EditorResourcePreview in Godot – Complete Guide

When delving into the world of game development, one often encounters the Godot engine – a versatile and powerful tool that empowers developers to bring their creative visions to life. Among the many features Godot provides, the EditorResourcePreview class in Godot 4 stands out as a particularly useful node for enhancing the design and development workflow. This class enables developers to generate previews for resources and files, which is critical when managing graphical assets and ensuring the game’s visual consistency.

What is EditorResourcePreview?

The EditorResourcePreview is a node in Godot 4 that serves a vital function: generating visual previews for different resources or files within the editor. This can include textures, models, or any custom asset that you might be working with. The previews generated by this node can be crucial for quickly identifying assets, speeding up the development process, and avoiding the confusion that often accompanies a large collection of resources.

What is it for?

Imagine you’re sifting through a treasure chest of game assets, trying to find the perfect sprite or texture for your character. Without a preview, this task could become a tedious journey of opening each file individually. This is where EditorResourcePreview shines, as it provides a visual snippet of these assets directly within the editor, saving you time and effort.

Why Should I Learn It?

Learning to use the EditorResourcePreview class can be a game-changer, especially for those who want to streamline their development process. It’s not just about efficiency; it’s also about the visual quality of your game. Having the ability to preview and select the most fitting assets enhances the aesthetic coherence and polish of your project. Furthermore, understanding this class enhances your familiarity with Godot’s editor, making you a more competent and versatile developer. With this knowledge, you embark on a journey towards crafting an immersive and visually appealing game experience.

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Setting Up EditorResourcePreview

In this part of the tutorial, we’ll start by setting up the EditorResourcePreview in a sample Godot project. Before we can generate previews, we need to create an instance of the class and understand its basic functions.

var editor_resource_preview = EditorResourcePreview.new()

Once you create the instance, you can connect signals to your script that will notify you when the preview is ready.

editor_resource_preview.connect("preview_ready", self, "_on_preview_ready")
editor_resource_preview.connect("preview_invalidated", self, "_on_preview_invalidated")

Each time a preview is successfully generated or if a preview becomes invalid, these signals will be emitted, and your script will be notified.

Loading and Generating Previews

After setting up the EditorResourcePreview, we’ll proceed to generate a preview for an asset. Let’s create a simple function that requests a preview for a PNG file.

func _generate_preview_for_png(path_to_png):
    var image_texture = ImageTexture.new()
    editor_resource_preview.queue_resource_preview(path_to_png, self, "_on_preview_ready", image_texture)

You’ll need to provide callbacks to handle the results of the preview generation.

func _on_preview_ready(path, preview, userdata):
    if path == path_to_png and preview:
        userdata.create_from_image(preview)
        $YourSprite.texture = userdata

This code snippet will start generating a preview for the PNG file, and once it’s ready, it will set it as the texture for a sprite node in your scene.

Handling Invalidated Previews

Sometimes, the previews may be invalidated (for example, when the source file changes). It’s important to handle these cases to ensure that the assets represented in the editor are up-to-date.

func _on_preview_invalidated(path):
    if path == path_to_png:
        # The preview for the specified path was invalidated.
        # You might want to regenerate the preview or update your UI accordingly.
        print("Preview invalidated for: ", path)
        _generate_preview_for_png(path)

This function simply prints a message and regenerates the preview whenever it’s invalidated, ensuring that your game editor reflects the most recent changes to your assets.

Generating Multiple Previews

In real scenarios, you’ll often need to generate previews for multiple assets. Here is an example of how you could batch generate previews.

var loaded_previews = {}
func _generate_previews_for_files(paths):
    for path in paths:
        editor_resource_preview.queue_resource_preview(path, self, "_on_preview_batch_ready", path)

func _on_preview_batch_ready(path, preview, userdata):
    if preview: # Ensure the preview is valid
        loaded_previews[userdata] = preview
        # Here you could assign the previews to your UI elements, or perform additional logic.

You can store all generated previews in a dictionary and then reference them throughout your editor scripts or UI as needed.

In the next part, we’ll discuss how to incorporate these previews into the editor’s interface and how to use them in more complex scenarios. Stay tuned for more practical examples that will help you make the most of the EditorResourcePreview class in Godot 4.Integrating EditorResourcePreview into Your Workflow
When you’re developing a complex game with numerous assets, having a seamless method to preview and manage these assets becomes essential. The EditorResourcePreview class gives Godot 4 developers the ability to integrate this logic directly into their custom editor plugins or tools, allowing for rapid and informed decision-making while dealing with resources.

