GLTFAnimation in Godot – Complete Guide

Unlocking the Potential of GLTFAnimation in Godot 4

Animations bring life to our games, and with Godot 4, harnessing the power of animations has become more versatile and accessible for developers of all skill levels. In this tutorial, we’re delving into the GLTFAnimation class, an integral part of the new Godot 4 engine that enables us to manipulate animations in our games dynamically. Whether you’re just starting your journey in game development or you’re an experienced coder looking to expand your toolkit, understanding GLTFAnimation is a step towards creating more engaging and interactive gaming experiences.

What is GLTFAnimation?

The GLTFAnimation class is a type of Resource within the broader Godot engine ecosystem, dedicated to handling animations imported from GLTF files—a popular and versatile format for 3D scenes and models. GLTF, which stands for GL Transmission Format, is often referred to as the “JPEG of 3D” due to its ability to efficiently transmit 3D models and animations over the web.

What is it for?

In Godot 4, the GLTFAnimation class provides the necessary tools to control these imported animations. This includes setting whether an animation should loop, starting or pausing the animation, and integrating it with the game’s logic and events. It’s a powerful feature that allows developers to add a professional touch to their games by including seamless and intricate animations.

Why Should I Learn It?

Understanding and implementing GLTFAnimation in your Godot projects opens up a new realm of possibilities:

– **Enhance Game Realism**: Animations can make your game feel more realistic and immersive.
– **Create Interactive Experience**: Use animations to respond to player actions, setting the stage for an interactive and engaging game.
– **Optimization**: GLTF is a compact format that helps optimize your game’s performance, especially when dealing with complex 3D models and scenes.

Stay with us as we explore how the GLTFAnimation class works in Godot 4 with practical, bite-sized examples. You’ll learn how to bring your characters and environments to life with smooth and controllable animations.

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Importing and Accessing GLTFAnimation

Before diving into the manipulation of GLTF animations, we first need to understand how to import GLTF files and access their animations in Godot 4. Let’s start by importing a GLTF file that includes animations.

var gltf_importer = GLTFDocument.new()
var imported_scene = gltf_importer.import_gltf_scene("res://path_to_your_gltf_file.gltf", 0)
add_child(imported_scene)

Assuming you’ve successfully imported a GLTF file containing animations, it’s time to access these animations within your Godot project. You can access the animations by finding the AnimationPlayer node attached to your imported scene.

var animation_player = get_node("AnimationPlayer")
var animations = animation_player.get_animation_list()

With your `animations` listing at hand, we can now proceed to interact with the individual animations.

Controlling the Playback of Animations

The next step in our exploration is to play, pause, and stop the animations using the AnimationPlayer’s methods. Here’s how you can do just that:

To play an animation, simply call the `play` method with the name of the animation:

animation_player.play("WalkAnimation")

If you’d like to pause the animation, you can use the `stop` method with the `reset` parameter set to false so that it can be resumed later:

animation_player.stop(false)  # Pause the animation

To resume the paused animation, you just need to call `play` without any parameters:

animation_player.play()  # Resume the paused animation

Finally, if you want to stop and reset the animation completely:

animation_player.stop(true)   # Stop and reset the animation

Remember that these are only the very basics, and there are more functions and signals provided by the `AnimationPlayer` class to control animations even more precisely.

Looping Animations

Looping animations are essential for creating continuous effects, like a character’s idle motion or a spinning object. Let’s see the simple approach to loop an animation, assuming you have an animation called “IdleAnimation”.

First, you want to ensure the loop is enabled on the desired animation:

var animation = animation_player.get_animation("IdleAnimation")
animation.loop = true

Then you would play the animation as normal:

animation_player.play("IdleAnimation")

With the loop property set to true, the “IdleAnimation” will now repeat indefinitely until it is told to stop.

Adjusting Animation Parameters

Beyond playing and looping animations, you might want to fine-tune other parameters of the animation at runtime. Here’s how you can adjust the speed of an animation to create slow-motion or fast-forward effects.

To change the playback speed to half-speed (slow-motion):

animation_player.playback_speed = 0.5

Conversely, to play the animation at double speed (fast-forward):

animation_player.playback_speed = 2.0

Remember to set the `playback_speed` back to 1.0 when you want to play animations at their normal speed.

