ProgressBar in Godot – Complete Guide

Progress bars are ubiquitous UI elements that users encounter almost daily, whether they’re waiting for a file to download, a game level to load, or monitoring progress in a task. In game development, particularly when using Godot Engine 4, the ProgressBar class serves as a vital component in relaying information to the player visually and engagingly.

What is ProgressBar in Godot 4?

A ProgressBar is a visual component that represents a percentage, showing how much of a task has been completed or how much of a resource, such as health or mana, is left. In Godot 4, the ProgressBar node inherits from the Range class, ensuring that it’s not just a static bar but one that responds to the variables and parameters of the game.

What is it for?

This control is designed to visually communicate progress, often enhancing the player’s experience by providing clear and immediate feedback. Whether it’s displaying a character’s health declining in a battle or showing the loading progress of the next scene, the ProgressBar is an essential tool in the game developer’s UI kit.

Why should I learn it?

Mastering the ProgressBar class and understanding how to customize it to fit your game’s aesthetic and feedback requirements will elevate the player’s experience. It’s a versatile UI element that, when used correctly, can inform, motivate, and guide the player. Plus, learning how to use such components effectively is a stepping stone to creating more complex UI systems in your games.

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Creating a Simple ProgressBar in Godot 4

Let’s start by creating a basic ProgressBar in Godot 4. First, we need to add a ProgressBar node to our scene:

var progress_bar = ProgressBar.new()
add_child(progress_bar)

Then, you can set the value or progress of the bar directly using:

progress_bar.value = 50 # Sets the progress to 50%

You can also specify the minimum and maximum values for the ProgressBar:

progress_bar.min_value = 0
progress_bar.max_value = 100

With these properties, you can fine-tune how the ProgressBar behaves and what range of values it represents.

Updating ProgressBar Dynamically

Usually, you will want the ProgressBar to update according to in-game events. For example, reducing health with each hit taken:

func _on_Player_hit(damage):
    progress_bar.value -= damage

This code snippet would be placed within the script of your player node or relevant object. ProgressBars are often set to update during the ‘_process’ function, which is called every frame:

func _process(delta):
    progress_bar.value = current_health # Update progress bar to current health

Remember to ensure that the ‘current_health’ variable is initialized and correctly modified elsewhere in your code for this to work properly.

Customizing the Appearance of ProgressBar

Customize the appearance of your ProgressBar using theme overrides. You can do this through code as follows:

progress_bar.add_theme_override("fg", preload("res://path_to_your_stylebox.tres"))
progress_bar.add_theme_override("bg", preload("res://path_to_your_background_stylebox.tres"))

These lines set custom foreground and background designs for your ProgressBar. You’ll need to create ‘StyleBox’ resources in the Godot editor and reference their paths in the code above.

Interacting with ProgressBar via Signals

ProgressBars can emit signals when the value changes, which you can connect to other nodes or scripts:

progress_bar.connect("value_changed", self, "_on_ProgressBar_value_changed")

func _on_ProgressBar_value_changed(value):
    print("The value of the progress bar is now: ", value)

Using signals is a good practice to create responsive UI elements that can communicate with other parts of your game.

Animating ProgressBar Changes

For a smoother user experience, you may want the progress bar’s changes to be animated instead of abrupt. This can be achieved through interpolation:

var tween = Tween.new()
add_child(tween)

func set_progress_to(value):
    tween.interpolate_property(progress_bar, "value", progress_bar.value, value, 1.0, Tween.TRANS_LINEAR, Tween.EASE_IN_OUT)
    tween.start()

Call ‘set_progress_to’ with the new value where required in your game logic. The Tween node will take care of animating the ProgressBar’s value over the course of one second (which can be adjusted to your preference).

Understanding these fundamental uses of the ProgressBar in Godot 4, you can now implement functional, responsive, and visually pleasing progress indicators in your game. Stick around for the next section, where we’ll further explore advanced techniques and tips for mastering progress bars!

After establishing the basic use of a ProgressBar, let’s delve into some more advanced tips and tricks to enhance its functionality and aesthetics within your Godot 4 projects.

