InputEventMIDI in Godot – Complete Guide

Exploring the world of game development often leads to the discovery of unique ways to enhance player interaction. One such avenue that has been gaining traction in the realm of creative development is the use of MIDI devices for interactive input. Known primarily for its role in music production and composition, MIDI (Musical Instrument Digital Interface) is also a powerful tool for game developers looking to incorporate music-based mechanics or simply more diverse control schemes into their projects. In this tutorial, we dive deep into harnessing the capabilities of the InputEventMIDI class in Godot 4, a popular and versatile game engine that enables developers to create rich gaming experiences.

What Is InputEventMIDI?

The InputEventMIDI class is a specialized subset of Godot’s input event system which allows developers to capture and process input from MIDI devices such as keyboards, drum pads, and other musical interfaces. These devices can translate musical expression directly into game mechanics, broadening the horizon for games that want to tap into the rhythm and melody as part of their core gameplay.

What Can It Be Used For?

Imagine having players control a character by playing notes on a keyboard or chaining combos in a rhythm game by hitting drum pads – this is what InputEventMIDI allows you to achieve. It’s not just about mapping keys to actions, but also about capturing the nuance of pressure sensitivity, velocity, and pitch associated with musical performance.

Why Should I Learn About InputEventMIDI?

Delving into InputEventMIDI in Godot 4 can set your games apart by providing unique gameplay experiences. Whether you’re integrating MIDI as a fun way to navigate menus or as a core gameplay mechanic, understanding how to leverage MIDI inputs can be an invaluable skill in your game development toolkit. This knowledge not only adds an extra layer of interactivity to your creations but also invites a whole new audience of music lovers and creators to interact with your game in a totally new way.

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Setting Up MIDI Device Detection

To begin working with MIDI in Godot, we first need to set up our project to detect MIDI devices. This involves initializing the MIDI inputs and setting Godot to listen for any MIDI events. Here’s how you can start:

func _ready():
    # Initialize MIDI inputs
    for i in range(Input.get_connected_midi_inputs()):
        print("MIDI device %d: %s" % [i, Input.get_midi_device_name(i)])

In the `_ready()` function, the code loops through all connected MIDI inputs and prints out the name of each device. This helps confirm that your MIDI device is recognized by Godot.

Processing MIDI Events

Once we have our MIDI device connected, we need to process the MIDI events. This can be done by overriding the `_input(event)` method. Let’s look at how to process Note On events:

func _input(event):
    if event is InputEventMIDI:
        if event.get_command() == InputEventMIDI.MIDI_MESSAGE_NOTE_ON:
            print("Note On: %d - Velocity: %d" % [event.get_note(), event.get_velocity()])

The `get_command()` function helps identify the type of MIDI message. If it’s a Note On event (a key has been pressed), the code prints the note number and its velocity.

Mapping MIDI Controls

In a game, you typically want MIDI events to trigger specific actions. Here’s how we can map MIDI notes to in-game controls:

var midi_actions = {
    60: "action_jump",  # Middle C (Note 60) will trigger a 'jump' action
    61: "action_shoot"  # C# (Note 61) will trigger a 'shoot' action
}

func _process(delta):
    for note in midi_actions.keys():
        if Input.is_action_just_pressed(midi_actions[note]):
            handle_action(midi_actions[note])

func handle_action(action_name):
    match action_name:
        "action_jump":
            player.jump()  # Replace with your jump logic
        "action_shoot":
            player.shoot()  # Replace with your shooting logic

This script maps MIDI notes to actions and then checks if those notes are pressed, triggering the mapped game actions accordingly.

Handling MIDI Control Changes

Control Change events in MIDI can be used to adjust game parameters, such as the volume or effects. Here’s how you can handle Control Change messages:

func _input(event):
    if event is InputEventMIDI and event.get_command() == InputEventMIDI.MIDI_MESSAGE_CONTROL_CHANGE:
        print("Control Change: %d - Value: %d" % [event.get_control(), event.get_value()])

This code snippet will print out the control number and its corresponding value, providing real-time feedback whenever a MIDI controller knob or slider is moved.

In summary, these examples show how to detect MIDI devices, process MIDI note and control change events, and map MIDI messages to in-game actions. Next, we’ll look into how to manage velocity and other advanced MIDI features to take our game’s interactivity to the next level.Utilizing the full potential of MIDI in Godot involves more than just mapping notes to action. Advanced usage can include handling velocity sensitivity and integrating pitch bends or aftertouch for immersive gameplay experiences. Let’s continue with our exploration by incorporating these features.

