Shader in Godot – Complete Guide

Diving into the world of game development opens the door to crafting fantastic environments, compelling mechanics, and immersive experiences. At the heart of translating these ideas into visual reality are shaders – the quintessential instruments that orchestrate how objects are rendered in a game engine. Understanding shaders can significantly elevate your game’s look and feel, adding depth, dynamism, and realism to your scenes. In this tutorial, we will explore the Shader class in Godot 4, an immensely potent tool that brings artistic visions to life through the power of programming.

What is a Shader?

A shader is essentially a program that dictates the rendering of graphics in video games and other visual simulations. It’s the cornerstone of creating textures, lighting effects, shadows, and various intricate visual intricacies that you witness in modern games. Written in specialized shading languages, shaders instruct the rendering hardware on how to process vertices and pixels to generate the final look of an object or an environment.

What is the Shader Class in Godot 4 Used For?

In Godot 4, the Shader class serves as your canvas for the Godot Shader Language, an approachable but powerful language modeled on GLSL (OpenGL Shading Language). By using this class, you can produce custom visual effects that are tailored to your game’s specific stylistic and interaction needs. Be it modifying the visual aspects of 3D models or altering the properties of particles in a system, the Shader class is your gateway to customization in Godot’s rendering engine.

Why Should I Learn to Use Shaders?

Shaders are the secret sauce that can differentiate a game from the rest of the pack. They are not just for the seasoned programmer; even developers at the beginning of their journey can unlock incredible visual potential by learning the ropes of shader programming. By understanding the Shader class in Godot 4:

– You gain direct control over the graphical output of your games.
– It provides the means to implement high-performance graphics that can run smoothly even on less powerful hardware.
– Learning shaders enhances your creative freedom and design capabilities.

Armed with this knowledge, you’re well-equipped to venture into the fascinating realm of shaders. So, let’s start our journey by writing simple shaders that create compelling visual effects and make your game stand out.

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Creating a Simple Shader in Godot 4

Let’s begin by crafting a basic shader that will change the color of a sprite. To do this, we need to create a new ShaderMaterial and then attach a Shader to it.

Firstly, create the ShaderMaterial:

var material = ShaderMaterial.new()

Next, attach a new Shader to your material and specify the shader type:

var shader = Shader.new()
shader.set_code('shader_type canvas_item;')
material.shader = shader

Now let’s write a simple shader script to alter the sprite’s color:

shader.set_code('''
shader_type canvas_item;

void fragment() {
    COLOR = vec4(1.0, 0.0, 0.0, 1.0); // Red color
}
''')

When you attach this material to a sprite, the sprite will appear red. This is a very basic example of what shaders can do.

Integrating Vertex and Fragment Shaders

Godot’s shader language allows you to write vertex functions that manipulate the vertices of your mesh, and fragment functions that adjust how each pixel is colored. We’ll start simple and progress to a more complex example.

To modify the vertices of a mesh to create a wave effect:

shader.set_code('''
shader_type spatial;

void vertex() {
    VERTEX.x += sin(VERTEX.z + TIME) * 0.5;
}
''')

The above code manipulates the x-position of the mesh’s vertices to create a sine wave effect using the z-position and the time since the start of the game.

Now, let’s explore a fragment shader example that applies a checkerboard pattern to the object:

shader.set_code('''
shader_type spatial;

void fragment() {
    vec2 grid_position = floor(FRAGCOORD.xy / 20.0);
    float checker = mod(grid_position.x + grid_position.y, 2.0);
    vec3 color = checker < 1.0 ? vec3(0, 0, 0) : vec3(1, 1, 1);

    ALBEDO = color;
}
''')

The fragment shader uses the position of the fragment to determine if it should be black or white, creating a checkerboard pattern on your object.

Texturing and Light Interaction

Integrating texture and responding to light are common needs in game development. Let’s see how Godot shaders handle these:

For applying a texture:

shader.set_code('''
shader_type canvas_item;

uniform sampler2D my_texture;

void fragment() {
    COLOR = texture(my_texture, UV);
}
''')

Add your texture as a uniform, which allows you to pass the texture to the shader from your material properties, and then utilize it within the fragment function.

And for a basic lighting interaction:

shader.set_code('''
shader_type spatial;

uniform vec4 albedo_color : hint_color;

void fragment() {
    vec3 light_dir = normalize(vec3(1.0, 1.0, 1.0));
    float diff = max(dot(NORMAL, light_dir), 0.0);
    
    ALBEDO = albedo_color.rgb;
    DIFFUSE_LIGHT += diff;
}
''')

In this snippet, we’re calculating the angle (dot product) of the incident light against the surface normal and using it to determine the diffuse lighting applied to the model.

