VisualShaderNodeExpression in Godot – Complete Guide

Welcome to this comprehensive tutorial on the VisualShaderNodeExpression class in Godot 4. If you’ve dabbled with game development, you’ll know the crucial role that shaders play in bringing visuals to life. Godot’s powerful shader language allows game developers to create stunning visual effects, and understanding how to use VisualShaderNodeExpression unlocks even more potential for customization and control over your game’s graphics. So, whether you’re looking to elevate the aesthetic of your game or just curious about shader programming, this tutorial promises to be an engaging and enlightening journey into the world of Godot shaders.

What is VisualShaderNodeExpression?

VisualShaderNodeExpression is a feature within the Godot Engine that empowers developers to write custom shader expressions using the Godot Shading Language. It extends the base functionality of the visual shader editor, allowing for more complex and personalized visual effects in your game. With this node, you can directly inject code into a shader’s main function, be it for the vertex, fragment, or light stages of rendering.

What is it for?

The main utility of this expression node lies in your ability to customize and manipulate shader operations. VisualShaderNodeExpression gives you the flexibility to define intricate visual behaviors without the restrictions of preset nodes. This is perfect for creating unique visual effects tailored to specific use cases in your game.

Why should I learn it?

Knowing how to utilize VisualShaderNodeExpression in Godot 4 can significantly enhance your game’s visual sophistication with relatively straightforward expressions. While the node itself may seem daunting at first, getting comfortable with this concept allows for a greater depth in shader programming, enabling you to create more compelling and interactive gaming experiences. Plus, as shaders are a key aspect of modern game development, mastering this tool will expand your skillset and open up new possibilities for innovation and creativity in your projects.

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Creating a Simple Custom Expression

Let’s begin by creating a simple expression that alters the color of our object. We will modify the fragment shader to change the rendered color based on the object’s texture coordinates.

shader_type spatial;
void fragment() {
    COLOR = vec4(UV, 0.5, 1.0);
}

By using the `UV` coordinates, we ensure each pixel’s red and green channels relate to its position, giving us a gradient effect across the object.

Integrating VisualShaderNodeExpression

Now, let’s integrate a VisualShaderNodeExpression in our visual shader.

// Right-click in the Shader Graph workspace
// Choose 'Add Node', then navigate to 'Expression'
// Double-click or click 'Create' button to add it to the workspace

Once you have added the node, we will write a custom expression for the color output.

vec3 custom_color = vec3(UV, 0.0) + vec3(0.1, 0.2, 0.3);
COLOR.rgb = custom_color;

Here, we are adding to the UV coordinates a small constant vector to slightly change the colors, affecting the final RGB value outputted to `COLOR`.

Time-Dependent Animations

Animations often require shaders to change over time. We can use the `TIME` built-in variable to create a time-dependent effect.

float time = mod(TIME, 2.0 * PI);
COLOR.rgb = 0.5 + 0.5 * cos(time + UV.xyx * 6.2831);

This code will create a moving sinusoidal pattern across your object’s surface. The `TIME` variable increases continuously, and `mod` ensures the time value wraps around, producing a continuous animation.

Manipulating the Alpha Channel

Another aspect we can alter is the object’s transparency through its alpha channel. Let’s say we want to make the edges of our object fade away slowly.

float edge_fade = smoothstep(0.1, 0.3, abs(UV.x - 0.5));
COLOR.a = edge_fade;

`smoothstep` is a built-in function that interpolates smoothly between two edges. In this case, it is used to create a fade effect based on the `x` coordinate of the UVs.

Remember, to see the effect of alpha manipulation, your material’s alpha setting must not be set on opaque.

Implementing Conditionals and Mix

Within our expressions, we can also use conditional statements and mix functions to blend colors based on certain conditions.

vec3 color1 = vec3(1.0, 0.0, 0.0);
vec3 color2 = vec3(0.0, 0.0, 1.0);
bool is_greater = UV.x > 0.5;
COLOR.rgb = mix(color1, color2, float(is_greater));

In this example, we blend between two colors depending on the UV `x` coordinate. If `UV.x` is greater than 0.5, `COLOR.rgb` will be closer to `color2`, otherwise, to `color1`.

Through these examples, we’ve seen how to incorporate custom expressions to affect color, animate over time, manipulate transparency, and blend colors based on conditions. These basics provide a solid foundation to further explore and create even more complex visual effects in Godot 4 with VisualShaderNodeExpression.

Working With Textures

Textures can greatly enhance the appearance of your shaders. Let’s work with texture sampling to influence our visual output. Say we have a texture and we want it to affect our object’s color dynamically.

uniform sampler2D my_texture;
void fragment() {
    vec4 tex_color = texture(my_texture, UV);
    COLOR = tex_color;
}

This snippet samples a texture bound to `my_texture` and applies the retrieved color to the current fragment. The texture will be shown as is on the object’s surface.

