The Fragment Shader is a vital program on the GPU, determining the final color, depth, and other properties for each potential Pixel drawn to the screen. It breathes life into rendered geometry, making the visual output vibrant and detailed.
A basic fragment shader typically takes interpolated values from the Vertex Shader (like texture coordinates or normals) and calculates the final output color.
Example
Here's a simple GLSL (OpenGL Shading Language) example of a fragment shader that outputs a constant red color:
#version 330 core
out vec4 FragColor; // The output color of the fragment
void main()
{
FragColor = vec4(1.0f, 0.0f, 0.0f, 1.0f); // Set output color to red (R, G, B, A)
}
This example simply sets every pixel to solid red. More complex shaders would involve calculations based on lighting, textures, and other attributes to produce realistic or stylized visuals.
Beyond simple colors, fragment shaders are instrumental in applying Textures by sampling image data, implementing complex Lighting models (such as Phong or physically-based rendering), and creating various Post-processing effects. They receive data from the Vertex Shader as interpolated varying variables, which can include texture coordinates, surface normals, or vertex colors, allowing for per-pixel calculations that contribute to the final rendered image.
