Custom GLSL Shaders in Three.js

Three.js allows you to use custom GLSL (OpenGL Shading Language) shaders to achieve highly customized visual effects that go beyond the capabilities of its built-in materials. This gives you direct control over how your 3D objects are rendered on the GPU.

What are GLSL Shaders?

GLSL is a C-like language specifically designed for programming Graphics Processing Units (GPUs). GPUs are highly parallel processors, making them extremely efficient for rendering graphics. In Three.js, you typically work with two main types of shaders:

• Vertex Shader: This shader processes each vertex of your 3D model. Its primary responsibilities include transforming the vertex's position from model space to screen space, and passing data (like color, normals, or UV coordinates) to the fragment shader.
• Fragment (or Pixel) Shader: This shader runs for every "fragment" (which often corresponds to a pixel) that makes up the rendered geometry. Its main job is to determine the final color of that fragment, taking into account lighting, textures, and other visual properties.

Using Custom Shaders in Three.js

You can create custom ShaderMaterial instances in Three.js, providing your own GLSL code for the vertex and fragment shaders. This gives you direct control over the rendering pipeline, allowing for effects like:

• Procedural textures
• Advanced lighting models
• Post-processing effects
• Custom animations based on vertex manipulation
• Non-photorealistic rendering

Example: Simple Custom Shader (Color Gradient)

This example demonstrates a basic custom shader that creates a color gradient on a plane based on its Y-coordinate. This requires a Three.js setup.