cranpose_liquid/

material.rs

//! The Liquid Glass material: Gaussian backdrop frost followed by wcKSRD
//! refraction applied to a composable's own bounds through
//! [`LiquidModifierExt::glass_effect`] — the analogue of SwiftUI's
//! `.glassEffect(_:in:)`.

use std::{
    cell::{Cell, RefCell},
    sync::OnceLock,
};

use cranpose_ui::{Modifier, current_density};
use cranpose_ui_graphics::{
    Color, GLASS_ACTIVITY_UNIFORM, GLASS_ADAPTIVE_FROST_UNIFORM, GLASS_ADAPTIVE_TONE_UNIFORM,
    GLASS_BLUR_RADIUS_UNIFORM, GLASS_DISPERSION_UNIFORM, GLASS_EDGE_REFRACTION_REACH_UNIFORM,
    GLASS_EDGE_RETURN_DEPTH_UNIFORM, GLASS_EDGE_SPECTRUM_UNIFORM, GLASS_EFFECT_DENSITY_UNIFORM,
    GLASS_FACE_LIGHTING_OFF_UNIFORM, GLASS_FACE_RESPONSE_UNIFORM, GLASS_FOLD_DEPTH_UNIFORM,
    GLASS_INNER_SHADOW_UNIFORM, GLASS_KEY_FILL_UNIFORM, GLASS_LAYER_CLIPPED_UNIFORM,
    GLASS_LIGHT_DIRECTION_UNIFORM, GLASS_MENISCUS_ABSORPTION_UNIFORM,
    GLASS_OPTICAL_PROJECTION_UNIFORM, GLASS_OPTICAL_ZOOM_ANCHOR_UNIFORM,
    GLASS_OPTICAL_ZOOM_UNIFORM, GLASS_PHYSICAL_REFRACTION_DEPTH_ENABLED_UNIFORM,
    GLASS_PHYSICAL_REFRACTION_DEPTH_UNIFORM, GLASS_REFRACTION_CURVE_UNIFORM,
    GLASS_REFRACTION_MODE_UNIFORM, GLASS_RESTING_TINT_UNIFORM, GLASS_TOUCH_RADIUS_UNIFORM,
    GLASS_TRANSMISSION_REFRACTION_UNIFORM, GraphicsLayer, LIQUID_GLASS_WGSL, LayerShape, Rect,
    RenderEffect, RoundedCornerShape, RuntimeShader, TileMode, liquid_glass_runtime_effect,
    specialize_liquid_glass,
};

use crate::{appearance::GlassTintAmount, theme::LiquidColors};

thread_local! {
    static GLASS_LIGHT_RETURN: Cell<(f32, f32)> = const { Cell::new((0.0, 1.0)) };
}

/// Sets the ambient glass light return direction (screen space, need not be
/// normalized — the shader normalizes). Feed device attitude here.
pub fn set_glass_light_direction(direction: (f32, f32)) {
    GLASS_LIGHT_RETURN.with(|cell| cell.set(direction));
}

/// The current ambient glass light return direction.
pub fn glass_light_direction() -> (f32, f32) {
    GLASS_LIGHT_RETURN.with(|cell| cell.get())
}

const CAPSULE_CLIP_RADIUS: f32 = 1.0e6;

const CAPSULE_SHADER_RADIUS: f32 = -1.0;

const WCKSRD_OPTICAL_BLUR_RADIUS_PX: f32 = 2.0;

/// The shape of a glass element (also its clip and shadow shape).
#[derive(Clone, Copy, Debug, PartialEq, Default)]
pub enum LiquidShape {
    /// A pill: corner radius follows the smaller half-extent.
    #[default]
    Capsule,
    /// Rounded rectangle with the radius in dp.
    RoundedRect(f32),
    /// A circle (capsule of a square node).
    Circle,
}

impl LiquidShape {
    /// The clip shape handed to the graphics layer.
    pub fn clip_shape(&self) -> RoundedCornerShape {
        match self {
            LiquidShape::Capsule | LiquidShape::Circle => {
                RoundedCornerShape::uniform(CAPSULE_CLIP_RADIUS)
            }
            LiquidShape::RoundedRect(radius) => RoundedCornerShape::uniform(*radius),
        }
    }

    /// The layer shape (clip + shadow geometry).
    pub fn layer_shape(&self) -> LayerShape {
        LayerShape::Rounded(self.clip_shape())
    }

    fn shader_radius_px(&self, density: f32) -> f32 {
        match self {
            LiquidShape::Capsule | LiquidShape::Circle => CAPSULE_SHADER_RADIUS,
            LiquidShape::RoundedRect(radius) => radius * density,
        }
    }
}

/// Material variant, mirroring SwiftUI's `.regular` / `.clear` glass, plus
/// the interactive lens.
#[derive(Clone, Copy, Debug, PartialEq, Eq, Default)]
pub enum GlassVariant {
    /// Frosted: strong backdrop blur, vibrancy boost, scheme-adaptive lift.
    #[default]
    Regular,
    /// Transparent: minimal blur, mild vibrancy — for media-rich backdrops.
    Clear,
    /// The interactive magnifying bubble (drag lenses, flying selection):
    /// no frost, no tone shift, a full-element dome and pronounced rainbow
    /// dispersion at the rim.
    Lens,
}

/// The projection used to transmit the captured backdrop through glass.
#[derive(Clone, Copy, Debug, PartialEq, Default)]
pub enum GlassRefraction {
    /// A radial projection toward the optical axis.
    #[default]
    Radial,
    /// A projection perpendicular to the nearest surface edge.
    Surface {
        /// Maximum inward sample displacement in dp, independent of its falloff depth.
        reach_dp: f32,
    },
    /// Successive outward and inward sample displacements with circular falloff profiles.
    /// The return amplitude is 17.5/9 times the outward amplitude. Its default depth
    /// is 7/36 of the outer profile; [`GlassDynamics::edge_return_depth_dp`] overrides it.
    EdgeLens {
        /// Outward warp amplitude in dp; refraction depth sets its falloff height.
        reach_dp: f32,
    },
}

impl GlassRefraction {
    fn shader_parameters(self) -> (f32, f32) {
        match self {
            Self::Radial => (0.0, 0.0),
            Self::Surface { reach_dp } => (1.0, normalized_refraction_reach(reach_dp)),
            Self::EdgeLens { reach_dp } => (2.0, normalized_refraction_reach(reach_dp)),
        }
    }
}

fn normalized_refraction_reach(reach_dp: f32) -> f32 {
    if reach_dp.is_finite() {
        reach_dp.max(0.0)
    } else {
        0.0
    }
}

/// Shadow owned by a glass surface. Morphing glass evaluates the same live
/// SDF for this shadow; clipped static glass forwards the values to the layer
/// shadow primitive.
#[derive(Clone, Copy, Debug, PartialEq)]
pub struct GlassShadow {
    pub color: Color,
    pub radius: f32,
    pub offset_y: f32,
    pub spread: f32,
}

impl GlassShadow {
    pub fn new(color: Color, radius: f32, offset_y: f32, spread: f32) -> Self {
        Self {
            color,
            radius: radius.max(0.0),
            offset_y,
            spread,
        }
    }

    fn uniforms(self) -> Option<[f32; 8]> {
        let values = [
            self.color.r(),
            self.color.g(),
            self.color.b(),
            self.color.a(),
            self.radius,
            self.offset_y,
            self.spread,
            1.0,
        ];
        (values.iter().all(|value| value.is_finite())
            && self.radius >= 0.0
            && (0.0..=1.0).contains(&self.color.a()))
        .then_some(values)
    }
}

/// Per-frame motion inputs for an interactive glass element, read lazily at
/// scene-build time (no recomposition per frame).
#[derive(Clone, Debug, PartialEq, Default)]
pub struct GlassDynamics {
    /// Independent inner return depth for an edge lens, in dp. Zero removes its depth.
    /// Nonfinite or negative values preserve the material's default depth ratio.
    pub edge_return_depth_dp: Option<f32>,
    /// Horizontal and vertical projection of the complete glass field about its primary center.
    /// Refraction, lighting and all scene shapes share the projection. Missing, nonfinite or
    /// nonpositive scales resolve to identity. This does not magnify the underlying backdrop.
    pub optical_projection: Option<(f32, f32)>,
    /// Continuous optical presence. `None` preserves the resolved material;
    /// `Some(0)` is an exact backdrop identity while retaining the same node,
    /// SDF, and pointer ride path.
    pub activity: Option<f32>,
    /// Base tint of the same persistent SDF surface at zero optical activity.
    /// Its alpha cross-fades out as the refractive material rises.
    pub resting_tint: Option<Color>,
    /// Extra specular intensity (0 = spec default; e.g. press boost).
    pub highlight_boost: f32,
    /// Per-frame saturation added to the resolved material. Interactive
    /// surfaces use this to raise chroma without changing their base tint.
    pub saturation_boost: f32,
    /// Optional per-frame multiplier for the material tint alpha. Values
    /// below one clear a resting wash; values above one densify a raised tint.
    pub tint_alpha_multiplier: Option<f32>,
    /// Shape morph: when set, the glass geometry is these node-local rects
    /// instead of the node cover — the shapeshift channel.
    pub morph: Option<GlassMorph>,
    /// Touch glow: `(x_dp, y_dp, intensity)` in node-local dp. A pressed
    /// surface concentrates saturation and a soft light in a radial
    /// gradient under the finger (never a flat recolor).
    pub touch: Option<(f32, f32, f32)>,
    /// Radius of the touch glow in dp; absent, nonpositive and nonfinite values use 58 dp.
    pub touch_radius_dp: Option<f32>,
    /// Dome press depth: how squashed the interactive dome is. At 1 the
    /// pressed dome refracts deep and vivid (wide rim band, strong
    /// chromatic split — the reference toggle's gray-hold rainbow); toward
    /// 0 the released bead relaxes shallow and its split fades with it
    /// (the reference's thin settled ring). `None` = 1.
    pub press_depth: Option<f32>,
}

impl GlassDynamics {
    fn projection(&self) -> (f32, f32) {
        self.optical_projection
            .filter(|(x, y)| x.is_finite() && y.is_finite() && *x > 0.0 && *y > 0.0)
            .unwrap_or((1.0, 1.0))
    }

