AnimationTree in Godot – Complete Guide

Welcome to the fascinating world of animation within Godot 4! If you’ve ever wanted to bring your game characters and scenes to life with fluid, dynamic motion, understanding the powerful tool that is AnimationTree is key. This tutorial is crafted to guide you through the intricacies of the AnimationTree class, where advanced animation transitions in Godot are not just a dream, but a reality you can grasp and implement today.

Whether you’re just starting out or you’re an experienced coder looking for ways to enhance your game animations, the journey through AnimationTree promises to be both rewarding and fun. Elevate your game development skills, and let’s step into the realm where characters move with purpose, storytelling becomes interactive, and your game world turns vivid with every animated detail.

What is AnimationTree?

AnimationTree in Godot 4 serves as a node designed for managing complex animation transitions and blending in your projects. It works in conjunction with an AnimationPlayer node but takes the lead in controlling animations through a system of AnimationNode(s), which define the logic for how and when animations play out.

What is it for?

The main purpose of the AnimationTree node is to enable a higher level of control over your animations. It allows for state-based animation management, blending, and makes use of various nodes like AnimationNodeStateMachine and AnimationNodeBlendTree to define detailed behavior. This intricate system ensures that your character’s walk cycle can flow seamlessly into a sprint, or that an attack animation can interrupt a jump, for example.

Why Should I Learn It?

Animation plays a pivotal role in conveying the essence of your game’s world and its inhabitants. Knowing how to wield the AnimationTree class can dramatically boost the quality of your game’s animation system, making it more robust and responsive, offering a more immersive experience for players. Not only does it open the door to creating more professional and engaging games, but it also gives you the edge in a competitive industry where standing out with impressive visuals is often a necessity. By mastering AnimationTree, you unlock the potential to infuse your characters with life-like depth and personality that resonates with your players.

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Creating an AnimationTree

Before diving into the complex world of transitions and state machines, it’s essential to set up the AnimationTree node correctly in Godot 4. Let’s start by creating an AnimationPlayer and adding some animations:

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

var walk_anim = Animation.new()
var run_anim = Animation.new()
# Imagine we add tracks and keys to our animations here.

anim_player.add_animation("walk", walk_anim)
anim_player.add_animation("run", run_anim)

Next, we add the AnimationTree node and link it to the AnimationPlayer:

var anim_tree = AnimationTree.new()
anim_tree.anim_player = anim_player
add_child(anim_tree)
anim_tree.active = true

With the basic setup done, it’s time to create the root of our AnimationTree, typically an AnimationNodeStateMachine for managing states:

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

Adding States and Transitions

With the state machine as the root, we append states, which represent the different animations:

var walk_state = AnimationNodeAnimation.new()
walk_state.animation = "walk"
state_machine.add_node("walk", walk_state)

var run_state = AnimationNodeAnimation.new()
run_state.animation = "run"
state_machine.add_node("run", run_state)

Once we have our states, it’s crucial to add transitions between them to allow for movement from one animation to another:

state_machine.add_transition("walk", "run", AnimationNodeStateMachineTransition.new())
state_machine.add_transition("run", "walk", AnimationNodeStateMachineTransition.new())

These transitions form the backbone of our character’s ability to shift from walking to running and vice versa.

Controlling the State Machine

Now we need to control the AnimationTree programmatically. For example, switch from walking to running based on the character’s speed:

func _physics_process(delta):
   var speed = get_speed() # Assume this function exists and returns the character's speed.

   if speed > WALK_SPEED_LIMIT and anim_tree.current_state != "run":
       anim_tree.set("parameters/playback", "run")
   elif speed <= WALK_SPEED_LIMIT and anim_tree.current_state != "walk":
       anim_tree.set("parameters/playback", "walk")

Adjusting Blends and Parameters

Finally, let’s refine our animations by adjusting blends and parameters which affect how animations transition between each other:

To smoothly transition between the walk and run animations:

var walk_to_run_transition = state_machine.get_transition("walk", "run")
walk_to_run_transition.xfade_time = 0.5

var run_to_walk_transition = state_machine.get_transition("run", "walk")
run_to_walk_transition.xfade_time = 0.5

With these blends in place, our character will not just snap from walking to running; instead, they will seamlessly shift from one motion to the next.

For further control such as turning on the spot or starting a jump, we can use parameters within AnimationBlendTrees:

var blend_tree = AnimationNodeBlendTree.new()
state_machine.add_node("turn_jump_blendtree", blend_tree)

var turn_anim = Animation.new()
var jump_anim = Animation.new()
# Here, we would add tracks and keys to the turn and jump animations.
anim_player.add_animation("turn", turn_anim)
anim_player.add_animation("jump", jump_anim)

We add animations to the blend tree and set up a blend parameter to control the mixture based on the character’s rotation or jump state:

blend_tree.add_node("turn", AnimationNodeAnimation.new())
blend_tree.set("nodes/turn/animation", "turn")

blend_tree.add_node("jump", AnimationNodeAnimation.new())
blend_tree.set("nodes/jump/animation", "jump")

var oneD_blend = AnimationNodeBlendSpace1D.new()
blend_tree.add_node("1D_blend", oneD_blend)

oneD_blend.add_point(0, blend_tree.get("nodes/turn"))
oneD_blend.add_point(1, blend_tree.get("nodes/jump"))
blend_tree.connect_node("1D_blend", "blend_position", blend_tree, "parameters/blend_amount")

