HowTo/Upgrade GameObject.GetId()

The following is an example of how to update a script which uses the obsolete script function GameObject.GetId(). It is intended to be read by content creators already familiar with TrainzScript, but perhaps unfamiliar with the more modern concepts invovled with Asynchronous Route Streaming.

It is recommended readers first familiarise themselves with topics covered in the following pages:

• Asynchronous Route Streaming
• Compatibility Mode Setting
• How to Upgrade Obsolete Script Functions

Overview

The script function GameObject.GetId() returns an integer ID which identifies an object within the script context. This ID is unique and constant for the life of the object only. When the specific object reference is released the ID becomes usable by other objects, and if the game is reloaded the world item represented by that GameObject (e.g. a Signal) will have some other ID.

This makes this ID of limited usefulness, and with the introduction of Route streaming they cannot be trusted and are considered obsolete. The modern replacement function is

public native GameObjectID GameObject.GetGameObjectID(void);

Getting an Object ID

The following example script shows a simple class which gets and stores objects integer ID.

class Example
{
  int             m_gameObjectID = -1;
  
  public void SetObject(GameObject obj)
  {
    // Save the objects ID.
    if (obj)
      m_gameObjectID = obj.GetId();
    else
      m_gameObjectID = -1;
  }
};

This class has a single member variable used to store the ID of an object, and a function which sets the object reference. To upgrade the script to support modern versions of Trainz, the integer ID must be replaced with a GameObjectID, and the GetId() call replaced with GetGameObjectID().

class Example
{
  GameObjectID    m_gameObjectID = null;
  
  public void SetObject(GameObject obj)
  {
    // Save the objects ID.
    if (obj)
      m_gameObjectID = obj.GetGameObjectID();
    else
      m_gameObjectID = null;
  }
};