    /// The universal touched-up state (user-directed law): a pressed
    /// liquid surface comes closer to the user while its OWN colors go
    /// HDR-bright and saturated, with a radial glow following the finger.
    /// Never a repaint with alternate colors — the boosts amplify whatever
    /// the surface already is. `press` is 0..1; `finger` is node-local dp
    /// (falls back to `center`, the surface's own heart).
    pub fn touched_up(
        mut self,
        press: f32,
        finger: Option<(f32, f32)>,
        center: (f32, f32),
    ) -> Self {
        let press = press.clamp(0.0, 1.0);
        if press <= 0.0 {
            return self;
        }
        self.highlight_boost += 0.85 * press;
        self.saturation_boost += 0.45 * press;
        let (fx, fy) = finger.unwrap_or(center);
        let carried = self.touch.map(|(_, _, i)| i).unwrap_or(0.0);
        self.touch = Some((fx, fy, (carried + press).clamp(0.0, 1.0)));
        self
    }
}

fn foreground_is_dark(foreground: Color) -> bool {
    let foreground_luma =
        0.2126 * foreground.r() + 0.7152 * foreground.g() + 0.0722 * foreground.b();
    foreground_luma < 0.5
}

fn boost_tint_saturation(tint: Color, boost: f32) -> Color {
    if boost.abs() <= f32::EPSILON {
        return tint;
    }
    let luma = 0.2126 * tint.r() + 0.7152 * tint.g() + 0.0722 * tint.b();
    let saturation = (1.0 + boost).max(0.0);
    Color::rgba(
        (luma + (tint.r() - luma) * saturation).clamp(0.0, 1.0),
        (luma + (tint.g() - luma) * saturation).clamp(0.0, 1.0),
        (luma + (tint.b() - luma) * saturation).clamp(0.0, 1.0),
        tint.a(),
    )
}

pub(crate) fn neutral_surface_tint(foreground: Color, light_alpha: f32, dark_alpha: f32) -> Color {
    if foreground_is_dark(foreground) {
        Color::BLACK.with_alpha(light_alpha.clamp(0.0, 1.0))
    } else {
        Color::WHITE.with_alpha(dark_alpha.clamp(0.0, 1.0))
    }
}

/// A liquid shapeshift frame: the primary shape plus any number of nearby
/// glass shapes, ALL smooth-unioned into one field — liquid glass glues to
/// whatever glass it passes near (a growing menu necks with a neighboring
/// button, the drag lens merges with the search circle). Up to
/// [`GlassMorph::MAX_SHAPES`] extra shapes; an angular wobble makes the
/// mid-flight field bubble like a droplet. All geometry is node-local dp:
/// `(center_x, center_y, width, height, corner_radius)`; radius sentinel
/// `-1` means capsule; `-2` means SUBTRACT capsule — the shape carves a
/// smooth hole in the field (the growing menu leaves its anchor button
/// crisp on top until it swallows it).
#[derive(Clone, Debug, PartialEq, Default)]
pub struct GlassMorph {
    /// The glass node's own size in dp. The shader receives all morph
    /// geometry in dp and derives px-per-dp from the renderer-injected node
    /// pixel rect divided by this — geometry then lands correctly at ANY
    /// render scale (live window density, robot captures at 1.0, fractional
    /// desktop scales). The authoring widget always knows its node size.
    pub node_size: (f32, f32),
    pub primary: (f32, f32, f32, f32, f32),
    /// Nearby glass shapes participating in the field.
    pub shapes: Vec<(f32, f32, f32, f32, f32)>,
    /// Smooth-union glue radius (dp): shapes within it neck together.
    pub glue: f32,
    /// Wobble amplitude (dp) and phase (radians).
    pub wobble_amplitude: f32,
    pub wobble_phase: f32,
    /// Viscous leading-edge bulge: while the shape travels or inflates, its
    /// side facing `bulge_direction` (radians, math convention) swells like a
    /// pulled droplet. Amplitude in dp, usually driven by morph velocity.
    pub bulge_amplitude: f32,
    pub bulge_direction: f32,
    /// Blends the primary rounded-rectangle field toward an ellipse. This is
    /// used by expanding droplets whose broad phase has continuous curvature
    /// rather than the straight sides of a capsule.
    pub ellipse_blend: f32,
    /// Smooths the primary capsule's straight-to-arc joins over this distance in dp.
    /// A positive value replaces its corner radius with the maximum capsule radius.
    /// The span is capped by half the difference between the primary side lengths.
    /// Zero or a nonfinite value preserves the primary outline.
    pub capsule_smoothing_dp: f32,
    /// Area-preserving affine strain applied to the primary shape. Extra
    /// scene shapes remain fixed so nearby glass can join the travelling
    /// droplet without being dragged through its local deformation.
    pub deformation: Option<GlassDeformation>,
    /// Offset (dp) of the optical-zoom axis from the primary SDF center. A
    /// leaning droplet's silhouette shifts toward its travel side while its
    /// curvature apex stays over the content it rides; anchoring the
    /// magnification there keeps the face filled by that content instead of
    /// pulling in whatever lies beyond it.
    pub zoom_anchor: (f32, f32),
}

/// A normalized motion axis and reciprocal scales for incompressible glass.
/// Construction derives the cross-axis scale, so callers cannot describe a
/// deformation that changes the bubble's area.
#[derive(Clone, Copy, Debug, PartialEq)]
pub struct GlassDeformation {
    axis: (f32, f32),
    along: f32,
}

impl GlassDeformation {
    pub fn incompressible(axis: (f32, f32), along: f32) -> Self {
        let length = (axis.0 * axis.0 + axis.1 * axis.1).sqrt();
        let axis = if length > f32::EPSILON {
            (axis.0 / length, axis.1 / length)
        } else {
            (1.0, 0.0)
        };
        Self {
            axis,
            along: along.max(f32::EPSILON),
        }
    }

    pub fn axis(self) -> (f32, f32) {
        self.axis
    }

    pub fn along(self) -> f32 {
        self.along
    }

    pub fn across(self) -> f32 {
        1.0 / self.along
    }
}

impl GlassMorph {
    /// Shader budget for extra scene shapes.
    pub const MAX_SHAPES: usize = 8;
}

/// Opposing edge lights whose color responds to the backdrop.
/// Nonfinite fields or nonpositive height or curvature disable this treatment.
#[derive(Clone, Copy, Debug, PartialEq)]
pub struct GlassKeyFill {
    /// Inward extent of the highlight, in dp.
    pub height_dp: f32,
    /// Linear reduction in brightness across the highlight's inward extent.
    pub curvature: f32,
    /// Direction of the first light in screen-space radians; the second is opposite.
    pub angle_radians: f32,
    /// Gain applied to the backdrop's chroma in the reflected color.
    pub saturation: f32,
    /// Gain applied to the backdrop's luminance in the reflected color.
    pub luma_gain: f32,
    /// Additive contribution to each reflected color channel.
    pub offset: f32,
    /// Whether the highlight width follows the surface transform or stays fixed on screen.
    pub scale_with_surface: bool,
}

impl GlassKeyFill {
    fn uniforms(self) -> Option<[f32; 7]> {
        let values = [
            self.height_dp,
            self.curvature,
            self.angle_radians,
            self.saturation,
            self.luma_gain,
            self.offset,
            f32::from(self.scale_with_surface),
        ];
        (values.iter().all(|value| value.is_finite())
            && self.height_dp > 0.0
            && self.curvature > 0.0)
            .then_some(values)
    }
}

/// Seven-tap RGB spectrum for an edge lens. Distances follow the surface transform.
/// Nonfinite values, negative extents, or opacities outside zero to one are ignored.
#[derive(Clone, Copy, Debug, PartialEq)]
pub struct GlassSpectrum {
    /// Angle θ in radians. For outward normal (x, y), the sampling direction is
    /// (y cosθ + x sinθ, (x cosθ − y sinθ) × vertical_scale).
    pub angle_radians: f32,
    /// Signed spacing between adjacent taps, in dp; negative values reverse the colors.
    pub step_dp: f32,
    /// Scale of the vertical component of the sampling direction.
    pub vertical_scale: f32,
    /// Spectral opacity at the silhouette edge.
    pub opacity_near: f32,
    /// Spectral opacity at and beyond the fade depth.
    pub opacity_far: f32,
    /// Inward distance in dp over which opacity interpolates linearly.
    pub fade_depth_dp: f32,
    /// Inward distance in dp beyond which the spectrum disappears.
    pub extent_dp: f32,
}

impl GlassSpectrum {
    fn uniforms(self) -> Option<[f32; 8]> {
        let values = [
            self.angle_radians,
            self.step_dp,
            self.vertical_scale,
            self.opacity_near,
            self.opacity_far,
            self.fade_depth_dp,
            self.extent_dp,
            1.0,
        ];
        (values.iter().all(|value| value.is_finite())
            && self.vertical_scale >= 0.0
            && (0.0..=1.0).contains(&self.opacity_near)
            && (0.0..=1.0).contains(&self.opacity_far)
            && self.fade_depth_dp >= 0.0
            && self.extent_dp >= 0.0)
            .then_some(values)
    }

    fn capture_reach(self) -> f32 {
        self.step_dp.abs() * 3.0 * self.vertical_scale.max(1.0)
    }
}

/// Face attenuation before edge lighting, followed by additive illumination.
/// Edge lenses attenuate the inner refraction image before chromatic sampling.
/// Invalid or nonfinite parameters disable the response.
#[derive(Clone, Copy, Debug, PartialEq)]
pub struct GlassFaceResponse {
    /// Interior color gain, from zero to one.
    pub gain: f32,
    /// Screen-space depth in dp where attenuation starts.
    pub start_dp: f32,
    /// Screen-space depth in dp where attenuation reaches its interior gain.
    /// Equal start and end apply the gain uniformly.
    pub end_dp: f32,
    /// Light added to each color channel inside the silhouette after edge lighting.
    pub illumination: f32,
}

impl GlassFaceResponse {
    fn uniforms(self) -> Option<[f32; 4]> {
        let values = [
            1.0 - self.gain,
            self.start_dp,
            self.end_dp,
            self.illumination,
        ];
        (values.iter().all(|value| value.is_finite())
            && (0.0..=1.0).contains(&self.gain)
            && self.start_dp >= 0.0
            && self.end_dp >= self.start_dp)
            .then_some(values)
    }
}

