PaperMC/patches/server-remapped/Optimize-Collision-to-not-load-chunks.patch

From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Aikar <aikar@aikar.co>
Date: Thu, 2 Apr 2020 02:37:57 -0400
Subject: [PATCH] Optimize Collision to not load chunks

The collision code takes an AABB and generates a cuboid of checks rather
than a cylinder, so at high velocity this can generate a lot of chunk checks.

Treat an unloaded chunk as a collision for entities, and also for players if
the "prevent moving into unloaded chunks" setting is enabled.

If that serting is not enabled, collisions will be ignored for players, since
movement will load only the chunk the player enters anyways and avoids loading
massive amounts of surrounding chunks due to large AABB lookups.

diff --git a/src/main/java/net/minecraft/server/players/PlayerList.java b/src/main/java/net/minecraft/server/players/PlayerList.java
index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000 100644
--- a/src/main/java/net/minecraft/server/players/PlayerList.java
+++ b/src/main/java/net/minecraft/server/players/PlayerList.java
@@ -0,0 +0,0 @@ import net.minecraft.server.MCUtil;
 import net.minecraft.server.MinecraftServer;
 import net.minecraft.server.PlayerAdvancements;
 import net.minecraft.server.ServerScoreboard;
+import net.minecraft.server.level.ServerLevel;
+import net.minecraft.server.level.ServerPlayer;
+import net.minecraft.server.level.ServerPlayerGameMode;
+import net.minecraft.server.level.TicketType;
+import net.minecraft.server.network.ServerGamePacketListenerImpl;
+import net.minecraft.server.network.ServerLoginPacketListenerImpl;
+import net.minecraft.sounds.SoundEvents;
+import net.minecraft.sounds.SoundSource;
+import net.minecraft.stats.ServerStatsCounter;
+import net.minecraft.stats.Stats;
 import net.minecraft.tags.BlockTags;
 import net.minecraft.tags.Tag;
 import net.minecraft.util.Mth;
 import net.minecraft.world.effect.MobEffectInstance;
 import net.minecraft.world.entity.Entity;
 import net.minecraft.world.entity.EntityType;
+import net.minecraft.world.level.ChunkPos;
 import net.minecraft.world.level.GameRules;
 import net.minecraft.world.level.GameType;
 import net.minecraft.world.level.Level;
@@ -0,0 +0,0 @@ import io.papermc.paper.adventure.PaperAdventure; // Paper
 import com.google.common.base.Predicate;
 import com.google.common.collect.Iterables;
 import net.minecraft.server.dedicated.DedicatedServer;
-import net.minecraft.server.level.ServerLevel;
-import net.minecraft.server.level.ServerPlayer;
-import net.minecraft.server.level.ServerPlayerGameMode;
-import net.minecraft.server.network.ServerGamePacketListenerImpl;
-import net.minecraft.server.network.ServerLoginPacketListenerImpl;
-import net.minecraft.sounds.SoundEvents;
-import net.minecraft.sounds.SoundSource;
-import net.minecraft.stats.ServerStatsCounter;
-import net.minecraft.stats.Stats;
 import org.bukkit.craftbukkit.CraftServer;
 import org.bukkit.craftbukkit.CraftWorld;
 
@@ -0,0 +0,0 @@ public abstract class PlayerList {
         entityplayer1.forceSetPositionRotation(location.getX(), location.getY(), location.getZ(), location.getYaw(), location.getPitch());
         // CraftBukkit end
 
+        worldserver1.getChunkSource().addRegionTicket(TicketType.POST_TELEPORT, new ChunkPos(location.getBlockX() >> 4, location.getBlockZ() >> 4), 1, entityplayer.getId()); // Paper
         while (avoidSuffocation && !worldserver1.noCollision(entityplayer1) && entityplayer1.getY() < 256.0D) {
             entityplayer1.setPos(entityplayer1.getX(), entityplayer1.getY() + 1.0D, entityplayer1.getZ());
         }
diff --git a/src/main/java/net/minecraft/world/entity/Entity.java b/src/main/java/net/minecraft/world/entity/Entity.java
index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000 100644
--- a/src/main/java/net/minecraft/world/entity/Entity.java
+++ b/src/main/java/net/minecraft/world/entity/Entity.java
@@ -0,0 +0,0 @@ public abstract class Entity implements Nameable, CommandSource, net.minecraft.s
     private CraftEntity bukkitEntity;
 
     ChunkMap.TrackedEntity tracker; // Paper
+    public boolean collisionLoadChunks = false; // Paper
     public Throwable addedToWorldStack; // Paper - entity debug
     public CraftEntity getBukkitEntity() {
         if (bukkitEntity == null) {
diff --git a/src/main/java/net/minecraft/world/level/CollisionGetter.java b/src/main/java/net/minecraft/world/level/CollisionGetter.java
index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000 100644
--- a/src/main/java/net/minecraft/world/level/CollisionGetter.java
+++ b/src/main/java/net/minecraft/world/level/CollisionGetter.java
@@ -0,0 +0,0 @@ public interface CollisionGetter extends BlockGetter {
     }
 
     default boolean noCollision(@Nullable Entity entity, AABB axisalignedbb, Predicate<Entity> predicate) {
+        try { if (entity != null) entity.collisionLoadChunks = true; // Paper
         return this.getCollisions(entity, axisalignedbb, predicate).allMatch(VoxelShape::isEmpty);
+        } finally { if (entity != null) entity.collisionLoadChunks = false; } // Paper
     }
 
