppressMetadataErrors = getBoolean("suppress-metadata-errors", false);
         shieldBlocking = getBoolean("shield-blocking", true);
         noDelayShieldBlocking = getBoolean("no-delay-shield-blocking", false);
+        showShieldWhenSwordInHand = getBoolean("show-shield-when-sword-in-hand", false);
         hologramPatch = getBoolean("hologram-patch", false);
         pistonAnimationPatch = getBoolean("piston-animation-patch", false);
         bossbarPatch = getBoolean("bossbar-patch", true);
@@ -177,6 +179,11 @@ public abstract class AbstractViaConfig extends Config implements ViaVersionConf
         return noDelayShieldBlocking;
     }
 
+    @Override
+    public boolean isShowShieldWhenSwordInHand() {
+        return showShieldWhenSwordInHand;
+    }
+
     @Override
     public boolean isHologramPatch() {
         return hologramPatch;

common/src/main/java/us/myles/ViaVersion/protocols/protocol1_9to1_8/packets/InventoryPackets.java

@@ -18,6 +18,7 @@
 package us.myles.ViaVersion.protocols.protocol1_9to1_8.packets;
 
 import us.myles.ViaVersion.api.PacketWrapper;
+import us.myles.ViaVersion.api.Via;
 import us.myles.ViaVersion.api.minecraft.item.Item;
 import us.myles.ViaVersion.api.protocol.Protocol;
 import us.myles.ViaVersion.api.remapper.PacketHandler;
@@ -113,6 +114,25 @@ public class InventoryPackets {
                     @Override
                     public void handle(PacketWrapper wrapper) throws Exception {
                         Item stack = wrapper.get(Type.ITEM, 0);
+
+                        boolean showShieldWhenSwordInHand = Via.getConfig().isShowShieldWhenSwordInHand()
+                                && Via.getConfig().isShieldBlocking();
+
+                        // Check if it is the inventory of the player
+                        if (showShieldWhenSwordInHand) {
+                            InventoryTracker inventoryTracker = wrapper.user().get(InventoryTracker.class);
+                            EntityTracker1_9 entityTracker = wrapper.user().get(EntityTracker1_9.class);
+
+                            short slotID = wrapper.get(Type.SHORT, 0);
+                            short windowId = wrapper.get(Type.BYTE, 0);
+
+                            // Store item in slot
+                            inventoryTracker.setItemId(windowId, slotID, stack == null ? 0 : stack.getIdentifier());
+
+                            // Sync shield item in offhand with main hand
+                            entityTracker.syncShieldWithSword();
+                        }
+
                         ItemRewriter.toClient(stack);
                     }
                 });
@@ -145,8 +165,29 @@ public class InventoryPackets {
                     @Override
                     public void handle(PacketWrapper wrapper) throws Exception {
                         Item[] stacks = wrapper.get(Type.ITEM_ARRAY, 0);
-                        for (Item stack : stacks)
+                        Short windowId = wrapper.get(Type.UNSIGNED_BYTE, 0);
+
+                        InventoryTracker inventoryTracker = wrapper.user().get(InventoryTracker.class);
+                        EntityTracker1_9 entityTracker = wrapper.user().get(EntityTracker1_9.class);
+
+                        boolean showShieldWhenSwordInHand = Via.getConfig().isShowShieldWhenSwordInHand()
+                                && Via.getConfig().isShieldBlocking();
+
+                        for (short i = 0; i < stacks.length; i++) {
+                            Item stack = stacks[i];
+
+                            // Store items in slots
+                            if (showShieldWhenSwordInHand) {
+                                inventoryTracker.setItemId(windowId, i, stack == null ? 0 : stack.getIdentifier());
+                            }
+
                             ItemRewriter.toClient(stack);
+                        }
+
+                        // Sync shield item in offhand with main hand
+                        if (showShieldWhenSwordInHand) {
+                            entityTracker.syncShieldWithSword();
+                        }
                     }
                 });
                 // Brewing Patch
@@ -185,6 +226,7 @@ public class InventoryPackets {
                     public void handle(PacketWrapper wrapper) throws Exception {
                         InventoryTracker inventoryTracker = wrapper.user().get(InventoryTracker.class);
                         inventoryTracker.setInventory(null);
+                        inventoryTracker.resetInventory(wrapper.get(Type.UNSIGNED_BYTE, 0));
                     }
                 });
             }
@@ -218,6 +260,22 @@ public class InventoryPackets {
                     @Override
                     public void handle(PacketWrapper wrapper) throws Exception {
                         Item stack = wrapper.get(Type.ITEM, 0);
+
+                        boolean showShieldWhenSwordInHand = Via.getConfig().isShowShieldWhenSwordInHand()
+                                && Via.getConfig().isShieldBlocking();
+
+                        if (showShieldWhenSwordInHand) {
+                            InventoryTracker inventoryTracker = wrapper.user().get(InventoryTracker.class);
+                            EntityTracker1_9 entityTracker = wrapper.user().get(EntityTracker1_9.class);
+                            short slotID = wrapper.get(Type.SHORT, 0);
+
+                            // Update item in slot
+                            inventoryTracker.setItemId((short) 0, slotID, stack == null ? 0 : stack.getIdentifier());
+
+                            // Sync shield item in offhand with main hand
+                            entityTracker.syncShieldWithSword();
+                        }
+
                         ItemRewriter.toServer(stack);
                     }
                 });
@@ -259,6 +317,18 @@ public class InventoryPackets {
                     @Override
                     public void handle(PacketWrapper wrapper) throws Exception {
                         Item stack = wrapper.get(Type.ITEM, 0);
+
+                        if (Via.getConfig().isShowShieldWhenSwordInHand()) {
+                            Short windowId = wrapper.get(Type.UNSIGNED_BYTE, 0);
+                            byte mode = wrapper.get(Type.BYTE, 1);
+                            short hoverSlot = wrapper.get(Type.SHORT, 0);
+                            byte button = wrapper.get(Type.BYTE, 0);
+
+                            // Move items in inventory to track the sword location
+                            InventoryTracker inventoryTracker = wrapper.user().get(InventoryTracker.class);
+                            inventoryTracker.handleWindowClick(windowId, mode, hoverSlot, button);
+                        }
+
                         ItemRewriter.toServer(stack);
                     }
                 });
@@ -305,12 +375,15 @@ public class InventoryPackets {
 