/// Builder describing a glass material. Resolved against the theme at the
/// composition site, then evaluated per frame for density and dynamics.
#[derive(Clone, Debug, PartialEq)]
pub struct Glass {
    pub variant: GlassVariant,
    pub shape: LiquidShape,
    /// Tint over the refracted backdrop; defaults to the theme's glass tint.
    pub tint: Option<Color>,
    /// Optional sharp/blurred pane blend, separate from the color tint.
    pub tint_amount: Option<GlassTintAmount>,
    /// Backdrop blur radius in dp (defaults per variant).
    pub blur_radius: Option<f32>,
    /// Radius in dp and opacity of the blurred backdrop mixed with an edge lens’s outer warp.
    pub backdrop_blur: Option<(f32, f32)>,
    /// Saturation boost (defaults per variant).
    pub saturation: Option<f32>,
    /// wcKSRD refraction depth as a fraction of the shape inradius. Regular
    /// frosted surfaces default to zero so their backdrop stays motion-stable;
    /// interactive lenses opt into optical displacement explicitly.
    pub refraction_depth: f32,
    /// Optional physical wcKSRD refraction depth in dp. When present, this
    /// keeps the optical band equally deep across surfaces with different
    /// inradii instead of scaling it from each surface's height.
    pub refraction_depth_dp: Option<f32>,
    /// Backdrop projection model.
    pub refraction: GlassRefraction,
    /// Normalized wcKSRD ray-return exponent.
    pub refraction_curve: f32,
    /// Normalized wcKSRD spectral ray separation.
    pub dispersion: f32,
    /// Optional directional spectrum for the edge-lens projection.
    pub edge_spectrum: Option<GlassSpectrum>,
    /// Fraction of the wcKSRD displacement applied to the transmitted
    /// backdrop. Regular frosted surfaces default to zero. The mirrored
    /// meniscus follows its own optical path.
    pub transmission_refraction: f32,
    /// Energy removed from the transmitted ray at the meniscus. Reflection
    /// and spectral return follow independent paths.
    pub meniscus_absorption: f32,
    /// Depth of the rim fold band in dp: the raised lens rim replays its
    /// interior mirrored toward the edge (a pure displacement). Zero
    /// disables the fold.
    pub fold_depth: f32,
    /// Uniform face magnification of a riding lens (1.0 = no zoom).
    /// The selected refraction model controls the surrounding rim band.
    pub optical_zoom: f32,
    /// Meniscus rim reflectivity multiplier (1.0 = the reference toggle's
    /// visible rim line; near 0 = the segmented lens's invisible body).
    pub rim_reflection: f32,
    /// Optical ink recolor: the lens recolors dark transmitted ink toward
    /// this color at the given strength (the reference tab bubble's
    /// color-mask act). None = off.
    pub ink_recolor: Option<(Color, f32)>,
    /// Specular rim intensity.
    pub highlight: f32,
    /// Whether the face receives the material's diffuse directional illumination.
    pub face_lighting: bool,
    /// Replaces dome lighting with a pair of opposing edge lights.
    pub key_fill: Option<GlassKeyFill>,
    /// Attenuation and illumination applied around the edge-light pass.
    pub face_response: Option<GlassFaceResponse>,
    /// Inset shadow on the transmitted face, covered by the chromatic foreground.
    pub inner_shadow: Option<GlassShadow>,
    /// Screen-lift override (brightening toward white; negative darkens).
    /// Defaults per variant.
    pub lift: Option<f32>,
    /// Tone-compression override around the shader's mid pivot (<1 pulls
    /// every backdrop toward mid-luminance — the reference dark menu reads
    /// bright magenta over deep purple AND dim gray over white through one
    /// law). Defaults per variant.
    pub contrast: Option<f32>,
    /// Drop shadow below the glass.
    pub shadow: bool,
    /// Per-surface shadow override.
    pub shadow_style: Option<GlassShadow>,
    /// Clip the layer to `shape`. Morphing glass disables this — coverage
    /// comes entirely from the shader's SDF.
    pub clip: bool,
    /// Foreground color whose contrast the frost must protect. `None` uses
    /// the theme label color.
    pub foreground: Option<Color>,
    /// Strength of backdrop+foreground frost adaptation.
    pub adaptive_frost: f32,
    /// Adapts the face transfer curve to the mean captured backdrop brightness.
    /// Foreground polarity selects the preferred light or dark treatment.
    pub adaptive_tone: bool,
}

impl Glass {
    /// A motion-stable frosted surface without optical displacement.
    pub fn regular() -> Self {
        Self {
            variant: GlassVariant::Regular,
            shape: LiquidShape::Capsule,
            tint: None,
            tint_amount: None,
            blur_radius: None,
            backdrop_blur: None,
            saturation: None,
            refraction_depth: 0.0,
            refraction_depth_dp: None,
            refraction: GlassRefraction::Radial,
            refraction_curve: 0.25,
            dispersion: 0.0,
            edge_spectrum: None,
            transmission_refraction: 0.0,
            meniscus_absorption: 1.0,
            fold_depth: 0.0,
            optical_zoom: 1.0,
            rim_reflection: 1.0,
            ink_recolor: None,
            highlight: 0.9,
            face_lighting: true,
            key_fill: None,
            face_response: None,
            inner_shadow: None,
            lift: None,
            contrast: None,
            shadow: true,
            shadow_style: None,
            clip: true,
            foreground: None,
            adaptive_frost: 0.65,
            adaptive_tone: false,
        }
    }

    pub fn clear() -> Self {
        Self {
            variant: GlassVariant::Clear,
            ..Self::regular()
        }
    }

    /// An interactive glass lens with a radial projection and spectral rim.
    /// [`Self::edge_refraction`] selects an outward rim around a uniformly magnified face.
    pub fn lens() -> Self {
        Self {
            variant: GlassVariant::Lens,
            shape: LiquidShape::Capsule,
            tint: Some(Color::rgba(1.0, 1.0, 1.0, 0.07)),
            tint_amount: None,
            blur_radius: None,
            backdrop_blur: None,
            saturation: None,
            refraction_depth: 0.34,
            refraction_depth_dp: None,
            refraction: GlassRefraction::Radial,
            refraction_curve: 1.0,
            dispersion: 0.30,
            edge_spectrum: None,
            transmission_refraction: 1.0,
            meniscus_absorption: 1.0,
            fold_depth: 0.0,
            optical_zoom: 1.0,
            rim_reflection: 1.0,
            ink_recolor: None,
            highlight: 1.15,
            face_lighting: true,
            key_fill: None,
            face_response: None,
            inner_shadow: None,
            lift: None,
            contrast: None,
            shadow: true,
            shadow_style: None,
            clip: true,
            foreground: None,
            adaptive_frost: 0.0,
            adaptive_tone: false,
        }
    }

    /// Enables or disables diffuse face illumination without changing the specular rim.
    pub fn face_lighting(mut self, enabled: bool) -> Self {
        self.face_lighting = enabled;
        self
    }

    /// Uses opposing edge lights with a backdrop-dependent reflected color.
    /// [`Self::highlight`] controls their opacity.
    pub fn key_fill(mut self, lighting: GlassKeyFill) -> Self {
        self.key_fill = Some(lighting);
        self
    }

    /// Sets the face attenuation and illumination around the edge-light pass.
    pub fn face_response(mut self, response: GlassFaceResponse) -> Self {
        self.face_response = Some(response);
        self
    }

    /// Adds an inset shadow with a Gaussian falloff from the live surface outline.
    /// The chromatic foreground covers this shadow without refracting it.
    /// Nonfinite values, negative radii, and opacity outside zero to one disable it.
    pub fn inner_shadow(mut self, shadow: GlassShadow) -> Self {
        self.inner_shadow = shadow.uniforms().map(|_| shadow);
        self
    }

    pub fn shape(mut self, shape: LiquidShape) -> Self {
        self.shape = shape;
        self
    }

    pub fn tint(mut self, tint: Color) -> Self {
        self.tint = Some(tint);
        self
    }

    pub fn blur_radius(mut self, radius_dp: f32) -> Self {
        self.blur_radius = Some(radius_dp);
        self
    }

    pub fn saturation(mut self, saturation: f32) -> Self {
        self.saturation = Some(saturation);
        self
    }

    pub fn refraction_depth(mut self, fraction: f32) -> Self {
        self.refraction_depth = fraction.clamp(0.0, 2.0);
        self.refraction_depth_dp = None;
        self
    }

    /// Uses a density-stable physical refraction depth instead of a fraction
    /// of the live shape inradius.
    pub fn refraction_depth_dp(mut self, depth_dp: f32) -> Self {
        self.refraction_depth_dp = Some(depth_dp.max(0.0));
        self
    }

    /// Selects a circular depth profile along the surface normal, preserving
    /// tangential background coordinates along straight edges. `reach_dp` sets the inward
    /// displacement independently of depth; both remain fixed under surface scaling.
    /// Negative and nonfinite reach values become zero.
    pub fn surface_refraction(mut self, reach_dp: f32) -> Self {
        self.refraction = GlassRefraction::Surface {
            reach_dp: normalized_refraction_reach(reach_dp),
        };
        self
    }

    /// Overrides the edge lens's spectrum; radial and surface projections use `dispersion`.
    /// Invalid profiles are ignored. The signed spacing supports continuous color reversal.
    pub fn edge_spectrum(mut self, spectrum: GlassSpectrum) -> Self {
        self.edge_spectrum = spectrum.uniforms().map(|_| spectrum);
        self
    }

    /// Selects a rim that enters inward, crests outward and returns smoothly to the face.
    /// `reach_dp` controls its maximum outward displacement; negative and nonfinite values become zero.
    /// Its inward return uses the amplitude and depth ratios in [`GlassRefraction::EdgeLens`].
    pub fn edge_refraction(mut self, reach_dp: f32) -> Self {
        self.refraction = GlassRefraction::EdgeLens {
            reach_dp: normalized_refraction_reach(reach_dp),
        };
        self
    }

    pub fn refraction_curve(mut self, curve: f32) -> Self {
        self.refraction_curve = curve.clamp(0.05, 1.0);
        self
    }

    pub fn dispersion(mut self, strength: f32) -> Self {
        self.dispersion = strength.clamp(0.0, 1.0);
        self
    }

    pub fn transmission_refraction(mut self, strength: f32) -> Self {
        self.transmission_refraction = strength.clamp(0.0, 1.0);
        self
    }

    pub fn meniscus_absorption(mut self, strength: f32) -> Self {
        self.meniscus_absorption = strength.clamp(0.0, 1.0);
        self
    }

    /// Sets the rim fold band depth in dp (zero disables the fold).
    pub fn fold_depth(mut self, depth_dp: f32) -> Self {
        self.fold_depth = depth_dp.max(0.0);
        self
    }

    /// Sets the uniform face magnification of a riding lens (1.0 = none).
    pub fn optical_zoom(mut self, zoom: f32) -> Self {
        self.optical_zoom = zoom.max(1.0);
        self
    }

    /// Sets the meniscus rim reflectivity (1.0 = full reference line).
    pub fn rim_reflection(mut self, reflectivity: f32) -> Self {
        self.rim_reflection = reflectivity.clamp(0.0, 2.0);
        self
    }

    /// The lens recolors dark transmitted ink toward `color` at `strength`
    /// (0..1) — the reference bubble's color-mask act as a material optic.
    pub fn ink_recolor(mut self, color: Color, strength: f32) -> Self {
        self.ink_recolor = Some((color, strength.clamp(0.0, 1.0)));
        self
    }

    pub fn highlight(mut self, highlight: f32) -> Self {
        self.highlight = highlight;
        self
    }

