Diving into the realm of game development can be both exciting and daunting, especially when it comes to understanding the intricate aspects of shader programming. However, unlocking the capabilities of shaders can transform your game’s visual appeal significantly. In this fascinating tutorial, we’ll learn about an intriguing class in Godot 4, the VisualShaderNodeGlobalExpression. It’s a powerful tool in the Godot Shader Language that can often seem complex but proves to be incredibly potent once harnessed.
Table of contents
What is VisualShaderNodeGlobalExpression?
VisualShaderNodeGlobalExpression is a resource within Godot 4’s robust development toolkit designed for creating custom shaders. Shaders are small programs that tell the computer how to render each pixel on the screen, and they can be used for a variety of visual effects, from simple changes in color to complex transformations in a 3D view. The VisualShaderNodeGlobalExpression class allows you to write custom global shader graph expressions using the Godot Shading Language, which will be applied across your entire shader, providing a means for defining functions, varyings, uniforms, and global constants.
What is it for?
Imagine you’re crafting a unique look for your game, perhaps a shimmering water surface or a dynamic shadow that responds to an in-game event. These are the types of effects that can be achieved with VisualShaderNodeGlobalExpression. By giving you the ability to write global expressions, this node class is there to help encapsulate complex shading logic that can be reused across different parts of your shader graph. This promotes a more organized, modular, and efficient approach to shader programming.
Why Should You Learn It?
Shaders are a staple in modern game development, and mastering them can be your ticket to bringing your creative vision to life. With VisualShaderNodeGlobalExpression, Godot 4 provides you with the flexibility to create more advanced, high-quality visuals right out of the box. Learning how to use this class effectively can set your game apart, making it feel more immersive and engaging for players. Whether you are just starting out or already have some experience under your belt, understanding how to utilize this powerful tool is crucial to the development of visually stunning games.
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Creating a Simple Global Expression
To kick things off, let’s start by creating a simple global expression. This will help set the stage for understanding the basics of using VisualShaderNodeGlobalExpression in Godot 4.
// Define a global float variable
global float customTime;
// Initialize customTime in the shader's start
void start() {
customTime = TIME;
}Here, we’ve declared a global floating-point variable named `customTime` and initialized it with Godot’s built-in `TIME` variable. This simple global expression can now be accessed in any part of our shader.
Using the Global Expression in Vertex and Fragment Shaders
The global expression can be utilized across different shader functions. Let’s see how `customTime` can be used in both vertex and fragment shaders to create a pulsating vertex displacement and a color change over time.
In the vertex shader:
void vertex() {
// Use customTime for vertex displacement
VERTEX.x += sin(customTime) * 0.1;
VERTEX.y += cos(customTime) * 0.1;
}And in the fragment shader:
void fragment() {
// Apply customTime to color for a fading effect
ALBEDO.rgb = vec3(sin(customTime), cos(customTime), sin(customTime * 0.5));
}By incorporating `customTime` in different shaders, we create an animation effect that combines both displacing vertices and changing colors.
Adding Uniforms to Global Expressions
Uniforms are variables that can be set from outside the shader, allowing for real-time manipulation. We can define a uniform within a global expression and utilize it just like a regular global variable.
// Define a custom global uniform
global uniform float waveIntensity;
void start() {
// ... other global expressions
}To apply this uniform in the vertex shader, we can modify the previous example:
void vertex() {
// Use waveIntensity to control the displacement strength
VERTEX.x += sin(customTime * waveIntensity) * 0.1;
VERTEX.y += cos(customTime * waveIntensity) * 0.1;
}Working with Functions in Global Expressions
Functions are fundamental building blocks in shading. They help you encapsulate reusable logic. Defining functions in a global expression can greatly enhance the flexibility and maintainability of your shader code.