             @Override
             public void registerMap() {
+                map(Type.UNSIGNED_BYTE); // 0 - Window ID
+
                 // Inventory tracking
                 handler(new PacketHandler() {
                     @Override
                     public void handle(PacketWrapper wrapper) throws Exception {
                         InventoryTracker inventoryTracker = wrapper.user().get(InventoryTracker.class);
                         inventoryTracker.setInventory(null);
+                        inventoryTracker.resetInventory(wrapper.get(Type.UNSIGNED_BYTE, 0));
                     }
                 });
             }
@@ -319,14 +392,30 @@ public class InventoryPackets {
         protocol.registerIncoming(ServerboundPackets1_9.HELD_ITEM_CHANGE, new PacketRemapper() {
             @Override
             public void registerMap() {
+                map(Type.SHORT); // 0 - Slot id
+
                 // Blocking patch
                 handler(new PacketHandler() {
                     @Override
                     public void handle(PacketWrapper wrapper) throws Exception {
+                        boolean showShieldWhenSwordInHand = Via.getConfig().isShowShieldWhenSwordInHand()
+                                && Via.getConfig().isShieldBlocking();
+
                         EntityTracker1_9 entityTracker = wrapper.user().get(EntityTracker1_9.class);
                         if (entityTracker.isBlocking()) {
                             entityTracker.setBlocking(false);
-                            entityTracker.setSecondHand(null);
+
+                            if (!showShieldWhenSwordInHand) {
+                                entityTracker.setSecondHand(null);
+                            }
+                        }
+
+                        if (showShieldWhenSwordInHand) {
+                            // Update current held item slot index
+                            entityTracker.setHeldItemSlot(wrapper.get(Type.SHORT, 0));
+
+                            // Sync shield item in offhand with main hand
+                            entityTracker.syncShieldWithSword();
                         }
                     }
                 });

common/src/main/java/us/myles/ViaVersion/protocols/protocol1_9to1_8/packets/PlayerPackets.java

