From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Aikar <aikar@aikar.co>
Date: Sun, 10 May 2020 22:12:46 -0400
Subject: [PATCH] Ensure Entity AABB's are never invalid

If anything used setPositionRaw, it left potential for an AABB
to be left stale at their old location, which could cause massive
AABB boxes if movement ever then got called on the new position.

This guarantees any time we set the entities position, we also
update their AABB.

diff --git a/src/main/java/net/minecraft/server/Entity.java b/src/main/java/net/minecraft/server/Entity.java
index c005734f835fd07b121fdb885d981e55f8be81b4..c5adac15d726dd03853cef10758a21e5ce690567 100644
--- a/src/main/java/net/minecraft/server/Entity.java
+++ b/src/main/java/net/minecraft/server/Entity.java
@@ -416,10 +416,11 @@ public abstract class Entity implements INamableTileEntity, ICommandListener, Ke
 
     public void setPosition(double d0, double d1, double d2) {
         this.setPositionRaw(d0, d1, d2);
-        float f = this.size.width / 2.0F;
-        float f1 = this.size.height;
-
-        this.a(new AxisAlignedBB(d0 - (double) f, d1, d2 - (double) f, d0 + (double) f, d1 + (double) f1, d2 + (double) f));
+        // Paper start - move into setPositionRaw
+        //float f = this.size.width / 2.0F;
+        //float f1 = this.size.height;
+        //this.a(new AxisAlignedBB(d0 - (double) f, d1, d2 - (double) f, d0 + (double) f, d1 + (double) f1, d2 + (double) f));
+        // Paper end
         if (valid) ((WorldServer) world).chunkCheck(this); // CraftBukkit
     }
 
@@ -2981,6 +2982,7 @@ public abstract class Entity implements INamableTileEntity, ICommandListener, Ke
         return new AxisAlignedBB(vec3d, vec3d1);
     }
 
+    public final void setBoundingBox(AxisAlignedBB axisalignedbb) { a(axisalignedbb); } // Paper - OBFHELPER
     public void a(AxisAlignedBB axisalignedbb) {
         // CraftBukkit start - block invalid bounding boxes
         double minX = axisalignedbb.minX,
@@ -3439,6 +3441,14 @@ public abstract class Entity implements INamableTileEntity, ICommandListener, Ke
     }
 
     public void setPositionRaw(double d0, double d1, double d2) {
+        // Paper start - never allow AABB to become desynced from position
+        // hanging has its own special logic
+        if (!(this instanceof EntityHanging) && (locX != d0 || locY != d1 || locZ != d2)) {
+            float f = this.size.width / 2.0F;
+            float f1 = this.size.height;
+            this.setBoundingBox(new AxisAlignedBB(d0 - (double) f, d1, d2 - (double) f, d0 + (double) f, d1 + (double) f1, d2 + (double) f));
+        }
+        // Paper end
         this.locX = d0;
         this.locY = d1;
         this.locZ = d2;