// Define a function to calculate a waving motion
global float waveMotion(float intensity, float offset) {
return sin(customTime * intensity + offset);
}
void start() {
// ... other global expressions
}Now, we can refactor our vertex shader to use our `waveMotion` function:
void vertex() {
// Use the waveMotion function to simplify the displacement
VERTEX.x += waveMotion(waveIntensity, 0.0) * 0.1;
VERTEX.y += waveMotion(waveIntensity, PI / 2.0) * 0.1; // PI / 2.0 adds a 90-degree phase offset
}By encapsulating the wave logic into a function, we can easily apply it with different parameters for more complex and varied visual effects.Continuing with our immersion into VisualShaderNodeGlobalExpression, we’ll expand our repertoire of examples to cover a range of applications. Each snippet exemplifies how Godot’s shader language empowers developers to bring their visual ideas to life.
Let’s start by introducing conditionals into our global expressions:
// Defining a global function with a conditional
global float conditionalColorChange(float threshold) {
if (TIME > threshold) {
return 1.0;
} else {
return 0.5;
}
}
void start() {
// ... other global expressions
}Next, we’ll see how this can be applied in a fragment shader to dynamically change the color based on time:
void fragment() {
// Calling conditionalColorChange to determine the color's brightness
float brightness = conditionalColorChange(5.0);
ALBEDO.rgb = vec3(brightness, brightness, brightness);
}Shaders also allow for loop constructs, which can be used for repetitive and iterative effects:
// A global function using a loop to create a pattern
global float loopedPattern(float scale) {
float pattern = 0.0;
for (int i = 0; i < 10; i++) {
pattern += sin(customTime + float(i) * scale);
}
return pattern;
}
void start() {
// ... other global expressions
}We implement this in the fragment shader to create a dynamic textured pattern:
void fragment() {
// Use loopedPattern to affect the ALBEDO's red channel
ALBEDO.r = loopedPattern(0.1);
}Let’s experiment with sending vertex data to the fragment shader. Here we calculate a vertex color based on position and pass it to the fragment shader:
void vertex() {
// Set a vertex color based on its x position
VERTEX_COLOR = vec4(VERTEX.x, 0.0, 0.0, 1.0);
}
void fragment() {
// The fragment color is affected by the passed vertex color
ALBEDO.rgb *= VERTEX_COLOR.rgb;
}Furthermore, if we want to work with textures, we can write global expressions that manipulate UV coordinates:
// Global expression for scaling UVs
global vec2 scaleUVs(vec2 uvs, float scaleFactor) {
return uvs * scaleFactor;
}
void start() {
// ... other global expressions
}Subsequently, we use our function to scale texture coordinates, creating a zoom effect on a texture:
void fragment() {
// Modify UVs with our scaleUVs function before using the texture
UV = scaleUVs(UV, 2.0);
ALBEDO.rgb = texture(TEXTURE, UV).rgb;
}Touching upon lighting, we can redefine how surface information impacts light interaction by modifying the surface shader:
// Global expression to pulse the specular value
global float modulateSpecular(float intensity) {
return sin(customTime) * intensity;
}
void start() {
// ... other global expressions
}The aforementioned global function can then be incorporated to modulate the specular highlights dynamically:
void light() {
// The specular value pulses with time
SPECULAR = modulateSpecular(0.5);
}As we see from these examples, the potential to express creative visual programming with VisualShaderNodeGlobalExpression is vast. Each of these snippets offers a glimpse into the versatility and control that Godot’s shader language and shader nodes offer. These tools enable us not just to enhance our games visually but to craft experiences that resonate with players through dynamic, responsive, and compelling visual narratives.One of the beauties of shader programming is the ability to simulate environmental factors. Let’s take a look at how to create a shader that reacts to the virtual wind, giving life to static objects by making them sway.