Animating the ProgressBar’s appearance can make the change in value much more noticeable and appealing. Here, we’ll create a function that smoothly changes its color based on its current value:

func update_bar_color():
    var color = Color(1.0 - progress_bar.value / 100, progress_bar.value / 100, 0)
    progress_bar.add_theme_override("fg_color", color)

This code snippet creates a gradient effect from red to green based on the progress value. The ‘fg_color’ property can be overridden to dynamically alter the ProgressBar’s foreground color.

One simple trick for giving players a better sense of progress is to display the numerical value or a percentage on top of the ProgressBar. To do this, add a Label as a child node and update its text:

var progress_label = Label.new()
progress_bar.add_child(progress_label)
progress_label.rect_min_size = progress_bar.rect_min_size # Ensure the label fits the bar

func _process(delta):
    progress_label.text = str(int(progress_bar.value)) + "%"

Here, the Label’s text is updated every frame to reflect the ProgressBar’s current percentage value. Aligning the Label’s size with the ProgressBar’s makes sure it fits perfectly.

You can also handle cases where the ProgressBar might exceed its maximum or minimum values by clamping the value within an acceptable range:

func adjust_progress(value):
    progress_bar.value = clamp(progress_bar.value + value, progress_bar.min_value, progress_bar.max_value)

The ‘clamp’ function keeps the ‘value’ within the specified minimum and maximum range. This is helpful to prevent bugs where the progress can go beyond the expected limits.

To create a more complex and informative ProgressBar, consider adding ticks or milestones. For example, in an RPG game, levels might be marked on the experience bar. This requires a bit of custom drawing. Override the ‘_draw’ function in the ProgressBar’s script to add custom draw calls:

func _draw():
    var ticks = 5 # Number of ticks
    var step_size = rect_size.x / ticks
    for i in 1 to ticks:
        var x_pos = step_size * i
        draw_line(Vector2(x_pos, 0), Vector2(x_pos, rect_size.y), Color(1, 1, 1))

This will draw vertical white lines across the ProgressBar to represent ticks. The number and spacing of these ticks can be adjusted to suit your design.

Lastly, for creators interested in building a radial or circular progress bar, Godot’s drawing API can be leveraged to create non-linear progress indicators. The ‘draw_arc’ function can be used:

func _draw():
    var center = Vector2(rect_size.x / 2, rect_size.y / 2)
    var radius = min(center.x, center.y)
    var end_angle = progress_bar.value / 100 * 2 * PI
    draw_arc(center, radius, 0, end_angle, 32, Color(1.0, 0.5, 0.0), 4)

This script draws a partial circle that represents the ProgressBar. The ‘end_angle’ is calculated based on the current value, creating an arc that fills up as the value increases. The ‘draw_arc’ parameters can be adjusted to change the number of points in the arc, its color, and its thickness.

These examples showcase just a fraction of what’s possible with Godot 4’s ProgressBar. With creativity and code, you can tailor every aspect to better fit your gameplay and visual style. These enhancements not only improve the visual appeal but often result in a more intuitive and polished game experience for your players.

Integrating progress bars into more complex scenes requires a blend of scripting, design, and timing. Let’s dig deeper into interaction with other nodes and employing timers for effect.

Consider a game scenario where a progress bar fills up over time, simulating a countdown or a buildup to an event. This can be achieved using a Timer node. Below illustrates setting up and connecting a timer to gradually increase a progress bar’s value.

var timer = Timer.new()
add_child(timer)
timer.wait_time = 0.1 # Time between 'timeout' signal emissions
timer.autostart = true # Start counting upon entering the scene

timer.connect("timeout", self, "_on_Timer_timeout")

func _on_Timer_timeout():
    if progress_bar.value < progress_bar.max_value:
        progress_bar.value += 1

This code will increase the progress bar’s value by 1 unit every 0.1 seconds. Adjust ‘wait_time’ to change how quickly the progress bar fills.

For an RPG-style skill cooldown effect, where the progress bar represents the time until a skill can be used again, reverse the procedure:

func start_cooldown(duration):
    progress_bar.max_value = duration
    progress_bar.value = duration
    timer.start(duration)

func _on_Timer_timeout():
    if progress_bar.value > progress_bar.min_value:
        progress_bar.value -= 1

The Timer counts down the cooldown period, and the progress bar reflects this countdown visually by decreasing.

