Skeleton3D in Godot – Complete Guide

Welcome to the fascinating world of Skeleton3D in Godot 4! If you’ve ever wanted to dive into the mesmerizing realm of 3D character animation, understanding how skeletal hierarchies work is crucial. In today’s tutorial, we’ll explore the Skeleton3D class—a cornerstone for creating animated and lively characters in your Godot 3D games.

The power of skeletal animation lies in its ability to bring detailed and complex movements to life with simplicity and efficiency. Through this journey, we’ll demystify the concepts of bones, poses, and how they amalgamate to form the backbone of 3D animation.

What is Skeleton3D?

Skeleton3D is a class in the Godot 4 game engine. It serves as a container for a hierarchy of bones, which you can manipulate to create 3D skeletal animations. Whether it’s the gentle sway of a character’s limbs as they walk or the dramatic motions of a combat scene, Skeleton3D is the tool that makes such animations possible in a 3D space.

Understanding the Role of Skeleton3D

In simple terms, Skeleton3D allows you to control the structure and movement of character models. It consists of a series of bones—each with its pose and resting state—working collectively to animate a 3D mesh. Animators can rig a mesh to these bones, enabling them to move the model’s parts independently and create life-like animations.

Furthermore, Godot’s Skeleton3D can integrate with ragdoll physics for added realism. It’s a feature-rich class that supports everything from posing each bone with precise control to managing complex animations that blend together seamlessly.

Why Learn Skeleton3D?

Learning Skeleton3D is essential for anyone aiming to create 3D games with animated characters. It’s not just about making characters move; it’s about giving them the lifelike quality that players connect with. Knowing how to properly use Skeleton3D can be the difference between a stiff, unrealistic model and one that moves with believable grace.

Animating a character is like giving a performance where the model’s bones are its actors. As you learn to direct this performance through Skeleton3D, you’ll discover how rewarding it can be to see your creations reflect the stories and emotions you wish to convey.

Now that we’ve introduced the concept of Skeleton3D, let’s dive straight into the coding aspect and start bringing our animations to life. Stay tuned for a thrilling learning experience!

CTA Small Image
FREE COURSES AT ZENVA
LEARN GAME DEVELOPMENT, PYTHON AND MORE
ACCESS FOR FREE
AVAILABLE FOR A LIMITED TIME ONLY

Adding Bones and Setting Poses

Let’s begin by creating the skeleton structure for our character model. Start by adding a Skeleton3D node to your scene and attaching it to your 3D model.

var skeleton = Skeleton3D.new()
add_child(skeleton)

Next, we add bones to our Skeleton3D node, each bone requires a name and a parent bone id. Remember, the root bone has a parent id of -1.

skeleton.add_bone("root")
skeleton.add_bone("spine", skeleton.find_bone("root"))
skeleton.add_bone("head", skeleton.find_bone("spine"))

Now that we have our basic bone structure, we can set the initial pose of each bone. Pose positions are relative to their parent bones.

skeleton.set_bone_pose_position(0, Vector3(0, 0, 0))
skeleton.set_bone_pose_position(1, Vector3(0, 1, 0))
skeleton.set_bone_pose_position(2, Vector3(0, 1, 0.5))

Animating Bones

With our bones in place, let’s move on to animating them. We can rotate and translate bones to animate our character.

# Rotate spine bone by 45 degrees around the X axis
skeleton.set_bone_pose_rotation(1, Quat(Vector3(1, 0, 0), deg2rad(45)))

# Move head bone along the Y axis by 0.2 units
skeleton.set_bone_pose_translation(2, Vector3(0, 0.2, 0))

You can create a simple animation by interpolating the pose of a bone over time.

# Assuming delta is passed to this method from _process(delta)
func animate_head_bone(delta):
    var head_bone_id = skeleton.find_bone("head")
    var current_pos = skeleton.get_bone_pose_position(head_bone_id)
    var target_pos = Vector3(0, 1.2, 0.5)
    var new_pos = current_pos.linear_interpolate(target_pos, delta * 0.5)
    skeleton.set_bone_pose_position(head_bone_id, new_pos)

Applying IK (Inverse Kinematics)

Godot 4 offers built-in support for inverse kinematics (IK), making it easier to animate complex movements. You can use the ‘set_bone_global_pose_override’ function to solve IK.

# Set up an IK target position for the hand bone
var hand_ik_target = Vector3(2, 1, 0)
var hand_bone_id = skeleton.find_bone("hand")

# Apply IK by overriding the global pose
skeleton.set_bone_global_pose_override(hand_bone_id, Transform(Basis(), hand_ik_target), 0.8, true)

Animating with AnimationPlayers

While scripting animations is powerful, you can also use the AnimationPlayer node to create more complex animations.

