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 13725b794e923a4de0d06edcba1adf1b04611c95..4c0e12d9f36c78eeae4dcb2f58d41503d3a046e4 100644
--- a/src/main/java/net/minecraft/server/level/ServerLevel.java
+++ b/src/main/java/net/minecraft/server/level/ServerLevel.java
@@ -2149,6 +2149,15 @@ public class ServerLevel extends Level implements WorldGenLevel {
             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 360e322ee298048bd280160a49f000384d930c3a..6f687387d8f817646dacf0e0373d50db8ee80dd5 100644
--- a/src/main/java/net/minecraft/world/entity/Entity.java
+++ b/src/main/java/net/minecraft/world/entity/Entity.java
@@ -320,7 +320,27 @@ public abstract class Entity implements Nameable, EntityAccess, CommandSource, S
     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;
     }
@@ -2055,6 +2075,15 @@ public abstract class Entity implements Nameable, EntityAccess, CommandSource, S
                 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");
@@ -2182,6 +2211,20 @@ public abstract class Entity implements Nameable, EntityAccess, CommandSource, S
             }
             // 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 0f51f05f334d262b3435cebce47c3b9f08936398..85d77772b003e56382f8c3b55fc11a9ae1ec535f 100644
--- a/src/main/java/org/bukkit/craftbukkit/entity/CraftEntity.java
+++ b/src/main/java/org/bukkit/craftbukkit/entity/CraftEntity.java
@@ -936,4 +936,21 @@ 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
 }