ArrayOccluder3D in Godot – Complete Guide

Exploring the three-dimensional world in a game can be both mesmerizing and demanding; the beauty of a sprawling environment can give way to the complexities of performance optimization. The Godot Engine has evolved over time to offer a treasure trove of features for game developers striving for that delicate balance between stunning visuals and smooth gameplay. Enter the realm of occlusion culling, a technique that smartly determines which parts of the 3D world need to be rendered based on the player’s current viewpoint. The ArrayOccluder3D, a class in the upcoming Godot 4, stands at the center of this technique, managing 3D polygon shapes that help streamline the rendering process.

What is ArrayOccluder3D?

The ArrayOccluder3D is a powerful asset in Godot’s occlusion culling system—a tool that can significantly improve performance in 3D games. It allows developers to define arbitrary 3D polygon shapes which the engine can use to determine which areas of the scene are not visible to the camera and therefore, do not need to be rendered.

What is it for?

This class is especially useful for large, complex 3D environments where not every element needs to be rendered in every frame. By using occlusion culling with ArrayOccluder3D, it is possible to reduce the workload on the Graphics Processing Unit (GPU), which can lead to smoother frame rates and better performance on a wide range of hardware. It essentially acts as a visibility manager for your 3D scenes.

Why should I learn it?

Understanding how ArrayOccluder3D works unlocks a multitude of benefits for your game development journey:

– **Performance Optimization**: Create games that run efficiently by only rendering what’s necessary.
– **Deepen Technical Knowledge**: Learn a critical aspect of 3D game optimization that is applicable across multiple engines and platforms.
– **Enhanced Game Experience**: Provide players with more complex and detailed worlds without compromising on performance.
– **Skill Versatility**: Apply these principles not just in Godot, but understand a concept that’s key in all 3D rendering engines.

By mastering ArrayOccluder3D and occlusion culling, you’re equipping yourself with techniques to make your game stand out in terms of both aesthetics and performance. Let’s get started on how to use ArrayOccluder3D in your Godot projects.

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Setting Up ArrayOccluder3D in Godot

Before diving into the code, it is essential to have a basic scene setup in Godot. Ensure you have a 3D environment with a camera and at least a few mesh instances that will serve as our test for occlusion culling.

extends Spatial

# This function is called when the node enters the scene tree for the first time.
func _ready():
    var occluder = ArrayOccluder3D.new()
    add_child(occluder)

The first step is creating an instance of the ArrayOccluder3D class and adding it to the scene. This snippet places a new occluder in the scene, which we’ll define more precisely in the following steps.

Defining the Occlusion Polygon

ArrayOccluder3D requires a set of points to define the occlusion area. These points form a polygonal shape that Godot uses for its culling calculations. To define this shape, we first create an array of Vector3 points that outline our polygon.

func _ready():
    var occluder = ArrayOccluder3D.new()
    add_child(occluder)

    # Define the polygon's vertices
    var points = PoolVector3Array([
        Vector3(0, 0, 0),
        Vector3(0, 1, 0),
        Vector3(1, 1, 0),
        Vector3(1, 0, 0)
    ])

    # Set the polygon to the occluder
    occluder.polygons = [points]

In the above code, a simple square polygon is defined. The points should be defined in a counter-clockwise order when looking towards the inside of the polygon to be occluded.

Updating the Occlusion Polygon

You may need to update the occlusion geometry at runtime if your game includes moving objects or destructible environments. The example below demonstrates how to modify the occlusion polygon dynamically.

var occluder = ArrayOccluder3D.new()

func update_occlusion_polygon(new_points):
    occluder.polygons = [PoolVector3Array(new_points)]

To update the occlusion polygon, you pass a new set of points into the `update_occlusion_polygon()` function, which refreshes the `polygons` property of the occluder.

Checking Occlusion State

Once everything is set up, Godot will automatically use the occlusion polygons to determine visibility. You can perform further checks in code by using the `is_occluded()` method provided by the `VisualInstance` class, which many node types such as `MeshInstance` inherit from.

