Attribute Macro react_filter 

#[react_filter]

Turn a named-field struct into a typed custom filter for the layer-based filter style chain.

Derives serde::Deserialize — adding #[serde(deny_unknown_fields)], so unknown param keys reject like the built-ins; per-field #[serde(default)] attributes you write are preserved — plus ts_rs::TS, and implements bevy_react::filters::ReactFilter. Built-in filters stay hand-written (they share canonical shader layouts); this macro is for custom filters, which pack against their own shader.

Arguments:

• name = "..." (optional) — the wire name; defaults to the struct ident with its first letter lowercased (Glow → "glow").
• shader = "path/to.wgsl" (required) — loaded with AssetServer::load, so a plain asset path relative to your assets dir; embedded:// paths also work verbatim.
• outset = <number> (optional, default 0.0) — extra logical px the effect bleeds outside the node’s rect.
• time = <bool> (optional, default false) — a time-driven effect re-renders its layer every frame.

The generated pack() fills the shader’s params vec4 array contiguously in field declaration order, mapped by field type. Params pack into at most MAX_FILTER_PARAM_VECS (8) vec4s, enforced at resolve time — an over-cap filter is rejected at runtime with a devtools warning, not a compile error. Shader-side, the packed array is uniforms.params via #import bevy_react::filter (see crates/core/src/layer/filter_prelude.wgsl for the full binding contract).

field type	packs as	components
f32	scalar	1
Vec2/Vec3/Vec4	scalars	2/3/4
[f32; 2..=4]	scalars	2–4
Angle	radians (a bare wire number is degrees)	1
Length	logical px (px-only; other units reject the filter use via outset/resolve)	1
FilterColor	linear straight-alpha RGBA	4

A multi-component param that would straddle a vec4 boundary pads to the next vec4 (the skipped components stay zero) — a ParamSlot never crosses a vec4. Any other field type fails compilation with an error naming the field and listing the supported types.

#[react_filter(name = "glow", shader = "shaders/glow.wgsl", outset = 4.0)]
struct GlowParams {
    intensity: f32,          // params[0].x
    direction: Vec2,         // params[0].yz
    tint: FilterColor,       // params[1] (padded past params[0].w)
}