Paper/patches/unapplied/server/0337-Fix-items-not-falling-correctly.patch

From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: AJMFactsheets <AJMFactsheets@gmail.com>
Date: Fri, 17 Jan 2020 17:17:54 -0600
Subject: [PATCH] Fix items not falling correctly

Since 1.14, Mojang has added an optimization which skips checking if
an item should fall every fourth tick.

However, Spigot's entity activation range class also has an
optimization which skips ticking active entities every fourth tick.
This can result in a state where an item will never properly fall
due to its move method never being called.

This patch resolves the conflict by offsetting checking Spigot's entity
activation range check from an item's move method.

diff --git a/src/main/java/net/minecraft/world/entity/item/ItemEntity.java b/src/main/java/net/minecraft/world/entity/item/ItemEntity.java
index 007625b1a121f1e7241f7cbfba0b1f168e8be5df..6836288bd380651007f3aa76e608767f612f6644 100644
--- a/src/main/java/net/minecraft/world/entity/item/ItemEntity.java
+++ b/src/main/java/net/minecraft/world/entity/item/ItemEntity.java
@@ -149,7 +149,7 @@ public class ItemEntity extends Entity implements TraceableEntity {
                 }
             }
 
-            if (!this.onGround || this.getDeltaMovement().horizontalDistanceSqr() > 9.999999747378752E-6D || (this.tickCount + this.getId()) % 4 == 0) {
+            if (!this.onGround || this.getDeltaMovement().horizontalDistanceSqr() > 9.999999747378752E-6D || (this.tickCount + this.getId()) % 4 == 0) { // Paper - Diff on change
                 this.move(MoverType.SELF, this.getDeltaMovement());
                 float f1 = 0.98F;
 
diff --git a/src/main/java/org/spigotmc/ActivationRange.java b/src/main/java/org/spigotmc/ActivationRange.java
index e2dfc4d9a16a738dd0fe91838603e1d4370afa56..08bf9f85fe02a3f89640a2f3ae23089a119a394a 100644
--- a/src/main/java/org/spigotmc/ActivationRange.java
+++ b/src/main/java/org/spigotmc/ActivationRange.java
@@ -257,7 +257,7 @@ public class ActivationRange
                 isActive = true;
             }
             // Add a little performance juice to active entities. Skip 1/4 if not immune.
-        } else if ( !entity.defaultActivationState && entity.tickCount % 4 == 0 && !ActivationRange.checkEntityImmunities( entity ) )
+        } else if ( !entity.defaultActivationState && (entity.tickCount + entity.getId()) % 4 == 0 && !ActivationRange.checkEntityImmunities( entity ) ) // Paper - Ensure checking item movement is offset from Spigot's entity activation range check
         {
             isActive = false;
         }