Don't mutate the position of Items for MC-4 Fix (#12702)

paper-server/patches/sources/net/minecraft/network/protocol/game/VecDeltaCodec.java.patch

@@ -1,6 +1,6 @@
 --- a/net/minecraft/network/protocol/game/VecDeltaCodec.java
 +++ b/net/minecraft/network/protocol/game/VecDeltaCodec.java
-@@ -5,16 +_,16 @@
+@@ -5,7 +_,7 @@
  
  public class VecDeltaCodec {
      private static final double TRUNCATION_STEPS = 4096.0;
@@ -9,14 +9,3 @@
  
      @VisibleForTesting
      static long encode(double value) {
--        return Math.round(value * 4096.0);
-+        return Math.round(value * 4096.0); // Paper - Fix MC-4; diff on change
-     }
- 
-     @VisibleForTesting
-     static double decode(long value) {
--        return value / 4096.0;
-+        return value / 4096.0; // Paper - Fix MC-4; diff on change
-     }
- 
-     public Vec3 decode(long x, long y, long z) {

paper-server/patches/sources/net/minecraft/world/entity/Entity.java.patch

@@ -1786,7 +1786,7 @@
      }
  
      public void addDeltaMovement(Vec3 addend) {
-@@ -3661,9 +_,45 @@
+@@ -3661,9 +_,35 @@
          return this.getZ((2.0 * this.random.nextDouble() - 1.0) * scale);
      }
  
@@ -1815,16 +1815,6 @@
 +            return;
 +        }
 +        // Paper end - Block invalid positions and bounding box
-+        // Paper start - Fix MC-4
-+        if (this instanceof ItemEntity) {
-+            if (io.papermc.paper.configuration.GlobalConfiguration.get().misc.fixEntityPositionDesync) {
-+                // encode/decode from VecDeltaCodec todo computation changed?
-+                x = Mth.lfloor(x * 4096.0) * (1 / 4096.0);
-+                y = Mth.lfloor(y * 4096.0) * (1 / 4096.0);
-+                z = Mth.lfloor(z * 4096.0) * (1 / 4096.0);
-+            }
-+        }
-+        // Paper end - Fix MC-4
          if (this.position.x != x || this.position.y != y || this.position.z != z) {
 +            synchronized (this.posLock) { // Paper - detailed watchdog information
              this.position = new Vec3(x, y, z);

paper-server/patches/sources/net/minecraft/world/entity/item/ItemEntity.java.patch

@@ -24,6 +24,21 @@
      }
  
      public ItemEntity(Level level, double posX, double posY, double posZ, ItemStack itemStack, double deltaX, double deltaY, double deltaZ) {
+@@ -79,6 +_,14 @@
+         this.bobOffs = other.bobOffs;
+     }
+ 
++    // Paper start - Require item entities to send their location precisely (Fixes MC-4)
++    {
++        if (io.papermc.paper.configuration.GlobalConfiguration.get().misc.sendFullPosForItemEntities) {
++            this.setRequiresPrecisePosition(true);
++        }
++    }
++    // Paper end - Require item entities to send their location precisely (Fixes MC-4)
++
+     @Override
+     public boolean dampensVibrations() {
+         return this.getItem().is(ItemTags.DAMPENS_VIBRATIONS);
 @@ -116,7 +_,7 @@
      @Override
      public void tick() {

paper-server/src/main/java/io/papermc/paper/configuration/GlobalConfiguration.java

@@ -343,7 +343,7 @@ public class GlobalConfiguration extends ConfigurationPart {
             }
         }
         public int maxJoinsPerTick = 5;
-        public boolean fixEntityPositionDesync = true;
+        public boolean sendFullPosForItemEntities = false;
         public boolean loadPermissionsYmlBeforePlugins = true;
         @Constraints.Min(4)
         public int regionFileCacheSize = 256;

paper-server/src/main/java/io/papermc/paper/configuration/RemovedConfigurations.java

@@ -82,6 +82,7 @@ interface RemovedConfigurations {
         path("unsupported-settings", "allow-grindstone-overstacking"),
         path("unsupported-settings", "allow-tripwire-disarming-exploits"),
         path("commands", "fix-target-selector-tag-completion"),
+        path("misc", "fix-entity-position-desync")
     };
 
 }