Seed based feature search (Fixes #2312) (#2852)

Spigot-Server-Patches/0434-Seed-based-feature-search.patch

@@ -0,0 +1,113 @@
+From f6980b7867cefdfbb83471c04034465e6e3f004e 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 fixes 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 using the same seed checking functionality that is used
+by the server when generating these features before actually attempting
+to load the chunk to check if a feature is available in it.
+
+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 3b8488d3f..bce502181 100644
+--- a/src/main/java/com/destroystokyo/paper/PaperWorldConfig.java
++++ b/src/main/java/com/destroystokyo/paper/PaperWorldConfig.java
+@@ -359,6 +359,12 @@ 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 e96f544f1..68423645d 100644
+--- a/src/main/java/net/minecraft/server/BiomeManager.java
++++ b/src/main/java/net/minecraft/server/BiomeManager.java
+@@ -12,10 +12,12 @@ public class BiomeManager {
+         this.c = genlayerzoomer;
+     }
+ 
++    public BiomeManager withProvider(WorldChunkManager worldchunkmanager) { return a(worldchunkmanager); } // Paper - OBFHELPER
+     public BiomeManager a(WorldChunkManager worldchunkmanager) {
+         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 f2a19acd8..09f1308b0 100644
+--- a/src/main/java/net/minecraft/server/ChunkCoordIntPair.java
++++ b/src/main/java/net/minecraft/server/ChunkCoordIntPair.java
+@@ -64,10 +64,12 @@ 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 e8ce2ecf2..acfe732af 100644
+--- a/src/main/java/net/minecraft/server/StructureGenerator.java
++++ b/src/main/java/net/minecraft/server/StructureGenerator.java
+@@ -109,6 +109,15 @@ public abstract class StructureGenerator<C extends WorldGenFeatureConfiguration>
+                             if (flag1 || flag2) {
+                                 ChunkCoordIntPair chunkcoordintpair = this.a(chunkgenerator, seededrandom, j, k, i1, j1);
+                                 if (!world.getWorldBorder().isChunkInBounds(chunkcoordintpair.x, chunkcoordintpair.z)) { continue; } // Paper
++                                // Paper start - seed based feature search
++                                if (world.paperConfig.seedBasedFeatureSearch) {
++                                    BiomeManager biomeManager = world.getBiomeManager().withProvider(chunkgenerator.getWorldChunkManager());
++                                    BiomeBase biomeBase = biomeManager.getBiome(new BlockPosition(chunkcoordintpair.getBlockX() + 9, 0, chunkcoordintpair.getBlockZ() + 9));
++                                    if (!shouldGenerate(biomeManager, chunkgenerator, seededrandom, chunkcoordintpair.x, chunkcoordintpair.z, biomeBase)) {
++                                        continue;
++                                    }
++                                }
++                                // Paper end
+                                 StructureStart structurestart = world.getChunkAt(chunkcoordintpair.x, chunkcoordintpair.z, ChunkStatus.STRUCTURE_STARTS).a(this.b());
+ 
+                                 if (structurestart != null && structurestart.e()) {
+@@ -165,6 +174,7 @@ public abstract class StructureGenerator<C extends WorldGenFeatureConfiguration>
+         return new ChunkCoordIntPair(i + k, j + l);
+     }
+ 
++    public boolean shouldGenerate(BiomeManager biomemanager, ChunkGenerator<?> chunkgenerator, Random random, int chunkX, int chunkZ, BiomeBase biomebase) { return a(biomemanager, chunkgenerator, random, chunkX, chunkZ, biomebase); } // Paper - OBFHELPER
+     public abstract boolean a(BiomeManager biomemanager, ChunkGenerator<?> chunkgenerator, Random random, int i, int j, BiomeBase biomebase);
+ 
+     public abstract StructureGenerator.a a();
+diff --git a/src/main/java/net/minecraft/server/World.java b/src/main/java/net/minecraft/server/World.java
+index 9df079d8a..8a2bb79ad 100644
+--- a/src/main/java/net/minecraft/server/World.java
++++ b/src/main/java/net/minecraft/server/World.java
+@@ -1588,8 +1588,8 @@ 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;
+     }
+ }
+-- 
+2.18.0.windows.1
+