    /// Overrides the screen-lift (how hard the glass brightens what it
    /// shows; the bar lens uses a near-zero lift to stay transmissive).
    pub fn lift(mut self, lift: f32) -> Self {
        self.lift = Some(lift);
        self
    }

    /// Overrides the tone compression around the shader's mid pivot
    /// (values below one pull every backdrop toward mid-luminance).
    pub fn contrast(mut self, contrast: f32) -> Self {
        self.contrast = Some(contrast.max(0.05));
        self
    }

    pub fn adaptive_frost(mut self, foreground: Color, strength: f32) -> Self {
        self.foreground = Some(foreground);
        self.adaptive_frost = strength.clamp(0.0, 1.0);
        self
    }

    /// Uses the captured backdrop's mean brightness to adapt the face transfer curve.
    /// This replaces local frost adaptation, saturation, contrast, lift and
    /// the key/fill color response. Tint and edge-light geometry still apply.
    /// The foreground chooses the preferred polarity, with dark treatment over black
    /// backgrounds and light treatment over white backgrounds.
    pub fn adaptive_tone(mut self, foreground: Color) -> Self {
        self.foreground = Some(foreground);
        self.adaptive_tone = true;
        self.adaptive_frost = 0.0;
        self
    }

    pub fn shadow(mut self, shadow: bool) -> Self {
        self.shadow = shadow;
        self
    }

    pub fn shadow_style(mut self, shadow: GlassShadow) -> Self {
        self.shadow_style = Some(shadow);
        self
    }

    /// Disables the layer clip: the shader's SDF coverage is the only shape
    /// (required while morphing across geometry the clip can't follow).
    pub fn no_clip(mut self) -> Self {
        self.clip = false;
        self
    }

    /// Uses a sharp/blurred backdrop blend controlled by the tint percentage.
    /// This replaces the whole-backdrop blur for this material.
    pub fn tint_amount(mut self, amount: GlassTintAmount) -> Self {
        self.tint_amount = Some(amount);
        self
    }

    /// Crossfades the edge lens’s outer warp with a fixed-radius blurred backdrop.
    /// Radius uses the renderer's Gaussian convention: twice the standard deviation, in dp.
    /// Nonfinite values disable the blend; finite radius is nonnegative and opacity is clamped to 0–1.
    pub fn backdrop_blur(mut self, radius_dp: f32, opacity: f32) -> Self {
        self.backdrop_blur = (radius_dp.is_finite() && opacity.is_finite())
            .then_some((radius_dp.max(0.0), opacity.clamp(0.0, 1.0)));
        self
    }

    fn default_blur_radius(&self) -> f32 {
        match self.variant {
            GlassVariant::Regular => 8.0,
            GlassVariant::Clear => 3.0,
            GlassVariant::Lens => 0.0,
        }
    }

    fn default_saturation(&self) -> f32 {
        match self.variant {
            GlassVariant::Regular => 1.5,
            GlassVariant::Clear => 1.25,
            GlassVariant::Lens => 1.0,
        }
    }

    /// The backdrop effect this material produces for a node at `density`
    /// under `dynamics`, resolved against `colors`: the render effect the
    /// glass modifiers install, for a layer built without them.
    pub fn backdrop_effect(
        &self,
        colors: &LiquidColors,
        density: f32,
        dynamics: GlassDynamics,
    ) -> RenderEffect {
        self.resolve(colors).backdrop_effect(density, dynamics)
    }

    fn preferred_foreground(&self, colors: &LiquidColors) -> Color {
        self.foreground
            .filter(|color| {
                [color.r(), color.g(), color.b(), color.a()]
                    .iter()
                    .all(|value| value.is_finite())
            })
            .unwrap_or(colors.label)
    }

    pub(crate) fn resolve(&self, colors: &LiquidColors) -> ResolvedGlass {
        let lift = self.lift.unwrap_or(match (self.variant, colors.is_dark) {
            (GlassVariant::Regular, false) => 0.42,
            (GlassVariant::Regular, true) => -0.38,
            (GlassVariant::Clear, false) => 0.12,
            (GlassVariant::Clear, true) => -0.12,
            (GlassVariant::Lens, false) => 0.10,
            (GlassVariant::Lens, true) => -0.08,
        });
        let foreground = self.preferred_foreground(colors);
        let shadow = self.shadow_style.unwrap_or_else(|| {
            GlassShadow::new(
                Color::BLACK.with_alpha(match (self.variant, colors.is_dark) {
                    (GlassVariant::Lens, false) => 0.14,
                    (GlassVariant::Lens, true) => 0.28,
                    (_, false) => 0.16,
                    (_, true) => 0.5,
                }),
                if self.variant == GlassVariant::Lens {
                    10.0
                } else {
                    22.0
                },
                if self.variant == GlassVariant::Lens {
                    3.0
                } else {
                    8.0
                },
                if self.variant == GlassVariant::Lens {
                    -6.0
                } else {
                    -2.0
                },
            )
        });
        ResolvedGlass {
            shape: self.shape,
            tint: self.tint.unwrap_or(colors.glass_tint),
            tint_amount: self.tint_amount,
            backdrop_blur: self.backdrop_blur,
            blur_radius_dp: self
                .blur_radius
                .unwrap_or_else(|| self.default_blur_radius()),
            saturation: self.saturation.unwrap_or_else(|| self.default_saturation()),
            refraction_depth: self.refraction_depth,
            refraction_depth_dp: self.refraction_depth_dp,
            refraction: self.refraction,
            refraction_curve: self.refraction_curve,
            dispersion: self.dispersion,
            edge_spectrum: self.edge_spectrum,
            transmission_refraction: self.transmission_refraction,
            meniscus_absorption: self.meniscus_absorption,
            fold_depth: self.fold_depth,
            optical_zoom: self.optical_zoom,
            rim_reflection: self.rim_reflection,
            ink_recolor: self.ink_recolor,
            highlight: self.highlight,
            face_lighting: self.face_lighting,
            key_fill: self.key_fill,
            face_response: self.face_response,
            inner_shadow: self.inner_shadow,
            lift,
            contrast: self.contrast.unwrap_or(match self.variant {
                GlassVariant::Lens => 1.0,
                _ => 1.03,
            }),
            shadow: self.shadow,
            clip: self.clip,
            foreground_luma: 0.2126 * foreground.r()
                + 0.7152 * foreground.g()
                + 0.0722 * foreground.b(),
            adaptive_frost: self.adaptive_frost,
            adaptive_tone: self.adaptive_tone,
            rim_style: if self.variant == GlassVariant::Lens {
                1.0
            } else {
                0.0
            },
            shadow_color: shadow.color,
            shadow_radius: shadow.radius,
            shadow_offset_y: shadow.offset_y,
            shadow_spread: shadow.spread,
        }
    }
}

impl Default for Glass {
    fn default() -> Self {
        Self::regular()
    }
}

#[derive(Clone, Debug, PartialEq)]
pub(crate) struct ResolvedGlass {
    pub shape: LiquidShape,
    pub tint: Color,
    tint_amount: Option<GlassTintAmount>,
    backdrop_blur: Option<(f32, f32)>,
    pub blur_radius_dp: f32,
    pub saturation: f32,
    pub refraction_depth: f32,
    pub refraction_depth_dp: Option<f32>,
    pub refraction: GlassRefraction,
    pub refraction_curve: f32,
    pub dispersion: f32,
    pub edge_spectrum: Option<GlassSpectrum>,
    pub transmission_refraction: f32,
    pub meniscus_absorption: f32,
    pub fold_depth: f32,
    pub optical_zoom: f32,
    pub rim_reflection: f32,
    pub ink_recolor: Option<(Color, f32)>,
    pub highlight: f32,
    pub face_lighting: bool,
    pub key_fill: Option<GlassKeyFill>,
    /// Attenuation and illumination applied around the edge-light pass.
    pub face_response: Option<GlassFaceResponse>,
    pub lift: f32,
    /// Inset shadow on the transmitted face, covered by the chromatic foreground.
    pub inner_shadow: Option<GlassShadow>,
    pub contrast: f32,
    pub shadow: bool,
    pub clip: bool,
    pub rim_style: f32,
    pub foreground_luma: f32,
    pub adaptive_frost: f32,
    pub adaptive_tone: bool,
    pub shadow_color: Color,
    pub shadow_radius: f32,
    pub shadow_offset_y: f32,
    pub shadow_spread: f32,
}

fn set_edge_return_depth(shader: &mut RuntimeShader, depth: Option<f32>) {
    if let Some(depth) = depth.filter(|depth| depth.is_finite() && *depth >= 0.0) {
        shader.set_float2(GLASS_EDGE_RETURN_DEPTH_UNIFORM, depth, 1.0);
    }
}

impl ResolvedGlass {
    /// The same glass as a flat surface, for a person who asked the system
    /// for less transparency: the surface color with no blur, no refraction
    /// and no spectrum, the shape and the shadow as they were.
    pub(crate) fn without_transparency(mut self, colors: &LiquidColors) -> Self {
        self.tint = colors.surface;
        self.tint_amount = None;
        self.backdrop_blur = None;
        self.blur_radius_dp = 0.0;
        self.saturation = 1.0;
        self.refraction_depth = 0.0;
        self.refraction_depth_dp = None;
        self.dispersion = 0.0;
        self.edge_spectrum = None;
        self.transmission_refraction = 0.0;
        self.meniscus_absorption = 0.0;
        self.rim_reflection = 0.0;
        self.adaptive_frost = 0.0;
        self
    }

    fn clips_in_shader(&self) -> bool {
        self.key_fill.and_then(GlassKeyFill::uniforms).is_some()
    }
    pub(crate) fn backdrop_effect(&self, density: f32, dynamics: GlassDynamics) -> RenderEffect {
        self.runtime_effect(density, &dynamics, false)
    }

    fn blur_radii(&self, density: f32, activity: f32, content_mask: bool) -> (f32, f32) {
        if content_mask || self.tint_amount.is_some() {
            return (0.0, 0.0);
        }
        let radius = self.blur_radius_dp * density * activity;
        if radius > WCKSRD_OPTICAL_BLUR_RADIUS_PX {
            (0.0, radius)
        } else {
            (radius, 0.0)
        }
    }

    fn runtime_effect(
        &self,
        density: f32,
        dynamics: &GlassDynamics,
        content_mask: bool,
    ) -> RenderEffect {
        self.runtime_effect_with_content(density, dynamics, content_mask, false)
    }