     Stream<VoxelShape> getEntityCollisions(@Nullable Entity entity, AABB axisalignedbb, Predicate<Entity> predicate);
diff --git a/src/main/java/net/minecraft/world/level/CollisionSpliterator.java b/src/main/java/net/minecraft/world/level/CollisionSpliterator.java
index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000 100644
--- a/src/main/java/net/minecraft/world/level/CollisionSpliterator.java
+++ b/src/main/java/net/minecraft/world/level/CollisionSpliterator.java
@@ -0,0 +0,0 @@ import java.util.function.Consumer;
 import javax.annotation.Nullable;
 import net.minecraft.core.BlockPos;
 import net.minecraft.core.Cursor3D;
+import net.minecraft.server.MCUtil;
+import net.minecraft.server.level.ServerPlayer;
+import net.minecraft.server.level.WorldGenRegion;
 import net.minecraft.util.Mth;
 import net.minecraft.world.entity.Entity;
 import net.minecraft.world.level.block.Blocks;
@@ -0,0 +0,0 @@ import net.minecraft.world.phys.shapes.VoxelShape;
 public class CollisionSpliterator extends AbstractSpliterator<VoxelShape> {
 
     @Nullable
-    private final Entity source;
+    private final Entity source; final Entity getEntity() { return this.source; } // Paper - OBFHELPER
     private final AABB box;
     private final CollisionContext context;
     private final Cursor3D cursor;
-    private final BlockPos.MutableBlockPos pos;
+    private final BlockPos.MutableBlockPos pos; final BlockPos.MutableBlockPos getMutablePos() { return this.pos; } // Paper - OBFHELPER
     private final VoxelShape entityShape;
-    private final CollisionGetter collisionGetter;
+    private final CollisionGetter collisionGetter; final CollisionGetter getCollisionAccess() { return this.collisionGetter; } // Paper - OBFHELPER
     private boolean needsBorderCheck;
     private final BiPredicate<BlockState, BlockPos> predicate;
 
@@ -0,0 +0,0 @@ public class CollisionSpliterator extends AbstractSpliterator<VoxelShape> {
     boolean collisionCheck(Consumer<? super VoxelShape> consumer) {
         while (true) {
             if (this.cursor.advance()) {
-                int i = this.cursor.nextX();
-                int j = this.cursor.nextY();
-                int k = this.cursor.nextZ();
+                int i = this.cursor.nextX(); final int x = i;
+                int j = this.cursor.nextY(); final int y = j;
+                int k = this.cursor.nextZ(); final int z = k;
                 int l = this.cursor.getNextType();
 
                 if (l == 3) {
                     continue;
                 }
 
-                BlockGetter iblockaccess = this.getChunk(i, k);
-
-                if (iblockaccess == null) {
+                // Paper start - ensure we don't load chunks
+                Entity entity = this.getEntity();
+                BlockPos.MutableBlockPos blockposition_mutableblockposition = this.getMutablePos();
+                boolean far = entity != null && MCUtil.distanceSq(entity.getX(), y, entity.getZ(), x, y, z) > 14;
+                blockposition_mutableblockposition.setValues(x, y, z);
+
+                boolean isRegionLimited = this.getCollisionAccess() instanceof WorldGenRegion;
+                BlockState iblockdata = isRegionLimited ? Blocks.VOID_AIR.defaultBlockState() : ((!far && entity instanceof ServerPlayer) || (entity != null && entity.collisionLoadChunks)
+                    ? this.getCollisionAccess().getBlockState(blockposition_mutableblockposition)
+                    : this.getCollisionAccess().getTypeIfLoaded(blockposition_mutableblockposition)
+                );
+
+                if (iblockdata == null) {
+                    if (!(entity instanceof ServerPlayer) || entity.level.paperConfig.preventMovingIntoUnloadedChunks) {
+                        VoxelShape voxelshape3 = Shapes.of(far ? entity.getBoundingBox() : new AABB(new BlockPos(x, y, z)));
+                        consumer.accept(voxelshape3);
+                        return true;
+                    }
                     continue;
                 }
-
-                this.pos.set(i, j, k);
-                BlockState iblockdata = iblockaccess.getBlockState(this.pos);
+                // Paper - moved up
+                // Paper end
 
                 if (!this.predicate.test(iblockdata, this.pos) || l == 1 && !iblockdata.hasLargeCollisionShape() || l == 2 && !iblockdata.is(Blocks.MOVING_PISTON)) {
                     continue;
diff --git a/src/main/java/net/minecraft/world/phys/shapes/Shapes.java b/src/main/java/net/minecraft/world/phys/shapes/Shapes.java
index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000 100644
--- a/src/main/java/net/minecraft/world/phys/shapes/Shapes.java
+++ b/src/main/java/net/minecraft/world/phys/shapes/Shapes.java
@@ -0,0 +0,0 @@ public final class Shapes {
 
                             if (k2 < 3) {
                                 blockposition_mutableblockposition.set(enumaxiscycle1, i2, j2, l1);
-                                BlockState iblockdata = world.getBlockState(blockposition_mutableblockposition);
+                                BlockState iblockdata = world.getTypeIfLoaded(blockposition_mutableblockposition); // Paper
+                                if (iblockdata == null) return 0.0D; // Paper
 
                                 if ((k2 != 1 || iblockdata.hasLargeCollisionShape()) && (k2 != 2 || iblockdata.is(Blocks.MOVING_PISTON))) {
                                     initial = iblockdata.getCollisionShape((BlockGetter) world, blockposition_mutableblockposition, context).collide(enumdirection_enumaxis2, box.move((double) (-blockposition_mutableblockposition.getX()), (double) (-blockposition_mutableblockposition.getY()), (double) (-blockposition_mutableblockposition.getZ())), initial);