A WebGPU uniform is a shader global held constant for every invocation of one draw call

A uniform is like a global variable for a shader: you set its value before executing the shader and every invocation in that draw sees the same value, then you can set a different value before the next draw. This contrasts with per-vertex data (from vertex buffers) which changes each invocation. Uniforms are how you feed a shader whole-frame parameters — time, resolution, a transform matrix, a colour — for audio-reactive or generative visuals. You supply them by creating a GPU buffer with UNIFORM usage, referencing it from a bind group, calling setBindGroup before drawing, and reading it in WGSL via a var binding.

Examples

Pass an audio level and elapsed time as a uniform struct each frame; the fragment shader reads uniforms.time and uniforms.level to drive colour and motion identically for every pixel of that frame, then the CPU updates the buffer next frame.

Assessment

Explain how a uniform differs from per-vertex data, and outline the four steps needed to get a per-frame ‘time’ value from JavaScript into a WGSL fragment shader.