Properly handle item display rotation change

Fixes #3354

api/src/main/java/com/viaversion/viaversion/api/minecraft/Quaternion.java

@@ -50,4 +50,14 @@ public final class Quaternion {
     public float w() {
         return w;
     }
+
+    @Override
+    public String toString() {
+        return "Quaternion{" +
+                "x=" + x +
+                ", y=" + y +
+                ", z=" + z +
+                ", w=" + w +
+                '}';
+    }
 }

common/src/main/java/com/viaversion/viaversion/protocols/protocol1_20to1_19_4/packets/EntityPackets.java

@@ -23,10 +23,10 @@ import com.github.steveice10.opennbt.tag.builtin.IntTag;
 import com.github.steveice10.opennbt.tag.builtin.ListTag;
 import com.github.steveice10.opennbt.tag.builtin.StringTag;
 import com.github.steveice10.opennbt.tag.builtin.Tag;
-import com.viaversion.viaversion.api.data.entity.TrackedEntity;
+import com.viaversion.viaversion.api.minecraft.Quaternion;
 import com.viaversion.viaversion.api.minecraft.entities.Entity1_19_4Types;
 import com.viaversion.viaversion.api.minecraft.entities.EntityType;
-import com.viaversion.viaversion.api.protocol.remapper.PacketHandler;
+import com.viaversion.viaversion.api.minecraft.metadata.Metadata;
 import com.viaversion.viaversion.api.protocol.remapper.PacketHandlers;
 import com.viaversion.viaversion.api.type.Type;
 import com.viaversion.viaversion.api.type.types.version.Types1_19_4;
@@ -37,105 +37,18 @@ import com.viaversion.viaversion.rewriter.EntityRewriter;
 
 public final class EntityPackets extends EntityRewriter<ClientboundPackets1_19_4, Protocol1_20To1_19_4> {
 
+    private static final Quaternion Y_FLIPPED_ROTATION = new Quaternion(0, 1, 0, 0);
+
     public EntityPackets(final Protocol1_20To1_19_4 protocol) {
         super(protocol);
     }
 
     @Override
     public void registerPackets() {
+        registerTrackerWithData1_19(ClientboundPackets1_19_4.SPAWN_ENTITY, Entity1_19_4Types.FALLING_BLOCK);
         registerMetadataRewriter(ClientboundPackets1_19_4.ENTITY_METADATA, Types1_19_4.METADATA_LIST, Types1_20.METADATA_LIST);
         registerRemoveEntities(ClientboundPackets1_19_4.REMOVE_ENTITIES);
 
