SoftBody3D in Godot – Complete Guide

Welcome to our comprehensive guide on harnessing the power of the SoftBody3D class in Godot 4, where the world of game development meets the fascinating realm of physics-based simulations! Whether you’re looking to create a flag that flutters in the wind, a bouncy trampoline, or realistic clothing for your characters, understanding SoftBody3D can add an extra layer of realism and interactivity to your 3D environments. Let’s dive into what makes SoftBody3D worth learning and how it can elevate your game development projects.

What Is SoftBody3D?

SoftBody3D is a class in the Godot Engine dedicated to creating deformable 3D objects. These objects can exhibit behaviors akin to soft, flexible materials in the real world such as cloth, jelly, or even human tissue. Unlike rigid bodies that maintain their shape, soft bodies can squish, stretch, and bend based on physical interactions.

What Is SoftBody3D Used For?

SoftBody3D is utilized to infuse a sense of realism into a game scene. It allows developers to simulate physical properties of materials that need to demonstrate elasticity and deformability. Imagine the dynamic movement of a flowing cape on a hero character or the structural give of a bridge made from linchpins and rope when a character crosses it. That’s where SoftBody3D shines.

Why Should I Learn About SoftBody3D?

Learning about SoftBody3D will not only enhance your skills in physics-based game development but also give you the tools to create more immersive and dynamic gaming experiences. Although there are bugs and limitations noted in the documentation, understanding and experimenting with these kinds of physics simulations can be incredibly rewarding. They can contribute significantly to the aesthetic and interactive features of your game, setting it apart from those with more static environments.

Furthermore, as Godot continues to evolve, early knowledge of potentially complex systems like SoftBody3D ensures your skillset remains up-to-date and versatile, allowing you to tackle a wide array of creative challenges within your game development endeavors.

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Setting Up a Basic SoftBody3D Object

First, let’s start with how to set up a basic SoftBody3D object in Godot 4. We will create a simple jelly-like cube that can wobble and deform.

var soft_body = SoftBody3D.new()
soft_body.mesh = preload("res://cube_mesh.tres")
soft_body.simulation_precision = 5
soft_body.total_mass = 1
soft_body.linear_damp = 0.5
add_child(soft_body)

Here’s a breakdown of the code:

  • We create a new instance of SoftBody3D.
  • Then, we assign a mesh to it, which must be a SoftBody-compatible mesh resource.
  • We set its simulation_precision which determines the quality of the simulation.
  • The total_mass of the soft body affects how gravity and other forces affect it.
  • linear_damp dampens the movement over time, simulating friction.

After this setup, you would have a basic soft body object in your scene that reacts to physics.

Applying Forces to SoftBody3D

To see the SoftBody3D in action, we can apply forces to it. In this example, we will add a script that lets us click on the soft body to apply a force at the point of click.

func _input(event):
    if event is InputEventMouseButton and event.pressed:
        var camera = get_node("Camera3D")
        var from = camera.project_ray_origin(event.position)
        var to = from + camera.project_ray_normal(event.position) * 1000
        var space_state = get_world_3d().direct_space_state
        var result = space_state.intersect_ray(from, to)
        
        if result.collider == soft_body:
            var local_point = soft_body.to_local(result.position)
            soft_body.apply_central_impulse(local_point.normalized() * 10)

Here, we define an input function that applies a central impulse to the point we click on our SoftBody3D.

  • We check if the input event is a mouse button event and if the button is pressed.
  • We calculate a ray from the camera using the mouse position.
  • An intersection test finds where the ray hits the soft body.
  • If it hits, we apply an impulse at that point.

This will allow you to interact with the SoftBody3D by clicking it and watching it deform accordingly.

SoftBody3D Collisions

Interactions with other physical objects in the scene are also a crucial aspect of working with SoftBody3D. To demonstrate this, let’s have our soft body collide with a simple rigid body.

var rigid_body = RigidBody3D.new()
rigid_body.collision_layer = 1
rigid_body.collision_mask = 1
rigid_body.mesh = preload("res://sphere_mesh.tres")

var shape = SphereShape3D.new()
shape.radius = 1.0

var collision_shape = CollisionShape3D.new()
collision_shape.shape = shape

rigid_body.add_child(collision_shape)
add_child(rigid_body)

This code creates a new sphere RigidBody3D with a CollisionShape3D and positions it in the path of our soft body.

  • We set the collision layer and mask to ensure collisions are detected.
  • We define a sphere shape for the rigid body and attach it to the collision shape.

When you run the scene, the soft body should collide with the sphere and react to it based on the physical properties we have set for each.

Adjusting Material Properties

The material properties of a SoftBody3D influence its reaction to forces and collisions. Godot allows you to fine-tune these properties for different effects. Let’s modify the material of our soft body.

var soft_body_material = SoftBodyMaterial.new()
soft_body_material.linear_stiffness = 0.8
soft_body_material.area_stiffness = 0.9
soft_body_material.volume_stiffness = 0.9
soft_body_material.drag_coefficient = 0.4
soft_body.soft_body_material = soft_body_material

Creating and setting a SoftBodyMaterial on our soft body will let us control how stiff and draggy it is. This directly affects how the body wobbles and settles after being deformed.

