Follow this comprehensive guide to create a basic enemy NPC for your game using GameMaker Studio. This guide will walk you through the necessary steps for setting up the object, defining its variables, and programming its behavior.
Video Link: http://www.youtube.com/watch?v=zOQ64k-NzMY
Building the Enemy Object
The first step in creating your enemy is to set up the object itself. You’ll need to create a new object and give it a clear name, such as obj_enemy. To ensure it functions correctly and can inherit properties, it’s a good practice to assign it to a parent object. In this case, you can set the parent as obj_parent_enemy.
Next, you need to assign a visual representation to your enemy. You can do this by creating a new sprite. Make sure the sprite is centered properly before assigning it to the enemy object. This will help with accurate positioning and collision detection later on. You can then drag and drop this new enemy object into your game’s room to see it in the game world.
Once the object is in place, you’ll need to add a few variables to control its behavior. In the Create event, add the following variables: HP (hit points), damage, speed, and distance_to_player. These will be the core stats for your enemy and will dictate how it interacts with the player.
Programming Enemy Behavior with Events
GameMaker Studio uses events to manage object behavior, and for our enemy NPC, we’ll focus on three main events: Create, Step, and Alarm.
The Create Event
The Create event is where you’ll initialize your enemy’s properties. It runs only once when the enemy object is first created in the game room. This is the perfect place to set initial values for the variables we just created. For example, you might set the enemy’s HP to 3 and its speed to a value like 1. This event is also where you will set up an alarm to control the enemy’s movement pattern.
The Step Event
The Step event runs continuously for every frame of the game. This is where you will add code for things that need constant updating, like tracking the distance to the player and checking for collisions. A key function here is point_distance, which you can use to calculate the distance between the enemy and the player object. This value is then stored in the distance_to_player variable, which will be used by the enemy’s AI to decide its next action.
The Alarm Event
The Alarm event is the core of the enemy’s AI. It’s used to trigger actions at specific intervals. In our case, it will control the enemy’s movement and make decisions based on the player’s location.
Inside the Alarm event, you will write a conditional statement to check if the player is within a certain range. If distance_to_player is less than a certain value (e.g., 200), the enemy will move toward the player. If the player is not close enough, the enemy will instead choose to move randomly. To create this random movement, you can use the random_range function to set a new direction and speed for the enemy every time the alarm triggers.
Advanced Concepts and Next Steps
Once you have the basic movement and AI in place, you can build on this foundation to add more complexity. You can expand the Step event to handle collisions with the player, which would trigger a health deduction. You could also introduce different states for the enemy, such as an “idle” state, a “chasing” state, and an “attacking” state.
In the future we’ll talk about adding combat mechanics, which would involve setting up a system for the player to damage the enemy and for the enemy to react to being hit. This could include adding an if statement to check if the enemy’s HP has dropped to zero and, if so, destroying the enemy instance. By following these steps and continuing to experiment with different events and variables, you can create a truly dynamic and engaging enemy for your game.
Creating an Enemy NPC in GameMaker Studio was originally found on Access 2 Learn