@@ -498,7 +498,9 @@ public class PlayerPackets {
                             // cancel any blocking >.>
                             EntityTracker1_9 tracker = wrapper.user().get(EntityTracker1_9.class);
                             if (tracker.isBlocking()) {
-                                tracker.setSecondHand(null);
+                                if(!Via.getConfig().isShowShieldWhenSwordInHand()) {
+                                    tracker.setSecondHand(null);
+                                }
                                 tracker.setBlocking(false);
                             }
                         }

common/src/main/java/us/myles/ViaVersion/protocols/protocol1_9to1_8/packets/WorldPackets.java

@@ -269,7 +269,9 @@ public class WorldPackets {
                             EntityTracker1_9 entityTracker = wrapper.user().get(EntityTracker1_9.class);
                             if (entityTracker.isBlocking()) {
                                 entityTracker.setBlocking(false);
-                                entityTracker.setSecondHand(null);
+                                if (!Via.getConfig().isShowShieldWhenSwordInHand()) {
+                                    entityTracker.setSecondHand(null);
+                                }
                             }
                         }
                     }
@@ -296,23 +298,36 @@ public class WorldPackets {
                         if (Via.getConfig().isShieldBlocking()) {
                             EntityTracker1_9 tracker = wrapper.user().get(EntityTracker1_9.class);
 
+                            // Check if the shield is already there or if we have to give it here
+                            boolean showShieldWhenSwordInHand = Via.getConfig().isShowShieldWhenSwordInHand();
+
                             if (item != null && Protocol1_9To1_8.isSword(item.getIdentifier())) {
                                 if (hand == 0) {
                                     if (!tracker.isBlocking()) {
                                         tracker.setBlocking(true);
-                                        Item shield = new Item(442, (byte) 1, (short) 0, null);
+
-                                        tracker.setSecondHand(shield);
+                                        // Check if the shield is already in the offhand
+                                        if (!showShieldWhenSwordInHand || tracker.getItemInSecondHand() == null) {
+
+                                            // Set shield in offhand when interacting with main hand
+                                            Item shield = new Item(442, (byte) 1, (short) 0, null);
+                                            tracker.setSecondHand(shield);
+                                        }
                                     }
                                 }
 
-                                // Uses left or right hand to start blocking depending on the no delay setting
+                                // Use the main hand to trigger the blocking
-                                boolean noDelayBlocking = Via.getConfig().isNoDelayShieldBlocking();
+                                boolean blockUsingMainHand = Via.getConfig().isNoDelayShieldBlocking()
+                                        && !showShieldWhenSwordInHand;
 
-                                if (noDelayBlocking && hand == 1 || !noDelayBlocking && hand == 0) {
+                                if (blockUsingMainHand && hand == 1 || !blockUsingMainHand && hand == 0) {
                                     wrapper.cancel();
                                 }
                             } else {
-                                tracker.setSecondHand(null);
+                                if (!showShieldWhenSwordInHand) {
+                                    // Remove the shield from the offhand
+                                    tracker.setSecondHand(null);
+                                }
                                 tracker.setBlocking(false);
                             }
                         }

common/src/main/java/us/myles/ViaVersion/protocols/protocol1_9to1_8/storage/EntityTracker1_9.java

@@ -66,6 +66,8 @@ public class EntityTracker1_9 extends EntityTracker {
     private boolean teamExists = false;
     private GameMode gameMode;
     private String currentTeam;
+    private int heldItemSlot;
+    private Item itemInSecondHand = null;
 
     public EntityTracker1_9(UserConnection user) {
         super(user, EntityType.PLAYER);
@@ -89,7 +91,7 @@ public class EntityTracker1_9 extends EntityTracker {
         PacketWrapper wrapper = new PacketWrapper(0x3C, null, getUser());
         wrapper.write(Type.VAR_INT, entityID);
         wrapper.write(Type.VAR_INT, 1); // slot
-        wrapper.write(Type.ITEM, item);
+        wrapper.write(Type.ITEM, this.itemInSecondHand = item);
         try {
             wrapper.send(Protocol1_9To1_8.class);
         } catch (Exception e) {
@@ -97,6 +99,31 @@ public class EntityTracker1_9 extends EntityTracker {
         }
     }
 