  • linear_stiffness impacts how much the soft body resists stretching.
  • area_stiffness affects the resistance to area changes, like inflating or deflating.
  • volume_stiffness determines the resistance to volume changes.
  • drag_coefficient controls the amount of air resistance.

Each of these settings can be tweaked to simulate different types of materials, whether you’re looking for the tight snap of rubber or the gentle drape of cloth. Understanding and mastering these properties is key to creating believable and interactive soft body simulations in Godot 4.

To deepen our understanding, let’s look at additional code examples and dive into more advanced features of SoftBody3D.

One interesting aspect of SoftBody3D is the ability to pin certain parts of the mesh. This can be used to create effects like flags anchored on a pole or clothing attached to a character. Here is how we can pin vertices of a soft body:

foreach var vertex_index in pinned_vertex_indices:
    soft_body.set_point_pinned(vertex_index, true)

In this snippet:

  • We loop through a predefined array of vertex indices we want to pin.
  • We call set_point_pinned() on our SoftBody3D instance, toggling the pin status to true for each vertex.

Moving on, let’s interact with the SoftBody3D’s physics state throughout the game. For instance, we can adjust the soft body’s mass in real-time, perhaps in response to a game event like submerging in water:

func adjust_mass(new_mass):
    soft_body.total_mass = new_mass

This function allows us to modify the total_mass property, immediately affecting how the soft body reacts to physical forces.

Another way to interact with SoftBody3D is by altering its mesh at runtime, which might represent, for example, damage being dealt to a soft object like a blob monster:

func update_mesh(new_mesh):
    soft_body.mesh = new_mesh

A change in the mesh could represent the blob splitting apart or changing shape due to in-game effects. The change in mesh would need to comply with SoftBody3D requirements for it to behave correctly after the update.

We can also use signals to detect when the SoftBody3D is interacting with other objects. For instance, to execute a function when the soft body enters a collision with another body:

func _ready():
    soft_body.connect("body_entered", self, "_on_SoftBody3D_body_entered")

func _on_SoftBody3D_body_entered(body):
    print("Collided with", body.name)

In the code:

  • We connect the “body_entered” signal from our SoftBody3D to a custom function in our script.
  • Whenever the soft body collides with another physics body, the function will print the name of the colliding object.

Another interaction could be detecting the deformation of the soft body beyond a certain threshold to trigger an event, like breaking or tearing:

func check_deformation():
    var max_deformation = 0.0
    for vertex in range(soft_body.get_point_count()):
        var deformation = soft_body.get_point_deformation(vertex)
        max_deformation = max(max_deformation, deformation)
    
    if max_deformation > critical_deformation_threshold:
        print("Soft body too deformed!")

Here we are iterating through each vertex to calculate its deformation:

  • We use the get_point_deformation() method to get the deformation value of each vertex.
  • The maximum deformation is compared against a predefined critical threshold to determine if the soft body is overly deformed.

Lastly, let’s look at how you can change the area where the SoftBody3D reacts to collisions by adjusting its collision mask:

func adjust_collision_mask(new_mask):
    soft_body.collision_mask = new_mask

This simple method allows us to determine which layers the soft body will collide with by changing its collision_mask. This can be dynamically adjusted to reflect different game states or environments.

Through these examples, you can see how SoftBody3D provides a toolkit for dynamic and realistic game physics. Experimentation with these methods is key, as each game will have unique requirements and challenges that can be addressed through the sophisticated use of SoftBody3D.

As you can tell, SoftBody3D is a versatile class in the Godot Engine allowing for a myriad of possibilities. Whether you are new to Godot or an experienced game developer, understanding and implementing these capabilities can significantly elevate your game’s aesthetic and functionality. We encourage you to explore, experiment, and leverage these tools to create the most engaging and interactive 3D environments possible!

If you’ve been following along with the previous sections, you’re already becoming quite adept with Godot’s SoftBody3D class. Now, let’s turn complexity up a notch and delve into more advanced examples that can bring nuanced physics interactions into your games. We’ll cover a variety of scenarios and provide code snippets along the way.

Imagine a scenario where a soft body can interact with the in-game environment. For instance, let’s simulate a soft body reacting when it receives in-game raindrops:

func simulate_raindrop_impact(drop_position, drop_force):
    var local_impact = soft_body.to_local(drop_position)
    soft_body.apply_impulse(local_impact, Vector3.DOWN * drop_force)

This function will simulate the impact of raindrops by applying an impulse at the point of contact, with a force directed downward.

What about a soft body that needs to respond to an explosion nearby? Here’s how you might simulate the shockwave affecting a soft body:

func apply_explosion_force(explosion_center, explosion_radius, explosion_force):
    for vertex in range(soft_body.get_point_count()):
        var vertex_global_pos = soft_body.global_transform.xform(soft_body.get_point_global_position(vertex))
        var distance = vertex_global_pos.distance_to(explosion_center)
        if distance < explosion_radius:
            var impulse_direction = (vertex_global_pos - explosion_center).normalized()
            var impulse_magnitude = (1.0 - distance / explosion_radius) * explosion_force
            soft_body.apply_impulse(vertex_global_pos, impulse_direction * impulse_magnitude)

This code calculates an impulse for each vertex of the soft body based on its distance from the explosion center, giving you a ripple effect that tapers off with distance.

