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 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000 100644
--- a/src/main/java/com/destroystokyo/paper/PaperWorldConfig.java
+++ b/src/main/java/com/destroystokyo/paper/PaperWorldConfig.java
@@ -0,0 +0,0 @@ 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/world/level/ChunkCoordIntPair.java b/src/main/java/net/minecraft/world/level/ChunkCoordIntPair.java
index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000 100644
--- a/src/main/java/net/minecraft/world/level/ChunkCoordIntPair.java
+++ b/src/main/java/net/minecraft/world/level/ChunkCoordIntPair.java
@@ -0,0 +0,0 @@ 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/world/level/World.java b/src/main/java/net/minecraft/world/level/World.java
index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000 100644
--- a/src/main/java/net/minecraft/world/level/World.java
+++ b/src/main/java/net/minecraft/world/level/World.java
@@ -0,0 +0,0 @@ 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;
     }
 
diff --git a/src/main/java/net/minecraft/world/level/biome/BiomeManager.java b/src/main/java/net/minecraft/world/level/biome/BiomeManager.java
index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000 100644
--- a/src/main/java/net/minecraft/world/level/biome/BiomeManager.java
+++ b/src/main/java/net/minecraft/world/level/biome/BiomeManager.java
@@ -0,0 +0,0 @@ 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/world/level/levelgen/feature/StructureGenerator.java b/src/main/java/net/minecraft/world/level/levelgen/feature/StructureGenerator.java
index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000 100644
--- a/src/main/java/net/minecraft/world/level/levelgen/feature/StructureGenerator.java
+++ b/src/main/java/net/minecraft/world/level/levelgen/feature/StructureGenerator.java
@@ -0,0 +0,0 @@ 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);