This example illustrates how to set up a simple 1D blend space to manage animation blending. AnimationTree is highly flexible and can be expanded in complexity to suit any game’s needs. Using these techniques, your animations will not only look smoother but also be more in tune with the game’s logic and character control.Continuing with our exploration of the AnimationTree in Godot 4, let’s dive deeper into how we can harness its power for more advanced animation techniques, such as using blend trees for 2D motion and setting up a state machine for handling a character’s various states.

Creating a Blend Tree for 2D Motion

Let’s say we want to animate a character that can move in all directions. To do this, we’ll need an AnimationNodeBlendSpace2D within our AnimationTree:

var blend_space_2d = AnimationNodeBlendSpace2D.new()
state_machine.add_node("move_blend_space_2d", blend_space_2d)

We insert animations corresponding to directions:

blend_space_2d.set_animation("walk_north", walk_n_anim)
blend_space_2d.set_animation("walk_south", walk_s_anim)
blend_space_2d.set_animation("walk_east", walk_e_anim)
blend_space_2d.set_animation("walk_west", walk_w_anim)

And create points in the blend space for each direction:

blend_space_2d.add_blend_point(blend_space_2d.get_animation("walk_north"), Vector2(0, -1))
blend_space_2d.add_blend_point(blend_space_2d.get_animation("walk_south"), Vector2(0, 1))
blend_space_2d.add_blend_point(blend_space_2d.get_animation("walk_east"), Vector2(1, 0))
blend_space_2d.add_blend_point(blend_space_2d.get_animation("walk_west"), Vector2(-1, 0))

Using this setup, we can control our character’s direction based on input:

func _process(delta):
   var direction = Vector2.ZERO
   direction.x = Input.get_action_strength("move_right") - Input.get_action_strength("move_left")
   direction.y = Input.get_action_strength("move_down") - Input.get_action_strength("move_up")
   direction = direction.normalized()

   anim_tree.set("parameters/move_blend_space_2d/blend_position", direction)

Customizing Transitions for Smoothness and Control

Not all animation transitions require the same time to switch; some may need to be faster or more immediate depending on the action. Let’s tweak our transitions accordingly:

var fast_transition = state_machine.get_transition("walk", "run")
fast_transition.xfade_time = 0.2

var slow_transition = state_machine.get_transition("idle", "jump")
slow_transition.xfade_time = 1.0

These customizations allow you to have unique control over the flow of your animations, providing a more dynamic reaction to user input.

Implementing State-Driven Animation

Sometimes you may want animations to trigger only when certain conditions are met, such as a character being grounded before they can jump. Here’s how we could implement such logic:

state_machine.add_node("jump", jump_state)
state_machine.add_node("fall", fall_state)

state_machine.add_transition("idle", "jump", grounded_transition)
state_machine.add_transition("jump", "fall", airborne_transition)

And in our physics function, we manage states based on character conditions:

func _physics_process(delta):
   if is_on_floor():
       if Input.is_action_just_pressed("jump"):
           anim_tree.set("parameters/playback", "jump")
   else:
       if velocity.y > 0: # Falling
           anim_tree.set("parameters/playback", "fall")

This approach ensures that only appropriate animations are played, giving your character realistic and context-sensitive behavior.

Parametrizing Animations Through AnimationTree

AnimationTree also allows for parametrization of animations through the use of timescale and sliders for properties such as weight. For example, to slow down an animation you can set the timescale like this:

anim_tree.set("parameters/run/timescale", 0.5)

On the flip side, if you want to speed up the animation, you can increase the timescale:

anim_tree.set("parameters/run/timescale", 2.0)

Adjusting the weight of a blend can be done with:

anim_tree.set("parameters/1D_blend/blend_amount", blend_value)

In summary, Godot’s AnimationTree offers deep control over animation states, transitions, and parameters to bring high-quality, responsive animation to your games. By harnessing these tools, you can elevate your animation work to create an engaging and memorable experience for players. Whether you’re dealing with complex character animations, environmental effects, or interactive storytelling elements, understanding and applying the concepts of AnimationTree in your Godot projects will put you at the forefront of game design and development.As we delve deeper into the capabilities of Godot’s AnimationTree, we’ll explore even more advanced functionalities, including handling variables to control animations, using signals to transition between states, and blending multiple animations together for a convincing and dynamic character behavior.

Animating characters based on variables can provide a high level of detail. For instance, consider a situation where your character’s speed determines the blend between walking and running animations:

func _process(delta):
   var speed = get_player_speed() # Let's say this function returns the player's velocity.
   