+    public Item getItemInSecondHand() {
+        return itemInSecondHand;
+    }
+
+    /**
+     * It will set a shield to the offhand if a sword is in the main hand.
+     * The item in the offhand will be cleared if there is no sword in the main hand.
+     */
+    public void syncShieldWithSword() {
+        InventoryTracker inventoryTracker = getUser().get(InventoryTracker.class);
+
+        // Get item in new selected slot
+        int inventorySlot = this.heldItemSlot + 36; // Hotbar slot index to inventory slot
+        int itemIdentifier = inventoryTracker.getItemId((short) 0, (short) inventorySlot);
+
+        boolean isSword = Protocol1_9To1_8.isSword(itemIdentifier);
+
+        // Update if the state changed
+        if (isSword == (this.itemInSecondHand == null)) {
+
+            // Update shield in off hand depending if a sword is in the main hand
+            setSecondHand(isSword ? new Item(442, (byte) 1, (short) 0, null) : null);
+        }
+    }
+
     @Override
     public void removeEntity(int entityId) {
         super.removeEntity(entityId);
@@ -395,4 +422,8 @@ public class EntityTracker1_9 extends EntityTracker {
     public void setCurrentTeam(String currentTeam) {
         this.currentTeam = currentTeam;
     }
+
+    public void setHeldItemSlot(int heldItemSlot) {
+        this.heldItemSlot = heldItemSlot;
+    }
 }

common/src/main/java/us/myles/ViaVersion/protocols/protocol1_9to1_8/storage/InventoryTracker.java

@@ -20,9 +20,16 @@ package us.myles.ViaVersion.protocols.protocol1_9to1_8.storage;
 import us.myles.ViaVersion.api.data.StoredObject;
 import us.myles.ViaVersion.api.data.UserConnection;
 
+import java.util.HashMap;
+import java.util.Map;
+
 public class InventoryTracker extends StoredObject {
     private String inventory;
 