First, add an AnimationPlayer to your scene and create a new animation.

var animation_player = AnimationPlayer.new()
skeleton.add_child(animation_player)
var animation = animation_player.create_animation("Wave")

Next, insert keys into your animation for the bones you’d like to animate. This example makes the character wave their hand.

# Assuming you have a bone named 'hand' and 'arm'
animation.track_insert_key(0, 0, skeleton.get_bone_global_pose_no_override(skeleton.find_bone("arm")))
animation.track_insert_key(0, 1, Transform(Basis().rotated(Vector3(0, 0, 1), deg2rad(45)), Vector3()))
animation.track_insert_key(1, 0, skeleton.get_bone_global_pose_no_override(skeleton.find_bone("hand")))
animation.track_insert_key(1, 1, Transform(Basis().rotated(Vector3(0, 0, 1), deg2rad(90)), Vector3(1, 0, 0)))

Finally, play the animation to see your character waving.

animation_player.play("Wave")

Through these examples, you’re now equipped with the knowledge of setting up a basic skeletal structure, animating bones, utilizing IK, and creating animations using the AnimationPlayer. Stay tuned as we continue to build upon this with more intricate animation techniques in the next part of our tutorial.Continuing with our exploration of Skeleton3D, we will delve into blending animations, utilizing blend spaces, and further optimizing our skeletal animations in Godot 4. These techniques add depth and smooth transitions to your character’s movements, making them more dynamic and believable.

Blending animations is crucial for creating smooth transitions between different animations. You can manage this by using the ‘advance’ function on the AnimationPlayer and manipulating the playback speed.

# Set the playback speed of the 'Walk' animation to half speed.
animation_player.playback_speed = 0.5
animation_player.play("Walk")

# Blend from 'Walk' to 'Run' over 0.5 seconds.
animation_player.advance(0.5)
animation_player.play("Run")

Blend spaces offer a more sophisticated way to blend animations based on parameters such as speed or direction. You can create a blend space by using an AnimationTree node.

var animation_tree = AnimationTree.new()
animation_tree.set_tree_root(AnimationNodeBlendSpace2D.new())
add_child(animation_tree)
animation_tree.active = true

Configure your blend space with different animations at various points, assigning them to correspond to parameters like speed (x-axis) and direction (y-axis).

var blend_space = animation_tree.tree_root
blend_space.add_blend_point(animation_player.get_animation("Idle"), Vector2(0, 0))
blend_space.add_blend_point(animation_player.get_animation("Walk"), Vector2(1, 0))
blend_space.add_blend_point(animation_player.get_animation("Run"), Vector2(2, 0))

You can then control the blend space by setting the blend position to reflect the character’s current speed and direction.

# Assuming 'speed' ranges from 0 to 2 and 'direction' is either -1, 0, or 1
animation_tree.set("parameters/blend_position", Vector2(speed, direction))

Ragdoll animations can add realistic physics-based movements to your character, especially when they’re hit or fall. Here’s how you can set up a simple ragdoll system that works with the skeleton.

First, enable ragdoll physics by setting the bone physics properties:

# Enable physics simulation on the 'spine' bone
skeleton.physics_simulation_enabled = true
skeleton.set_bone_physical_mode(skeleton.find_bone("spine"), Skeleton3D.PHYSICAL_MODE_SIMULATED)

Next, toggle between ragdoll and animated states as needed:

func toggle_ragdoll(enabled):
    for i in range(skeleton.get_bone_count()):
        skeleton.set_bone_physical_mode(i, Skeleton3D.PHYSICAL_MODE_RAGDOLL if enabled else Skeleton3D.PHYSICAL_MODE_ANIMATED)

Finally, integrate the ragdoll state with your character’s logic to simulate impacts or falls. Below is a hypothetical response to damage:

func on_character_hit():
    toggle_ragdoll(true)
    # Logic to handle the character hit, for example:
    # - Apply a force to the ragdoll.
    # - Start a timer to get back up after a certain delay.

Lastly, optimizing your skeletal animations with methods like ‘isolate_bones’ can be very useful. This feature allows you to focus on animating certain parts of the skeleton while others remain static:

# Isolate the 'arm' and 'hand' bones for exclusive animation without affecting the rest of the skeleton
skeleton.isolate_bones(["arm", "hand"])

Utilizing all of these techniques can significantly enrich the animation system in your Godot 4 projects. From seamless blending of gait cycles to the dramatic realism of ragdoll physics, and the efficiency of bone isolation, these skills are vital for any game developer looking to create compelling 3D character animations.

Don’t forget to catch the next part of this tutorial where we’ll dive deeper into customizing blend spaces and harnessing advanced IK setups to truly bring your animations to life. Happy animating!Building on our foundational knowledge, let’s push further into advanced animation techniques using Godot 4’s Skeleton3D. We’re about to explore the power of procedural animation and detailed Inverse Kinematics (IK) systems that elevate the fluidity and realism of our character models.