    fn runtime_effect_with_content(
        &self,
        density: f32,
        dynamics: &GlassDynamics,
        content_mask: bool,
        separate_content: bool,
    ) -> RenderEffect {
        let density = density.max(f32::EPSILON);
        let activity = dynamics
            .activity
            .filter(|value| value.is_finite())
            .unwrap_or(1.0)
            .clamp(0.0, 1.0);
        static SHADER: OnceLock<RuntimeShader> = OnceLock::new();
        let mut shader = SHADER
            .get_or_init(|| {
                let mut shader = RuntimeShader::new(LIQUID_GLASS_WGSL);
                shader.set_float(GLASS_ACTIVITY_UNIFORM, 1.0);
                shader.set_float2(GLASS_OPTICAL_ZOOM_ANCHOR_UNIFORM, 0.0, 0.0);
                specialize_liquid_glass(&mut shader);
                shader
            })
            .clone();
        if let Some(morph) = dynamics.morph.as_ref() {
            set_morph_uniforms(&mut shader, morph, activity);
        } else {
            shader.set_float2(0, 0.0, 0.0);
            shader.set_float(6, self.shape.shader_radius_px(density));
        }
        let projection = dynamics.projection();
        shader.set_float2(GLASS_OPTICAL_PROJECTION_UNIFORM, projection.0, projection.1);
        let press_depth = dynamics.press_depth.unwrap_or(1.0).clamp(0.0, 1.0);
        shader.set_float(9, self.refraction_depth * activity * press_depth);
        let (refraction_mode, refraction_reach) = self.refraction.shader_parameters();
        shader.set_float(GLASS_REFRACTION_MODE_UNIFORM, refraction_mode);
        set_edge_return_depth(&mut shader, dynamics.edge_return_depth_dp);
        shader.set_float(
            GLASS_EDGE_REFRACTION_REACH_UNIFORM,
            refraction_reach * activity * press_depth,
        );
        shader.set_float(
            GLASS_PHYSICAL_REFRACTION_DEPTH_UNIFORM,
            self.refraction_depth_dp.unwrap_or(0.0) * activity * press_depth,
        );
        shader.set_float(
            GLASS_PHYSICAL_REFRACTION_DEPTH_ENABLED_UNIFORM,
            if self.refraction_depth_dp.is_some() {
                1.0
            } else {
                0.0
            },
        );
        shader.set_float(
            GLASS_REFRACTION_CURVE_UNIFORM,
            self.refraction_curve * activity,
        );
        shader.set_float(
            GLASS_DISPERSION_UNIFORM,
            self.dispersion * activity * press_depth,
        );
        let spectrum_reach = self.set_spectrum_uniforms(&mut shader);
        shader.set_float(
            GLASS_TRANSMISSION_REFRACTION_UNIFORM,
            self.transmission_refraction * activity,
        );
        shader.set_float(
            GLASS_MENISCUS_ABSORPTION_UNIFORM,
            self.meniscus_absorption * press_depth,
        );
        shader.set_float(
            GLASS_FOLD_DEPTH_UNIFORM,
            self.fold_depth.max(0.0) * press_depth,
        );
        shader.set_float(
            GLASS_OPTICAL_ZOOM_UNIFORM,
            1.0 + (self.optical_zoom - 1.0).max(0.0) * activity,
        );
        let zoom_anchor = dynamics
            .morph
            .as_ref()
            .map(|morph| morph.zoom_anchor)
            .unwrap_or((0.0, 0.0));
        shader.set_float2(
            GLASS_OPTICAL_ZOOM_ANCHOR_UNIFORM,
            zoom_anchor.0,
            zoom_anchor.1,
        );
        shader.set_float(121, self.rim_reflection.max(0.001));
        let (ink_color, ink_strength) = self
            .ink_recolor
            .map(|(color, strength)| (color, strength * activity))
            .unwrap_or((Color::TRANSPARENT, 0.0));
        shader.set_float(124, ink_color.r());
        shader.set_float(125, ink_color.g());
        shader.set_float(126, ink_color.b());
        shader.set_float(127, ink_strength);
        let (light_x, light_y) = glass_light_direction();
        shader.set_float(GLASS_LIGHT_DIRECTION_UNIFORM, light_x);
        shader.set_float(GLASS_LIGHT_DIRECTION_UNIFORM + 1, light_y);
        self.set_lighting_uniforms(&mut shader, dynamics);
        shader.set_float(GLASS_EFFECT_DENSITY_UNIFORM, density);
        shader.set_float(
            11,
            (self.highlight + dynamics.highlight_boost).clamp(0.0, 2.0) * activity,
        );
        let dynamic_tint = boost_tint_saturation(self.tint, dynamics.saturation_boost);
        let dynamic_tint_alpha = (dynamic_tint.a()
            * dynamics
                .tint_alpha_multiplier
                .unwrap_or(1.0)
                .clamp(0.0, 2.0)
            * activity)
            .clamp(0.0, 1.0);
        shader.set_float4(
            14,
            dynamic_tint.r(),
            dynamic_tint.g(),
            dynamic_tint.b(),
            dynamic_tint_alpha,
        );
        let saturation = (self.saturation + dynamics.saturation_boost).max(0.0);
        shader.set_float(18, 1.0 + (saturation - 1.0) * activity);
        shader.set_float(20, self.lift * activity);
        shader.set_float(21, 0.5 * activity);
        shader.set_float2(22, 0.0, 1.0);
        shader.set_float(24, 1.0 + (self.contrast - 1.0) * activity);
        shader.set_float(28, self.rim_style * activity);
        let (wcksrd_blur_radius, gaussian_blur_radius) =
            self.blur_radii(density, activity, content_mask);
        shader.set_float(GLASS_BLUR_RADIUS_UNIFORM, wcksrd_blur_radius);
        shader.set_float(GLASS_ACTIVITY_UNIFORM, activity);
        let resting_tint = dynamics.resting_tint.unwrap_or(Color::TRANSPARENT);
        shader.set_float4(
            GLASS_RESTING_TINT_UNIFORM,
            resting_tint.r(),
            resting_tint.g(),
            resting_tint.b(),
            resting_tint.a(),
        );
        shader.set_float(112, if content_mask { 1.0 } else { 0.0 });
        shader.set_float(GLASS_ADAPTIVE_FROST_UNIFORM, self.adaptive_frost * activity);
        shader.set_float(97, self.foreground_luma);
        shader.set_float(GLASS_ADAPTIVE_TONE_UNIFORM, f32::from(self.adaptive_tone));
        self.set_backdrop_uniforms(&mut shader, density, content_mask);
        shader.set_float(
            cranpose_ui_graphics::GLASS_FOREGROUND_CONTENT_UNIFORM,
            f32::from(separate_content),
        );
        let dynamic_shadow = !self.clip && self.shadow;
        shader.set_float(
            102,
            if dynamic_shadow {
                self.shadow_color.a() * 0.55 * activity
            } else {
                0.0
            },
        );
        shader.set_float(103, self.shadow_radius);
        shader.set_float(104, self.shadow_offset_y);
        shader.set_float(105, self.shadow_spread);
        let morph_pad = dynamics
            .morph
            .as_ref()
            .map(|morph| {
                let (px, py, pw, ph, _) = morph.primary;
                let (left, top) = (px - pw * 0.5, py - ph * 0.5);
                let (right, bottom) = (px + pw * 0.5, py + ph * 0.5);
                let mut shape_reach = 0.0f32;
                for (sx, sy, sw, sh, _) in &morph.shapes {
                    let reach_x = ((sx + sw * 0.5) - right)
                        .max(left - (sx - sw * 0.5))
                        .max(0.0);
                    let reach_y = ((sy + sh * 0.5) - bottom)
                        .max(top - (sy - sh * 0.5))
                        .max(0.0);
                    shape_reach = shape_reach.max(reach_x.max(reach_y));
                }
                let glue_pad = if morph.shapes.is_empty() {
                    0.0
                } else {
                    morph.glue * 2.0
                };
                morph.wobble_amplitude * 2.0 + morph.bulge_amplitude + shape_reach + glue_pad
            })
            .unwrap_or(0.0);
        shader.set_input_padding(
            (self.input_padding()
                + if refraction_mode >= 1.5 {
                    refraction_reach * (26.5 / 9.0) + spectrum_reach
                } else {
                    refraction_reach
                }
                + morph_pad
                + wcksrd_blur_radius / density)
                * projection.0.max(projection.1).max(1.0),
        );
        if let Some(morph) = dynamics.morph.as_ref() {
            let shadow_reach = if dynamic_shadow {
                self.shadow_radius + self.shadow_offset_y.abs() + self.shadow_spread.max(0.0)
            } else {
                0.0
            };
            let support = morph_output_support(
                morph,
                activity,
                morph_pad,
                shadow_reach,
                if dynamic_shadow {
                    self.shadow_offset_y.abs()
                } else {
                    0.0
                },
            );
            let (cx, cy, _, _, _) = morph.primary;
            let support = Rect {
                x: cx + (support.x - cx) * projection.0,
                y: cy + (support.y - cy) * projection.1,
                width: support.width * projection.0,
                height: support.height * projection.1,
            };
            let (node_w, node_h) = morph.node_size;
            let overhang = (-support.x)
                .max(-support.y)
                .max(support.x + support.width - node_w)
                .max(support.y + support.height - node_h)
                .max(0.0);
            shader.set_output_padding((morph_pad + shadow_reach + 4.0).max(overhang));
            shader.set_output_support(Some(support));
        }

        let optical_effect = liquid_glass_runtime_effect(shader);
        if gaussian_blur_radius > f32::EPSILON {
            RenderEffect::blur_with_edge_treatment(gaussian_blur_radius, TileMode::Mirror)
                .then(optical_effect)
        } else {
            optical_effect
        }
    }

    fn set_backdrop_uniforms(&self, shader: &mut RuntimeShader, density: f32, content_mask: bool) {
        if let Some(amount) = self.tint_amount {
            shader.set_float(
                cranpose_ui_graphics::GLASS_PANE_BLEND_UNIFORM,
                8.0 * density,
            );
            shader.set_float(
                cranpose_ui_graphics::GLASS_PANE_BLEND_UNIFORM + 1,
                amount.percent() / 100.0,
            );
        }
        if !content_mask && let Some((radius, opacity)) = self.backdrop_blur {
            shader.set_float2(
                cranpose_ui_graphics::GLASS_BACKDROP_BLUR_UNIFORM,
                radius * density,
                opacity,
            );
        }
    }

    fn set_spectrum_uniforms(&self, shader: &mut RuntimeShader) -> f32 {
        let spectrum = self
            .edge_spectrum
            .and_then(|spectrum| spectrum.uniforms().map(|values| (spectrum, values)));
        if let Some((spectrum, values)) = spectrum {
            for (index, value) in values.into_iter().enumerate() {
                shader.set_float(GLASS_EDGE_SPECTRUM_UNIFORM + index, value);
            }
            spectrum.capture_reach()
        } else {
            40.787 * self.dispersion
        }
    }

