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 2edc55f09b79ac75788a0ded8b3d2a6800674470..9b9d491c7c41590c93d606414902329b6636419f 100644
--- a/src/main/java/net/minecraft/world/entity/item/ItemEntity.java
+++ b/src/main/java/net/minecraft/world/entity/item/ItemEntity.java
@@ -150,7 +150,7 @@ 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 1d9ce6dae17ff572d4528971c69c63d0f85b313c..305d9772f2af22e8bdf73235cdb15ea01ac2c3b3 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;
         }