Chapter 08

Built-ins

The built-in library is where WGSL feels less like syntax and more like a GPU toolbox: numeric functions, vector operations, texture access, packing helpers, atomics, barriers, and subgroup operations.

Math and vector built-ins

Functions such as sin, cos, dot, normalize, and mix work best when the input types are already intentional. Let types lead; then pick the helper.

@fragment
fn fs(@builtin(position) frag : vec4f) -> @location(0) vec4f {
  let uv = frag.xy / vec2f(800.0, 600.0);
  let wave = 0.5 + 0.5 * sin(uv.x * 24.0);
  return vec4f(uv, wave, 1.0);
}

Textures and sampling built-ins

Texture functions carry pipeline-stage rules, sampler state, coordinate types, and sometimes uniformity requirements. When a sampling diagnostic appears, inspect both the texture type and the control flow around the call.

Synchronization built-ins

workgroupBarrier, storageBarrier, and atomic built-ins are coordination tools. Reach for them only after the memory sharing pattern is clear.