Paper/patches/server/0316-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 9badb48b6004c5799132ed70ddcc767bdd72510c..7d12bedc4b80b9bcf50f468a9204191bea0894c1 100644
--- a/src/main/java/net/minecraft/world/entity/item/ItemEntity.java
+++ b/src/main/java/net/minecraft/world/entity/item/ItemEntity.java
@@ -168,7 +168,7 @@ 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 e5ff35531a933268f2b8b6c15c234de4482931d5..90df7e83d9166c22a56a31db22d843768229b9ab 100644
--- a/src/main/java/org/spigotmc/ActivationRange.java
+++ b/src/main/java/org/spigotmc/ActivationRange.java
@@ -254,7 +254,7 @@ 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;
         }