AnimationNodeStateMachine in Godot – Complete Guide

Animating games can be like bringing a static painting to life; it’s the process that infuses a sense of dynamism and personality into your game’s characters and environments, turning a series of static images into fluid action that captivates players’ imaginations. With animation being such an integral part of game development, understanding the tools at your disposal is paramount. In this tutorial, we’re diving into the AnimationNodeStateMachine class in Godot 4 – a powerful feature that handles complex animations with ease.

What is AnimationNodeStateMachine?
The AnimationNodeStateMachine (ANSM) belongs to the family of animation nodes accessible in the Godot Engine, specifically designed for managing states within your game’s animations. Consider it the director of an animation play, where each actor – in this case, an animation state – has a role, and the ANSM seamlessly orchestrates their entrances and exits on the stage, which is your game scene.

What is it for?

In any vibrant game, characters might have various states they can be in – idle, running, jumping, or falling, to name a few. The ANSM serves as the control system that dictates how and when a character transitions from one state to another. It leverages a graph of animation states and manages transitions to ensure characters move smoothly from one animation sequence to the next.

Why Should I Learn It?

Understanding the ANSM is pivotal for anyone looking to create professional-looking animations within their games. It provides you with a versatile set of tools to construct complex animation sequences without overwhelming you with code. Learning how to leverage this system can lead to:

– More dynamic and responsive character animation
– The ability to create intricate animations with multiple states
– Control over transitions for seamless gameplay
– Efficient animation state management that could otherwise be cumbersome

By mastering the ANSM, you equip yourself with the knowledge to bring more polished and interactive animations to your games, elevating the player’s experience. Let’s embark on this journey to master game animations with the versatile power of Godot’s AnimationNodeStateMachine!

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Setting Up Your Animation Player and Animation Tree

Before we delve into the AnimationNodeStateMachine, we need to set up the basic building blocks. You’ll need an AnimationPlayer node and an AnimationTree node, where the latter will host our AnimationNodeStateMachine.

var anim_player = AnimationPlayer.new()
var anim_tree = AnimationTree.new()
anim_tree.anim_player = anim_player
add_child(anim_player)
add_child(anim_tree)

Once the nodes are in place, we’ll create animations within the AnimationPlayer. For example, let’s create two animations: “Idle” and “Run”.

var idle_anim = anim_player.create_animation("Idle")
idle_anim.add_track(Animation.TYPE_VALUE)
idle_anim.add_key(0.0, "parameters/playback")

var run_anim = anim_player.create_animation("Run")
run_anim.add_track(Animation.TYPE_VALUE)
run_anim.add_key(0.0, "parameters/playback")

Creating AnimationNodeStateMachine and States

It’s time to create our AnimationNodeStateMachine within the AnimationTree.

var state_machine = AnimationNodeStateMachine.new()
anim_tree.root = state_machine

Now, let’s add the “Idle” and “Run” states to our state machine, linking them to the animations we created earlier.

state_machine.add_node("Idle", AnimationNodeAnimation.new())
state_machine.set_animation("Idle", "Idle")

state_machine.add_node("Run", AnimationNodeAnimation.new())
state_machine.set_animation("Run", "Run")

Programming Transitions Between States

Transitions are crucial for creating smooth animations. Here we define conditions under which our character changes from “Idle” to “Run” and back.

// From Idle to Run when a condition 'is_running' is true
state_machine.add_transition("Idle", "Run", AnimationNodeStateMachineTransition.new())
state_machine.set_transition_condition("Idle", "Run", "is_running")
state_machine.set_transition_priority("Idle", "Run", 1)

// From Run to Idle when 'is_running' is false
state_machine.add_transition("Run", "Idle", AnimationNodeStateMachineTransition.new())
state_machine.set_transition_condition("Idle", "Run", "not is_running")
state_machine.set_transition_priority("Run", "Idle", 1)

Make sure to set up the appropriate conditions within your game logic to toggle ‘is_running’ for these transitions to work.

