MeshInstance3D in Godot – Complete Guide

Diving into the world of game development is an exciting journey filled with endless possibilities. When working in 3D environments, mastering the control and manipulation of meshes—the graphical building blocks of your 3D world—is essential. In today’s tutorial, we’re going to explore the MeshInstance3D node in Godot 4, a powerful tool that helps bring your creative visions to life. Whether you’re just starting out or looking to polish your existing Godot skills, understanding MeshInstance3D is an invaluable step in your development repertoire. So let’s get started!

What is MeshInstance3D?

MeshInstance3D is a fundamental class in the Godot Engine, specifically designed for 3D game development. At its core, it is responsible for instancing meshes in a 3D scene. The concept of a “mesh” refers to a collection of vertices, edges, and faces that define the shape of a 3D object. Using MeshInstance3D in Godot allows developers to reuse and manage these 3D objects efficiently.

What is it for?

The MeshInstance3D node serves as the main workhorse for rendering 3D geometry in your games. Whether you are crafting a detailed character, an intricate environment, or any other 3D asset, you’ll be using MeshInstance3D to add these assets into your scene. With MeshInstance3D, you can instance a single mesh in multiple locations throughout your game, optimizing your resources and ensuring your game runs smoothly.

Why Should I Learn It?

As a developer, you’re not just creating static scenery; you’re building interactive worlds. Learning how to use MeshInstance3D empowers you to create these worlds with greater control and efficiency. It’s not just about making your game look good—it’s also about optimizing performance, enabling collisions, and manipulating geometries. By mastering MeshInstance3D, you elevate the quality of your games while cultivating a versatile skill set that applies to a wide range of 3D projects in Godot.

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Creating a Simple MeshInstance3D

Let’s start by creating a basic MeshInstance3D node in Godot. You’ll find out how to instantiate a simple mesh and add it to your 3D scene.

var mesh_instance = MeshInstance3D.new()
var cube_mesh = CubeMesh.new()
mesh_instance.mesh = cube_mesh
add_child(mesh_instance)

In the code above, we first instantiate the MeshInstance3D node and then a CubeMesh, which is the most basic type of 3D primitive shape in Godot. We assign the cube mesh to our MeshInstance3D and add it to the scene as a child node.

Positioning the MeshInstance3D

Once you’ve created your mesh, you might want to position it within your scene. Godot uses a Vector3 to represent 3D space positions.

mesh_instance.transform.origin = Vector3(0, 0, 0)

In this example, we’re placing the mesh at the origin point of the scene, which is (0,0,0).

Scaling the MeshInstance3D

To scale the MeshInstance3D, we modify the scale property of the node’s transform.

mesh_instance.transform = Transform(mesh_instance.transform.basis, mesh_instance.transform.origin)
mesh_instance.transform = mesh_instance.transform.scaled(Vector3(2, 2, 2))

Here, we’re doubling the size of the mesh in all three dimensions (x, y, and z).

Rotating the MeshInstance3D

Rotation in 3D is a bit more complex as it involves defining the rotation axis and the angle. Godot handles this with the Quat (quaternion) or Basis (rotation matrix) classes.

mesh_instance.rotate_x(deg2rad(45))
mesh_instance.rotate_y(deg2rad(45))
mesh_instance.rotate_z(deg2rad(45))

We use three separate rotate functions for the x, y, and z axes, and convert our desired angle from degrees to radians using the deg2rad function.

Applying a Material to MeshInstance3D

Now, let’s enhance the appearance of our MeshInstance3D by applying a material. Creating a simple material and assigning it can significantly change the way your mesh looks.

var material = SpatialMaterial.new()
material.albedo_color = Color(1, 0, 0)
mesh_instance.set_surface_material(0, material)

This snippet creates a SpatialMaterial, sets its color to red, and applies this material to the surface of the MeshInstance3D.