Let’s begin by customizing the blender spaces even further to control our character with more precision. Improving on the previously created blend space, you can now adjust the blend space by adding an animation for diagonal movement.

// Add blend points for diagonal animations
blend_space.add_blend_point(animation_player.get_animation("Walk_Forward_Left"), Vector2(-1, 1))
blend_space.add_blend_point(animation_player.get_animation("Walk_Forward_Right"), Vector2(1, 1))

Now, let’s refine our IK setup to dynamically follow a moving target, such as having a character look at a ball moving around the field.

// Retrieve the bone id for the head bone
var head_bone_id = skeleton.find_bone("head")

// Update this every frame with the target's global position
func update_head_ik(target_global_position):
    var head_global_pose = skeleton.get_bone_global_pose(head_bone_id)
    var new_orientation = head_global_pose.looking_at(target_global_position, Vector3(0, 1, 0)).basis
    skeleton.set_bone_pose_orientation(head_bone_id, new_orientation)

For a touch of procedural animation, you can make the character’s hand reach towards an object procedurally, rather than relying solely on predefined animations.

// Calculate IK for hand reaching towards an object
func update_hand_ik(target_global_position):
    var hand_bone_id = skeleton.find_bone("hand")
    var hand_ik_global_pose = skeleton.get_bone_global_pose(hand_bone_id)
    // IK solver logic or methods to find the appropriate pose
    // ...
    // Apply the pose
    skeleton.set_bone_global_pose_override(hand_bone_id, new_hand_pose, 1.0, true)

Imagine a scenario where your character needs to traverse uneven terrain. Applying procedural animation logic to adjust the foot placement can significantly enhance the realism. Here’s an example:

// Assume we have raycasts set up for each foot to detect the ground
func update_foot_ik():
    for foot in ["left_foot", "right_foot"]:
        var foot_bone_id = skeleton.find_bone(foot)
        var raycast = get_node(foot + "_raycast")
        if raycast.is_colliding():
            var ground_pos = raycast.get_collision_point()
            var foot_pose = Transform(Basis(), ground_pos)
            skeleton.set_bone_global_pose_override(foot_bone_id, foot_pose, 0.5, true)

Lastly, we can even make our character dynamically adapt its spine curvature when looking up or down, going beyond static spine poses.

// Adjust spine curvature based on head orientation
func update_spine_curvature():
    var head_orientation = skeleton.get_bone_pose_orientation(skeleton.find_bone("head"))
    var spine_bone_id = skeleton.find_bone("spine")
    var new_spine_orientation = head_orientation.slerp(Basis(), 0.5) // Adjust this ratio as needed
    skeleton.set_bone_pose_orientation(spine_bone_id, new_spine_orientation)

These advanced techniques represent just a glimpse into the depth and flexibility of Godot 4’s animation system. By incorporating these methods into your game, you can achieve a high level of polish and responsiveness that will make your characters feel alive and integrated into their virtual environment.

As you experiment with these coding examples, remember that the key to mastering character animation is understanding the interplay between bone structures, physics, and animation states. Play around with the parameters, timing, and transitions to find the perfect balance for your game’s unique style.

Stay creative and continue to iterate on your animations—there’s always room for refinement in the world of game development!

Continue Your Game Development Journey

Embarking on the road of 3D animation in Godot 4 is just the beginning of your game development adventure. If you’ve enjoyed the steps we’ve taken so far and are eager to delve deeper into Godot 4 and beyond, we invite you to explore our Godot Game Development Mini-Degree. This comprehensive curriculum is designed to take you from the basics all the way to creating your own cross-platform games.

Whether you’re brand new to coding or looking to broaden your skills, our mini-degree offers an array of courses across various game genres and topics. You’ll gain hands-on experience with 2D and 3D assets, GDScript, gameplay control flow, and much more, all while building the confidence to take your game development to professional heights.

For a more extensive look at our offerings, check out our full collection of Godot courses. Each course is designed with the learner in mind, featuring flexible learning options and interactive content. Plus, upon completion, you’ll earn certificates to validate your hard-earned skills.

Jump in and continue learning at your own pace, knowing that with Zenva, you’re always one step closer to mastering game development and turning your creative visions into playable realities.

Conclusion

As we wrap up our exploration of Skeleton3D in Godot 4, remember that every line of code is a step towards crafting living, breathing worlds in your games. The journey of learning and mastery is ongoing, and the ability to animate with such detail and precision is what sets apart good game developers from great ones.

Don’t stop here. Continue to refine your skills with our Godot Game Development Mini-Degree, where you can transform curiosity into expertise. Each animation you create is a narrative in motion, and we can’t wait to see the incredible experiences you’ll build. Dive deeper, keep innovating, and turn the virtual into reality.

FREE COURSES
Python Blog Image

FINAL DAYS: Unlock coding courses in Unity, Godot, Unreal, Python and more.