Let’s take a look at how we can integrate the preview functionality into a custom editor plugin.

Creating an Editor Plugin

To extend Godot’s editor, one common approach is to create an editor plugin. Here’s a skeleton code structure for a plugin that uses EditorResourcePreview.

tool
extends EditorPlugin

var preview_generator = EditorResourcePreview.new()

func _enter_tree():
    add_custom_type("MyCustomNode", "Control", preload("res://my_custom_node.gd"), preload("res://my_icon.png"))
    preview_generator.connect("preview_ready", self, "_on_preview_ready")
    # Request previews here or setup additional logic for your custom editor

func _exit_tree():
    remove_custom_type("MyCustomNode")

func _on_preview_ready(path, preview, userdata):
    # Assign the preview to your custom editor interface or handle it as needed

This plugin will now have the ability to generate previews for use in its interface or any other custom functionality you wish to implement.

Previewing 3D Model Thumbnails

3D assets can be particularly challenging to manage, but EditorResourcePreview can help. Here’s how to create thumbnails for 3D models in your custom editor.

func _generate_3d_model_thumbnail(model_path):
    editor_resource_preview.queue_resource_preview(model_path, self, "_on_model_preview_ready", model_path)

func _on_model_preview_ready(path, preview, userdata):
    if path == userdata:
        var texture_button = $VBoxContainer/TextureButton
        texture_button.texture_normal = preview

After this function is executed, the thumbnail of the 3D model will be displayed on a TextureButton in your editor.

Handling Multiple Preview Sizes

You might want different sizes for your previews depending on where they’re displayed in your editor. Here’s how to handle that:

func _generate_preview_with_size(path_to_asset, preview_size):
    var image_texture = ImageTexture.new()
    editor_resource_preview.queue_resource_preview(path_to_asset, self, "_on_preview_ready_with_size", [image_texture, preview_size])

func _on_preview_ready_with_size(path, preview, userdata):
    var [image_texture, size] = userdata
    if preview:
        preview.resize(size.x, size.y) # Resize the preview image
        image_texture.create_from_image(preview)
        # Now use image_texture wherever you need this preview size

By resizing the preview image according to your needs, you can ensure consistency across your editor’s interface.

Cache Previews for Efficiency

Caching previews can greatly improve performance, especially if you’re working with a large number of assets.

var previews_cache = {}

func _cache_preview(path, preview):
    previews_cache[path] = preview

func _get_cached_preview(path):
    if previews_cache.has(path):
        return previews_cache[path]
    else:
        return null

Before requesting a new preview, always check whether it exists in the cache. This will prevent unnecessary generation and enhance the responsiveness of your editor.

Customizing Previews for Different Asset Types

Different assets may require distinct preview generation logic. You might want to customize the previews for textures, scenes, scripts, etc.

func _generate_custom_preview(resource):
    match typeof(resource):
        TYPE_IMAGE_TEXTURE:
            _generate_texture_preview(resource)
        TYPE_PCK_FILE:
            _generate_scene_preview(resource)
        TYPE_SCRIPT:
            _generate_script_preview(resource)
        # Add more cases as necessary for your project

func _generate_texture_preview(texture):
    # Custom texture preview logic here
func _generate_scene_preview(pck_file):
    # Custom scene preview logic here
func _generate_script_preview(script):
    # Custom script preview logic here

By creating custom preview logic for different types of resources, you ensure each asset’s preview is optimized for clarity and relevance, making your editor plugin even more powerful.

Through these examples, we can see how the EditorResourcePreview class can be leveraged in Godot 4 to create a robust, intuitive editing environment, directly contributing to a more efficient and enjoyable game development process.When working with complex scenes and multiple objects, it’s often necessary to batch process countless previews to maintain a coherent overview. The EditorResourcePreview class in Godot 4 is designed to handle such heavy-duty tasks with ease. Let’s explore how we can enhance our workflow with additional code examples and information.

Caching and Retrieving Batch Previews

As mentioned previously, caching is key for efficiency. Here is an example on how to extend our caching strategy to handle and retrieve a batch of generated previews.

func _generate_previews_for_batch(paths):
    for path in paths:
        var cached = _get_cached_preview(path)
        if cached:
            _apply_preview_to_ui(path, cached)
        else:
            editor_resource_preview.queue_resource_preview(path, self, "_on_batch_preview_ready", path)

func _on_batch_preview_ready(path, preview, userdata):
    if preview and not previews_cache.has(path):
        _cache_preview(path, preview)
        _apply_preview_to_ui(path, preview)

func _apply_preview_to_ui(path, preview):
    # Logic to integrate the preview into your UI, e.g., assigning to a TextureRect:
    $YourUIPathToTextureRect.set_texture(preview)

This function first checks the cache before requesting a new preview, and once generated, the preview is stored for future use.

