From e5393751430b80662bb303c66d9d2be841edfd82 Mon Sep 17 00:00:00 2001
From: RK_01 <50594595+RaphiMC@users.noreply.github.com>
Date: Wed, 30 Oct 2024 21:43:27 +0100
Subject: [PATCH] Only apply chunk loading fix for 1.21.2 clients (#14)

---
 .../protocols/v1_21to1_21_2/Protocol1_21To1_21_2.java  |  9 ++++++++-
 .../rewriter/BlockItemPacketRewriter1_21_2.java        | 10 +++++++++-
 .../rewriter/EntityPacketRewriter1_21_2.java           |  5 ++++-
 3 files changed, 21 insertions(+), 3 deletions(-)

diff --git a/common/src/main/java/com/viaversion/viaversion/protocols/v1_21to1_21_2/Protocol1_21To1_21_2.java b/common/src/main/java/com/viaversion/viaversion/protocols/v1_21to1_21_2/Protocol1_21To1_21_2.java
index 609a0e5f2..cef630da6 100644
--- a/common/src/main/java/com/viaversion/viaversion/protocols/v1_21to1_21_2/Protocol1_21To1_21_2.java
+++ b/common/src/main/java/com/viaversion/viaversion/protocols/v1_21to1_21_2/Protocol1_21To1_21_2.java
@@ -27,6 +27,7 @@ import com.viaversion.viaversion.api.protocol.packet.PacketWrapper;
 import com.viaversion.viaversion.api.protocol.packet.State;
 import com.viaversion.viaversion.api.protocol.packet.provider.PacketTypesProvider;
 import com.viaversion.viaversion.api.protocol.packet.provider.SimplePacketTypesProvider;
+import com.viaversion.viaversion.api.protocol.version.ProtocolVersion;
 import com.viaversion.viaversion.api.rewriter.ComponentRewriter;
 import com.viaversion.viaversion.api.type.Types;
 import com.viaversion.viaversion.api.type.types.misc.ParticleType;
@@ -234,8 +235,14 @@ public final class Protocol1_21To1_21_2 extends AbstractProtocol<ClientboundPack
         addEntityTracker(connection, new EntityTracker1_21_2(connection));
         connection.put(new BundleStateTracker());
         connection.put(new PlayerPositionStorage());
-        connection.put(new ChunkLoadTracker());
         connection.put(new GroundFlagTracker());
+
+        // <= 1.21.1 clients allowed loaded chunks to get replaced with new data without unloading them first.
+        // 1.21.2 introduced a graphical bug where it doesn't properly render the new data unless the chunk is unloaded beforehand.
+        // 1.21.4 fixed this bug, so the workaround is no longer needed.
+        if (connection.getProtocolInfo().protocolVersion().equals(ProtocolVersion.v1_21_2)) {
+            connection.put(new ChunkLoadTracker());
+        }
     }
 
     @Override
diff --git a/common/src/main/java/com/viaversion/viaversion/protocols/v1_21to1_21_2/rewriter/BlockItemPacketRewriter1_21_2.java b/common/src/main/java/com/viaversion/viaversion/protocols/v1_21to1_21_2/rewriter/BlockItemPacketRewriter1_21_2.java
index 9a3865987..c40b3e9a8 100644
--- a/common/src/main/java/com/viaversion/viaversion/protocols/v1_21to1_21_2/rewriter/BlockItemPacketRewriter1_21_2.java
+++ b/common/src/main/java/com/viaversion/viaversion/protocols/v1_21to1_21_2/rewriter/BlockItemPacketRewriter1_21_2.java
@@ -376,6 +376,10 @@ public final class BlockItemPacketRewriter1_21_2 extends StructuredItemRewriter<
             }
 
             final ChunkLoadTracker chunkLoadTracker = wrapper.user().get(ChunkLoadTracker.class);
+            if (chunkLoadTracker == null) {
+                return;
+            }
+
             if (chunkLoadTracker.isChunkLoaded(chunk.getX(), chunk.getZ())) {
                 // Unload the old chunk, so the new one can be loaded without graphical glitches
                 // Bundling it prevents the client from falling through the world during the chunk swap
@@ -401,7 +405,11 @@ public final class BlockItemPacketRewriter1_21_2 extends StructuredItemRewriter<
         });
         protocol.registerClientbound(ClientboundPackets1_21.FORGET_LEVEL_CHUNK, wrapper -> {
             final ChunkPosition chunkPosition = wrapper.passthrough(Types.CHUNK_POSITION);
-            wrapper.user().get(ChunkLoadTracker.class).removeChunk(chunkPosition.chunkX(), chunkPosition.chunkZ());
+
+            final ChunkLoadTracker chunkLoadTracker = wrapper.user().get(ChunkLoadTracker.class);
+            if (chunkLoadTracker != null) {
+                chunkLoadTracker.removeChunk(chunkPosition.chunkX(), chunkPosition.chunkZ());
+            }
         });
     }
 
diff --git a/common/src/main/java/com/viaversion/viaversion/protocols/v1_21to1_21_2/rewriter/EntityPacketRewriter1_21_2.java b/common/src/main/java/com/viaversion/viaversion/protocols/v1_21to1_21_2/rewriter/EntityPacketRewriter1_21_2.java
index aba23c3a8..5ed1ce96c 100644
--- a/common/src/main/java/com/viaversion/viaversion/protocols/v1_21to1_21_2/rewriter/EntityPacketRewriter1_21_2.java
+++ b/common/src/main/java/com/viaversion/viaversion/protocols/v1_21to1_21_2/rewriter/EntityPacketRewriter1_21_2.java
@@ -159,7 +159,10 @@ public final class EntityPacketRewriter1_21_2 extends EntityRewriter<Clientbound
 
             final EntityTracker entityTracker = tracker(wrapper.user());
             if (entityTracker.currentWorld() != null && !entityTracker.currentWorld().equals(world)) {
-                wrapper.user().get(ChunkLoadTracker.class).clear();
+                final ChunkLoadTracker chunkLoadTracker = wrapper.user().get(ChunkLoadTracker.class);
+                if (chunkLoadTracker != null) {
+                    chunkLoadTracker.clear();
+                }
             }
 
             trackWorldDataByKey1_20_5(wrapper.user(), dimensionId, world);