-        protocol.registerClientbound(ClientboundPackets1_19_4.SPAWN_ENTITY, new PacketHandlers() {
-            @Override
-            public void register() {
-                map(Type.VAR_INT); // Entity id
-                map(Type.UUID); // Entity UUID
-                map(Type.VAR_INT); // Entity type
-                map(Type.DOUBLE); // X
-                map(Type.DOUBLE); // Y
-                map(Type.DOUBLE); // Z
-                map(Type.BYTE); // Pitch
-                map(Type.BYTE); // Yaw
-                map(Type.BYTE); // Head yaw
-                map(Type.VAR_INT); // Data
-                handler(trackerHandler());
-                handler(wrapper -> {
-                    int entityId = wrapper.get(Type.VAR_INT, 0);
-                    EntityType entityType = tracker(wrapper.user()).entityType(entityId);
-                    if (entityType == Entity1_19_4Types.FALLING_BLOCK) {
-                        wrapper.set(Type.VAR_INT, 2, protocol.getMappingData().getNewBlockStateId(wrapper.get(Type.VAR_INT, 2)));
-                    } else if (entityType == Entity1_19_4Types.ITEM_DISPLAY) {
-                        // Turn it upside down
-                        wrapper.set(Type.BYTE, 0, (byte) -wrapper.get(Type.BYTE, 0));
-                        wrapper.set(Type.BYTE, 1, (byte) (wrapper.get(Type.BYTE, 1) - 128));
-                    }
-                });
-            }
-        });
-
-        final PacketHandler displayYawPitchHandler = wrapper -> {
-            final TrackedEntity trackedEntity = tracker(wrapper.user()).entity(wrapper.get(Type.VAR_INT, 0));
-            if (trackedEntity == null || trackedEntity.entityType() != Entity1_19_4Types.ITEM_DISPLAY) {
-                return;
-            }
-
-            // Turn it upside down
-            wrapper.set(Type.BYTE, 0, (byte) (wrapper.get(Type.BYTE, 0) - 128));
-            wrapper.set(Type.BYTE, 1, (byte) -wrapper.get(Type.BYTE, 1));
-        };
-        protocol.registerClientbound(ClientboundPackets1_19_4.ENTITY_POSITION_AND_ROTATION, new PacketHandlers() {
-            @Override
-            protected void register() {
-                map(Type.VAR_INT); // Entity id
-                map(Type.SHORT);   // Delta X
-                map(Type.SHORT);   // Delta Y
-                map(Type.SHORT);   // Delta Z
-                map(Type.BYTE);    // Yaw
-                map(Type.BYTE);    // Pitch
-                handler(displayYawPitchHandler);
-            }
-        });
-        protocol.registerClientbound(ClientboundPackets1_19_4.ENTITY_ROTATION, new PacketHandlers() {
-            @Override
-            protected void register() {
-                map(Type.VAR_INT); // Entity id
-                map(Type.BYTE);    // Yaw
-                map(Type.BYTE);    // Pitch
-                handler(displayYawPitchHandler);
-            }
-        });
-
-        protocol.registerClientbound(ClientboundPackets1_19_4.ENTITY_HEAD_LOOK, wrapper -> {
-            final TrackedEntity trackedEntity = tracker(wrapper.user()).entity(wrapper.passthrough(Type.VAR_INT));
-            if (trackedEntity == null || trackedEntity.entityType() != Entity1_19_4Types.ITEM_DISPLAY) {
-                return;
-            }
-
-            wrapper.write(Type.BYTE, (byte) (wrapper.read(Type.BYTE) - 128));
-        });
-
-        protocol.registerClientbound(ClientboundPackets1_19_4.ENTITY_TELEPORT, new PacketHandlers() {
-            @Override
-            protected void register() {
-                map(Type.VAR_INT); // Entity id
-                map(Type.DOUBLE);  // X
-                map(Type.DOUBLE);  // Y
-                map(Type.DOUBLE);  // Z
-                map(Type.BYTE);    // Yaw
-                map(Type.BYTE);    // Pitch
-                handler(wrapper -> {
-                    TrackedEntity trackedEntity = tracker(wrapper.user()).entity(wrapper.get(Type.VAR_INT, 0));
-                    if (trackedEntity == null || trackedEntity.entityType() != Entity1_19_4Types.ITEM_DISPLAY) {
-                        return;
-                    }
-
-                    wrapper.set(Type.BYTE, 0, (byte) (wrapper.get(Type.BYTE, 0) - 128));
-                    wrapper.set(Type.BYTE, 1, (byte) -wrapper.get(Type.BYTE, 1));
-                });
-            }
-        });
-
         protocol.registerClientbound(ClientboundPackets1_19_4.JOIN_GAME, new PacketHandlers() {
             @Override
             public void register() {
@@ -218,6 +131,21 @@ public final class EntityPackets extends EntityRewriter<ClientboundPackets1_19_4
         filter().handler((event, meta) -> meta.setMetaType(Types1_20.META_TYPES.byId(meta.metaType().typeId())));
         registerMetaTypeHandler(Types1_20.META_TYPES.itemType, Types1_20.META_TYPES.blockStateType, Types1_20.META_TYPES.optionalBlockStateType, Types1_20.META_TYPES.particleType);
 
+        // Rotate item display by 180 degrees around the Y axis
+        filter().filterFamily(Entity1_19_4Types.DISPLAY).handler((event, meta) -> {
+            if (event.trackedEntity().hasSentMetadata() || event.hasExtraMeta()) {
+                return;
+            }
+
+            if (event.metaAtIndex(12) == null) {
+                event.createExtraMeta(new Metadata(12, Types1_20.META_TYPES.quaternionType, Y_FLIPPED_ROTATION));
+            }
+        });
+        filter().filterFamily(Entity1_19_4Types.DISPLAY).index(12).handler((event, meta) -> {
+            final Quaternion quaternion = meta.value();
+            meta.setValue(rotateY180(quaternion));
+        });
+
         filter().filterFamily(Entity1_19_4Types.MINECART_ABSTRACT).index(11).handler((event, meta) -> {
             final int blockState = meta.value();
             meta.setValue(protocol.getMappingData().getNewBlockStateId(blockState));
@@ -228,4 +156,8 @@ public final class EntityPackets extends EntityRewriter<ClientboundPackets1_19_4
     public EntityType typeFromId(final int type) {
         return Entity1_19_4Types.getTypeFromId(type);
     }
+
+    private Quaternion rotateY180(final Quaternion quaternion) {
+        return new Quaternion(-quaternion.z(), quaternion.w(), quaternion.x(), -quaternion.y());
+    }
 }

common/src/main/java/com/viaversion/viaversion/rewriter/EntityRewriter.java

@@ -101,11 +101,11 @@ public abstract class EntityRewriter<C extends ClientboundPacketType, T extends
     }
 
