ShaderGlobalsOverride in Godot – Complete Guide

Shaders are an incredible tool for game developers to add visual effects and dynamic rendering to a game scene. In Godot 4, shaders have received quite an upgrade with more capabilities and flexibility, allowing creators to enhance their games in various ways. If you’re looking to fine-tune how your game’s aesthetics feel in specific scenes, understanding how to use the ShaderGlobalsOverride class will be instrumental. As we unravel the power of shaders and ShaderGlobalsOverride together, you’ll find that tailoring the visual experience of your game can be both simple and fun.

What Is ShaderGlobalsOverride?

The ShaderGlobalsOverride class in Godot 4 is akin to a magic wand for developers. It allows you to adjust the global parameters of shaders within a specific scene dynamically. This means you can alter the look and feel of your game environment in real-time without having to rewrite or adjust individual shaders for each object within the scene.

What Is It for?

Imagine entering a mystical forest in your game where everything glows with an ethereal light, or a dungeon where shadows creep around the corners in a very specific manner. ShaderGlobalsOverride helps you create these kinds of unique atmospheric effects by overriding the default shader parameters with new ones that only apply to the current scene.

Why Should I Learn It?

Diving into the ShaderGlobalsOverride class will empower you to add another level of polish and professionalism to your Godot 4 projects. Not only does it assist in creating immersive environments, but it also ensures your scenes transition smoothly in terms of visual style from one to another. By mastering ShaderGlobalsOverride, you’ll be able to:

– Enhance scene-specific visual themes.
– Ensure consistency in environmental effects across different levels.
– Optimize your game by reusing shaders with different parameters.

Learning how to use ShaderGlobalsOverride is essential if you want to push the visual boundaries of your Godot 4 games and create unforgettable experiences for your players.

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Setting Up ShaderGlobalsOverride

Before we delve into specific examples, let’s set up the ShaderGlobalsOverride class in our Godot 4 environment. Firstly, ensure you have a Shader Material with a global parameter that we will be overriding with our class. Here’s a foundational setup that we might have:

shader_type spatial;
uniform vec4 global_color : hint_color;

void fragment() {
    ALBEDO = global_color.rgb;
}

With this simple shader in place, it manipulates the albedo color of a material, using a uniform that we’ll override.

Now, let’s look at how to create the ShaderGlobalsOverride node within Godot. Dragging this node into your scene tree, it should be structured like this:

// Assuming you have set up a basic project with a 3D scene.

// Add a new ShaderGlobalsOverride node
var shader_globals_override = ShaderGlobalsOverride.new()
add_child(shader_globals_override)

// Now let's set it up to override our global uniform 'global_color'
shader_globals_override.set_shader_override('global_color', Color(1, 0, 0, 1)) // Setting it to red

In this example, we’ve set the override to a red color. You can change the color to whatever matches your scene atmosphere.

Dynamic Changes with ShaderGlobalsOverride

Now, let’s create dynamic changes to our global shader parameters as our game is running. Perhaps we want to change the environment’s mood based on an in-game event, like entering a different area or triggering a special effect.

func _on_SpecialArea_entered():
    shader_globals_override.set_shader_override('global_color', Color(0, 1, 0, 1)) // Changing to green when entering a special area

Here, we hook up a function to the signal for when a character moves into a certain area, triggering a change in the global_color to green.

func _process(delta):
    var time = OS.get_ticks_msec() / 1000.0
    var color_value = abs(sin(time))
    shader_globals_override.set_shader_override('global_color', Color(color_value, 0, color_value, 1)) // This will create a pulsating purple effect

This piece of code in the _process() function creates a pulsating effect by leveraging the sine of the elapsed time to change the global_color.

Utilizing ShaderGlobalsOverride for Environmental Effects

Let’s use ShaderGlobalsOverride for more complex scene changes. Imagine our game has a day-night cycle, and we want to change the ambient lighting gradually over time.

func _process(delta):
    var hour = get_in_game_hour() // This is a function you might have that returns the current in-game hour
    var normalized_hour = hour / 24.0
    var ambient_light_strength = max(0.1, sin(normalized_hour * PI * 2.0))
    shader_globals_override.set_shader_override('ambient_light_strength', ambient_light_strength)

This code snippet calculates an ‘ambient_light_strength’ based on the in-game hour and applies it to the shaders globally.

