Question: How do you get a variable from another object in GameMaker?

Answer

In GameMaker, you can access variables from other instances (objects) using the dot operator or with specific functions like object_get_variable or instance_find. Here’s how you do it:

Using the Dot Operator

If you know the instance ID of the object from which you want to get a variable, you can use the dot operator to access its variables. The instance ID is often obtained when you create an object using instance_create_layer or instance_create_depth. For example:

var other_instance_id = instance_create_layer(x, y, "Instances", obj_Enemy);
var enemy_health = other_instance_id.health;

In this code, obj_Enemy has a variable named health, and we are accessing it using the instance ID stored in other_instance_id.

Using Instance Functions

If you don’t have the instance ID but know that there is only one instance of the object in the room, you can use instance_find to get the instance ID:

var enemy_instance_id = instance_find(obj_Enemy, 0);
var enemy_health = enemy_instance_id.health;

This finds the first instance of obj_Enemy in the room.

Accessing Variables by Object Index

When there are multiple instances of an object and you want any one of them, you could use the object index directly:

var enemy_health = obj_Enemy.health;

This will get the health variable from the first instance of obj_Enemy that was created.

Using with Statement

You can also use the with statement to perform operations on all instances of an object. If you just want to retrieve a value once, you should assign it to a variable outside of the with scope:

var first_enemy_health;
with (obj_Enemy) {
    first_enemy_health = health; // Assuming 'health' is a variable within obj_Enemy
    break; // This exits the with structure after getting the first instance's health
}

Cautionary Notes

• Ensure that the object or instance you're trying to access the variable from is active and exists in the current context; otherwise, you'll get an error.
• It is good practice to use instance_exists before trying to access a variable from another instance to avoid runtime errors.

These are some of the ways you can get a variable from another object in GameMaker. Choose the method that best fits your situation.