Change darkness->blindness in 1.19->1.18.2 (#908)

common/src/main/java/com/viaversion/viabackwards/ViaBackwardsConfig.java

@@ -36,6 +36,7 @@ public class ViaBackwardsConfig extends Config implements com.viaversion.viaback
     private boolean handlePingsAsInvAcknowledgements;
     private boolean bedrockAtY0;
     private boolean sculkShriekersToCryingObsidian;
+    private boolean mapDarknessEffect;
     private boolean suppressEmulationWarnings;
 
     public ViaBackwardsConfig(File configFile, Logger logger) {
@@ -57,6 +58,7 @@ public class ViaBackwardsConfig extends Config implements com.viaversion.viaback
         handlePingsAsInvAcknowledgements = getBoolean("handle-pings-as-inv-acknowledgements", false);
         bedrockAtY0 = getBoolean("bedrock-at-y-0", false);
         sculkShriekersToCryingObsidian = getBoolean("sculk-shriekers-to-crying-obsidian", false);
+        mapDarknessEffect = getBoolean("map-darkness-effect", true);
         suppressEmulationWarnings = getBoolean("suppress-emulation-warnings", false);
     }
 
@@ -100,6 +102,11 @@ public class ViaBackwardsConfig extends Config implements com.viaversion.viaback
         return sculkShriekersToCryingObsidian;
     }
 
+    @Override
+    public boolean mapDarknessEffect() {
+        return mapDarknessEffect;
+    }
+
     @Override
     public boolean suppressEmulationWarnings() {
         return suppressEmulationWarnings;

common/src/main/java/com/viaversion/viabackwards/api/ViaBackwardsConfig.java

@@ -78,6 +78,13 @@ public interface ViaBackwardsConfig extends Config {
      */
     boolean sculkShriekerToCryingObsidian();
 
+    /**
+     * Maps the darkness effect to blindness for 1.18.2 clients on 1.19+ servers.
+     *
+     * @return true if enabled
+     */
+    boolean mapDarknessEffect();
+
     /**
      * Suppresses warnings of missing emulations for certain features that are not supported (e.g. world height in 1.17+).
      *

common/src/main/java/com/viaversion/viabackwards/protocol/v1_19to1_18_2/Protocol1_19To1_18_2.java

@@ -28,11 +28,11 @@ import com.viaversion.viabackwards.protocol.v1_19to1_18_2.rewriter.BlockItemPack
 import com.viaversion.viabackwards.protocol.v1_19to1_18_2.rewriter.CommandRewriter1_19;
 import com.viaversion.viabackwards.protocol.v1_19to1_18_2.rewriter.EntityPacketRewriter1_19;
 import com.viaversion.viabackwards.protocol.v1_19to1_18_2.storage.DimensionRegistryStorage;
+import com.viaversion.viabackwards.protocol.v1_19to1_18_2.storage.EntityTracker1_19;
 import com.viaversion.viabackwards.protocol.v1_19to1_18_2.storage.NonceStorage;
 import com.viaversion.viaversion.api.Via;
 import com.viaversion.viaversion.api.connection.UserConnection;
 import com.viaversion.viaversion.api.minecraft.RegistryType;
-import com.viaversion.viaversion.api.minecraft.entities.EntityTypes1_19;
 import com.viaversion.viaversion.api.minecraft.signature.SignableCommandArgumentsProvider;
 import com.viaversion.viaversion.api.minecraft.signature.model.DecoratableMessage;
 import com.viaversion.viaversion.api.minecraft.signature.model.MessageMetadata;
@@ -40,7 +40,6 @@ import com.viaversion.viaversion.api.minecraft.signature.storage.ChatSession1_19
 import com.viaversion.viaversion.api.protocol.packet.State;
 import com.viaversion.viaversion.api.protocol.remapper.PacketHandlers;
 import com.viaversion.viaversion.api.type.Types;
-import com.viaversion.viaversion.data.entity.EntityTrackerBase;
 import com.viaversion.viaversion.libs.gson.JsonElement;
 import com.viaversion.viaversion.protocols.base.ClientboundLoginPackets;
 import com.viaversion.viaversion.protocols.base.ServerboundLoginPackets;
@@ -364,7 +363,7 @@ public final class Protocol1_19To1_18_2 extends BackwardsProtocol<ClientboundPac
     @Override
     public void init(final UserConnection user) {
         user.put(new DimensionRegistryStorage());
-        addEntityTracker(user, new EntityTrackerBase(user, EntityTypes1_19.PLAYER));
+        addEntityTracker(user, new EntityTracker1_19(user));
     }
 
     @Override

common/src/main/java/com/viaversion/viabackwards/protocol/v1_19to1_18_2/rewriter/EntityPacketRewriter1_19.java