Through these examples, you’ve learned how to import GLTF files, access their animations, control playback, loop animations, and adjust playback parameters. These are the foundation to building more complex and interactive animation behaviors in your Godot 4 projects. As we continue to the next part of this tutorial, we’ll delve into bringing our animations in line with the game’s events and conditions. Stay tuned!

Connecting Animations with Game Events

A critical aspect of game development is making sure that animations reflect what’s happening in the game. Let’s examine how to connect character animations with gameplay events, such as starting an action when the player hits the ground or playing a different animation when a power-up is collected.

Consider a scenario where your character needs to switch from a running animation to a jumping animation when the spacebar is pressed:

if Input.is_action_just_pressed("ui_jump"):
    animation_player.play("JumpAnimation")

Now, let’s add functionality to play a landing animation when the character hits the ground after a jump:

func _on_character_lands():
    animation_player.play("LandAnimation")

This function would be connected to a signal that gets emitted when the character makes contact with the ground.

Another common event is changing the animation speed when a character is sprinting. Here’s how you could double the speed of the running animation:

if Input.is_action_pressed("ui_sprint"):
    animation_player.playback_speed = 2.0
    animation_player.play("RunAnimation")
else:
    animation_player.playback_speed = 1.0
    animation_player.play("RunAnimation")

And suppose you want to play a victory dance animation when the player reaches the end of the level:

func _on_player_wins():
    animation_player.play("VictoryDance")

You would tie `_on_player_wins` to the victory condition of your game, such as when the character reaches a certain point.

Blending Animations for Smooth Transitions

Blending animations is vital when you want smooth transitions between actions. Suppose you want your character to transition from a run to a walk animation based on their speed. Let’s say we have a variable `character_speed` that determines the speed of the character, and we want to blend our animations accordingly:

var blend = clamp(character_speed / max_speed, 0, 1)
animation_player.play("RunWalkBlend")
animation_player.set_blend_time("RunAnimation", "WalkAnimation", blend)

By adjusting the blend factor, we’re controlling how much of each animation is being played, creating a seamless transition from running to walking based on the character’s speed.

Syncing Multiple Animations

Sometimes you might want to synchronize multiple animations. For example, you need to sync the movement of a character’s lips with the audio of them speaking. In this case, you would synchronize a lip-sync animation with the dialogue audio:

var audio_position = audio_player.get_playback_position()
animation_player.seek(audio_position, true)
animation_player.play("LipSyncAnimation")

This assumes that both the animation and the audio are exactly the same length, allowing them to stay in sync effectively.

Animating Properties with AnimationPlayer

In Godot, you can animate properties, not just characters and objects. You might want to animate the intensity or colour of a light over time:

var animation = Animation.new()
animation.set_length(2.0)  # 2 seconds long
animation.track_insert_key(0, 0, Color(1, 1, 1))  # Start with white light
animation.track_insert_key(0, 2, Color(1, 0, 0))  # Change to red light over 2 seconds

var animation_track = animation_player.add_track(Animation.TYPE_VALUE)
animation_player.track_set_path(animation_track, "DirectionalLight:color")
animation_player.add_animation("ColourShift", animation)
animation_player.play("ColourShift")

This would create a two-second-long animation where the colour of a directional light smoothly transitions from white to red.

By now, you should have a clearer picture of the power and flexibility of animating with the GLTFAnimation class and AnimationPlayer in Godot 4. We’ve covered not only playing and looping animations but also blending them better and reacting to game events, which helps you create truly responsive and engaging gameplay. Enjoy incorporating these techniques into your projects – we can’t wait to see what you bring to life!In the next step of integrating GLTFAnimation into our Godot 4 games, let’s explore advanced control by changing animation tracks selectively and responding to animation signals.

Selective Animation Track Control

In Godot, you have control over specific animation tracks within an animation. This allows you to change or modify parts of an animation while keeping the rest unchanged. If you want to alter only the facial expression of a character without affecting the rest of the body, here’s the snippet you could use:

animation_player.set_track_disable(track_idx, true)  # Disable the specific track
animation_player.advance(0.5)  # Advance the animation by 0.5 seconds
animation_player.set_track_disable(track_idx, false)  # Re-enable the track

Remember, you need to know the index of the track (`track_idx`) that you intend to disable or enable. This information can typically be retrieved from the animation resource or the AnimationPlayer node’s track list.