Activating the AnimationNodeStateMachine

Finally, to bring your state machine to life, you must activate it within the AnimationTree.

anim_tree.active = true
anim_tree.set("parameters/playback", "Idle")

At this point, your AnimationNodeStateMachine is configured. Your character should now be able to transition between an “Idle” and “Run” state, with our conditions dictating the flow of your animation states. Keep iterating on the complexity and conditions to craft the nuances of your game’s animations.Great! Let’s enhance our AnimationNodeStateMachine with more functionality. We’re going to add more states, discuss how to manage animations programmatically, and show how to use signals to enhance your character’s interactivity.

Adding More Animation States

Let’s say you have two additional animations for your character: “Jump” and “Fall”. Here’s how you add them to the state machine:

state_machine.add_node("Jump", AnimationNodeAnimation.new())
state_machine.set_animation("Jump", "Jump")

state_machine.add_node("Fall", AnimationNodeAnimation.new())
state_machine.set_animation("Fall", "Fall")

Now, we’ll define transitions similar to the previous step, ensuring continuity and smoothness between states:

// From Run to Jump
state_machine.add_transition("Run", "Jump", AnimationNodeStateMachineTransition.new())
state_machine.set_transition_condition("Run", "Jump", "is_jumping")

// From Jump to Fall
state_machine.add_transition("Jump", "Fall", AnimationNodeStateMachineTransition.new())
state_machine.set_transition_condition("Jump", "Fall", "is_falling")

// And back to Run from Fall
state_machine.add_transition("Fall", "Run", AnimationNodeStateMachineTransition.new())
state_machine.set_transition_condition("Fall", "Run", "is_landed")

Remember to implement the game logic that updates ‘is_jumping’, ‘is_falling’, and ‘is_landed’ based on your character’s interaction with the game world.

Managing States Programmatically

Sometimes you’ll want to change states based on certain game events. Here’s how to start the “Jump” animation via code:

if Input.is_action_just_pressed("jump") && state_machine.current_state == "Run":
    anim_tree.set("parameters/playback", "Jump")

Similarly, if you want to go back to “Idle” from “Jump” when the character lands, you might have something like this:

if character_has_landed:
    anim_tree.set("parameters/playback", "Idle")

Utilizing Signals for Special Effects

Animation nodes in Godot can emit signals at certain keyframes. This is helpful to trigger sound effects, particle systems, or other gameplay events:

anim_player.connect("animation_finished", self, "_on_Animation_finished")

func _on_Animation_finished(anim_name):
    if anim_name == "Jump":
        # Play sound effect for landing
        play_landing_sound()

Accessing Animation Properties

You can access or modify animation properties in real-time. For example, you might want to adjust the playback speed of an animation or check its progress. Here’s how you do it:

// Speed up the run animation
anim_tree.set("parameters/Run/playback_speed", 2.0)

// Check the progress of the current animation
var current_time = anim_tree.get("parameters/playback/current_animation_position")

Adjusting these properties can help you synchronize your animations with gameplay dynamically, making your character’s movements feel more integrated with the game world.

By expanding your use of the AnimationNodeStateMachine with more complex states, utilizing code to manage these states, and incorporating signals, you’re making your character feel alive and responsive. These techniques are fundamental in professional game development, and mastering them will allow you to create truly engaging and dynamic game experiences.Adding more layers of interaction through user input is a key aspect of game development. Let’s implement this by using the InputEvent system in Godot to make our character animations more interactive.

Responding to User Input

In Godov 4, we can handle input events to trigger state changes in the animation state machine. Here’s how you might make the character jump when the player presses a specific key:

func _unhandled_input(event: InputEvent) -> void:
    if event is InputEventKey and event.pressed and event.scancode == KEY_SPACE:
        anim_tree.set("parameters/playback", "Jump")

This piece of code checks for a key event, specifically the spacebar press, and changes the animation state to “Jump”. Remember, you’ll have to ensure your logic also takes care of returning to the appropriate state after the jump is completed.