These examples should give you a grounding in Godot’s Shader class and its fundamental uses. Stay tuned, as we’ll delve deeper into more complex shader operations in our next section, taking your skills to the next level.In this section, we’ll explore additional capabilities of shaders in Godot 4, including blending modes, noise generation, utilising depth information, and post-processing effects. These techniques can enhance the visual appeal or create unique visual effects for your games.

Blending Modes

Control over blending is vital for achieving various transparency and layering effects. In Godot, you can define custom blending modes in your shader scripts:

shader.set_code('''
shader_type canvas_item;

void fragment() {
    COLOR = texture(TEXTURE, UV) * vec4(1.0, 0.5, 0.5, 0.5);
}

render_mode blend_mix;
''')

In this example, `blend_mix` is set, which is the default blending mode, akin to normal blending in image editing software. The texture’s color is blended with a reddish translucent tint.

Noise Generation

Procedural noise is useful for creating a variety of effects, from textures to movement. Godot provides built-in functions to generate noise:

shader.set_code('''
shader_type spatial;

uniform sampler2D noise_tex;
uniform float time_speed = 1.0;

void fragment() {
    float noise_value = texture(noise_tex, UV * TIME * time_speed).r;
    ALBEDO = vec3(noise_value);
}
''')

Here we’re creating a grayscale pattern driven by a noise texture that evolves over time, adjustable with the `time_speed` uniform.

Depth-Based Effects

Using depth information, you can create atmospheric effects, like fog, or apply effects only to certain depth levels.

Below is a code snippet for a simple fog shader:

shader.set_code('''
shader_type spatial;

uniform vec3 fog_color = vec3(0.5);
uniform float fog_start = 10.0;
uniform float fog_end = 50.0;

void fragment() {
    float depth = DEPTH;
    float fog_factor = smoothstep(fog_start, fog_end, depth);
    ALBEDO = mix(ALBEDO, fog_color, fog_factor);
}
''')

This shader gradually blends objects with a fog color based on their depth.

Post-Processing Effects

Post-processing refers to effects that are applied after the scene has been rendered. Godot allows you to apply shaders to the entire screen as well.

Creating a vignette effect is a common post-processing technique:

shader.set_code('''
shader_type canvas_item;

void fragment() {
    vec2 position = (FRAGCOORD.xy / SCREEN_PIXEL_SIZE) - vec2(0.5 * SCREEN_SIZE);
    float len = length(position);
    float vignette = smoothstep(0.4, 0.5, len);
    COLOR.rgb = mix(COLOR.rgb, vec3(0.0), vignette);
}
''')

The vignette effect darkens the edges of the screen, drawing attention to the center.

Let’s also create a simple chromatic aberration effect:

shader.set_code('''
shader_type canvas_item;

void fragment() {
    vec3 color;
    vec2 uv = UV;
    color.r = texture(TEXTURE, vec2(uv.x + 0.01, uv.y)).r;
    color.g = texture(TEXTURE, uv).g;
    color.b = texture(TEXTURE, vec2(uv.x - 0.01, uv.y)).b;
    COLOR = vec4(color, 1.0);
}
''')

In this effect, we’re slightly offsetting the red and blue channels to simulate the look of misaligned color channels in a camera.

As you experiment with different aspects of shaders in Godot 4, you’ll find that the possibilities are vast. From creating incredible visual effects to optimizing your game’s performance, mastering shaders can give you a significant advantage in crafting high-quality games.

We hope these examples have inspired you to experiment and learn more. Remember, practice is key to mastering shaders, and we encourage you to try out these examples and create your own effects. With Godot 4 and its Shader class, you’re well-equipped to bring your creative visions to life!As you become more comfortable with the basics of shader programming in Godot 4, you can begin to explore effects that are more complex and nuanced. Environmental effects, interactive shaders that respond to player actions, and complex transformations are just a few of the areas where shaders can truly shine. Let’s delve into some more advanced shader examples.

First, consider an environmental effect such as simulating water caustics. This fascinating play of light through water can add a layer of realism to underwater scenes:

shader.set_code('''
shader_type spatial;

uniform sampler2D caustics_texture;
uniform float speed = 1.0;

void fragment() {
    vec2 causticUV = UV + vec2(TIME * speed, 0.0);
    vec3 causticColor = texture(caustics_texture, causticUV).rgb;
    ALBEDO *= causticColor;
}
''')

This shader multiplies the object’s albedo with a moving caustics texture, simulating the effect of light passing through a water surface.

Next, let’s create a shader that responds to the distance from the player. This could be used to highlight objects when the player is near:

shader.set_code('''
shader_type spatial;

uniform float highlight_distance = 5.0;
uniform vec3 player_position;

void fragment() {
    float dist = distance(VERTEX, player_position);
    if(dist < highlight_distance) {
        ALBEDO = mix(ALBEDO, vec3(1.0), 1.0 - (dist / highlight_distance));
    }
}
''')

The object will become increasingly highlighted as the player approaches, based on the specified distance.

