From d1ca33ace69f0cd276ba58742fe9ff06482f4473 Mon Sep 17 00:00:00 2001
From: Aikar <aikar@aikar.co>
Date: Fri, 18 Mar 2016 21:22:56 -0400
Subject: [PATCH] Optimized Light Level Comparisons

Use an optimized method to test if a block position meets a desired light level.

This method benefits from returning as soon as the desired light level matches.

diff --git a/src/main/java/net/minecraft/server/BlockCrops.java b/src/main/java/net/minecraft/server/BlockCrops.java
index 1506c9ede0..6ae6fc3ecb 100644
--- a/src/main/java/net/minecraft/server/BlockCrops.java
+++ b/src/main/java/net/minecraft/server/BlockCrops.java
@@ -44,7 +44,7 @@ public class BlockCrops extends BlockPlant implements IBlockFragilePlantElement
 
     public void a(IBlockData iblockdata, World world, BlockPosition blockposition, Random random) {
         super.a(iblockdata, world, blockposition, random);
-        if (world.getLightLevel(blockposition.up(), 0) >= 9) {
+        if (world.isLightLevel(blockposition.up(), 9)) { // Paper
             int i = this.k(iblockdata);
 
             if (i < this.e()) {
diff --git a/src/main/java/net/minecraft/server/BlockSapling.java b/src/main/java/net/minecraft/server/BlockSapling.java
index 42478d1fed..7426d14cbf 100644
--- a/src/main/java/net/minecraft/server/BlockSapling.java
+++ b/src/main/java/net/minecraft/server/BlockSapling.java
@@ -30,7 +30,7 @@ public class BlockSapling extends BlockPlant implements IBlockFragilePlantElemen
 
     public void a(IBlockData iblockdata, World world, BlockPosition blockposition, Random random) {
         super.a(iblockdata, world, blockposition, random);
-        if (world.getLightLevel(blockposition.up()) >= 9 && random.nextInt(Math.max(2, (int) (((100.0F / world.spigotConfig.saplingModifier) * 7) + 0.5F))) == 0) { // Spigot
+        if (world.isLightLevel(blockposition.up(), 9) && random.nextInt(Math.max(2, (int) (((100.0F / world.spigotConfig.saplingModifier) * 7) + 0.5F))) == 0) { // Spigot // Paper
             // CraftBukkit start
             world.captureTreeGeneration = true;
             // CraftBukkit end
diff --git a/src/main/java/net/minecraft/server/BlockStem.java b/src/main/java/net/minecraft/server/BlockStem.java
index dd309030e5..7cddfc380c 100644
--- a/src/main/java/net/minecraft/server/BlockStem.java
+++ b/src/main/java/net/minecraft/server/BlockStem.java
@@ -27,7 +27,7 @@ public class BlockStem extends BlockPlant implements IBlockFragilePlantElement {
 
     public void a(IBlockData iblockdata, World world, BlockPosition blockposition, Random random) {
         super.a(iblockdata, world, blockposition, random);
-        if (world.getLightLevel(blockposition.up(), 0) >= 9) {
+        if (world.isLightLevel(blockposition.up(), 9)) { // Paper
             float f = BlockCrops.a((Block) this, (IBlockAccess) world, blockposition);
 
             if (random.nextInt((int) ((100.0F / (this == Blocks.PUMPKIN_STEM ? world.spigotConfig.pumpkinModifier : world.spigotConfig.melonModifier)) * (25.0F / f)) + 1) == 0) { // Spigot
diff --git a/src/main/java/net/minecraft/server/EntityMonster.java b/src/main/java/net/minecraft/server/EntityMonster.java
index f3cc2cef0a..7cba60e475 100644
--- a/src/main/java/net/minecraft/server/EntityMonster.java
+++ b/src/main/java/net/minecraft/server/EntityMonster.java
@@ -63,8 +63,18 @@ public abstract class EntityMonster extends EntityCreature implements IMonster {
         if (this.world.getBrightness(EnumSkyBlock.SKY, blockposition) > this.random.nextInt(32)) {
             return false;
         } else {
-            int i = this.world.Y() ? this.world.d(blockposition, 10) : this.world.getLightLevel(blockposition);
-            return i <= this.random.nextInt(8);
+            // Paper start - optimized light check, returns faster
+            boolean passes;
+            if (this.world.Y()) {
+                final int orig = world.getSkylightSubtracted();
+                world.setSkylightSubtracted(10);
+                passes = !this.world.isLightLevel(blockposition, this.random.nextInt(8));
+                world.setSkylightSubtracted(orig);
+            } else {
+                passes = !this.world.isLightLevel(blockposition, this.random.nextInt(8));
+            }
+            return passes;
+            // Paper end
         }
     }
 
diff --git a/src/main/java/net/minecraft/server/EntityZombie.java b/src/main/java/net/minecraft/server/EntityZombie.java
index 1ab3072cc3..e5170bff5b 100644
--- a/src/main/java/net/minecraft/server/EntityZombie.java
+++ b/src/main/java/net/minecraft/server/EntityZombie.java
@@ -263,7 +263,7 @@ public class EntityZombie extends EntityMonster {
                     int j1 = j + MathHelper.nextInt(this.random, 7, 40) * MathHelper.nextInt(this.random, -1, 1);
                     int k1 = k + MathHelper.nextInt(this.random, 7, 40) * MathHelper.nextInt(this.random, -1, 1);
 
-                    if (this.world.getType(new BlockPosition(i1, j1 - 1, k1)).q() && this.world.getLightLevel(new BlockPosition(i1, j1, k1)) < 10) {
+                    if (this.world.getType(new BlockPosition(i1, j1 - 1, k1)).q() && !this.world.isLightLevel(new BlockPosition(i1, j1, k1), 10)) { // Paper
                         entityzombie.setPosition((double) i1, (double) j1, (double) k1);
                         if (!this.world.isPlayerNearby((double) i1, (double) j1, (double) k1, 7.0D) && this.world.a_(entityzombie, entityzombie.getBoundingBox()) && this.world.getCubes(entityzombie, entityzombie.getBoundingBox()) && !this.world.containsLiquid(entityzombie.getBoundingBox())) {
                             this.world.addEntity(entityzombie, CreatureSpawnEvent.SpawnReason.REINFORCEMENTS); // CraftBukkit
-- 
2.19.0