From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Byteflux <byte@byteflux.net>
Date: Tue, 1 Mar 2016 23:45:08 -0600
Subject: [PATCH] Entity Origin API


diff --git a/src/main/java/net/minecraft/server/level/ServerLevel.java b/src/main/java/net/minecraft/server/level/ServerLevel.java
index f3633da64f990972cddc03f2fcfd34ced2955a7a..025363e6b51ff8aa089715b1ec2a0fa1caab65d6 100644
--- a/src/main/java/net/minecraft/server/level/ServerLevel.java
+++ b/src/main/java/net/minecraft/server/level/ServerLevel.java
@@ -2182,6 +2182,15 @@ public class ServerLevel extends Level implements ServerEntityGetter, WorldGenLe
             entity.updateDynamicGameEventListener(DynamicGameEventListener::add);
             entity.inWorld = true; // CraftBukkit - Mark entity as in world
             entity.valid = true; // CraftBukkit
+            // Paper start - Entity origin API
+            if (entity.getOriginVector() == null) {
+                entity.setOrigin(entity.getBukkitEntity().getLocation());
+            }
+            // Default to current world if unknown, gross assumption but entities rarely change world
+            if (entity.getOriginWorld() == null) {
+                entity.setOrigin(entity.getOriginVector().toLocation(getWorld()));
+            }
+            // Paper end - Entity origin API
         }
 
         public void onTrackingEnd(Entity entity) {
diff --git a/src/main/java/net/minecraft/world/entity/Entity.java b/src/main/java/net/minecraft/world/entity/Entity.java
index aba3e1b5d86940f91034ee6415c909529503a184..57960530e15f0e4b8fb40b725ff03aaf8ce6ffac 100644
--- a/src/main/java/net/minecraft/world/entity/Entity.java
+++ b/src/main/java/net/minecraft/world/entity/Entity.java
@@ -332,7 +332,27 @@ public abstract class Entity implements SyncedDataHolder, Nameable, EntityAccess
     public long activatedTick = Integer.MIN_VALUE;
     public void inactiveTick() { }
     // Spigot end
+    // Paper start - Entity origin API
+    @javax.annotation.Nullable
+    private org.bukkit.util.Vector origin;
+    @javax.annotation.Nullable
+    private UUID originWorld;
 
+    public void setOrigin(@javax.annotation.Nonnull Location location) {
+        this.origin = location.toVector();
+        this.originWorld = location.getWorld().getUID();
+    }
+
+    @javax.annotation.Nullable
+    public org.bukkit.util.Vector getOriginVector() {
+        return this.origin != null ? this.origin.clone() : null;
+    }
+
+    @javax.annotation.Nullable
+    public UUID getOriginWorld() {
+        return this.originWorld;
+    }
+    // Paper end - Entity origin API
     public float getBukkitYaw() {
         return this.yRot;
     }
@@ -2270,6 +2290,15 @@ public abstract class Entity implements SyncedDataHolder, Nameable, EntityAccess
                 this.bukkitEntity.storeBukkitValues(nbttagcompound);
             }
             // CraftBukkit end
+            // Paper start
+            if (this.origin != null) {
+                UUID originWorld = this.originWorld != null ? this.originWorld : this.level != null ? this.level.getWorld().getUID() : null;
+                if (originWorld != null) {
+                    nbttagcompound.putUUID("Paper.OriginWorld", originWorld);
+                }
+                nbttagcompound.put("Paper.Origin", this.newDoubleList(origin.getX(), origin.getY(), origin.getZ()));
+            }
+            // Paper end
             return nbttagcompound;
         } catch (Throwable throwable) {
             CrashReport crashreport = CrashReport.forThrowable(throwable, "Saving entity NBT");
@@ -2398,6 +2427,20 @@ public abstract class Entity implements SyncedDataHolder, Nameable, EntityAccess
             }
             // CraftBukkit end
 
+            // Paper start
+            ListTag originTag = nbt.getList("Paper.Origin", net.minecraft.nbt.Tag.TAG_DOUBLE);
+            if (!originTag.isEmpty()) {
+                UUID originWorld = null;
+                if (nbt.contains("Paper.OriginWorld")) {
+                    originWorld = nbt.getUUID("Paper.OriginWorld");
+                } else if (this.level != null) {
+                    originWorld = this.level.getWorld().getUID();
+                }
+                this.originWorld = originWorld;
+                origin = new org.bukkit.util.Vector(originTag.getDouble(0), originTag.getDouble(1), originTag.getDouble(2));
+            }
+            // Paper end
+
         } catch (Throwable throwable) {
             CrashReport crashreport = CrashReport.forThrowable(throwable, "Loading entity NBT");
             CrashReportCategory crashreportsystemdetails = crashreport.addCategory("Entity being loaded");
diff --git a/src/main/java/org/bukkit/craftbukkit/entity/CraftEntity.java b/src/main/java/org/bukkit/craftbukkit/entity/CraftEntity.java
index 978397e517a6fdb24c7d2b3f242545af07deeab0..ea27931d01c1f3c721b2f7ec12d41ea843fa158a 100644
--- a/src/main/java/org/bukkit/craftbukkit/entity/CraftEntity.java
+++ b/src/main/java/org/bukkit/craftbukkit/entity/CraftEntity.java
@@ -964,4 +964,21 @@ public abstract class CraftEntity implements org.bukkit.entity.Entity {
         return this.spigot;
     }
     // Spigot end
+
+    // Paper start - entity origin API
+    @Override
+    public Location getOrigin() {
+        Vector originVector = this.getHandle().getOriginVector();
+        if (originVector == null) {
+            return null;
+        }
+        World world = this.getWorld();
+        if (this.getHandle().getOriginWorld() != null) {
+            world = org.bukkit.Bukkit.getWorld(this.getHandle().getOriginWorld());
+        }
+
+        //noinspection ConstantConditions
+        return originVector.toLocation(world);
+    }
+    // Paper end - entity origin API
 }