Responding to Animation Signals

Animations can emit signals at specific points, which can trigger functions in your code. Responding to such signals is a great way to coordinate game events with animations. Here is how you might connect a signal from an animation to a method in Godot:

animation_player.connect("animation_finished", self, "_on_animation_finished")

func _on_animation_finished(anim_name):
    if anim_name == "AttackAnimation":
        # Code to handle the attack end

The above code listens for the “animation_finished” signal and runs the `_on_animation_finished` method when the animation completes.

Integrating Animation with Physics

Godot’s physics system can also work hand-in-hand with its animation system. If you want to apply a force to a character at a certain point in an animation, such as leaping forward during a jump animation, use this method:

func _on_animation_jump_force():
    character.apply_central_impulse(Vector3(0, 10, 0))

animation_player.connect("animation_started", self, "_on_animation_jump_force")

You can connect to the “animation_started” signal or to a custom signal created at a specific frame of the animation.

Changing Animation Properties During Runtime

Sometimes you need to change the properties of an animation at runtime. Perhaps you want to adjust the rotation of a character’s arm during an arm-waving animation based on player input. Here’s how you might do it:

var new_rotation = Quat(camera.global_transform.basis)  # Assume the camera's orientation to adjust the arm rotation
var arm_track_idx = animation_player.find_track("Armature/Arm/Cube:transform/rotation_degrees")
animation_player.track_set_key_value(arm_track_idx, key_idx, new_rotation)

In this example, we use a Quaternion (`Quat`) to represent the new rotation, and we find the track index for the arm’s rotation track. Then, we set a new key value for the specified key index (`key_idx`).

Creating a Fade Transition Between Animations

A common need in game animation is to fade from one animation to another, such as transitioning from an idle to a run animation. You can use the `crossfade` function for a smoother transition:

animation_player.play("RunAnimation")
animation_player.crossfade("IdleAnimation", "RunAnimation", 0.5)

The `crossfade` function takes the names of two animations and the duration over which the transition should occur, in this case, a half-second.

Using AnimationTree for Complex Animation States

The `AnimationTree` node allows for complex animation states and blending, ideal for responsive character animations. Here’s how to set up an `AnimationTree`:

var animation_tree = $AnimationTree
var animation_state = animation_tree["parameters/playback"]

animation_tree.active = true
animation_state.travel("Idle")

And when you need to change the animation state based on in-game conditions:

if moving:
    animation_state.travel("Run")
else:
    animation_state.travel("Idle")

These examples should give you a clear understanding of the breadth of Godot 4’s animation capabilities, particularly with the GLTFAnimation class. Experiment with these snippets, integrate them into your games, and see how they enhance the fluidity and responsiveness of your animations. Your creativity is the only limit to bringing dynamic and immersive experiences to life in your game projects with Godot 4.

Continuing Your Godot Journey

Congratulations on taking the first steps in mastering GLTFAnimation in Godot 4! Now that you’ve delved into the basics and explored some advanced techniques, it’s time to keep the momentum going. Embrace the world of game development with confidence, expanding your skills and building your portfolio of projects.

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If you’re seeking a broader array of content, our selection of Godot courses offers a rich repository of knowledge, benefitting both novices and seasoned developers alike. As you venture through these interactive lessons, complete coding challenges, and maybe even ace a quiz or two, know that with each step, you’re not only building expertise and earning certificates but also crafting a path toward thriving in the high-demand arena of game development. Keep learning, keep creating, and remember, your next game could be the next big hit!

Conclusion

Through persistence and a creative spirit, mastering GLTFAnimation in Godot 4 is just the beginning of your game development odyssey. Every animation you integrate, every event you synchronize, and every game mechanic you implement is a brushstroke on the canvas of your game design masterpiece. We’ve equipped you with the tools and techniques, but it’s the ingenious ways you apply them to your projects that will truly captivate players.

Embark on your journey to game creation excellence with Zenva. Our comprehensive Game Development Mini-Degree stands ready to guide you through this fascinating realm, ensuring you emerge not just as a game developer, but as a game development virtuoso. Seize this opportunity to transform your ideas into digital realities, and let’s build the games of tomorrow, today.

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