+    private final Map<Short, Map<Short, Integer>> windowItemCache = new HashMap<>();
+    private int itemIdInCursor = 0;
+    private boolean dragging = false;
+
     public InventoryTracker(UserConnection user) {
         super(user);
     }
@@ -34,4 +41,142 @@ public class InventoryTracker extends StoredObject {
     public void setInventory(String inventory) {
         this.inventory = inventory;
     }
+
+    public void resetInventory(short windowId) {
+        // Reset the cursor state of the inventory
+        if (inventory == null) {
+            this.itemIdInCursor = 0;
+            this.dragging = false;
+
+            // Remove window from cache (Except players window)
+            if (windowId != 0) {
+                this.windowItemCache.remove(windowId);
+            }
+        }
+    }
+
+    public int getItemId(short windowId, short slot) {
+        Map<Short, Integer> itemMap = this.windowItemCache.get(windowId);
+        if (itemMap == null) {
+            return 0;
+        }
+
+        return itemMap.getOrDefault(slot, 0);
+    }
+
+    public void setItemId(short windowId, short slot, int itemId) {
+        if (windowId == -1 && slot == -1) {
+            // Set the cursor item
+            this.itemIdInCursor = itemId;
+        } else {
+            // Set item in normal inventory
+            this.windowItemCache.computeIfAbsent(windowId, k -> new HashMap<>()).put(slot, itemId);
+        }
+    }
+
+    /**
+     * Handle the window click to track the position of the sword
+     *
+     * @param windowId  Id of the current inventory
+     * @param mode      Inventory operation mode
+     * @param hoverSlot The slot number of the current mouse position
+     * @param button    The button to use in the click
+     */
+    public void handleWindowClick(short windowId, byte mode, short hoverSlot, byte button) {
+        EntityTracker1_9 entityTracker = getUser().get(EntityTracker1_9.class);
+
+        // Skip inventory background clicks
+        if (hoverSlot == -1) {
+            return;
+        }
+
+        // Interaction with the offhand slot
+        if (hoverSlot == 45) {
+            entityTracker.setSecondHand(null); // Remove it so we know that we can update it on ITEM_USE
+            return;
+        }
+
+        // It is not possible to put a sword into the armor or crafting result slot
+        boolean isArmorOrResultSlot = hoverSlot >= 5 && hoverSlot <= 8 || hoverSlot == 0;
+
+        switch (mode) {
+            case 0: // Click on slot
+
+                // The cursor is empty, so we can put an item to it
+                if (this.itemIdInCursor == 0) {
+                    // Move item to cursor
+                    this.itemIdInCursor = getItemId(windowId, hoverSlot);
+
+                    // Remove item in slot
+                    setItemId(windowId, hoverSlot, 0);
+                } else {
+                    // Dropping item
+                    if (hoverSlot == -999) {
+                        this.itemIdInCursor = 0;
+                    } else if (!isArmorOrResultSlot) {
+                        int previousItem = getItemId(windowId, hoverSlot);
+
+                        // Place item in inventory
+                        setItemId(windowId, hoverSlot, this.itemIdInCursor);
+
+                        // Pick up the other item
+                        this.itemIdInCursor = previousItem;
+                    }
+                }
+                break;
+            case 2: // Move item using number keys
+                if (!isArmorOrResultSlot) {
+                    short hotkeySlot = (short) (button + 36);
+
+                    // Get items to swap
+                    int sourceItem = getItemId(windowId, hoverSlot);
+                    int destinationItem = getItemId(windowId, hotkeySlot);
+
+                    // Swap
+                    setItemId(windowId, hotkeySlot, sourceItem);
+                    setItemId(windowId, hoverSlot, destinationItem);
+                }
+
+                break;
+            case 4: // Drop item
+                int hoverItem = getItemId(windowId, hoverSlot);
+
+                if (hoverItem != 0) {
+                    setItemId(windowId, hoverSlot, 0);
+                }
+
+                break;
+            case 5: // Mouse dragging
+                switch (button) {
+                    case 0: // Start left dragging
+                    case 4: // Start right dragging
+                        this.dragging = true;
+                        break;
+                    case 1: // Place item during left dragging
+                    case 5: // Place item during right dragging
+                        // Check dragging mode and item on cursor
+                        if (this.dragging && this.itemIdInCursor != 0 && !isArmorOrResultSlot) {
+                            int previousItem = getItemId(windowId, hoverSlot);
+
+                            // Place item on cursor in hovering slot
+                            setItemId(windowId, hoverSlot, this.itemIdInCursor);
+
+                            // Pick up the other item
+                            this.itemIdInCursor = previousItem;
+                        }
+                        break;
+                    case 2: // Stop left dragging
+                    case 6: // Stop right dragging
+                        this.dragging = false;
+                        break;
+                }
+
+                break;
+            default:
+                break;
+        }
+
+        // Update shield state in offhand
+        entityTracker.syncShieldWithSword();
+    }
 }

common/src/main/resources/assets/viaversion/config.yml

@@ -169,7 +169,12 @@ suppress-metadata-errors: false
 shield-blocking: true
 # If this setting is active, the main hand is used instead of the off hand to trigger the blocking of the player.
 # With the main hand the blocking starts way faster.
+# (Requires "show-shield-when-sword-in-hand" to be disabled)
 no-delay-shield-blocking: false
+# If this setting is active, the shield will appear immediately for 1.9+ when you hold a sword in your main hand.
+# The shield disappears when you switch to another item.
+# (Requires "shield-blocking" to be enabled)
+show-shield-when-sword-in-hand: false
 # Enable player tick simulation, this fixes eating, drinking, nether portals.
 simulate-pt: true
 # Should we use nms player to simulate packets, (may fix anti-cheat issues)