Bayer is an addon, and must be imported explicitly, see Installation#Addons.
import { bayer16 } from 'three/addons/tsl/math/Bayer.js';
This TSL function can be used to sample a Bayer16 texture which is a 16x16 texture with a Bayer Matrix pattern. It can be used for dithering effects but also as an alternative to blue-noise. When used with Ray Marching specifically in VolumeNodeMaterial#offsetNode, it reduces banding problem, thus being able to use fewer steps without affecting the visuals as much.
uv
The uv to sample the bayer16 texture.
Returns: The sampled bayer value.
This TSL function applies Bayer dithering to a color input. It uses a 4x4 Bayer matrix pattern to add structured noise before color quantization, which helps reduce visible color banding when limiting color depth.
color
The input color to apply dithering to.
steps
The number of color steps per channel.
Default is 32.
Returns: The dithered color ready for quantization.