     @Override
-    public void handleMetadata(int entityId, List<Metadata> metadataList, UserConnection connection) {
+    public void handleMetadata(final int entityId, final List<Metadata> metadataList, final UserConnection connection) {
         final TrackedEntity entity = tracker(connection).entity(entityId);
         final EntityType type = entity != null ? entity.entityType() : null;
         int i = 0; // Count index for fast removal
-        for (Metadata metadata : metadataList.toArray(EMPTY_ARRAY)) { // Copy the list to allow mutation
+        for (final Metadata metadata : metadataList.toArray(EMPTY_ARRAY)) { // Copy the list to allow mutation
             // Call handlers implementing the old handleMetadata
             if (!callOldMetaHandler(entityId, type, metadata, metadataList, connection)) {
                 metadataList.remove(i--);
@@ -113,18 +113,18 @@ public abstract class EntityRewriter<C extends ClientboundPacketType, T extends
             }
 
             MetaHandlerEvent event = null;
-            for (MetaFilter filter : metadataFilters) {
+            for (final MetaFilter filter : metadataFilters) {
                 if (!filter.isFiltered(type, metadata)) {
                     continue;
                 }
                 if (event == null) {
                     // Only initialize when needed and share event instance
-                    event = new MetaHandlerEventImpl(connection, type, entityId, metadata, metadataList);
+                    event = new MetaHandlerEventImpl(connection, entity, entityId, metadata, metadataList);
                 }
 
                 try {
                     filter.handler().handle(event, metadata);
-                } catch (Exception e) {
+                } catch (final Exception e) {
                     logException(e, type, metadataList, metadata);
                     metadataList.remove(i--);
                     break;

common/src/main/java/com/viaversion/viaversion/rewriter/meta/MetaHandlerEvent.java

@@ -18,11 +18,13 @@
 package com.viaversion.viaversion.rewriter.meta;
 
 import com.viaversion.viaversion.api.connection.UserConnection;
+import com.viaversion.viaversion.api.data.entity.TrackedEntity;
 import com.viaversion.viaversion.api.minecraft.entities.EntityType;
 import com.viaversion.viaversion.api.minecraft.metadata.Metadata;
-import java.util.List;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
+import java.util.List;
+
 public interface MetaHandlerEvent {
 
     /**
@@ -39,12 +41,21 @@ public interface MetaHandlerEvent {
      */
     int entityId();
 
+    /**
+     * Returns the tracked entity if present.
+     *
+     * @return tracked entity if present, else null
+     */
+    @Nullable TrackedEntity trackedEntity();
+
     /**
      * Returns the entity type of the entity the metadata belongs to if tracked.
      *
      * @return entity type of the entity if tracked, else null
      */
-    @Nullable EntityType entityType();
+    default @Nullable EntityType entityType() {
+        return trackedEntity() != null ? trackedEntity().entityType() : null;
+    }
 
     /**
      * Returns the metadata index.
@@ -110,6 +121,15 @@ public interface MetaHandlerEvent {
      */
     @Nullable List<Metadata> extraMeta();
 
+    /**
+     * Returns whether additionally created metadata will be added.
+     *
+     * @return true if additionally created metadata is present
+     */
+    default boolean hasExtraMeta() {
+        return extraMeta() != null;
+    }
+
     /**
      * Adds the given metadata to the metadata list.
      * This metadata will not be passed through handlers of the current loop.

common/src/main/java/com/viaversion/viaversion/rewriter/meta/MetaHandlerEventImpl.java

@@ -19,25 +19,26 @@
 package com.viaversion.viaversion.rewriter.meta;
 
 import com.viaversion.viaversion.api.connection.UserConnection;
-import com.viaversion.viaversion.api.minecraft.entities.EntityType;
+import com.viaversion.viaversion.api.data.entity.TrackedEntity;
 import com.viaversion.viaversion.api.minecraft.metadata.Metadata;
+import org.checkerframework.checker.nullness.qual.Nullable;
+
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.List;
-import org.checkerframework.checker.nullness.qual.Nullable;
 
 public class MetaHandlerEventImpl implements MetaHandlerEvent {
     private final UserConnection connection;
-    private final EntityType entityType;
+    private final TrackedEntity trackedEntity;
     private final int entityId;
     private final List<Metadata> metadataList;
     private final Metadata meta;
     private List<Metadata> extraData;
     private boolean cancel;
 
-    public MetaHandlerEventImpl(UserConnection connection, @Nullable EntityType entityType, int entityId, Metadata meta, List<Metadata> metadataList) {
+    public MetaHandlerEventImpl(UserConnection connection, @Nullable TrackedEntity trackedEntity, int entityId, Metadata meta, List<Metadata> metadataList) {
         this.connection = connection;
-        this.entityType = entityType;
+        this.trackedEntity = trackedEntity;
         this.entityId = entityId;
         this.meta = meta;
         this.metadataList = metadataList;
@@ -54,8 +55,8 @@ public class MetaHandlerEventImpl implements MetaHandlerEvent {
     }
 
     @Override
-    public @Nullable EntityType entityType() {
+    public @Nullable TrackedEntity trackedEntity() {
-        return entityType;
+        return trackedEntity;
     }
 
     @Override