Only send start fall flying if player has elytra on chestplate in 1.9->1.8

Closes #625

Author: FlorianMichael

bukkit/src/main/java/com/viaversion/viarewind/BukkitPlugin.java

@@ -18,13 +18,22 @@
 package com.viaversion.viarewind;
 
 import com.viaversion.viarewind.api.ViaRewindPlatform;
+import com.viaversion.viarewind.protocol.v1_9to1_8.provider.InventoryProvider;
+import com.viaversion.viarewind.provider.BukkitInventoryProvider;
 import com.viaversion.viaversion.api.Via;
 import java.io.File;
+import com.viaversion.viaversion.api.platform.providers.ViaProviders;
 import org.bukkit.plugin.java.JavaPlugin;
 
 public class BukkitPlugin extends JavaPlugin implements ViaRewindPlatform {
 
     public BukkitPlugin() {
         Via.getManager().addEnableListener(() -> this.init(new File(getDataFolder(), "config.yml")));
     }
+
+    @Override
+    public void onEnable() {
+        final ViaProviders providers = Via.getManager().getProviders();
+        providers.use(InventoryProvider.class, new BukkitInventoryProvider());
+    }
 }

bukkit/src/main/java/com/viaversion/viarewind/provider/BukkitInventoryProvider.java

@@ -0,0 +1,36 @@
+/*
+ * This file is part of ViaRewind - https://github.com/ViaVersion/ViaRewind
+ * Copyright (C) 2018-2025 ViaVersion and contributors
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+package com.viaversion.viarewind.provider;
+
+import com.viaversion.viarewind.protocol.v1_9to1_8.provider.InventoryProvider;
+import com.viaversion.viaversion.api.connection.UserConnection;
+import org.bukkit.Bukkit;
+import org.bukkit.Material;
+import org.bukkit.entity.Player;
+import org.bukkit.inventory.ItemStack;
+
+public final class BukkitInventoryProvider extends InventoryProvider {
+
+    @Override
+    public boolean hasElytra(final UserConnection connection) {
+        final Player player = Bukkit.getPlayer(connection.getProtocolInfo().getUuid());
+        final ItemStack chestplate = player.getInventory().getChestplate();
+        return chestplate != null && chestplate.getType() == Material.ELYTRA;
+    }
+
+}

common/src/main/java/com/viaversion/viarewind/protocol/v1_9to1_8/Protocol1_9To1_8.java

@@ -19,6 +19,7 @@
 
 import com.viaversion.viabackwards.api.BackwardsProtocol;
 import com.viaversion.viarewind.api.data.RewindMappingData;
+import com.viaversion.viarewind.protocol.v1_9to1_8.provider.InventoryProvider;
 import com.viaversion.viarewind.protocol.v1_9to1_8.rewriter.BlockItemPacketRewriter1_9;
 import com.viaversion.viarewind.protocol.v1_9to1_8.rewriter.EntityPacketRewriter1_9;
 import com.viaversion.viarewind.protocol.v1_9to1_8.rewriter.PlayerPacketRewriter1_9;
@@ -92,6 +93,8 @@ public void init(UserConnection connection) {
 
     @Override
     public void register(ViaProviders providers) {
+        providers.register(InventoryProvider.class, new InventoryProvider());
+
         Via.getManager().getScheduler().scheduleRepeating(new LevitationUpdateTask(), 0L, 50L, TimeUnit.MILLISECONDS);
         Via.getManager().getScheduler().scheduleRepeating(new CooldownIndicatorTask(), 0L, 50L, TimeUnit.MILLISECONDS);
     }

common/src/main/java/com/viaversion/viarewind/protocol/v1_9to1_8/provider/InventoryProvider.java

@@ -0,0 +1,29 @@
+/*
+ * This file is part of ViaRewind - https://github.com/ViaVersion/ViaRewind
+ * Copyright (C) 2018-2025 ViaVersion and contributors
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+package com.viaversion.viarewind.protocol.v1_9to1_8.provider;
+
+import com.viaversion.viaversion.api.connection.UserConnection;
+import com.viaversion.viaversion.api.platform.providers.Provider;
+
+public class InventoryProvider implements Provider {
+
+    public boolean hasElytra(final UserConnection connection) {
+        return false;
+    }
+
+}

common/src/main/java/com/viaversion/viarewind/protocol/v1_9to1_8/rewriter/PlayerPacketRewriter1_9.java

@@ -23,12 +23,14 @@
 import com.viaversion.viarewind.ViaRewind;
 import com.viaversion.viarewind.api.type.RewindTypes;
 import com.viaversion.viarewind.protocol.v1_9to1_8.Protocol1_9To1_8;
+import com.viaversion.viarewind.protocol.v1_9to1_8.provider.InventoryProvider;
 import com.viaversion.viarewind.protocol.v1_9to1_8.storage.BlockPlaceDestroyTracker;
 import com.viaversion.viarewind.protocol.v1_9to1_8.storage.BossBarStorage;
 import com.viaversion.viarewind.protocol.v1_9to1_8.storage.CooldownStorage;
 import com.viaversion.viarewind.protocol.v1_9to1_8.storage.EntityTracker1_9;
 import com.viaversion.viarewind.protocol.v1_9to1_8.storage.PlayerPositionTracker;
 import com.viaversion.viarewind.utils.ChatUtil;
+import com.viaversion.viaversion.api.Via;
 import com.viaversion.viaversion.api.data.entity.EntityTracker;
 import com.viaversion.viaversion.api.minecraft.BlockPosition;
 import com.viaversion.viaversion.api.minecraft.ClientWorld;
@@ -409,10 +411,12 @@ public void register() {
                 map(Types.VAR_INT); // Action parameter
                 handler(wrapper -> {
                     final PlayerPositionTracker tracker = wrapper.user().get(PlayerPositionTracker.class);
+                    final InventoryProvider provider = Via.getManager().getProviders().get(InventoryProvider.class);
                     final int action = wrapper.get(Types.VAR_INT, 1);
                     if (action == 6) { // Jump with horse
                         wrapper.set(Types.VAR_INT, 1, 7);
-                    } else if (action == 0 && !tracker.isOnGround()) { // Start sneaking
+                    } else if (action == 0 && provider.hasElytra(wrapper.user()) && !tracker.isOnGround()) { // Start sneaking
+                        System.out.println("Sending packet");
                         final PacketWrapper elytra = PacketWrapper.create(ServerboundPackets1_9.PLAYER_COMMAND, wrapper.user());
                         elytra.write(Types.VAR_INT, wrapper.get(Types.VAR_INT, 0));
                         elytra.write(Types.VAR_INT, 8);

gradle.properties

@@ -7,7 +7,7 @@ org.gradle.configuration-cache=true
 project_jvm_version=17
 
 project_group=com.viaversion
-project_version=4.0.11
+project_version=4.0.12-SNAPSHOT
 project_description=ViaVersion addon to allow 1.8.x and 1.7.x clients on newer server versions.
 
 publishing_dev_id=FlorianMichael