// Define a global function for wind <a class="wpil_keyword_link" href="https://gamedevacademy.org/best-simulation-game-tutorials/" target="_blank" rel="noopener" title="simulation" data-wpil-keyword-link="linked">simulation</a>
global vec3 applyWind(vec3 position, float intensity) {
float wind = sin(TIME) * intensity;
position.x += wind;
return position;
}We apply this effect to our vertex shader to make the mesh sway like it’s being blown by the wind:
void vertex() {
VERTEX = applyWind(VERTEX, 0.1);
}To introduce more complexity, we can simulate a wind direction using another global function:
// Additional global function for wind direction
global vec3 windDirection(float intensity, vec2 direction) {
vec3 windEffect;
windEffect.x = sin(TIME * direction.x) * intensity;
windEffect.z = cos(TIME * direction.y) * intensity;
return windEffect;
}And modify our previous implementation:
void vertex() {
VERTEX += windDirection(0.1, vec2(0.8, 0.6));
}Another example might be to generate a night-to-day cycle by changing the color of the ambient light using a uniform:
// Uniform for ambient light color
global uniform vec3 dayNightColor;
void light() {
AMBIENT_LIGHT = dayNightColor;
}Users could then adjust the `dayNightColor` uniform in real-time to smoothly transition from day to night in-game.
To add an interactive element, let’s consider making a shader that responds to the player’s actions. For instance, we could track the player’s position and adjust the shader accordingly:
// Global uniform to store player position
global uniform vec3 playerPosition;
global float playerProximityEffect(vec3 position, float maxDistance) {
// Calculate the distance between the player and the position
float distance = distance(playerPosition, position);
if (distance < maxDistance) {
// Returns a value that decreases as the distance increases
return (maxDistance - distance) / maxDistance;
}
return 0.0;
}In the vertex shader, we could use this proximity effect to produce an interesting interaction:
void vertex() {
// Displace the vertex based on the player's proximity
float proximity = playerProximityEffect(VERTEX, 5.0);
VERTEX.y += (1.0 - proximity) * 0.2;
}Lastly, shaders can be used to visually display health or other status effects. Let’s create an effect to visualize a heating object transitioning in color based on its temperature:
// Temperature uniform to control the effect
global uniform float temperature;
global vec3 heatColor(float temp) {
// Interpolate between blue (cold) and red (hot)
return mix(vec3(0.0, 0.0, 1.0), vec3(1.0, 0.0, 0.0), temp);
}And use that in the fragment shader to visually represent the heat level:
void fragment() {
ALBEDO.rgb = heatColor(temperature);
}This functionality not only serves aesthetic purposes but can also convey important gameplay information to the player.
Through these examples, we showcase not only the range of effects achievable with VisualShaderNodeGlobalExpression but also the depth of interaction and gameplay information that shaders can represent. The shader code provided is highly adaptable, allowing developers to personalize the visual experience of their games while serving functional gameplay roles.
Where to Go Next?
Embarking on the journey of learning shader programming with Godot 4 is a thrilling adventure, and we’re thrilled to see the progress you have made. If you’re inspired to delve deeper and take your skills to the next level, the Godot Game Development Mini-Degree is the perfect next step for you. This comprehensive collection of courses will guide you through the creation of cross-platform games, helping you consolidate your knowledge and refine your coding prowess.
Whether you’re just starting out or looking to polish your existing skills, the Godot 4 Game Development Mini-Degree is tailored to provide step-by-step instruction on a vast array of topics, with the flexibility to learn at your own pace. The courses within this Mini-Degree are designed to nurture your expertise and enable you to build an impressive portfolio of real-world projects. And if you’re eager to explore even more Godot courses, we have an extensive library at Zenva’s Godot courses catering to all levels of experience.
At Zenva, we believe in empowering developers. Our courses, created by seasoned game developers, are customized to ensure that you acquire both the theoretical knowledge and practical experience necessary for a rewarding career in game development. Join us on this transformative learning path, and let’s create extraordinary gaming experiences together!
Conclusion
As you have seen, understanding and using VisualShaderNodeGlobalExpression in Godot 4 opens a world of possibilities. Shading techniques, when mastered, not only breathe life into your games but also add a layer of polish and professionalism that stands out. We at Zenva are dedicated to equipping you with these indispensable skills and more, ensuring that you can bring to fruition the games you’ve always envisioned.
Don’t hesitate to take the leap and further your mastery in game development with our Godot Game Development Mini-Degree. It’s more than just a learning resource; it’s your gateway to becoming a proficient game developer, capable of crafting immersive and visually stunning game experiences. Take that step, continue learning, and let’s shape the future of gaming together!
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