Blending Animations for Smooth Transitions

In addition to switching states, you can blend animations together for smoother transitions. Say you want a character to start running from idle gradually rather than instantly snapping to the running state:

// Set up a blend time between 'Idle' and 'Run' states
state_machine.set_transition_blend_time("Idle", "Run", 0.5)
state_machine.set_transition_blend_time("Run", "Idle", 0.5)

The half-second blend creates a more natural transition as the animations mix for a smooth visual effect.

Tuning Transition Parameters for Responsive Control

Sometimes transitions need fine-tuning for more responsive control, especially in action-packed games where split-second decisions are necessary. This is where immediate transitions can be useful to bypass the blend time under certain conditions:

// Immediate transition from 'Jump' to 'Run' without blending
state_machine.set_transition_blend_time("Jump", "Run", 0.0)
state_machine.set_transition_auto_advance("Jump", "Run", true)

In this case, once the jump is complete, the character will transition back to running immediately, without any blend time, providing instant responsiveness to the player’s actions.

Querying State Information for Game Logic

It can be beneficial to query the state machine for information and adjust your game logic accordingly. For instance, ensuring that certain actions cannot occur unless the character is in a specific state:

// Only allow jumping if the character is in the 'Run' state
if state_machine.current_state == "Run" and Input.is_action_just_pressed("jump"):
    anim_tree.set("parameters/playback", "Jump")

Through this code, a jump can only be initiated if the character is currently running, providing logical consistency within your game.

Adding Custom Signals for Interaction

We can also create custom signals within the AnimationPlayer to trigger specific actions at precise moments in an animation:

// Connect a custom signal declared in your character script
anim_player.connect("landed", self, "_on_Character_landed")

func _on_Character_landed():
    # Handle landing logic here, such as resetting jump availability
    can_jump = true

You will need to emit the “landed” signal at the appropriate keyframe in your animation to call the connected method. This strategy is especially useful for timing effects or actions that need coordination with animation playback.

By integrating these interactive elements into your animations using Godot’s AnimationNodeStateMachine and responding to input and game logic, you’re providing a more rich and reactive gameplay experience. Through practice and experimentation, these techniques will enhance not only the visual quality but also the tactile responsiveness of your games.

Continuing Your Game Development Journey

Congratulations on taking these important steps into the world of animation with Godot 4! As you’ve seen, animations are integral to bringing your game characters and world to life. However, what you’ve learned today is just the tip of the iceberg. There’s so much more to explore, experiment with, and master in the vast universe of game development within Godot.

To keep growing your skills and knowledge, consider diving deeper into our Godot Game Development Mini-Degree. This comprehensive series of courses is tailored to help you transition from a curious beginner to a capable game developer, covering a wide array of crucial topics from 2D and 3D asset creation, to gameplay mechanics, UI systems, and beyond.

And if you’re looking to broaden your horizons with an array of Godot tutorials that fit your exact learning needs and pace, our selection of Godot courses is the perfect place to find your next learning adventure. Whether you’re starting out or refining advanced skills, we’re here to help you make your mark in the game development world. Keep creating, keep learning, and turn your game development dreams into reality with Zenva.

Conclusion

As we wrap up this tutorial, remember that the journey of learning game development is an ongoing adventure, filled with endless possibilities. Every new skill you acquire propels you further along the path to creating captivating game experiences that resonate with players. The AnimationNodeStateMachine in Godot is a testament to the incredible tools at your disposal, designed to make your animation process as intuitive and powerful as possible.

If you’re eager to continue growing, iterating on your game projects, and discovering the myriad of ways you can bring your game worlds to life, be sure to check out our Godot Game Development Mini-Degree. It’s your next step towards mastering the art of game development. Join us at Zenva, keep pushing the frontiers of your creativity, and turn the games you’ve always wanted to play into a reality.

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