refract

declare function refract<V extends vec2 | vec3 | vec4>(a0: V, a1: V, a2: (f32)): V
declare function refract<T extends Numeric>(i: T, n: T, eta: number): T

A number in a parameter or a return position is the scalar slot. The ambient file declares a GPU scalar as a branded number whose brand is optional, so a literal and any branded scalar both fill it.

type f32 = number & { readonly [f32Tag]?: true }

A declaration you write still needs a width, and a bare number on a field or a parameter is refused; the TypeScript constructs page carries that row with the compiler's own message.

A signature may name a type the ambient file declares for its own use. These are those declarations.

Numeric

type Numeric = number | vec2 | vec3 | vec4 | vec2i | vec3i | vec4i | vec2u | vec3u | vec4u