Finally, let’s add effects that respond to player actions, such as magic spells or abilities that alter the visual of the entire scene.

func cast_magic_spell():
    shader_globals_override.set_shader_override('global_color', Color(1, 0.5, 0, 1)) // A warm orange tint for a fire spell

    # Make sure to reset the override after the spell effect is over
    yield(get_tree().create_timer(2.0), "timeout")
    shader_globals_override.remove_shader_override('global_color')

In this code, we set the override to give the scene a warm orange tint when a fire spell is cast, and then remove the override once the spell effect has finished.

With these examples, you’ve learned how to set up and adjust the ShaderGlobalsOverride class to respond dynamically to game conditions and player interactions. These capabilities will significantly add to your game’s immersive quality and visual appeal.Using ShaderGlobalsOverride allows us to implement global environmental reactions, like simulating weather effects. For instance, if you want to create a rainfall effect in your game, you could dynamically control the intensity and color of the rain.

func _on_rain_started():
    shader_globals_override.set_shader_override('rain_intensity', 1.0)
    shader_globals_override.set_shader_override('rain_color', Color(0.2, 0.2, 1, 1))

func _on_rain_stopped():
    shader_globals_override.set_shader_override('rain_intensity', 0.0)
    // Gradually fade the rain color back to normal
    var tween = Tween.new()
    add_child(tween)
    tween.interpolate_property(shader_globals_override, "rain_color",
        shader_globals_override.get_shader_override('rain_color'), 
        Color(1, 1, 1, 1), 1.0, Tween.TRANS_LINEAR, Tween.EASE_IN_OUT)
    tween.start()

In these functions, `_on_rain_started()` simulates the start of rain by setting the rain’s intensity and color, while `_on_rain_stopped()` fades the rain away using a Tween to interpolate back to the original scene colors.

Visual indicators for health, energy, or other status effects can be globally applied to the scene using ShaderGlobalsOverride too. Below is an example of how you might signal a player’s low health status:

func update_health_status(health_percentage):
    if health_percentage < 0.2: # 20% health or less
        shader_globals_override.set_shader_override('scene_tint', Color(1, 0, 0, 0.5)) # Add a red tint to the scene
    else:
        shader_globals_override.set_shader_override('scene_tint', Color(1, 1, 1, 1)) # No tint

This example changes the scene’s tint based on the player’s health percentage, adding a sense of urgency when the health is low.

Additionally, we can use ShaderGlobalsOverride for cosmetic changes, like shifting the scene to sepia for a flashback sequence:

func start_flashback_sequence():
    shader_globals_override.set_shader_override('color_blend', Color(0.44, 0.26, 0.08, 1)) // Sepia tone
    shader_globals_override.set_shader_override('blend_strength', 0.8)

The above code snippet would give the scene a sepia overlay, suggesting a jump back in time or a memory sequence.

And it’s not just visual effects that can benefit from ShaderGlobalsOverride. Let’s see how it can be integrated with gameplay mechanics, like stealth elements where a player becomes more visible to enemies depending on the light exposure:

func stealth_mechanic(player_visibility):
    shader_globals_override.set_shader_override('player_visibility', player_visibility)
    # This player_visibility variable would control how visible the player is to enemies,
    # based on their exposure to light sources or shadowed areas.

This snippet directly ties the ShaderGlobalsOverride system to gameplay by controlling the player’s visibility globally through shaders.

Lastly, we’ll look at how to use ShaderGlobalsOverride to simulate different times of day in the same scene. By lerping between colors, we can gradually transition between dawn, day, dusk, and night:

func _process(delta):
    var game_time = get_game_time()
    
    var color_dawn = Color(1, 0.5, 0.25, 1)
    var color_noon = Color(1, 1, 1, 1)
    var color_dusk = Color(1, 0.5, 0.5, 1)
    var color_night = Color(0.1, 0.1, 0.5, 1)

    var current_color = color_noon # Default to midday

    match game_time:
        'Dawn':
            current_color = color_dawn
        'Dusk':
            current_color = color_dusk
        'Night':
            current_color = color_night
    
    shader_globals_override.set_shader_override('ambient_light_color', current_color)

In this piece of code, `get_game_time()` would be a function you’ve set up to return the current game time state. Depending on the time, we use the ShaderGlobalsOverride to transition the ‘ambient_light_color’ to create a convincing time-of-day effect.