Adding Texture Distortion

Now let’s introduce some distortion to this texture using noise.

uniform sampler2D my_texture;
uniform sampler2D noise_texture;

void fragment() {
    vec2 noise = texture(noise_texture, UV * 10.0).rg * 0.2;
    vec4 tex_color = texture(my_texture, UV + noise);
    COLOR = tex_color;
}

Here, we’re using a noise texture to create a distortion effect. We multiply the noise value with the texture coordinates before we sample our main texture to achieve a wavy effect.

Masking With Textures

We can also use textures to mask certain parts of our object, rendering some areas invisible or applying effects only to specific parts.

uniform sampler2D my_texture;
uniform sampler2D mask_texture;

void fragment() {
    float mask = texture(mask_texture, UV).r;
    vec4 tex_color = texture(my_texture, UV);
    COLOR = vec4(tex_color.rgb, mask);
}

This code uses the red channel of a mask texture to determine the alpha value of our object’s color. Areas with higher red values in the mask will be more opaque.

Animating Textures

Animating the texture coordinates can create interesting effects, such as scrolling textures, which is popular in creating an illusion of motion.

uniform sampler2D my_texture;
uniform float scroll_speed = 1.0;

void fragment() {
    vec2 uv = UV;
    uv.x += TIME * scroll_speed;
    vec4 tex_color = texture(my_texture, uv);
    COLOR = tex_color;
}

By adjusting the `x` component of the UV coordinates over time, we achieve a horizontal scrolling effect on our texture.

Adding Conditionals in Shaders

Now let’s use conditionals to apply effects based on certain criteria. For instance, we might highlight fragments close to the UV center.

void fragment() {
    float dist = distance(UV, vec2(0.5, 0.5));
    COLOR.rgb = dist < 0.1 ? vec3(1.0, 0, 0) : vec3(0.0, 0, 1.0);
}

This shader uses the ternary operator to test whether each fragment is within a certain distance from the center of the UV space, rendering it red if true, and blue otherwise.

Utilizing Functions and Loops

To encapsulate complex logic or repetitive calculations, you can define functions in your expressions. For example, let’s make a stripe pattern using a function.

float stripes(vec2 uv, float frequency) {
    return step(0.5, sin(uv.x * frequency));
}

void fragment() {
    COLOR.rgb = vec3(stripes(UV, 20.0));
}

The `stripes` function calculates whether a sine function at a certain `frequency` is above 0.5 for the given UV coordinates, creating a striped pattern.

Implementing Gradient with Loop

Looping within a shader allows us to execute a piece of code multiple times. Here, we build a gradient pattern using a loop.

void fragment() {
    vec3 gradient_color = vec3(0.0);
    for (int i = 0; i < 10; i++) {
        gradient_color += vec3(UV, 0) * (1.0 - float(i) / 10.0);
    }
    COLOR.rgb = gradient_color;
}

This fragment shader accumulates a color value by looping, each time multiplying the UV coordinates by a decreasing factor to create the effect of a gradient.

By understanding and experimenting with these shader components, you can begin to see the powerful visual effects possible in Godot. Whether it’s dynamic textures, conditional rendering, or complex looping patterns, the VisualShaderNodeExpression node helps you to realize your creative vision with precision and flair.Shaders are an integral part of modern graphic applications, providing flexibility and control over the visual aspects of a game. VisualShaderNodeExpression in Godot enables us to create sophisticated real-time effects using Godot Shading Language. Dive into these additional code examples to unleash even more capabilities of shaders.

Blending Textures

Blending multiple textures together can create complex materials or dynamic environments. Here, we seamlessly blend two textures based on a blend factor.

uniform sampler2D texture1;
uniform sampler2D texture2;
uniform float blend_factor;

void fragment() {
    vec4 tex1_color = texture(texture1, UV);
    vec4 tex2_color = texture(texture2, UV);
    COLOR = mix(tex1_color, tex2_color, blend_factor);
}

This example uses `mix` to interpolate between two texture samplers, `texture1` and `texture2`, based on `blend_factor`. This could simulate effects like changing seasons or time of day.

Creating Outline Effects

Outline shaders can make objects pop out or enhance visual understanding. A simple way to create an outline is by comparing the depth of nearby fragments.

uniform float outline_size;
uniform vec4 outline_color;

void fragment() {
    float depth = texture(DEPTH_TEXTURE, UV).r;
    float outline = 0.0;
    for (int y = -1; y <= 1; y++) {
        for (int x = -1; x <= 1; x++) {
            vec2 offset = vec2(x, y) * outline_size;
            float neighbor_depth = texture(DEPTH_TEXTURE, UV.xy + offset).r;
            outline = max(outline, step(depth, neighbor_depth));
        }
    }
    COLOR = mix(outline_color, COLOR, 1.0 - outline);
}

In this code, we’re comparing the depth of the current fragment with the surrounding ones. If the current depth is the closest one, we’re drawing an outline.