@@ -20,9 +20,11 @@ package com.viaversion.viabackwards.protocol.v1_19to1_18_2.rewriter;
 import com.viaversion.nbt.tag.CompoundTag;
 import com.viaversion.nbt.tag.ListTag;
 import com.viaversion.nbt.tag.NumberTag;
+import com.viaversion.viabackwards.ViaBackwards;
 import com.viaversion.viabackwards.api.rewriters.EntityRewriter;
 import com.viaversion.viabackwards.protocol.v1_19to1_18_2.Protocol1_19To1_18_2;
 import com.viaversion.viabackwards.protocol.v1_19to1_18_2.storage.DimensionRegistryStorage;
+import com.viaversion.viabackwards.protocol.v1_19to1_18_2.storage.EntityTracker1_19;
 import com.viaversion.viabackwards.protocol.v1_19to1_18_2.storage.LastDeathPosition;
 import com.viaversion.viabackwards.protocol.v1_19to1_18_2.storage.StoredPainting;
 import com.viaversion.viaversion.api.data.ParticleMappings;
@@ -111,6 +113,50 @@ public final class EntityPacketRewriter1_19 extends EntityRewriter<ClientboundPa
                 handler(wrapper -> {
                     // Remove factor data
                     wrapper.read(Types.OPTIONAL_NAMED_COMPOUND_TAG);
+
+                    if (!ViaBackwards.getConfig().mapDarknessEffect()) {
+                        return;
+                    }
+
+                    final EntityTracker1_19 tracker = tracker(wrapper.user());
+
+                    final int entityId = wrapper.get(Types.VAR_INT, 0);
+                    final int effectId = wrapper.get(Types.VAR_INT, 1);
+                    if (effectId == 33) { // Newly added darkness, rewrite to blindness
+                        tracker.getAffectedByDarkness().add(entityId);
+                        wrapper.set(Types.VAR_INT, 1, 15);
+                    } else if (effectId == 15) { // Track actual blindness effect for removal later
+                        tracker.getAffectedByBlindness().add(entityId);
+                    }
+                });
+            }
+        });
+
+        protocol.registerClientbound(ClientboundPackets1_19.REMOVE_MOB_EFFECT, new PacketHandlers() {
+            @Override
+            protected void register() {
+                map(Types.VAR_INT); // Entity id
+                map(Types.VAR_INT); // Effect id
+                handler(wrapper -> {
+                    if (!ViaBackwards.getConfig().mapDarknessEffect()) {
+                        return;
+                    }
+
+                    final int entityId = wrapper.get(Types.VAR_INT, 0);
+                    final int effectId = wrapper.get(Types.VAR_INT, 1);
+
+                    final EntityTracker1_19 tracker = tracker(wrapper.user());
+                    if (effectId == 33) { // Remove darkness and the fake blindness effect if the client doesn't have actual blindness
+                        tracker.getAffectedByDarkness().rem(entityId);
+                        if (!tracker.getAffectedByBlindness().contains(entityId)) {
+                            wrapper.set(Types.VAR_INT, 1, 15);
+                        }
+                    } else if (effectId == 15) { // Remove blindness and cancel if the client has darkness (will be removed by darkness removal)
+                        tracker.getAffectedByBlindness().rem(entityId);
+                        if (tracker.getAffectedByDarkness().contains(entityId)) {
+                            wrapper.cancel();
+                        }
+                    }
                 });
             }
         });

common/src/main/java/com/viaversion/viabackwards/protocol/v1_19to1_18_2/storage/EntityTracker1_19.java

@@ -0,0 +1,49 @@
+/*
+ * This file is part of ViaBackwards - https://github.com/ViaVersion/ViaBackwards
+ * Copyright (C) 2016-2024 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.viabackwards.protocol.v1_19to1_18_2.storage;
+
+import com.viaversion.viaversion.api.connection.UserConnection;
+import com.viaversion.viaversion.api.minecraft.entities.EntityTypes1_19;
+import com.viaversion.viaversion.data.entity.EntityTrackerBase;
+import com.viaversion.viaversion.libs.fastutil.ints.IntArrayList;
+import com.viaversion.viaversion.libs.fastutil.ints.IntList;
+
+public final class EntityTracker1_19 extends EntityTrackerBase {
+
+    private final IntList affectedByBlindness = new IntArrayList();
+    private final IntList affectedByDarkness = new IntArrayList();
+
+    public EntityTracker1_19(final UserConnection connection) {
+        super(connection, EntityTypes1_19.PLAYER);
+    }
+
+    @Override
+    public void removeEntity(final int id) {
+        super.removeEntity(id);
+        this.affectedByBlindness.rem(id);
+        this.affectedByDarkness.rem(id);
+    }
+
+    public IntList getAffectedByBlindness() {
+        return affectedByBlindness;
+    }
+
+    public IntList getAffectedByDarkness() {
+        return affectedByDarkness;
+    }
+}

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

@@ -28,5 +28,8 @@ bedrock-at-y-0: false
 # If disabled, the client will see them as end portal frames.
 sculk-shriekers-to-crying-obsidian: true
 #
+# Maps the darkness effect to blindness for 1.18.2 clients on 1.19+ servers.
+map-darkness-effect: true
+#
 # Suppresses warnings of missing emulations for certain features that are not supported (e.g. world height in 1.17+).
 suppress-emulation-warnings: false