const INV_PI: f32 = 0.31830988618

const CREST_FOAM_WHITE_COLOR: vec4<f32> = vec4( 1.0, 0.99634784, 0.97199994, 0.6862745, )

const CREST_FOAM_BUBBLE_COLOR: vec3<f32> = vec3(0.64, 0.83, 0.82)

const CREST_FOAM_BUBBLE_PARALLAX: f32 = 0.14

const CREST_FOAM_BUBBLE_COVERAGE: f32 = 1.68

const CREST_FOAM_NORMAL_STRENGTH: f32 = 3.5

const CREST_FOAM_SPECULAR_FALLOFF: f32 = 293.0

const CREST_FOAM_SPECULAR_BOOST: f32 = 0.15

const FINE_FOAM_ROTATION: mat2x2<f32> = mat2x2( vec2(0.798636, 0.601815), vec2(-0.601815, 0.798636), )

const FINE_FOAM_SCROLL_DIRECTION: vec2<f32> = vec2(-0.819152, 0.573576)

const FINE_FOAM_SCALE: f32 = 0.55

const CREST_FOAM_LINEAR_MEAN: f32 = 0.426906

fn cubic_weights ( ) -> vec4<f32>

fn sample_foam_bicubic ( ) -> f32

fn sample_foam_cascade ( ) -> f32

fn sample_foam_density ( ) -> f32

fn surface_foam_mask ( ) -> f32

fn river_streak_density ( ) -> f32

fn foam_bubble_colour ( ) -> vec3<f32>

fn local_foam_light ( ) -> vec3<f32>