Through these examples, we’ve covered ways to utilize ShaderGlobalsOverride class in Godot 4 to dynamically alter your game’s visuals based on different game states, events, and player interactions. This is just a glimpse into the boundless possibilities ShaderGlobalsOverride offers to make your game stand out visually and provide a richer player experience.In addition to environmental effects, the ShaderGlobalsOverride can be used for more subtle, but equally impactful visual details. Let’s explore further applications, including transition effects, player abilities, and global visual adjustments that can take a player’s experience to the next level.

Transition effects between scenes are an excellent place to start. We can alter the shader’s parameters to create a fading in or out effect, which is much more immersive than a simple cut. See how this could be implemented:

func fade_to_black(duration):
    var tween = Tween.new()
    add_child(tween)
    tween.interpolate_property(shader_globals_override, 'global_color',
        shader_globals_override.get_shader_override('global_color'), 
        Color(0, 0, 0, 1), duration, Tween.TRANS_LINEAR, Tween.EASE_IN_OUT)
    tween.start()

This code uses a Tween to gradually change the global shader parameter ‘global_color’ to black, creating a fade-to-black effect over the specified duration.

What about player abilities that have a global impact? We can use ShaderGlobalsOverride to visually represent a time-slowing ability for example:

func activate_time_slow():
    shader_globals_override.set_shader_override('time_scale', 0.5) # Slows down the passage of time visually

func deactivate_time_slow():
    shader_globals_override.set_shader_override('time_scale', 1.0) # Restores normal time passage

By adjusting a ‘time_scale’ parameter, you can influence shaders that play with time-based visuals, such as moving textures or particle systems that should slow down with time.

Moreover, global visual settings can benefit accessibility or player preferences. For instance, you might want to allow players to adjust the overall brightness of the game:

func adjust_brightness(level):
    shader_globals_override.set_shader_override('brightness', level)

Here, ‘brightness’ might be associated with a shader that multiplies the final color of each pixel by the given level, thus changing the overall brightness of the scene.

For in-game cutscenes, a vignette effect can add a cinematic quality. Here’s how we can apply a vignette globally:

func set_cinematic_vignette(on):
    if on:
        shader_globals_override.set_shader_override('vignette_strength', 0.75)
    else:
        shader_globals_override.set_shader_override('vignette_strength', 0.0)

In the above example, ‘vignette_strength’ controls the intensity of a vignette effect that the shader applies to the screen edges for a cinematic look.

Additionally, we can simulate vision impairments for brief moments, such as after taking damage, with a ‘blur’ effect:

func simulate_blurred_vision(duration):
    shader_globals_override.set_shader_override('blur_amount', 0.8) # Apply a significant blur to the scene
    # Use a timer to remove the effect after the duration
    yield(get_tree().create_timer(duration), "timeout")
    shader_globals_override.set_shader_override('blur_amount', 0.0) # Remove the blur effect

This snippet adds a blur amount to the scene, simulating disorientation, and then removes it after a set duration.

Finally, you might want to emphasize certain gameplay mechanics, such as staying in stealth zones. A shader can give visual feedback to players when successfully hiding:

func update_stealth_zone_visibility(is_in_stealth_zone):
    var stealth_visibility = is_in_stealth_zone ? 0.5 : 1.0
    shader_globals_override.set_shader_override('stealth_zone_alpha', stealth_visibility)

In this case, ‘stealth_zone_alpha’ adjusts the transparency of objects affected by the player’s stealth status, indicating whether they are successfully hidden.

Harnessing the power of ShaderGlobalsOverride in Godot 4 opens up a myriad of creative possibilities for game developers. By dynamically altering shader parameters based on gameplay mechanics, player actions, or environmental changes, we can create a rich, interactive world that is both beautiful and engaging. These code snippets offer just a glimpse of how ShaderGlobalsOverride can be used to enhance your game’s visual storytelling and gameplay experiences.

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Conclusion

With the mighty capabilities of ShaderGlobalsOverride in Godot 4, you now have the means to weave dynamic visuals and atmospheric storytelling into the fabric of your games. As you’ve seen, this powerful feature can seamlessly integrate with your gameplay mechanics to provide players with a richer, more immersive experience. Use it wisely, and your game worlds will not just be places players visit, but realms they truly inhabit.

We at Zenva are proud to be part of your journey in game development. Whether you’re looking to refine your skills or just starting out, we invite you to delve into our Godot Game Development Mini-Degree and become a creative force capable of bringing your unique visions to life. Together, let’s push the limits of what’s possible in game creation!

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