Dither

Dithering trades smooth tonal range for spatial noise so an image can survive quantization (8-bit output, low-bit colour palettes, alpha cut-outs) without visible banding. Each function below returns a per-pixel threshold in [0, 1) that you compare against your value before snapping it.

Pull one in by slug and apply it inline:

let main = r#"
@fragment fn fs_main(in: VertexOutput) -> @location(0) vec4<f32> {
    let v = in.uv.x;                              // smooth source
    let t = bayer4x4(vec2<i32>(in.position.xy));   // threshold
    let q = step(t, v);                           // 1-bit dither
    return vec4<f32>(vec3<f32>(q), 1.0);
}
"#;
let shader = Shader::new(&["dither/bayer4x4", main])?;

bayer2x2

Ordered dither threshold in [0, 1) for an integer pixel coord.

fn bayer2x2(p: vec2<i32>) -> f32

bayer4x4

Ordered dither threshold in [0, 1) for an integer pixel coord.

fn bayer4x4(p: vec2<i32>) -> f32

bayer8x8

8x8 ordered dither threshold in [0, 1) for an integer pixel coord.

fn bayer8x8(p: vec2<i32>) -> f32

interleaved_gradient_noise

Jorge Jimenez’s IGN — a fast, blue-noise-flavoured dither that breaks up banding without the regular grid look of Bayer matrices.

fn interleaved_gradient_noise(p: vec2<f32>) -> f32