# Assume mesh_instance is a MeshInstance3D node in your scene
if mesh_instance.is_occluded(camera.get_global_transform().origin):
    print("Mesh is occluded!")
else:
    print("Mesh is visible!")

In this code snippet, we’re checking whether a `MeshInstance` node is visible from the camera’s current position.

These basic examples cover the groundwork for implementing ArrayOccluder3D in Godot. In our tutorial’s next part, we will delve into more advanced usage and optimization techniques to fine-tune your game’s performance. Stay with us as we continue to explore the capabilities of Godot’s occlusion culling system.The power of occlusion culling with ArrayOccluder3D truly shines when your 3D environment becomes complex. Let’s now look at more advanced examples of how you can utilize ArrayOccluder3D to optimize your Godot game.

It’s essential to organize your occluders properly within your scene’s spatial hierarchy for maximal effectiveness. Here’s how you can create occluders for separate rooms in an indoor setting:

# Assuming you have a function to create a polygon for each room
func setup_room_occluders():
    for room in rooms:
        var occluder = ArrayOccluder3D.new()
        var points = room.get_polygon_points()
        occluder.polygons = [PoolVector3Array(points)]
        room.add_child(occluder)

In the following example, let’s improve our occluder by enabling it only when necessary. If the player is not in the same room as the occluder, there’s no need for it to be active:

func _process(delta):
    for room in rooms:
        var occluder = room.get_occluder()  # Assuming this is a method that you've defined
        occluder.set_monitoring(camera.is_inside(room))

The `set_monitoring()` method is used here to enable the occluder when the camera is inside the same room, thus saving on processing power when the occluder is not needed. If your game engine version doesn’t support `set_monitoring()`, you may have to handle this logic differently, possibly using `visible` property toggling or other means.

Monitoring the areas that are dynamically changing is also a critical aspect. Let’s say we have a destructible wall that reveals new sections of the map. You’ll need to update the occluder points accordingly:

func destroy_wall(wall_instance):
    wall_instance.queue_free()  # Remove the wall
    update_occlusion_polygon(wall_instance.get_new_occluder_points())  # Update the occluder shape

Combining occluders can be beneficial in some cases, especially for large and complex scenes. If you have several occluders that align perfectly along a plane, they can be combined to reduce the overhead of processing each one individually:

func combine_occluders(occluder_list):
    var new_points = PoolVector3Array()
    for occluder in occluder_list:
        new_points.append_array(occluder.polygons[0])
    var combined_occluder = ArrayOccluder3D.new()
    combined_occluder.polygons = [new_points]
    return combined_occluder

Finally, if you want to provide different levels of occlusion complexity, you can introduce a system to change the occluder polygons detail on the fly, like so:

func set_occlusion_detail(level):
    for occluder in occluders:
        var detail_points = occluder.get_detail_points(level)  # Assume this returns an array of Vector3 points based on the detail level
        occluder.polygons = [PoolVector3Array(detail_points)]

This approach can give you the flexibility of adjusting the occlusion detail for various performance targets, helping cater to a broader range of hardware capabilities.

Every example expands your toolkit when working within the Godot engine, enabling you to tailor occlusion culling techniques to the specific needs of your game. Next, we will explore how to debug and optimize ArrayOccluder3D usage to ensure your occlusion culling is effective and your scenes render as intended. Remember that at Zenva, we are always here to provide guidance, educational resources, and support as you endeavor into the world of game development using these advanced techniques.Debugging and optimizing ArrayOccluder3D usage is a critical step in ensuring your game runs smoothly and efficiently. Visual indicators can aid in this process, giving you a clearer picture of what’s happening behind the scenes with your occluders. Godot provides tools to visualize occlusion culling in the editor, but you can also create custom debug tools using GDScript.

Here is an example of how you might visualize the occlusion polygons at runtime:

# Assuming you have a DebugDrawer singleton with a draw_polygon method
func _process(delta):
    for occluder in occluders:
        DebugDrawer.draw_polygon(occluder.polygons[0], Color.red)

This script would call a hypothetical `draw_polygon` method, passing in the occluder’s polygon points and a color to draw with (in this case, red).