Transitioning to another aspect, let’s ensure our soft body interacts properly with environmental factors like wind. Below is an example that applies wind force over time:

func apply_wind_force(wind_vector, wind_strength):
    var area = get_overlapping_areas()
    for a in area:
        if a.name == "WindArea":
            for vertex in range(soft_body.get_point_count()):
                var vertex_global_pos = soft_body.global_transform.xform(soft_body.get_point_global_position(vertex))
                soft_body.add_force(vertex_global_pos, wind_vector * wind_strength)

Here, we check for an area named “WindArea” and, upon confirmation, apply a continuous force simulating wind pressure on each vertex.

Moving on, let’s create a function to recover the original shape of the soft body after deformation, often referred to as a “reset” function:

func reset_soft_body_shape():
    for vertex in range(soft_body.get_point_count()):
        soft_body.set_point_deformation(vertex, Vector3.ZERO)

Through this function, the set_point_deformation() method resets each vertex’s deformation, effectively making the soft body return to its original shape.

Lastly, we might want to influence how the soft body deforms based on player interactions. Suppose a player or AI can “grab” the soft body:

func grab_soft_body_at_point(grab_position):
    var closest_vertex_index = -1
    var closest_distance = INF
    for vertex in range(soft_body.get_point_count()):
        var vertex_global_pos = soft_body.global_transform.xform(soft_body.get_point_global_position(vertex))
        var distance = vertex_global_pos.distance_to(grab_position)
        if distance < closest_distance:
            closest_distance = distance
            closest_vertex_index = vertex
    if closest_vertex_index != -1:
        soft_body.set_point_pinned(closest_vertex_index, true)

In this snippet, we find the vertex closest to the grab position and pin it, effectively allowing for a part of the soft body to be “held” in place.

Let’s conclude with a function that animates the soft body’s vertices to create a pulsing effect, reminiscent of breathing or a heartbeat:

func pulse_soft_body(pulse_strength, pulse_rate):
    var timer = 0.0
    while true:
        yield(get_tree().create_timer(1.0 / pulse_rate), "timeout")
        for vertex_index in range(soft_body.get_point_count()):
            var pulse = Vector3(0, 1, 0) * sin(timer) * pulse_strength
            soft_body.add_force(soft_body.get_point_global_position(vertex_index), pulse)
        timer += 1.0 / pulse_rate

This continually applies an oscillating force up and down to create the visual effect of a pulse by using the sinusoidal function.

Godot’s SoftBody3D provides a playground for developers to craft authentic experiences that can give life to a game’s physics and aesthetics. These code examples are just the beginning, and as you become more proficient, you’ll find many other creative ways to use soft bodies in your projects. Get out there and have fun making the virtual worlds of your games feel as alive and interactive as possible!

Continuing Your Game Development Journey with Godot

Embarking on the path of game development with Godot’s powerful features, like SoftBody3D, is only the beginning of what you can achieve. To further hone your skills and delve deeper into the world of game creation, we highly recommend exploring our Godot Game Development Mini-Degree. This program offers a comprehensive learning journey, taking you from the basics all the way to crafting sophisticated gameplay experiences using Godot 4.

Whether you’re a complete beginner or looking to level up your existing development expertise, our Mini-Degree covers an array of essential topics. You’ll explore 2D and 3D game development, get fluent in GDScript, and engage with hands-on projects that cover different game genres and mechanics. All of this is presented in digestible, project-based courses that culminate in a personal portfolio to showcase your new competencies.

For those seeking an even broader knowledge base, we offer a variety of Godot courses that cater to all skill levels. By choosing Zenva, you’re opting for a flexible, engaging way to learn game development – at your own pace, on your own terms. Take the step: continue your learning journey, build new, in-demand skills, and create games that captivate players around the world!

Conclusion

In the vast universe of game development, mastering tools like Godot 4’s SoftBody3D exemplifies just one fragment of the boundless potential available to creators. With these skills under your belt, you stand on the brink of marrying the logical rigidity of code with the fluid creativity of design to forge immersive and dynamic worlds. Remember, the journey doesn’t end here with these tutorials – it’s a catapult that launches you into the myriad of possibilities that game creation holds. By tapping into the knowledge offered through our Godot Game Development Mini-Degree, your adventure is just getting started.

We at Zenva are committed to fueling your passion for learning and game development. Take the initiative to expand your skills, challenge yourself with complex game mechanics, and bring your unique vision to life. Embrace the community of like-minded developers, share your projects, learn collaboratively, and grow exponentially in your abilities. Every line of code you write, every bug you squash, and every level you design is a step towards creating the next great game. Continue your journey with us, and let’s build extraordinary gaming experiences together!

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