Asynchronous Batch Processing

For a smoother editor experience, we might want to avoid stalling the editor while generating a large number of previews. Async processing can help.

func _generate_previews_asynchronously(paths):
    for path in paths:
        call_deferred("_deferred_preview_request", path)

func _deferred_preview_request(path):
    editor_resource_preview.queue_resource_preview(path, self, "_on_batch_preview_ready", path)

# Handle the async result as before in _on_batch_preview_ready

By deferring the preview requests, you prevent the editor from becoming unresponsive and maintain a fluid workflow.

Updating Previews in Real-Time

If your assets are frequently modified, it’s useful to keep the previews up-to-date while the editor is running.

func _refresh_preview_on_change(path):
    # Let's say you have a FileSystem monitor or some watching mechanism
    editor_resource_preview.queue_resource_preview(path, self, "_on_batch_preview_ready", path)

    # You could connect this function to a file system monitoring signal to trigger whenever an asset file is modified

This way, our previews are always reflecting the current state of the asset files.

Preview Generation with Custom Metadata

Sometimes, you may want to attach custom metadata to your previews. This data can carry information relevant to the preview’s intended use.

func _generate_preview_with_metadata(path, metadata):
    editor_resource_preview.queue_resource_preview(path, self, "_on_preview_with_metadata_ready", [path, metadata])

func _on_preview_with_metadata_ready(resource_path, preview, userdata):
    var [path, metadata] = userdata
    if path == resource_path and preview:
        # Utilize metadata, such as placing the preview into a categorized UI container
        _place_in_category(preview, metadata["category"])

func _place_in_category(preview, category):
    # Display the preview within the specified category's UI container

This helps in providing context to previews and categorizing them accordingly across the editor’s UI.

Scheduling Preview Regeneration

Managing when previews should be regenerated is vital to keep the editor efficient and avoid redundant work.

var regeneration_queue = []
func _schedule_regeneration(path):
    if not regeneration_queue.has(path):
        regeneration_queue.append(path)
        # If you're not already processing the queue, start the process
        if regeneration_queue.size() == 1:
            _process_regeneration_queue()

func _process_regeneration_queue():
    while regeneration_queue:
        var path = regeneration_queue.pop_front()
        editor_resource_preview.queue_resource_preview(path, self, "_on_batch_preview_ready", path)
        # Optionally, add a delay or yield to space out requests

By queuing up regenerations like this, you can control the flow of preview generation instead of processing them all at once.

In summary, by effectively utilizing the EditorResourcePreview class in these various ways, you can elevate the functionality of your Godot editor and streamline your asset management process. Employing smart caching, asynchronous processing, real-time updating, and other such strategies will greatly contribute to an efficient and pleasant game development experience.

Continuing Your Godot Journey

Armed with the knowledge of how to use EditorResourcePreview in Godot 4, you’ve unlocked a new level of proficiency in game development. But this is just the beginning—there’s a whole world of game creation waiting for you to explore!

To keep advancing your skills, consider diving into our Godot Game Development Mini-Degree. It’s a carefully crafted curriculum that will take you from foundational concepts to advanced game mechanics. Whether you’re just starting out or looking to build on your existing knowledge, these comprehensive courses cover everything from 2D and 3D game development to UI design and beyond. Plus, with project-based learning, you’ll have plenty of opportunities to practice coding and even build your own game portfolio.

For an even broader selection of Godot content, check out our full range of Godot courses. At Zenva, we prioritize learning at your own pace, with access to a plethora of courses anytime you’re ready to take the next step. Endless possibilities await as you continue your journey with our expertly designed education pathways. Happy developing!

Conclusion

Your adventure through the realms of game development is ever-evolving, and mastering the EditorResourcePreview in Godot 4 is just one of the many milestones in this exciting journey. Embrace the power it brings to your development process, and take pride in the visually stunning games you’re now equipped to produce. Remember, this tool is but a glimpse of the capabilities waiting to be unfolded in the versatile world of Godot.

As you continue to forge paths in game creation, know that we at Zenva are here to support your growth every step of the way. Our Godot Game Development Mini-Degree is specifically designed to cater to your learning needs, offering a treasure trove of knowledge that will surely elevate your skills from fledgling to masterful. So why wait? Join us today, and let’s shape the future of gaming together!

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