From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Phoenix616 <mail@moep.tv>
Date: Mon, 13 Jan 2020 15:40:32 +0100
Subject: [PATCH] Seed based feature search

This tries to work around the issue where the server will load
surrounding chunks up to a radius of 100 chunks in order to search for
features e.g. when running the /locate command or for treasure maps
(issue #2312).
This is done by backporting Mojang's change in 1.17 which makes it so
that the biome (generated by the seed) is checked first if the feature
can be generated before actually to load the chunk.

The only downside of this is that it breaks once the seed or generator
changes but this should usually not happen. A config option to disable
this improvement is added though in case that should ever be necessary.

diff --git a/src/main/java/com/destroystokyo/paper/PaperWorldConfig.java b/src/main/java/com/destroystokyo/paper/PaperWorldConfig.java
index 9a0ade5875c34487a65f82f9380f9d25b4432586..ff0e4447b6574e91bf8815de4e04ce881ed7026d 100644
--- a/src/main/java/com/destroystokyo/paper/PaperWorldConfig.java
+++ b/src/main/java/com/destroystokyo/paper/PaperWorldConfig.java
@@ -331,6 +331,12 @@ public class PaperWorldConfig {
         }
     }
 
+    public boolean seedBasedFeatureSearch = true;
+    private void seedBasedFeatureSearch() {
+        seedBasedFeatureSearch = getBoolean("seed-based-feature-search", seedBasedFeatureSearch);
+        log("Feature search is based on seed: " + seedBasedFeatureSearch);
+    }
+
     public int maxCollisionsPerEntity;
     private void maxEntityCollision() {
         maxCollisionsPerEntity = getInt( "max-entity-collisions", this.spigotConfig.getInt("max-entity-collisions", 8) );
diff --git a/src/main/java/net/minecraft/server/BiomeManager.java b/src/main/java/net/minecraft/server/BiomeManager.java
index 5c992812e0c066109763a30c9399e5b71a335398..fddcd205ee4d841546463913f56f998059cba248 100644
--- a/src/main/java/net/minecraft/server/BiomeManager.java
+++ b/src/main/java/net/minecraft/server/BiomeManager.java
@@ -22,6 +22,7 @@ public class BiomeManager {
         return new BiomeManager(worldchunkmanager, this.b, this.c);
     }
 
+    public BiomeBase getBiome(BlockPosition blockposition) { return a(blockposition); } // Paper - OBFHELPER
     public BiomeBase a(BlockPosition blockposition) {
         return this.c.a(this.b, blockposition.getX(), blockposition.getY(), blockposition.getZ(), this.a);
     }
diff --git a/src/main/java/net/minecraft/server/ChunkCoordIntPair.java b/src/main/java/net/minecraft/server/ChunkCoordIntPair.java
index dcaf9f8574a9c913b64ba3a1d8b02220db720225..271fddbbf73ca5c0e4e2722d7246c14b778d6072 100644
--- a/src/main/java/net/minecraft/server/ChunkCoordIntPair.java
+++ b/src/main/java/net/minecraft/server/ChunkCoordIntPair.java
@@ -67,10 +67,12 @@ public class ChunkCoordIntPair {
         }
     }
 
+    public int getBlockX() { return d(); } // Paper - OBFHELPER
     public int d() {
         return this.x << 4;
     }
 
+    public int getBlockZ() { return e(); } // Paper - OBFHELPER
     public int e() {
         return this.z << 4;
     }
diff --git a/src/main/java/net/minecraft/server/StructureGenerator.java b/src/main/java/net/minecraft/server/StructureGenerator.java
index c3bd58069d8dbdf36f70f1dafd7c24000f31708b..a62c87bceab2c9700a7b3925f208b0ffa2b9b393 100644
--- a/src/main/java/net/minecraft/server/StructureGenerator.java
+++ b/src/main/java/net/minecraft/server/StructureGenerator.java
@@ -143,6 +143,14 @@ public abstract class StructureGenerator<C extends WorldGenFeatureConfiguration>
                             int j2 = i1 + k * l1;
                             ChunkCoordIntPair chunkcoordintpair = this.a(structuresettingsfeature, j, seededrandom, i2, j2);
                             if (!iworldreader.getWorldBorder().isChunkInBounds(chunkcoordintpair.x, chunkcoordintpair.z)) { continue; } // Paper
+                            // Paper start - seed based feature search
+                            if (structuremanager.getWorld().paperConfig.seedBasedFeatureSearch) {
+                                BiomeBase biomeBase = structuremanager.getWorld().getBiomeManager().getBiome(new BlockPosition(chunkcoordintpair.getBlockX() + 9, 0, chunkcoordintpair.getBlockZ() + 9));
+                                if (!biomeBase.e().a(this)) {
+                                    continue;
+                                }
+                            }
+                            // Paper end
                             IChunkAccess ichunkaccess = iworldreader.getChunkAt(chunkcoordintpair.x, chunkcoordintpair.z, ChunkStatus.STRUCTURE_STARTS);
                             StructureStart<?> structurestart = structuremanager.a(SectionPosition.a(ichunkaccess.getPos(), 0), this, ichunkaccess);
 
diff --git a/src/main/java/net/minecraft/server/World.java b/src/main/java/net/minecraft/server/World.java
index 822b587cc92bb25ec8618fd9d86ce2c9233a69b6..9ed21f434c5fb019b74dfe9ee0b802ccc5c07fd8 100644
--- a/src/main/java/net/minecraft/server/World.java
+++ b/src/main/java/net/minecraft/server/World.java
@@ -1451,8 +1451,8 @@ public abstract class World implements GeneratorAccess, AutoCloseable {
         return this.methodProfiler;
     }
 
-    @Override
-    public BiomeManager d() {
+    public BiomeManager getBiomeManager() { return d(); } // Paper - OBFHELPER
+    @Override public BiomeManager d() {
         return this.biomeManager;
     }
 
