From 9b61494eaa31126974f10637653cf39c1fcca4d2 Mon Sep 17 00:00:00 2001
From: Aikar <aikar@aikar.co>
Date: Mon, 26 Nov 2018 19:21:58 -0500
Subject: [PATCH] Prevent rayTrace from loading chunks

ray tracing into an unloaded chunk should be treated as a miss
this saves a ton of lag for when AI tries to raytrace near unloaded chunks.

diff --git a/src/main/java/net/minecraft/server/IBlockAccess.java b/src/main/java/net/minecraft/server/IBlockAccess.java
index 577b227758..c5586e44d4 100644
--- a/src/main/java/net/minecraft/server/IBlockAccess.java
+++ b/src/main/java/net/minecraft/server/IBlockAccess.java
@@ -41,7 +41,15 @@ public interface IBlockAccess {
 
     default MovingObjectPositionBlock rayTrace(RayTrace raytrace) {
         return (MovingObjectPositionBlock) a(raytrace, (raytrace1, blockposition) -> {
-            IBlockData iblockdata = this.getType(blockposition);
+            // Paper start - Prevent raytrace from loading chunks
+            IBlockData iblockdata = ((World)this).getTypeIfLoaded(blockposition);
+            if (iblockdata == null) {
+                // copied the last function parameter (listed below)
+                Vec3D vec3d = raytrace1.b().d(raytrace1.a());
+
+                return MovingObjectPositionBlock.a(raytrace1.a(), EnumDirection.a(vec3d.x, vec3d.y, vec3d.z), new BlockPosition(raytrace1.a()));
+            }
+            // Paper end
             Fluid fluid = this.getFluid(blockposition);
             Vec3D vec3d = raytrace1.b();
             Vec3D vec3d1 = raytrace1.a();
-- 
2.21.0