add region entity

src/main/java/emu/grasscutter/game/entity/EntityRegion.java

@@ -0,0 +1,74 @@
+package emu.grasscutter.game.entity;
+
+import emu.grasscutter.game.props.EntityIdType;
+import emu.grasscutter.game.world.Scene;
+import emu.grasscutter.net.proto.SceneEntityInfoOuterClass;
+import emu.grasscutter.scripts.data.SceneRegion;
+import emu.grasscutter.utils.Position;
+import it.unimi.dsi.fastutil.ints.Int2FloatOpenHashMap;
+import lombok.Getter;
+
+import java.util.Set;
+import java.util.concurrent.ConcurrentHashMap;
+
+@Getter
+public class EntityRegion extends GameEntity{
+    private final Position position;
+    private boolean hasNewEntities;
+    private final Set<Integer> entities; // Ids of entities inside this region
+    private final SceneRegion metaRegion;
+
+    public EntityRegion(Scene scene, SceneRegion region) {
+        super(scene);
+        this.id = getScene().getWorld().getNextEntityId(EntityIdType.REGION);
+        setGroupId(region.group.id);
+        setBlockId(region.group.block_id);
+        setConfigId(region.config_id);
+        this.position = region.pos.clone();
+        this.entities = ConcurrentHashMap.newKeySet();
+        this.metaRegion = region;
+    }
+
+    public void addEntity(GameEntity entity) {
+        if (this.getEntities().contains(entity.getId())) {
+            return;
+        }
+        this.getEntities().add(entity.getId());
+        this.hasNewEntities = true;
+    }
+
+    public boolean hasNewEntities() {
+        return hasNewEntities;
+    }
+
+    public void resetNewEntities() {
+        hasNewEntities = false;
+    }
+
+    public void removeEntity(GameEntity entity) {
+        this.getEntities().remove(entity.getId());
+    }
+
+    @Override
+    public Int2FloatOpenHashMap getFightProperties() {
+        return null;
+    }
+
+    @Override
+    public Position getPosition() {
+        return position;
+    }
+
+    @Override
+    public Position getRotation() {
+        return null;
+    }
+
+    @Override
+    public SceneEntityInfoOuterClass.SceneEntityInfo toProto() {
+        /**
+         * The Region Entity would not be sent to client.
+         */
+        return null;
+    }
+}