From 9eea5f5e252e3ae31c5996ea89ae5ca2d4a49a1f Mon Sep 17 00:00:00 2001
From: YoyoNow <jwsteam@nidido.de>
Date: Sat, 31 Oct 2026 22:24:51 +0100
Subject: [PATCH] Keep hidden block entities in chunks without their data

Hidden block entities were removed from chunk data, so the client did not
render blocks like shulker boxes at all. They are now sent with empty data,
hiding their contents but not the block itself.
---
 .../src/de/steamwar/techhider/ChunkHider.java | 33 ++++++++++++-------
 HiderCore/src/hidercore.accesswidener         |  1 +
 2 files changed, 23 insertions(+), 11 deletions(-)

diff --git a/HiderCore/src/de/steamwar/techhider/ChunkHider.java b/HiderCore/src/de/steamwar/techhider/ChunkHider.java
index 6cabee7b..ab4eb45e 100644
--- a/HiderCore/src/de/steamwar/techhider/ChunkHider.java
+++ b/HiderCore/src/de/steamwar/techhider/ChunkHider.java
@@ -23,6 +23,7 @@ import de.steamwar.core.ProtocolUtils;
 import de.steamwar.techhider.AccessPrivilegeProvider.ForPlayer;
 import io.netty.buffer.ByteBuf;
 import io.netty.buffer.Unpooled;
+import net.minecraft.nbt.CompoundTag;
 import net.minecraft.network.protocol.game.ClientboundLevelChunkPacketData;
 import net.minecraft.network.protocol.game.ClientboundLevelChunkWithLightPacket;
 import net.minecraft.util.SimpleBitStorage;
@@ -31,6 +32,7 @@ import net.minecraft.world.level.block.entity.BlockEntityType;
 import net.minecraft.world.level.block.state.BlockState;
 import org.bukkit.entity.Player;
 
+import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.List;
 import java.util.function.UnaryOperator;
@@ -263,21 +265,30 @@ public class ChunkHider {
     private List<ClientboundLevelChunkPacketData.BlockEntityInfo> filterBlockEntities(ForPlayer access, List<ClientboundLevelChunkPacketData.BlockEntityInfo> blockEntities, int chunkX, int chunkZ) {
         int fourBitBitmask = 0b0000_1111;
 
-        return blockEntities.stream()
-                .filter((blockEntityInfo) -> {
-                    BlockEntityType<?> type = blockEntityInfo.type;
-                    int packedXZ = blockEntityInfo.packedXZ;
+        List<ClientboundLevelChunkPacketData.BlockEntityInfo> filtered = new ArrayList<>(blockEntities.size());
+        for (ClientboundLevelChunkPacketData.BlockEntityInfo blockEntityInfo : blockEntities) {
+            BlockEntityType<?> type = blockEntityInfo.type;
+            int packedXZ = blockEntityInfo.packedXZ;
 
-                    int localX = (packedXZ >> 4) & fourBitBitmask;
-                    int localZ = packedXZ & fourBitBitmask;
+            int localX = (packedXZ >> 4) & fourBitBitmask;
+            int localZ = packedXZ & fourBitBitmask;
 
-                    int worldX = (chunkX * SECTION_SPAN_SIZE) + localX;
-                    int worldZ = (chunkZ * SECTION_SPAN_SIZE) + localZ;
+            int worldX = (chunkX * SECTION_SPAN_SIZE) + localX;
+            int worldZ = (chunkZ * SECTION_SPAN_SIZE) + localZ;
 
-                    int worldY = blockEntityInfo.y;
+            int worldY = blockEntityInfo.y;
 
-                    return access.canAccessPosition(worldX, worldY, worldZ) && access.canAccessBlockEntity(worldX, worldY, worldZ, type);
-                }).toList();
+            // A hidden position is obfuscated as a whole
+            if (!access.canAccessPosition(worldX, worldY, worldZ)) continue;
+
+            if (access.canAccessBlockEntity(worldX, worldY, worldZ, type)) {
+                filtered.add(blockEntityInfo);
+            } else {
+                // Without its block entity, the client would not render blocks like shulker boxes, so only their data is hidden
+                filtered.add(new ClientboundLevelChunkPacketData.BlockEntityInfo(packedXZ, worldY, type, new CompoundTag()));
+            }
+        }
+        return filtered;
     }
 
     private void copyOverSectionBiomeData(ByteBuf oldData, ByteBuf newData) {
diff --git a/HiderCore/src/hidercore.accesswidener b/HiderCore/src/hidercore.accesswidener
index 347067a1..9a266fac 100644
--- a/HiderCore/src/hidercore.accesswidener
+++ b/HiderCore/src/hidercore.accesswidener
@@ -25,3 +25,4 @@ accessible class net/minecraft/network/protocol/game/ClientboundLevelChunkPacket
 accessible field net/minecraft/network/protocol/game/ClientboundLevelChunkPacketData$BlockEntityInfo type Lnet/minecraft/world/level/block/entity/BlockEntityType;
 accessible field net/minecraft/network/protocol/game/ClientboundLevelChunkPacketData$BlockEntityInfo packedXZ I
 accessible field net/minecraft/network/protocol/game/ClientboundLevelChunkPacketData$BlockEntityInfo y I
+accessible method net/minecraft/network/protocol/game/ClientboundLevelChunkPacketData$BlockEntityInfo <init> (IILnet/minecraft/world/level/block/entity/BlockEntityType;Lnet/minecraft/nbt/CompoundTag;)V