Interactive shaders can also be impacted by player actions, such as casting spells or taking damage. Here is an example of a shader that changes color when an action occurs:

shader.set_code('''
shader_type canvas_item;

uniform bool is_affected;
uniform vec4 effect_color;

void fragment() {
    if(is_affected) {
        COLOR = effect_color;
    } else {
        COLOR = texture(TEXTURE, UV);
    }
}
''')

The sprite’s color changes to `effect_color` whenever `is_affected` is true, which you can control through your game logic.

Shaders can also manipulate UV coordinates to create interesting texture transformations. Here, we achieve a swirling effect:

shader.set_code('''
shader_type canvas_item;

uniform float swirl_strength = 1.0;
uniform float swirl_speed = 1.0;

void fragment() {
    vec2 center = vec2(0.5, 0.5);
    vec2 uvOffset = UV - center;
    float angle = swirl_speed * TIME + length(uvOffset) * swirl_strength;
    vec2 newUV = vec2(
       uvOffset.x * cos(angle) - uvOffset.y * sin(angle), 
       uvOffset.x * sin(angle) + uvOffset.y * cos(angle)
    ) + center;
    COLOR = texture(TEXTURE, newUV);
}
''')

The shader rotates the texture coordinates around the center of the image, with the strength and speed controlled by uniforms.

To tweak not just color and texture, but the object’s shape in a dramatic way, we can employ shaders, too. Consider a bulge distortion effect:

shader.set_code('''
shader_type canvas_item;

uniform float distortion_strength = 1.0;
uniform vec2 distortion_center;

void fragment() {
    vec2 uvOffset = UV - distortion_center;
    float dist = length(uvOffset);
    if(dist < 1.0) {
        float factor = pow(1.0 - dist, 2.0);
        uvOffset *= mix(1.0, smoothstep(0.0, 1.0, factor), distortion_strength);
    }
    COLOR = texture(TEXTURE, uvOffset + distortion_center);
}
''')

The bulge distortion pushes pixels out from the center of distortion, which could be animated or controlled via game logic.

Lastly, shaders have potency in non-visual gameplay applications as well. Consider a shader that dynamically masks parts of a level based on exploration:

shader.set_code('''
shader_type canvas_item;

uniform sampler2D mask_texture;

void fragment() {
    if(texture(mask_texture, UV).r < 0.5) {
        discard;
    } else {
        COLOR = texture(TEXTURE, UV);
    }
}
''')

This code makes the sprite transparent wherever the corresponding mask texture’s red channel is less than 0.5, effectively revealing or hiding portions of the game world.

These examples represent only a fraction of the potential that shaders unlock. By learning and applying these techniques, you can create truly interactive, dynamic, and visually stunning effects in your games using Godot 4. Each new technique you master will add to your toolkit as a game developer and allow you to push the boundaries of what you can create. Enjoy experimenting with these examples, and let your creativity flow!

Continue Your Godot Journey

Congratulations on completing this shader tutorial with Godot 4! You’ve taken an important step in your journey as a game developer, grasping the fundamentals of how powerful and transformative shaders can be for your projects. But don’t stop here—there’s a whole universe of possibilities waiting for you to explore within the Godot engine.

If you’re excited about diving deeper and expanding your knowledge, we invite you to check out our
Godot Game Development Mini-Degree. This extensive series of courses tailors a path from the basics to more advanced concepts, offering you the flexibility to learn at your own pace while building a portfolio of impressive projects. The Godot engine’s lightweight, free, and open-source nature makes it an excellent choice for both novice and seasoned developers, and our curriculum is designed to leverage these strengths.

For a broader array of tutorials and courses that cover various aspects of Godot, from 2D and 3D game development to mastering GDScript, visit our collection of
Godot courses. Each course aims to give you practical experience and insights to enhance your skills continuously. With Zenva Academy, you can evolve from a beginner to a professional game developer in no time. Begin your next chapter today, and keep on creating!

Conclusion

Embarking on a journey of mastering shaders in Godot 4 can truly transform the way you approach game development. With the skills you’ve begun to develop throughout this tutorial, you’re now poised to inject more life, realism, and interactivity into your games. Remember, proficiency with shaders might feel like an art form, but it’s one that comes with practice—a blend of creativity and technical know-how that grows with each project you undertake.

Whether you’re just starting or looking to refine your expertise, our
Godot Game Development Mini-Degree is the perfect next step to continue your learning adventure. With us at Zenva Academy, you’re never alone on your educational journey. We provide you with the content, community, and support to shine brightly in the gaming universe. So go ahead, push the boundaries of your imagination, and let the virtual worlds you create reflect your newfound shader prowess. Happy developing!

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