Handling Velocity Sensitivity

The velocity of a MIDI note can tell us how hard a key was pressed, allowing for dynamic control in games. This feature can be used to impact the intensity or the effect of a game action, such as changing the height of a jump or the power of an attack.

func _input(event):
    if event is InputEventMIDI and event.is_note_on():
        var velocity = event.get_velocity()
        # Scale the velocity to match the game's needs
        var scaled_velocity = velocity / 127.0 
        # Example: Modify jump height based on velocity
        player.jump(scaled_velocity)

In this example, the velocity is scaled down to a value between 0 and 1, which is then used to modulate the jump height in the game.

Implementing Pitch Bends

Pitch bends in MIDI can also be utilized, perhaps for steering vehicles in a racing game or affecting the trajectory of an object.

func _input(event):
    if event is InputEventMIDI and event.is_pitch_bend():
        var bend_value = event.get_pitch_bend()
        # Use the pitch bend value to steer the player
        player.steer(bend_value)

Here, `get_pitch_bend()` retrieves the value of the pitch bend, which can be translated into in-game steering commands.

Interpreting Aftertouch

Aftertouch, or pressure sensitivity after the initial key press, offers a level of expression that can be harnessed in your Godot games. For instance, the pressure applied can change the color or size of an object.

func _input(event):
    if event is InputEventMIDI and event.is_aftertouch():
        var pressure = event.get_aftertouch()
        # Adjust the size of an object based on pressure
        object.scale(pressure)

This snippet uses the aftertouch data to affect the scale of an in-game object dynamically.

Managing Multiple MIDI Inputs

Games that require multiple MIDI inputs can be quite complex. It’s important to be able to differentiate between them and handle their input independently.

var midi_input_map = {}

func _ready():
    # Assign unique identifiers to each MIDI input
    for i in range(Input.get_connected_midi_inputs()):
        var device_name = Input.get_midi_device_name(i)
        midi_input_map[device_name] = i

func _input(event):
    if event is InputEventMIDI:
        var device_id = event.get_device()
        var device_name = Input.get_midi_device_name(device_id)
        # Process events for each device independently
        match device_name:
            "MIDI Keyboard":
                handle_keyboard_input(event)
            "Drum Pad":
                handle_drum_pad_input(event)
# Add corresponding handler functions

In the above code, MIDI devices are stored in a dictionary with their names as keys, allowing you to process events depending on the device.

Custom MIDI Mapping

Games often require customized control schemes. Mapping various MIDI commands to specific game functions can be as versatile as you need.

var midi_note_to_function = {
    60: self.method("player_action_1"),  # Replace method with actual method name
    61: self.method("player_action_2"),
    # etc.
}

func _input(event):
    if event is InputEventMIDI and event.is_note_on():
        var note = event.get_note()
        if note in midi_note_to_function:
            midi_note_to_function[note].call()

In this scenario, the `method()` function provides a callable method object that can be executed when the associated note is pressed.

Each of these examples helps to integrate MIDI input into your project, providing your game with a multitude of creative possibilities. Experimenting with these features can lead to innovative gameplay mechanics that help your games stand out in the marketplace. Remember, our goal at Zenva is to inspire and educate developers with high-quality content so you can bring your most ambitious game ideas to life.Incorporating MIDI into Godot games not only elevates the interactive experience but also unlocks creative avenues for gameplay design. Let’s delve further into practical examples that showcase the adaptability of MIDI inputs within the Godot engine.

Creating Dynamic Music Systems

A MIDI-driven music system can react in real-time to player actions or events in the game. For instance, altering the background score based on the intensity of gameplay:

func _input(event):
    if event is InputEventMIDI and event.is_control_change():
        var intensity = map_midi_to_intensity(event.get_value())
        adjust_music_volume(intensity)
        
func map_midi_to_intensity(midi_value):
    # Assuming MIDI values range from 0 to 127
    return midi_value / 127.0

func adjust_music_volume(intensity):
    var new_volume_db = linear2db(intensity)
    AudioServer.set_bus_volume_db(AudioServer.get_bus_index("Music"), new_volume_db)

This example takes a MIDI control change event, maps the MIDI value to an intensity value, and then adjusts the music volume accordingly.