To toggle the visibility of these debug drawings based on a keyboard input, you might add:

var show_debug = false

func _input(event):
    if event.is_action_pressed("toggle_debug"):
        show_debug = !show_debug

func _process(delta):
    if show_debug:
        # Rest of debug drawing code here

For optimization purposes, you might want to ensure that your occluders are functioning as expected. One way to do this is by tracking the number of times an object is culled:

var cull_count = {}

func _process(delta):
    for mesh_instance in mesh_instances:
        if mesh_instance.is_occluded():
            var key = mesh_instance.get_name()
            if key in cull_count:
                cull_count[key] += 1
            else:
                cull_count[key] = 1

This code would maintain a dictionary where keys are mesh instance names and values are counts of how often they’ve been occluded.

Sometimes the occluder polygons may not align perfectly with the environment due to floating point precision issues or other reasons. You can use a simple expansion of the occluder points to ensure the culling works correctly:

func expand_occluder(occluder, margin):
    for i in range(len(occluder.polygons[0])):
        var dir = occluder.polygons[0][i].normalized()
        occluder.polygons[0][i] += dir * margin

In the code above, `margin` is the distance you want to expand each point by, taking into account the direction from the origin.

Also, remember to clean up your occluders when they are no longer needed. If an occluder is associated with a mesh that gets removed from the scene, the occluder should be removed as well:

func remove_occluder(occluder):
    occluder.queue_free()

If you are dynamically creating and destroying many objects in your game, you will want to ensure that occluders are added and removed with these objects to avoid unnecessary memory usage:

func spawn_object_with_occluder(spawn_transform):
    var new_object = preload("res://path/to/your/scene.tscn").instance()
    var new_occluder = ArrayOccluder3D.new()
    # Setup the new_occluder as necessary...
    new_object.add_child(new_occluder)
    add_child(new_object)
    new_object.global_transform = spawn_transform

Just as you add occluders when new objects are spawned, you should also remove them when objects are destroyed:

func destroy_object_with_occluder(object):
    var occluder = object.get_occluder()  # Assuming this returns the associated occluder
    remove_occluder(occluder)
    object.queue_free()

Remember that at Zenva, we believe that the best way to learn is by doing. We encourage you to take this knowledge and apply it to your own projects, experiment, and see how your changes affect performance. The more you tinker with these tools, the more proficient you’ll become in creating efficient, performant 3D games in Godot.

Continuing Your Game Development Journey with Godot

With the foundations of occlusion culling and the ArrayOccluder3D now firmly under your belt, you might be wondering where to take your newfound skills next. The incredible world of game development is vast, and there’s always more to explore, more to learn, and more games to create. If you’re eager to take your experience further, our Godot Game Development Mini-Degree is the ideal next step. This comprehensive course is tailored to provide you with a deep understanding of Godot 4, covering a wide array of game development topics across various genres.

Our Mini-Degree is perfect for those looking to expand their portfolio with a variety of game projects, from RPGs to platformers, ensuring that you have plenty of practical experience. You’ll not only learn the mechanics of game development but also complete mini-projects that solidify your learning and boost your portfolio. It’s designed for beginners and advanced learners alike, offering a flexible learning path with on-demand access and certificates of completion.

For a broader exploration of what you can achieve with this versatile engine, be sure to check out our full collection of Godot courses. Whether you’re building your first game or looking to add sophisticated features like occlusion culling, we at Zenva are here to support your growth every step of the way! Keep learning, keep creating, and take your games from concept to reality.

Conclusion

Venturing into the vast realm of game development with Godot, armed with the understanding of occlusion culling and the power of ArrayOccluder3D, is just the beginning. As you continue to grow your skills and expand upon your gaming projects, remember that the key to mastery lies in continual practice and learning. Embrace the challenges and the triumphs of game creation, knowing that with each line of code, you’re crafting unique experiences for players around the world.

Don’t stop here; continue your game development adventure with us at Zenva! Check out our Godot Game Development Mini-Degree and become the game developer you’ve always dreamed of. We’re committed to providing you with the highest quality education to turn your passion for games into reality. Let’s build incredible gaming experiences together—your journey is just getting started.

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