This activity is included in an 8-part, 1 hour series to learn Game Maker. Short, focused topics with guided practice will give you practical experience building useful logic for creating games.
Begin Game Maker 5
Trigger Logic with Messages
🟡 MEDIUM
In this activity, you will learn how to set up behaviors and components to create simple logic systems with objects as you explore the basics of communications in Game Maker using messages to create cause and effect.
Launch Game Maker
Open or create an Experience and move to an area with empty space.
Let's turn the grid off and focus on logic.
Some behaviors and components are only available as [MP], which means they are multiplayer synchronized. For this activity, choose [MP] only when a [SP] option isn't available.
Designing gameplay with [SP] and [MP] logic will be explored later.
Collisions & Messages
Behaviours and components are needed to make objects active and/or interactive. This logic provides a framework so messages can be sent and received to trigger gameplay events.
Tags and Broadcast Type allow for greater control over how events are triggered.
Add the following objects to the viewport:
Asset: Door (any)
No behavior
Asset: Door (any)
Door behaviour
Pressing E next to an object sends the message Interact to it.
Test (Press TAB)
Press E to interact with each door. One door is only a prop. The other animates to appear open and turns off its collisions so players can pass through.
Most objects must have collisions to prevent players from passing through them. You can control if an object has collisions, is visible, or has gravity in the Properties Panel.
Toggle Behaviours On/Off
A message sent to an object's Toggle component can turn it's behaviour on or off. Think of it as locking or unlocking a behaviour.
Add an object that sends a message:
Asset: Museum Info Panel
Button component
Message to Send:Door.Unlocked
Broadcast Type: EveryoneInRange
Create a custom message by typing it into the message field and click to Add it.
Add two objects in range (the yellow sphere) of the first object to receive the message:
Asset: Door (any)
Door behavior
Message to Open:Door.Unlocked
Select the existing message from the message dropdown list.
Asset: Door (any)
Door behavior
Message to Open:Interact
Toggle component
Turn On Message:Door.Unlocked
Initial Behaviour State: False
(behavior inactive at game start)
Test (Press TAB)
Neither door can be opened. Interact with the panel to send its message, and then:
One door opens
The other door's behaviour is toggled on so players can open the door with E.
Trigger & Filter Messages
Add the following objects to the viewport:
TRIGGER: AVATAR DETECTED
Message sent to everything in the Experience (location doesn't matter)
Asset: Door (any)
Name: DoorA
Door behaviour
Message to Open:DoorA.Open
Asset: Ancient Lever
Message Broadcaster behaviour
Message to Send:DoorA.Open
Broadcast Type: All
Wait Before Broadcast: True
Message Required: Interact
TRIGGER: OBJECT COLLECTED
Message sent to specific objects
Asset: Door (any)
Name: DoorB
Door behavior
Message to Open:DoorB.Open
Asset: Key (any)
Collectable component
Message On Collect:DoorB.Open
Broadcast Type: SelectedActors
Broadcast Targets: DoorB
Alternative Method: Add a tag to the door, set the key to broadcast the message to SpecificTagsInRange, and adjust the key's broadcast range to include the door's location.
TRIGGER: TAG DETECTED
Message sent to self
(when the object detects a specific tag in range)
Asset: Door (any)
Name: DoorC
Door behavior
Message to Open:DoorC.Open
Speaker component
Detection Type: SpecificTagsinRange
Include Tags:DoorC.Key
Message to Send:DoorC.Open
Broadcast Type: Self
Asset: Key (any)
Tag:DoorC.Key
Pickable component
Test (Press TAB)
Trigger doors A, B, and C to open based on the logic set up. Imagine ways to use these simple trigger methods for other design needs!
The lights do not move with the car. Let's create a relationship in the hierarchy to fix that.
Modify
Set the "Headlight" assets to move with the car's platform motion. Open the hierarchy, select them, and drag them onto the Car. This makes them child objects and the car the parent object.
Test (Press TAB)
The location of the "Headlight" assets is now controlled by their parent object's motion.
Messages with Arguments
Some special messages appear in yellow and allow you to send information (an argument) with a message.
You can also create custom messages with arguments that will appear yellow in the message dropdown list. These will be explored in a later activity.
Continue with the previous example so weather and the streetlight will gradually change.
Add objects to communicate special messages:
Asset: Logic Asset
Name: Street Light Trigger
Message Broadcaster behaviour
Message to Send:LightColor
Time: 10
Wait Before Broadcast: True
Message Required:Night
Asset: Logic Asset
Name: Weather Trigger
Message Broadcaster behaviour
Message to Send:WeatherFade
Time: 10
Wait Before Broadcast: True
Message Required:Night
Modify existing objects to receive the special messages:
Asset: Logic Light Asset
Name: Street Light
Message Turn ON:Night
Message Turn ON:LightColor
Asset: Weather Asset
Name: Night
Message Required:Night
Message Required:WeatherFade
Test (Press TAB)
The weather and streetlight gradually change using these special messages.
Save your Experience so this logic is available for use in another activity.
Follow Up
This activity introduced new tools and concepts to understand objects more and how to make them communicate in custom ways.
In the next activity, you will learn to integrate quests with some of the logic from this activity so you can begin designing a flow for players with clear guidance to play through your Experience.
Ready for More Practice?
This activity leaves room for you to test out your own ideas when the player exits the Trigger Volume and the message Day is sent. Test out custom weather profiles and light colours, too!
Remember that the special message LightColor sets transition timing and colour.
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