    fn set_lighting_uniforms(&self, shader: &mut RuntimeShader, dynamics: &GlassDynamics) {
        let (touch_x, touch_y, touch_intensity) = dynamics.touch.unwrap_or((0.0, 0.0, 0.0));
        shader.set_float(118, touch_x);
        shader.set_float(119, touch_y);
        shader.set_float(120, touch_intensity.clamp(0.0, 1.0));
        shader.set_float(
            GLASS_FACE_LIGHTING_OFF_UNIFORM,
            f32::from(!self.face_lighting),
        );
        shader.set_float(
            GLASS_TOUCH_RADIUS_UNIFORM,
            dynamics
                .touch_radius_dp
                .filter(|radius| radius.is_finite() && *radius > 0.0)
                .unwrap_or(58.0),
        );
        shader.set_float(
            GLASS_LAYER_CLIPPED_UNIFORM,
            f32::from(self.clip && !self.clips_in_shader()),
        );
        if let Some(values) = self.key_fill.and_then(GlassKeyFill::uniforms) {
            for (index, value) in values.into_iter().enumerate() {
                shader.set_float(GLASS_KEY_FILL_UNIFORM + index, value);
            }
        }
        if let Some(values) = self.face_response.and_then(GlassFaceResponse::uniforms) {
            for (index, value) in values.into_iter().enumerate() {
                shader.set_float(GLASS_FACE_RESPONSE_UNIFORM + index, value);
            }
        }
        if let Some(values) = self.inner_shadow.and_then(GlassShadow::uniforms) {
            for (index, value) in values.into_iter().enumerate() {
                shader.set_float(GLASS_INNER_SHADOW_UNIFORM + index, value);
            }
        }
    }

    fn input_padding(&self) -> f32 {
        2.0
    }
}

/// Modifier extension installing the Liquid Glass material.
pub trait LiquidModifierExt {
    /// Applies the glass material to this composable's bounds: backdrop blur +
    /// lens shader, clipped to `glass.shape`, with a soft drop shadow.
    ///
    /// Must be called in composable context (the material resolves theme
    /// colors at the call site).
    fn glass_effect(self, glass: Glass) -> Modifier;

    /// [`glass_effect`](Self::glass_effect) with per-frame motion inputs; the
    /// closure is read at scene-build time, so animating tilt or highlight
    /// does not recompose.
    fn glass_effect_with(
        self,
        glass: Glass,
        dynamics: impl Fn() -> GlassDynamics + 'static,
    ) -> Modifier;
}

impl LiquidModifierExt for Modifier {
    fn glass_effect(self, glass: Glass) -> Modifier {
        self.glass_effect_with(glass, GlassDynamics::default)
    }

    fn glass_effect_with(
        self,
        glass: Glass,
        dynamics: impl Fn() -> GlassDynamics + 'static,
    ) -> Modifier {
        let colors = crate::theme::liquid_colors();
        let options = cranpose_services::local_accessibility_options().current();
        let resolved = if options.reduce_transparency {
            glass.resolve(&colors).without_transparency(&colors)
        } else {
            glass.resolve(&colors)
        };
        let shape = resolved.shape;

        let mut modifier = self;
        if resolved.shadow && resolved.clip {
            let shadow_color = resolved.shadow_color;
            let (radius, offset_y, spread) = (
                resolved.shadow_radius,
                resolved.shadow_offset_y,
                resolved.shadow_spread,
            );
            modifier = modifier.drop_shadow(shape.layer_shape(), move |scope| {
                scope.radius = radius;
                scope.spread = spread;
                scope.offset.y = offset_y;
                scope.color = shadow_color;
                scope.cutout = true;
            });
        }

        let layer = cached_glass_layer(resolved);
        modifier.graphics_layer(move || layer(current_density(), dynamics()))
    }
}

struct CachedGlassLayer<T> {
    density: u32,
    light: [u32; 2],
    dynamics: GlassDynamics,
    value: T,
}

fn cached_glass_layer(resolved: ResolvedGlass) -> impl Fn(f32, GlassDynamics) -> GraphicsLayer {
    cached_glass_layers(resolved, false, std::convert::identity)
}

pub(crate) fn cached_glass_content_layers(
    resolved: ResolvedGlass,
) -> impl Fn(f32, GlassDynamics) -> [GraphicsLayer; 2] {
    cached_glass_layers(resolved, true, |mut layer| {
        let Some(RenderEffect::Chain { first, second }) = layer.backdrop_effect.take() else {
            panic!("content layers require a sequential edge lens");
        };
        layer.backdrop_effect = Some((*second).clone());
        [
            GraphicsLayer {
                backdrop_effect: Some((*first).clone()),
                ..Default::default()
            },
            layer,
        ]
    })
}

fn cached_glass_layers<T: Clone>(
    resolved: ResolvedGlass,
    separate_content: bool,
    assemble: impl Fn(GraphicsLayer) -> T,
) -> impl Fn(f32, GlassDynamics) -> T {
    let cached = RefCell::new(None::<CachedGlassLayer<T>>);
    move |density, dynamics| {
        let direction = glass_light_direction();
        let light = [direction.0, direction.1].map(f32::to_bits);
        let mut cached = cached.borrow_mut();
        if let Some(previous) = &*cached
            && previous.density == density.to_bits()
            && previous.light == light
            && glass_dynamics_match(&previous.dynamics, &dynamics)
        {
            return previous.value.clone();
        }
        let render_effect = ((!resolved.clip && dynamics.morph.is_some())
            || (resolved.clip && resolved.clips_in_shader()))
        .then(|| resolved.runtime_effect(density, &dynamics, true));
        let layer = GraphicsLayer {
            backdrop_effect: Some(resolved.runtime_effect_with_content(
                density,
                &dynamics,
                false,
                separate_content,
            )),
            render_effect,
            shape: resolved.shape.layer_shape(),
            clip: resolved.clip && !resolved.clips_in_shader(),
            ..Default::default()
        };
        let value = assemble(layer);
        *cached = Some(CachedGlassLayer {
            density: density.to_bits(),
            light,
            dynamics,
            value: value.clone(),
        });
        value
    }
}

fn glass_dynamics_match(a: &GlassDynamics, b: &GlassDynamics) -> bool {
    let bits = |d: &GlassDynamics| {
        let GlassDynamics {
            edge_return_depth_dp,
            optical_projection,
            activity,
            resting_tint,
            highlight_boost,
            saturation_boost,
            tint_alpha_multiplier,
            morph: _,
            touch,
            touch_radius_dp,
            press_depth,
        } = d;
        (
            edge_return_depth_dp.map(f32::to_bits),
            optical_projection.map(|(x, y)| [x, y].map(f32::to_bits)),
            activity.map(f32::to_bits),
            resting_tint.map(|Color(r, g, b, a)| [r, g, b, a].map(f32::to_bits)),
            [*highlight_boost, *saturation_boost].map(f32::to_bits),
            tint_alpha_multiplier.map(f32::to_bits),
            touch.map(|(x, y, strength)| [x, y, strength].map(f32::to_bits)),
            press_depth.map(f32::to_bits),
            touch_radius_dp.map(f32::to_bits),
        )
    };
    bits(a) == bits(b)
        && match (&a.morph, &b.morph) {
            (None, None) => true,
            (Some(a), Some(b)) => glass_morphs_match(a, b),
            _ => false,
        }
}

fn glass_morphs_match(a: &GlassMorph, b: &GlassMorph) -> bool {
    let shape_bits =
        |&(x, y, w, h, r): &(f32, f32, f32, f32, f32)| [x, y, w, h, r].map(f32::to_bits);
    let bits = |m: &GlassMorph| {
        let GlassMorph {
            node_size,
            primary,
            shapes: _,
            glue,
            wobble_amplitude,
            wobble_phase,
            bulge_amplitude,
            bulge_direction,
            ellipse_blend,
            capsule_smoothing_dp,
            deformation,
            zoom_anchor,
        } = m;
        (
            [
                node_size.0,
                node_size.1,
                *glue,
                *wobble_amplitude,
                *wobble_phase,
                *bulge_amplitude,
                *bulge_direction,
                *ellipse_blend,
                *capsule_smoothing_dp,
                zoom_anchor.0,
                zoom_anchor.1,
            ]
            .map(f32::to_bits),
            shape_bits(primary),
            deformation
                .map(|GlassDeformation { axis, along }| [axis.0, axis.1, along].map(f32::to_bits)),
        )
    };
    bits(a) == bits(b)
        && a.shapes
            .iter()
            .map(shape_bits)
            .eq(b.shapes.iter().map(shape_bits))
}

fn morph_output_support(
    morph: &GlassMorph,
    activity: f32,
    morph_pad: f32,
    shadow_reach: f32,
    shadow_offset: f32,
) -> Rect {
    let (px, py, pw, ph, _) = morph.primary;
    let (along, (ax, ay)) = morph.deformation.map_or((1.0, (1.0, 0.0)), |deformation| {
        (
            1.0 + (deformation.along() - 1.0) * activity,
            deformation.axis(),
        )
    });
    let across = 1.0 / along;
    let smallest_strain = along.min(across);
    let reach = (morph_pad + shadow_reach + 4.0) / smallest_strain;
    let rows = [
        (
            (along * ax * ax + across * ay * ay).abs(),
            ((along - across) * ax * ay).abs(),
        ),
        (
            ((along - across) * ax * ay).abs(),
            (along * ay * ay + across * ax * ax).abs(),
        ),
    ];
    let half = (pw * 0.5 + reach, ph * 0.5 + reach);
    let extent_x = rows[0].0 * half.0 + rows[0].1 * half.1;
    let extent_y = rows[1].0 * half.0 + rows[1].1 * half.1;
    let (mut left, mut top) = (px - extent_x, py - extent_y);
    let (mut right, mut bottom) = (px + extent_x, py + extent_y);
    for (sx, sy, sw, sh, _) in &morph.shapes {
        left = left.min(sx - sw * 0.5 - reach);
        top = top.min(sy - sh * 0.5 - reach);
        right = right.max(sx + sw * 0.5 + reach);
        bottom = bottom.max(sy + sh * 0.5 + reach);
    }
    Rect {
        x: left,
        y: top - shadow_offset,
        width: right - left,
        height: bottom - top + 2.0 * shadow_offset,
    }
}

