From 50d294d2c40846fbbfb0dd3eb1e2e2dbdd8c4744 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 8753bea614..039f27312a 100644
--- a/src/main/java/net/minecraft/server/IBlockAccess.java
+++ b/src/main/java/net/minecraft/server/IBlockAccess.java
@@ -27,7 +27,15 @@ 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();
@@ -96,7 +104,7 @@ public interface IBlockAccess {
                 double d13 = d10 * (i1 > 0 ? 1.0D - MathHelper.h(d4) : MathHelper.h(d4));
                 double d14 = d11 * (j1 > 0 ? 1.0D - MathHelper.h(d5) : MathHelper.h(d5));
 
-                Object object;
+                T object; // Paper - decompile fix (TODO move to mcdev)
 
                 do {
                     if (d12 > 1.0D && d13 > 1.0D && d14 > 1.0D) {
-- 
2.21.0