Fresnel Effect

The Fresnel effect adds realism to objects by simulating the way light reflects off surfaces at glancing angles, often used to enhance the look of glass or liquid surfaces.

uniform float fresnel_bias;
uniform float fresnel_scale;
uniform float fresnel_power;

void fragment() {
    float fresnel = fresnel_bias + fresnel_scale * pow(1.0 + dot(NORMAL, VIEW), fresnel_power);
    COLOR.rgb *= fresnel;
}

We use the dot product between the normal and the view direction to determine the fresnel term, which then scales the color based on the angle of view.

Heat Distortion

Simulating heat distortion can add a feel of realism to hot surfaces or environments. We achieve this by warping the UV coordinates in the fragment shader.

uniform sampler2D noise_texture;
uniform float distortion_strength;
uniform float distortion_scale;

void fragment() {
    vec2 noise = texture(noise_texture, UV * distortion_scale).rg;
    vec2 distorted_uv = UV + noise * distortion_strength;
    COLOR.rgb = texture(SCREEN_TEXTURE, distorted_uv).rgb;
}

The above code samples a noise texture and uses the result to distort the UVs while sampling the screen’s texture. This creates an illusion of air refracting due to heat.

Creating a Dissolve Effect

Dissolve effects are visually appealing ways to simulate an object disintegrating or materializing. This can be done by using a noise texture and thresholding.

uniform sampler2D noise_texture;
uniform float dissolve_cutoff;

void fragment() {
    float noise_value = texture(noise_texture, UV).r;
    if (noise_value < dissolve_cutoff) {
        discard;
    }
    COLOR = texture(SCREEN_TEXTURE, UV);
}

We sample the noise texture and compare the value to a cutoff threshold. Pixels with noise below the threshold are discarded, creating the effect of the object dissolving.

Using Lights and Shadows

Shaders can also directly respond to light and shadows in a scene, adding depth and realism.

void fragment() {
    vec4 albedo_color = vec4(0.8, 0.2, 0.2, 1.0);
    vec3 light_dir = normalize(LIGHT - WORLD_POSITION);
    float diff = max(dot(NORMAL, light_dir), 0.0);
    ALBEDO = albedo_color.rgb * diff;
}

This fragment shader computes a simple directional light effect. It calculates the dot product of the light direction and the normal to determine how much light hits each pixel.

Real-Time Toon Shading

Toon shading, or cel shading, gives a game a more stylized, cartoon-like appearance.

uniform vec4 base_color;
uniform vec4 shadow_color;

void fragment() {
    float shadow = dot(NORMAL, LIGHT_DIRECTION);
    if (shadow > 0.9) {
        COLOR.rgb = base_color.rgb;
    } else {
        COLOR.rgb = shadow_color.rgb;
    }
}

The `dot` between `NORMAL` and `LIGHT_DIRECTION` determines whether the color should be the base color or a shadow color based on the defined cutoff.

These examples demonstrate the sheer diversity of effects that can be achieved with Godot’s VisualShaderNodeExpression. As we progress through these tutorials, you’ll gain a deeper understanding of how to manipulate visual properties to create engaging and dynamic visuals for your games.

Continuing Your Game Development Journey

If you’ve enjoyed delving into the intricacies of Godot’s VisualShaderNodeExpression and you’re eager to further your game development skills, we invite you to explore our Godot Game Development Mini-Degree. This collection of carefully curated courses will lead you through the many capabilities of the Godot Engine. Learn at your own pace as you build cross-platform games, and cover a diverse range of subjects from 2D and 3D game development to advanced gameplay mechanics.

Consolidate your knowledge with hands-on projects that hone your skills and contribute to a professional portfolio, an invaluable asset in your game development career. Our courses are designed to guide you from the very beginning to advanced levels of game creation, ensuring a comprehensive learning experience.

For a wider array of tutorials and courses that cover additional aspects and genres of game development in Godot, feel free to browse our complete selection of Godot courses. At Zenva, we’re dedicated to providing high-quality education that can take you from learning the basics to mastering the skills needed to become a professional in the exciting world of game development.

Conclusion

As you have ventured through the world of Godot’s VisualShaderNodeExpression, it’s evident that the capacity to craft visually stunning and interactive game elements is right at your fingertips. Whether you’re just starting your journey or looking to push the boundaries of what you can achieve in Godot, harnessing the power of shaders is a step towards bringing your unique creative visions to life.

Remember, the key to mastering game development is consistent practice and exploration. Continue to build, experiment, and expand your knowledge with our Godot Game Development Mini-Degree, and witness your game worlds transform with each line of code. From all of us at Zenva, happy coding, and we look forward to seeing the incredible games you’ll create!

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