Animating Characters with MIDI

Using MIDI to animate characters can add a layer of depth and responsiveness. Acting on MIDI note inputs, the following script might trigger different animations:

func _input(event):
    if event is InputEventMIDI and event.is_note_on():
        match event.get_note():
            64: # Note for walking
                character.play("walk")
            65: # Note for jumping
                character.play("jump")

Here, hitting either note 64 or 65 could trigger the character’s walk or jump animation sequences.

Using MIDI for Puzzle Mechanics

MIDI input can also be used in puzzle games to allow players to interact with the environment in novel ways. For instance, using specific notes to unlock doors or solve riddles:

func _process(delta):
    # Assuming we've stored the required 'unlock' sequence
    var unlock_sequence = [60, 62, 64, 67, 69]
    check_midi_sequence(unlock_sequence)

func check_midi_sequence(sequence):
    for note in sequence:
        if not Input.is_action_pressed("midi_" + str(note)):
            return
    # If all notes in the sequence are being held down
    unlock_door()

func unlock_door():
    # Your door unlocking logic here

All notes in the `unlock_sequence` array must be held down simultaneously to unlock the door.

Interacting with UI Elements via MIDI

MIDI can be used for non-traditional UI interaction. Sliders and knobs on MIDI controllers could adjust settings seamlessly within a game menu:

func _input(event):
    if event is InputEventMIDI and event.is_control_change():
        match event.get_control():
            1: # Typically Modulation Wheel on MIDI keyboards
                ui_element.adjust_brightness(event.get_value())
            2: # Another MIDI control number
                ui_element.adjust_volume(event.get_value())

func adjust_ui_element_with_midi(control, value):
    # Map MIDI values to UI element properties
    # Example UI adjustment method for a custom element
    ui_element.custom_method(control, value)

In this example, control change events from a MIDI device allow interaction with UI elements like brightness and volume sliders.

Each of these code segments illustrates creative ways to meld the versatility of MIDI with Godot’s robust input system. As you can see, the integration of MIDI into Godot is not only limited to traditional musical applications but also extends to various game mechanics and player interactions.

Remember that these examples are just a starting point. As game developers, we have the freedom to experiment and push the boundaries, using MIDI in ways that might surprise and delight our players. Our commitment at Zenva is to provide you with the knowledge to craft these unique gaming moments, pushing the envelope of what’s possible in game development.

Continuing Your Game Development Journey with Godot

Embarking on the game development journey is an exhilarating experience that opens up a world of possibilities. After diving into the nuances of using MIDI in Godot, you might be curious about what other game-making secrets you can unlock. There’s no better way to keep building on your newfound skills than by exploring further educational resources.

We at Zenva understand the thrill of learning and the desire to continually push the boundaries of your knowledge. That’s why we’ve crafted the Godot Game Development Mini-Degree, a comprehensive collection of courses designed to take you through the ins and outs of creating both 2D and 3D games with Godot 4. Whether you’re new to the engine or looking to hone your existing skills, our mini-degree caters to all levels with project-based learning that’s flexible and accessible.

Additionally, our broader collection of Godot courses covers everything from the essentials of GDScript to advanced gameplay mechanics. By learning with Zenva, you’ll be joining a community that fosters growth and innovation in game development.

Remember, the journey doesn’t end here. Whether you’re aiming to publish your own games, enhance your professional portfolio, or simply revel in the joy of creation, continuing your education is key. We are here to support you every step of the way, from beginner to professional. Keep creating, keep learning, and let’s build the world of tomorrow through the games of today.

Conclusion

As you step forward in your game development quest, the knowledge of incorporating MIDI with InputEventMIDI in Godot 4 is a formidable tool in your arsenal. Breaking new ground with interactive experiences, your games can resonate more deeply with players, creating memories and fun fueled by the power of music and interactivity. With the Godot Game Development Mini-Degree, this adventure has just begun, opening doors to more learning opportunities that await your curious and creative spirit.

Embrace the challenges ahead with the enthusiasm of a composer crafting a symphony, and remember that with each line of code, you’re weaving the digital fabric of future entertainment. Trust in your skills, backed by Zenva’s resources, and you’ll not only build games; you’ll craft experiences that linger long after the screen goes dark. The stage is yours, so let the games begin!

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