In certain cases, you might want the progress bar to act as a health bar, reflecting damage taken in real-time. Using signals from an ‘Enemy’ node for when the player takes damage, you could connect the ProgressBar as follows:

enemy.connect("player_damaged", self, "_on_Player_damaged")

func _on_Player_damaged(damage_amount):
    set_progress_to(progress_bar.value - damage_amount)

This will update the progress bar when the ‘player_damaged’ signal is emitted, showing the loss of health.

Adding a pause or ‘buffer’ phase to your ProgressBar can create suspense and emphasise progression. To implement this, modify the ‘set_progress_to’ function with an added delay parameter:

func set_progress_to(value, delay):
    timer.wait_time = delay
    timer.one_shot = true
    timer.start()
    yield(timer, "timeout")
    tween.interpolate_property(progress_bar, "value", progress_bar.value, value, 1.0, Tween.TRANS_LINEAR, Tween.EASE_IN_OUT)
    tween.start()

You simply call ‘set_progress_to’ with your desired delay to see the effect take place after the specified pause.

Another common use for progress bars is during scene loading. Godot’s ‘Thread’ can be used to execute heavy loading operations without freezing the UI:

var thread = Thread.new()

func load_scene_async(path_to_scene):
    thread.start(self, "_run_load_scene", path_to_scene)

func _run_load_scene(path_to_scene):
    var packed_scene = ResourceLoader.load_interactive(path_to_scene)
    while not packed_scene.poll().is_invalid():
        progress_bar.value = packed_scene.get_stage() / packed_scene.get_stage_count() * 100
        OS.delay_msec(100) # Give time back to the main loop to update the UI
    var scene = packed_scene.get_resource()
    get_tree().change_scene_to(scene)

This will load the new scene in a separate thread, updating the progress bar as the loading progresses, and then it will change to the new scene after loading is complete.

Finally, giving your progress bar natural inertia can make it feel more dynamic. Let’s use a Tween node’s interpolation method to implement this:

func smooth_update_progress_to(new_value):
    tween.interpolate_property(progress_bar, "value", progress_bar.value, new_value, 1.0, Tween.TRANS_BOUNCE, Tween.EASE_OUT)
    tween.start()

By using the ‘TRANS_BOUNCE’ transition type and an ‘EASE_OUT’ easing mode, the value update now simulates a bouncing effect at the end of its movement.

These methods demonstrate the power and flexibility of the ProgressBar node in Godot 4. By embedding this knowledge into your workflow, you can create interactive, visually satisfying progress indicators that elevate your game’s overall experience. It’s this level of detail that keeps players charmed and engaged, exemplifying the craftsmanship of a skilled game designer.

Continue Your Game Development Journey

Mastering the ProgressBar node in Godot 4 is just the beginning of your game development adventure. To enhance your skills and knowledge further, we invite you to explore our Godot Game Development Mini-Degree. This comprehensive program will guide you through creating cross-platform games using the latest version of the Godot engine. From understanding 2D and 3D assets to developing intricate game mechanics for different genres, our self-paced courses empower you to learn at your own rhythm without putting your life on hold.

Whether you’re just starting out or looking to solidify your existing knowledge, our range of topics have been designed to cater to all skill levels. Additionally, by browsing our broader Godot courses collection at Zenva’s Godot courses, you’ll discover an array of learning opportunities to keep honing your expertise.

Seize the chance to build exciting, engaging games and join the ranks of professional developers. With Zenva, from the basics to the nitty-gritty of advanced concepts, you can go from a beginner to a pro, all at your own pace. Start your next learning chapter with us today, and turn your passion for game development into reality.

Conclusion

Now that you’ve seen the versatility and capabilities of the ProgressBar node in Godot 4, it’s time to take your game development skills to the next level. Harnessing the power of dynamic UI elements is key to crafting immersive and interactive gaming experiences. Remember, the ProgressBar is just the tip of the iceberg when it comes to the vast potential of Godot Engine 4.

We at Zenva are committed to providing you with high-quality, practical tutorials and courses tailored for real-world application. Dive deeper into Godot and beyond with our Godot Game Development Mini-Degree, where we’ll guide you through every step of the way as you bring your creative visions to life. Don’t just play games—create them and shape the future of gaming with your own unique touch. Embark on your journey with us today and be the game developer you’ve always wanted to be!

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