Creating Multiple Instances of a Mesh

To demonstrate the power of instancing, we’ll create multiple cubes in different positions using a loop.

for i in range(5):
    var new_mesh_instance = MeshInstance3D.new()
    new_mesh_instance.mesh = cube_mesh
    new_mesh_instance.transform.origin = Vector3(i * 2, 0, 0)
    add_child(new_mesh_instance)

Each iteration of the loop creates a new MeshInstance3D with the same cube mesh, positions it with a growing offset on the x-axis, and adds it to the scene. By reusing the cube mesh, we optimize our game’s memory usage.

Animating the MeshInstance3D

Animations can breathe life into your 3D models. Here’s a quick way to animate our MeshInstance3D using a Tween node to interpolate its position.

var tween = Tween.new()
add_child(tween)
tween.interpolate_property(mesh_instance, "transform:origin",
                           mesh_instance.transform.origin, 
                           Vector3(10, 0, 0), 1,
                           Tween.TRANS_LINEAR, Tween.EASE_IN_OUT)
tween.start()

The code above creates a Tween node, interpolates the position of our mesh_instance from its current origin to the point (10,0,0) over 1 second with linear transition and ease in-out.

Adding Collision to MeshInstance3D

For a mesh to interact with other objects in Godot, it needs a collision shape. Let’s create a collision body and assign a collision shape.

var collision_instance = StaticBody3D.new()
var collision_shape = CollisionShape3D.new()
collision_shape.shape = cube_mesh.create_trimesh_shape()
collision_instance.add_child(collision_shape)
add_child(collision_instance)

This snippet sets up a StaticBody3D with a CollisionShape3D that has the same shape as our cube mesh. By adding the collision_instance to the scene, our mesh can now participate in physics simulations.

Using MeshInstance3D in a Shader Material

To take our MeshInstance3D’s appearance to the next level, we can use a shader material. Creating a basic shader that changes the color dynamically:

var shader_material = ShaderMaterial.new()
shader_material.shader_code = """
shader_type spatial;
void fragment() {
    ALBEDO = vec3(TIME, 0.5f, 0.5f);
}
"""
mesh_instance.material_override = shader_material

The shader code changes the mesh’s color over time using the `TIME` built-in variable in the shader.

Instance MeshInstance3D with a Preloaded Mesh

Godot allows you to preload assets for improved performance. Here’s how we can preload a mesh and use it for our MeshInstance3D.

var preloaded_mesh = preload("res://path_to_your_mesh.tres")
var mesh_instance = MeshInstance3D.new()
mesh_instance.mesh = preloaded_mesh
add_child(mesh_instance)

This code snippet loads a mesh resource from a file and instances it with the MeshInstance3D node.

Changing MeshInstance3D Visibility

In some games, you might want to toggle the visibility of an object. It’s simple to do so with MeshInstance3D.

mesh_instance.visible = false  # Hide mesh
mesh_instance.visible = true   # Show mesh

Setting the `visible` property to `false` will hide the mesh from the scene, while setting it to `true` will make it visible again.

Using these techniques, you now have a greater toolbox at your disposal to build and enhance your 3D worlds within Godot. Each of these examples illustrates the versatility and creativity you can achieve with MeshInstance3D. As you integrate and expand upon these basics, your game environments will start to come alive with dynamic objects, animations, and interactions. Stay tuned for more tips and tutorials to help you level up your game development skills with us at Zenva!Combining multiple MeshInstance3D nodes to create complex objects is a staple in 3D game design. You can build intricate structures by attaching various MeshInstance3D as children to a parent node.

var parent_node = Spatial.new()

for i in range(3):
    var mesh_instance = MeshInstance3D.new()
    mesh_instance.mesh = preloaded_mesh
    mesh_instance.transform.origin = Vector3(0, i * 2, 0)
    parent_node.add_child(mesh_instance)

add_child(parent_node)

In this script, we’re creating a parent Spatial node and attaching three MeshInstance3D nodes to it, each one placed above the last. We’re essentially constructing a vertical stack of meshes, which could simulate a totem pole or a pillar.