   # Adjust the blend amount based on the speed.
   var blend_amount = clamp(speed / MAX_SPEED, 0.0, 1.0)
   anim_tree.set("parameters/1D_blend/blend_amount", blend_amount)

In this scenario, we’re assuming `MAX_SPEED` is the top speed at which our character transitions fully into a run animation. The `clamp()` function ensures that our blend amount stays between 0 and 1.

Let’s also consider using signals within your GameState to transition between animations. Imagine a health system where your character needs to play a hurt animation whenever they take damage:

# Connect the take_damage signal to our method.
player.connect("take_damage", self, "_on_Player_take_damage")

func _on_Player_take_damage(damage):
   if damage > 0:
       anim_tree.set("parameters/playback", "hurt")
       yield(get_tree().create_timer(hurt_animation.length()), "timeout")
       anim_tree.set("parameters/playback", "idle")

Here, when the `take_damage` signal is emitted, we play the hurt animation and then go back to idle after the hurt animation’s length has passed.

What about situations where your character is able to perform actions such as attacking while moving? We can blend animations together to achieve this:

var blend_tree = anim_tree.get("parameters/blend_tree")
var attack_anim = Animation.new()
anim_player.add_animation("attack", attack_anim)

var move_and_attack = AnimationNodeBlend2.new() # To blend two animations
blend_tree.add_node("move_and_attack", move_and_attack)

move_and_attack.add_input("parameters/move_blend_space_2d")
move_and_attack.add_input("parameters/attack_animation")

# Activating the attack while moving
func attack():
   anim_tree.set("parameters/move_and_attack/blend_amount", 1.0)
   anim_tree.set("parameters/playback", "move_and_attack")

The above code sets up a blend node to mix moving and attacking animations, allowing both to play at the same time.

Often, there’s a delay before an action is visibly reflected in the game due to the nature of animation transitions. AnimationTree allows us to fine-tune these transitions, even introducing immediate changes when necessary:

var hit_transition = state_machine.get_transition(from: "idle", to: "hit")
hit_transition.auto_advance = true # Automatically return to the previous state
hit_transition.switch_mode = AnimationNodeStateMachineTransition.SWITCH_MODE_IMMEDIATE

state_machine.get_node("hit").connect("finished", self, "return_to_idle")

func return_to_idle():
   state_machine.set("playback", "idle")

In this snippet, when transitioning to the hit state, the transition happens immediately without blending, and after the animation finishes, it returns to the idle state.

Character customization often includes different outfits or accessories that can be toggled on and off. Here’s how you could handle such a situation with AnimationTree:

var hat_visibility = anim_tree.get("parameters/hat_visibility")
anim_player.get_animation("walk").track_set_key_value(hat_visibility_track, time, true)

func toggle_hat(visible):
   anim_tree.set("parameters/hat_visibility", visible)

This small piece of code demonstrates the versatility of the AnimationTree, not just in creating smooth transitions and responsive character controls, but also in handling game mechanics and character properties dynamically.

Utilizing these advanced features of the AnimationTree, you can elevate the animation system of your Godot 4 game to a level of professionalism that deeply immerses players in the game world. By combining logical control flow with detailed animation states and transitions, you can create a responsive, lifelike, and engaging gaming experience. Whether the character navigates a treacherous platforming sequence or engages in intense combat, these techniques ensure the animation contributes to both the aesthetics and functionality of your game.

Where to Go Next in Your Godot Journey

Embarking on a journey through the complexities of game development with Godot 4 can be as thrilling as it is beneficial for your future projects. If you’re enthusiastic about taking your skills further and truly mastering this versatile engine, our Godot Game Development Mini-Degree provides an extensive pathway to do just that. Dive into a broad spectrum of topics that will bolster your knowledge from the foundations to more advanced aspects of game creation.

Through a series of structured courses, you’ll have the opportunity to learn at your own pace, creating a portfolio of real projects that showcases your growing expertise. Whether new to coding or looking to refine your craft, these lessons cover essential elements, including 2D and 3D game design, GDScript, UI systems, and mechanics across various genres. Transform your interest into insightful, practical experience that can light the path to publishing your games, bolstering your resume, or even launching your own business.

For an even broader range of resources, make sure to explore our complete collection of Godot courses. Each course is designed to help you step confidently into the realm of game development, underpinned by the guidance of experienced developers. Continue your journey, expand your toolkit, and join a community of learners who have turned their passion into a tangible, rewarding craft. With Zenva, you’re on track to bring your visions to life—one line of code, one animation, one game at a time.

Conclusion

In the enchanting craft of game development, mastering tools like Godot’s AnimationTree is akin to giving your characters the gift of graceful motion and responsive action. Whether your game is a quiet narrative driven by subtle character interactions, or a bustling, action-packed adventure, the skills you’ve honed here are invaluable. As you weave these new techniques into your projects, each line of animation code deepens the connection between your players and the world you’ve created.

Embark on a comprehensive learning trajectory with our Godot Game Development Mini-Degree and take your first step—or your next step—towards building the games of your dreams. The path ahead is illuminated with the glow of your future creations, and we at Zenva are here to guide you towards that horizon. Let your journey continue, let your skills flourish, and let the games you craft resonate with the beat of your creative heart.

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