fn set_morph_uniforms(shader: &mut RuntimeShader, morph: &GlassMorph, activity: f32) {
    let (node_w, node_h) = morph.node_size;
    let (cx, cy, w, h, radius) = morph.primary;
    shader.set_float2(0, node_w.max(1.0), node_h.max(1.0));
    shader.set_float2(2, cx, cy);
    shader.set_float2(4, w, h);
    shader.set_float(6, radius);
    let count = morph.shapes.len().min(GlassMorph::MAX_SHAPES);
    shader.set_float(30, count as f32);
    for (index, (sx, sy, sw, sh, sr)) in morph.shapes.iter().take(count).enumerate() {
        let base = 36 + index * 5;
        shader.set_float(base, *sx);
        shader.set_float(base + 1, *sy);
        shader.set_float(base + 2, *sw);
        shader.set_float(base + 3, *sh);
        shader.set_float(base + 4, *sr);
    }
    shader.set_float(31, morph.glue);
    shader.set_float(32, morph.wobble_amplitude * activity);
    shader.set_float(33, morph.wobble_phase);
    shader.set_float(26, morph.bulge_amplitude * activity);
    shader.set_float(27, morph.bulge_direction);
    shader.set_float(110, morph.ellipse_blend.clamp(0.0, 1.0) * activity);
    shader.set_float(
        cranpose_ui_graphics::liquid_glass::GLASS_CAPSULE_SMOOTHING_UNIFORM,
        if morph.capsule_smoothing_dp.is_finite() {
            morph.capsule_smoothing_dp.max(0.0) * activity
        } else {
            0.0
        },
    );
    if let Some(deformation) = morph.deformation {
        let axis = deformation.axis();
        let along = 1.0 + (deformation.along() - 1.0) * activity;
        shader.set_float2(106, axis.0, axis.1);
        shader.set_float(108, along);
        shader.set_float(109, 1.0 / along);
    } else {
        shader.set_float2(106, 1.0, 0.0);
        shader.set_float2(108, 1.0, 1.0);
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn backdrop_blur_validates_radius_and_opacity() {
        for (radius, opacity, expected) in [
            (2.0, 0.5, Some((2.0, 0.5))),
            (-2.0, 3.0, Some((0.0, 1.0))),
            (2.0, -1.0, Some((2.0, 0.0))),
            (f32::NAN, 1.0, None),
            (2.0, f32::INFINITY, None),
        ] {
            assert_eq!(
                Glass::lens().backdrop_blur(radius, opacity).backdrop_blur,
                expected
            );
        }
        let glass = Glass::lens()
            .backdrop_blur(2.0, 0.75)
            .edge_refraction(0.0)
            .resolve(&light_colors());
        let shader = terminal_shader(glass.backdrop_effect(3.0, GlassDynamics::default()));
        assert_eq!(shader.uniforms()[172..174], [6.0, 0.75]);
        let mask = terminal_shader(glass.runtime_effect(3.0, &GlassDynamics::default(), true));
        assert_eq!(
            mask.uniforms().get(172..174).unwrap_or(&[0.0, 0.0]),
            [0.0, 0.0]
        );
    }

    #[test]
    fn pane_tint_preserves_the_sharp_source_at_every_percentage() {
        for percent in [0.0, 25.0, 50.0, 100.0] {
            let amount = GlassTintAmount::from_percent(percent).unwrap();
            let glass = Glass::regular()
                .adaptive_frost(Color::BLACK, 0.0)
                .tint_amount(amount);
            assert_eq!(glass.tint_amount, Some(amount));
            let effect = glass.backdrop_effect(&light_colors(), 3.0, GlassDynamics::default());
            let RenderEffect::Shader { shader } = effect else {
                panic!("the sharp backdrop must not be destroyed by a preceding blur");
            };
            assert_eq!(
                shader.uniforms()[cranpose_ui_graphics::GLASS_PANE_BLEND_UNIFORM],
                24.0
            );
            assert_eq!(
                shader.uniforms()[cranpose_ui_graphics::GLASS_PANE_BLEND_UNIFORM + 1],
                percent / 100.0
            );
            assert_eq!(
                shader.substrates(),
                &[cranpose_ui_graphics::SubstrateSpec::Blur { radius_px: 24.0 }]
            );
        }
    }

    fn light_colors() -> LiquidColors {
        LiquidColors::light(Color::from_rgb_u8(0, 122, 255))
    }

    fn terminal_shader(effect: RenderEffect) -> RuntimeShader {
        match effect {
            RenderEffect::Shader { shader } => std::sync::Arc::unwrap_or_clone(shader),
            RenderEffect::Chain { second, .. } => {
                terminal_shader(std::sync::Arc::unwrap_or_clone(second))
            }
            effect => panic!("expected runtime shader, got {effect:?}"),
        }
    }

    #[test]
    fn optical_projection_validates_scales_and_projects_output_support() {
        let glass = Glass::lens().resolve(&light_colors());
        let mut dynamics = GlassDynamics {
            morph: Some(GlassMorph {
                node_size: (200.0, 120.0),
                primary: (100.0, 60.0, 111.0, 70.0, 35.0),
                ..Default::default()
            }),
            ..Default::default()
        };
        let base = terminal_shader(glass.backdrop_effect(3.0, dynamics.clone()));
        for projection in [
            None,
            Some((0.0, 1.0)),
            Some((-1.0, 1.0)),
            Some((1.0, f32::NAN)),
            Some((f32::INFINITY, 1.0)),
        ] {
            dynamics.optical_projection = projection;
            let shader = terminal_shader(glass.backdrop_effect(3.0, dynamics.clone()));
            assert_eq!(
                &shader.uniforms()
                    [GLASS_OPTICAL_PROJECTION_UNIFORM..GLASS_OPTICAL_PROJECTION_UNIFORM + 2],
                &[1.0, 1.0]
            );
            assert_eq!(shader.output_support(), base.output_support());
        }
        dynamics.optical_projection = Some((1.2, 0.8));
        let projected = terminal_shader(glass.backdrop_effect(3.0, dynamics));
        assert_eq!(
            &projected.uniforms()
                [GLASS_OPTICAL_PROJECTION_UNIFORM..GLASS_OPTICAL_PROJECTION_UNIFORM + 2],
            &[1.2, 0.8]
        );
        let a = base.output_support().unwrap();
        let b = projected.output_support().unwrap();
        assert!((b.width - a.width * 1.2).abs() < 0.001);
        assert!((b.height - a.height * 0.8).abs() < 0.001);
    }

    #[test]
    fn content_layers_preserve_the_complete_material_effect_and_cache() {
        let resolved = Glass::lens()
            .edge_refraction(9.0)
            .no_clip()
            .resolve(&light_colors());
        let layers = cached_glass_content_layers(resolved.clone());
        for density in [1.0, 3.0] {
            for activity in [0.0, 0.5, 1.0] {
                let dynamics = GlassDynamics {
                    activity: Some(activity),
                    ..Default::default()
                };
                let actual = layers(density, dynamics.clone());
                let joined = actual[0]
                    .backdrop_effect
                    .clone()
                    .unwrap()
                    .then(actual[1].backdrop_effect.clone().unwrap());
                assert_eq!(
                    joined,
                    resolved.runtime_effect_with_content(density, &dynamics, false, true)
                );
                assert!(actual[0].render_effect.is_none());
                assert!(!actual[0].clip);
                assert_eq!(
                    terminal_shader(actual[1].backdrop_effect.clone().unwrap()).uniforms()[147],
                    3.0
                );
                let mut repeated = layers(density, dynamics.clone());
                assert_eq!(actual, repeated);
                repeated[0].backdrop_effect = None;
                assert_eq!(actual, layers(density, dynamics));
            }
        }
    }

    #[test]
    fn cached_glass_layers_refresh_all_live_inputs_and_keep_clones_independent() {
        let resolved = Glass::regular().no_clip().resolve(&light_colors());
        let layer = cached_glass_layer(resolved.clone());
        let mut dynamics = GlassDynamics::default();
        let mut density = 2.0;
        let mut previous = None;
        for step in 0..16 {
            match step {
                1 => density = 3.0,
                2 => set_glass_light_direction((0.5, -0.5)),
                3 => dynamics.highlight_boost = 0.25,
                4 => dynamics.saturation_boost = 0.4,
                5 => dynamics.activity = Some(0.5),
                6 => dynamics.resting_tint = Some(Color::RED),
                7 => dynamics.tint_alpha_multiplier = Some(0.3),
                8 => dynamics.touch = Some((5.0, 8.0, 0.7)),
                9 => dynamics.press_depth = Some(0.4),
                10 => {
                    dynamics.morph = Some(GlassMorph {
                        node_size: (60.0, 30.0),
                        primary: (30.0, 15.0, 50.0, 20.0, 4.0),
                        shapes: vec![(10.0, 15.0, 8.0, 8.0, -1.0)],
                        ..Default::default()
                    })
                }
                11 => {
                    let morph = dynamics.morph.as_mut().unwrap();
                    morph.primary.0 += 3.0;
                    morph.shapes[0].0 += 2.0;
                    morph.deformation = Some(GlassDeformation::incompressible((1.0, 1.0), 1.3));
                }
                12 => dynamics.morph = None,
                13 => dynamics.touch_radius_dp = Some(144.0),
                14 => dynamics.edge_return_depth_dp = Some(3.5),
                15 => dynamics.optical_projection = Some((1.2, 0.8)),
                _ => {}
            }
            let actual = layer(density, dynamics.clone());
            let expected = GraphicsLayer {
                backdrop_effect: Some(resolved.backdrop_effect(density, dynamics.clone())),
                render_effect: dynamics
                    .morph
                    .as_ref()
                    .map(|_| resolved.runtime_effect(density, &dynamics, true)),
                shape: resolved.shape.layer_shape(),
                clip: resolved.clip,
                ..Default::default()
            };
            assert_eq!(actual, expected, "live input step {step}");
            assert_ne!(
                previous.as_ref(),
                Some(&actual),
                "input change must reach the layer at step {step}"
            );
            let mut repeated = layer(density, dynamics.clone());
            assert_eq!(repeated, actual);
            repeated.backdrop_effect = None;
            assert_eq!(layer(density, dynamics.clone()), actual);
            previous = Some(actual);
        }
        set_glass_light_direction((0.0, 1.0));
        let replacement = cached_glass_layer(
            Glass::clear()
                .shape(LiquidShape::RoundedRect(9.0))
                .resolve(&light_colors()),
        );
        assert_ne!(
            replacement(density, dynamics.clone()),
            layer(density, dynamics)
        );
    }

    #[test]
    fn glass_cache_input_equality_preserves_signed_zero_and_nan_bits() {
        let mut a = GlassDynamics {
            touch: Some((0.0, 1.0, 0.5)),
            ..Default::default()
        };
        let mut b = a.clone();
        b.touch.as_mut().unwrap().0 = -0.0;
        assert!(!glass_dynamics_match(&a, &b));
        a.highlight_boost = f32::NAN;
        assert!(glass_dynamics_match(&a, &a));
        a.morph = Some(GlassMorph::default());
        b = a.clone();
        b.morph.as_mut().unwrap().zoom_anchor.0 = -0.0;
        assert!(!glass_dynamics_match(&a, &b));
        b = a.clone();
        b.morph
            .as_mut()
            .unwrap()
            .shapes
            .push((0.0, 1.0, 2.0, 3.0, 4.0));
        assert!(!glass_dynamics_match(&a, &b));
    }