To manipulate all the child MeshInstance3D nodes at once, for example to rotate the entire structure, you would alter the transform of the parent_node:

parent_node.rotate_y(deg2rad(90))

By applying a rotation to the parent_node, all attached MeshInstance3D nodes will rotate as one single object around the parent’s origin.

Looking to add a dynamic touch? Programmatically altering the mesh of a MeshInstance3D in runtime allows for changing shapes and effects:

mesh_instance.mesh = new_mesh_at_runtime

This line could represent a scenario where, based on a game’s condition, the shape of an object changes. `new_mesh_at_runtime` could be any mesh that you’ve prepared to replace the current one.

Next, let’s look into how to modify the properties of the mesh material in real time, which can add unique visual effects or feedback to the player’s actions:

var shader_material = mesh_instance.material as ShaderMaterial
shader_material.set_shader_param("my_param", value)

By casting the material of a MeshInstance3D to ShaderMaterial, we can directly manipulate its shader parameters. `my_param` would be a user-defined parameter in the shader code, and `value` the new value you’re setting.

Finally, consider the need to retrieve the current mesh within the MeshInstance3D node, perhaps to check a property or make a decision:

var current_mesh = mesh_instance.mesh

Here, `current_mesh` will contain the Mesh resource currently used by our MeshInstance3D. You could leverage this to gather information, such as the number of vertices or the assigned material.

By now, you should see how versatile the MeshInstance3D node can be and how it serves as a fundamental building block for 3D game development in Godot. From simple manipulations like scaling and positioning to more advanced aspects like run-time mesh alterations and shader parameter adjustments, your toolkit is expanding rapidly, enabling richer gameplay and more visually compelling experiences. Keep experimenting with these functions and parameters to discover the full potential hidden within your 3D games.

Continuing Your Game Development Journey

Embarking on the path of game development with Godot 4 is just the beginning! If you’ve enjoyed creating with MeshInstance3D and are eager to dive deeper into the world of game creation, we are here to support you every step of the way. At Zenva, we believe in the transformative power of learning through doing, which is why our Godot Game Development Mini-Degree is the perfect next step on your educational journey.

This robust learning path is packed with practical courses that will elevate your understanding and ability to build cross-platform games. You’ll navigate through a variety of vital game development topics, including but not limited to 2D and 3D asset creation, GDScript, gameplay mechanics, and building full-fledged games in different genres. Whether you’re just starting out or you’re looking to deepen your existing skills, this Mini-Degree is crafted to match your learning pace and expand your creative potential.

For an even broader palette of learning opportunities and to keep growing in this exciting field, explore our full range of Godot courses. Each course, including our Godot Game Development Mini-Degree, is designed to be approachable, comprehensive, and reflective of real-world scenarios, preparing you for an exciting career in game development. Join us and continue to forge your path in the dynamic world of game creation!

Conclusion

As we wrap up our exploration of the MeshInstance3D in Godot 4, we hope you feel inspired and equipped with new tools to craft stunning 3D games. Understanding the capabilities and applications of MeshInstance3D can truly unlock a new realm of creativity and efficiency in your development process. Whether you’ve followed along by creating whimsical characters or designing intricate environments, you’re not just coding—you’re bringing imaginative worlds to life, and that’s what game development is all about.

Never stop learning and building; with each new project, you’re honing your skills and moving closer to your game development dreams. Remember, the knowledge and techniques acquired here are just the foundation. For those eager to continue expanding their game development prowess, we invite you to further your education with Zenva’s Godot Game Development Mini-Degree. By joining our comprehensive courses, you are not merely taking a course—you’re joining a vibrant community of creators, innovators, and dreamers. So what are you waiting for? Let’s create, learn, and grow together with Zenva!

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