    #[test]
    fn glass_light_direction_defaults_overhead_and_reaches_the_shader() {
        assert_eq!(glass_light_direction(), (0.0, 1.0));
        let resolved = Glass::regular().resolve(&light_colors());
        let effect = resolved.backdrop_effect(2.0, GlassDynamics::default());
        let shader = terminal_shader(effect);
        let u = shader.uniforms();
        assert_eq!(u[GLASS_LIGHT_DIRECTION_UNIFORM], 0.0);
        assert_eq!(u[GLASS_LIGHT_DIRECTION_UNIFORM + 1], 1.0);

        set_glass_light_direction((1.0, 0.0));
        let effect = resolved.backdrop_effect(2.0, GlassDynamics::default());
        let u_rotated = terminal_shader(effect);
        let u_rotated = u_rotated.uniforms();
        assert_eq!(u_rotated[GLASS_LIGHT_DIRECTION_UNIFORM], 1.0);
        assert_eq!(u_rotated[GLASS_LIGHT_DIRECTION_UNIFORM + 1], 0.0);
        set_glass_light_direction((0.0, 1.0));
    }

    #[test]
    fn liquid_shape_builds_matching_clip_and_layer_shapes() {
        for shape in [
            LiquidShape::Capsule,
            LiquidShape::Circle,
            LiquidShape::RoundedRect(12.0),
        ] {
            assert_eq!(shape.layer_shape(), LayerShape::Rounded(shape.clip_shape()));
        }
    }

    #[test]
    fn glass_shadow_clamps_negative_radius() {
        let shadow = GlassShadow::new(Color::BLACK, -2.0, 3.0, -1.0);
        assert_eq!(shadow.radius, 0.0);
        assert_eq!(shadow.offset_y, 3.0);
        assert_eq!(shadow.spread, -1.0);
    }

    #[test]
    fn incompressible_deformation_normalizes_axis_and_conserves_area() {
        let deformation = GlassDeformation::incompressible((3.0, 4.0), 1.25);
        assert_eq!(deformation.axis(), (0.6, 0.8));
        assert_eq!(deformation.along(), 1.25);
        assert!((deformation.along() * deformation.across() - 1.0).abs() < 1.0e-6);
        assert_eq!(
            GlassDeformation::incompressible((0.0, 0.0), 0.0).axis(),
            (1.0, 0.0)
        );
    }

    #[test]
    fn glass_builders_clamp_physical_inputs() {
        let glass = Glass::lens()
            .shape(LiquidShape::Circle)
            .tint(Color::BLACK)
            .blur_radius(-2.0)
            .saturation(1.2)
            .refraction_depth(3.0)
            .refraction_depth_dp(-3.0)
            .refraction_curve(2.0)
            .dispersion(2.0)
            .transmission_refraction(2.0)
            .meniscus_absorption(2.0)
            .highlight(0.4)
            .lift(-0.2)
            .adaptive_frost(Color::WHITE, 2.0)
            .shadow(false)
            .no_clip();
        assert_eq!(glass.shape, LiquidShape::Circle);
        assert_eq!(glass.tint, Some(Color::BLACK));
        assert_eq!(glass.blur_radius, Some(-2.0));
        assert_eq!(glass.saturation, Some(1.2));
        assert_eq!(glass.refraction_depth, 2.0);
        assert_eq!(glass.refraction_depth_dp, Some(0.0));
        assert_eq!(glass.refraction_curve, 1.0);
        assert_eq!(glass.dispersion, 1.0);
        assert_eq!(glass.transmission_refraction, 1.0);
        assert_eq!(glass.meniscus_absorption, 1.0);
        assert_eq!(glass.highlight, 0.4);
        assert_eq!(glass.lift, Some(-0.2));
        assert_eq!(glass.adaptive_frost, 1.0);
        assert!(!glass.shadow);
        assert!(!glass.clip);
    }

    #[test]
    fn material_variants_resolve_distinct_frost_levels() {
        let regular = Glass::regular().resolve(&light_colors());
        let clear = Glass::clear().resolve(&light_colors());
        let lens = Glass::lens().resolve(&light_colors());
        assert!(regular.blur_radius_dp > clear.blur_radius_dp);
        assert!(clear.blur_radius_dp > lens.blur_radius_dp);
        assert!(regular.saturation > clear.saturation);
        assert_eq!(lens.rim_style, 1.0);
        assert_eq!(regular.refraction_depth, 0.0);
        assert_eq!(regular.transmission_refraction, 0.0);
        assert_eq!(regular.refraction_curve, 0.25);
        assert_eq!(lens.refraction_curve, 1.0);
        assert_eq!(regular.dispersion, 0.0);
        assert_eq!(lens.dispersion, 0.30);
    }

    #[test]
    fn neutral_surface_helpers_follow_foreground_polarity() {
        assert_eq!(
            neutral_surface_tint(Color::BLACK, 0.08, 0.10),
            Color::BLACK.with_alpha(0.08)
        );
        assert_eq!(
            neutral_surface_tint(Color::WHITE, 0.08, 0.10),
            Color::WHITE.with_alpha(0.10)
        );
    }

    #[test]
    fn dynamic_saturation_reaches_the_material_tint() {
        let resting = Color::from_rgb_u8(0, 199, 208);
        let raised = boost_tint_saturation(resting, 0.55);
        assert_eq!(raised.r(), 0.0);
        assert!(raised.g() > resting.g());
        assert!(raised.b() > resting.b());
        assert_eq!(raised.a(), resting.a());
    }

    #[test]
    fn template_specialization_follows_each_materials_dispersion_and_activity() {
        for (dispersion, activity) in [(0.6, 0.0), (0.0, 0.5), (0.3, 1.0), (0.0, 0.0)] {
            let resolved = Glass::regular()
                .dispersion(dispersion)
                .resolve(&light_colors());
            let mut shader = terminal_shader(resolved.backdrop_effect(
                1.0,
                GlassDynamics {
                    activity: Some(activity),
                    ..GlassDynamics::default()
                },
            ));
            cranpose_ui_graphics::specialize_liquid_glass_with_folds(&mut shader, true);
            assert_eq!(
                shader.uniforms()[GLASS_DISPERSION_UNIFORM],
                dispersion * activity
            );
            assert_eq!(shader.uniforms()[GLASS_ACTIVITY_UNIFORM], activity);
            assert_eq!(
                shader
                    .overrides()
                    .iter()
                    .any(|(name, _)| { *name == cranpose_ui_graphics::GLASS_DISPERSION_OFF_FLAG }),
                dispersion * activity == 0.0
            );
        }
    }

    fn spectrum_fixture() -> GlassSpectrum {
        GlassSpectrum {
            angle_radians: 0.7,
            step_dp: -1.5,
            vertical_scale: 1.25,
            opacity_near: 0.25,
            opacity_far: 0.75,
            fade_depth_dp: 3.5,
            extent_dp: 12.0,
        }
    }

    #[test]
    fn edge_spectrum_preserves_signed_taps_and_captures_every_ray() {
        let spectrum = spectrum_fixture();
        let material = Glass::lens()
            .edge_refraction(9.0)
            .dispersion(0.0)
            .edge_spectrum(spectrum);
        assert_eq!(material.edge_spectrum, Some(spectrum));
        let resolved = material.resolve(&light_colors());
        let shader = terminal_shader(resolved.backdrop_effect(3.0, GlassDynamics::default()));
        assert_eq!(
            &shader.uniforms()[GLASS_EDGE_SPECTRUM_UNIFORM..GLASS_EDGE_SPECTRUM_UNIFORM + 8],
            &spectrum.uniforms().unwrap()
        );
        let ordinary = Glass::lens()
            .edge_refraction(9.0)
            .dispersion(0.0)
            .resolve(&light_colors());
        let base = terminal_shader(ordinary.backdrop_effect(3.0, GlassDynamics::default()));
        assert!((shader.input_padding() - base.input_padding() - 5.625).abs() < 0.001);
    }

    #[test]
    fn edge_spectrum_rejects_invalid_fields_at_both_entry_points() {
        for index in 0..7 {
            for invalid in [f32::NAN, f32::INFINITY, f32::NEG_INFINITY] {
                let mut spectrum = spectrum_fixture();
                let fields = [
                    &mut spectrum.angle_radians,
                    &mut spectrum.step_dp,
                    &mut spectrum.vertical_scale,
                    &mut spectrum.opacity_near,
                    &mut spectrum.opacity_far,
                    &mut spectrum.fade_depth_dp,
                    &mut spectrum.extent_dp,
                ];
                *fields.into_iter().nth(index).unwrap() = invalid;
                assert_eq!(Glass::lens().edge_spectrum(spectrum).edge_spectrum, None);
                let material = Glass {
                    edge_spectrum: Some(spectrum),
                    ..Glass::lens()
                };
                let shader = terminal_shader(
                    material
                        .resolve(&light_colors())
                        .backdrop_effect(1.0, GlassDynamics::default()),
                );
                assert_eq!(
                    shader
                        .uniforms()
                        .get(GLASS_EDGE_SPECTRUM_UNIFORM + 7)
                        .copied()
                        .unwrap_or(0.0),
                    0.0
                );
            }
        }
        for index in 2..7 {
            let mut spectrum = spectrum_fixture();
            let fields = [
                &mut spectrum.vertical_scale,
                &mut spectrum.opacity_near,
                &mut spectrum.opacity_far,
                &mut spectrum.fade_depth_dp,
                &mut spectrum.extent_dp,
            ];
            *fields.into_iter().nth(index - 2).unwrap() = -0.1;
            assert_eq!(Glass::lens().edge_spectrum(spectrum).edge_spectrum, None);
        }
        for near in [true, false] {
            let mut spectrum = spectrum_fixture();
            if near {
                spectrum.opacity_near = 1.1;
            } else {
                spectrum.opacity_far = 1.1;
            }
            assert_eq!(Glass::lens().edge_spectrum(spectrum).edge_spectrum, None);
        }
        let zero = GlassSpectrum {
            angle_radians: 0.0,
            step_dp: 0.0,
            vertical_scale: 0.0,
            opacity_near: 0.0,
            opacity_far: 1.0,
            fade_depth_dp: 0.0,
            extent_dp: 0.0,
        };
        assert_eq!(Glass::lens().edge_spectrum(zero).edge_spectrum, Some(zero));
    }

    #[test]
    fn material_template_preserves_each_instances_optical_zoom_anchor() {
        let resolved = Glass::lens().resolve(&light_colors());
        for anchor in [(3.5, -2.25), (0.0, 0.0), (-7.0, 11.0)] {
            let shader = terminal_shader(resolved.backdrop_effect(
                1.5,
                GlassDynamics {
                    morph: Some(GlassMorph {
                        node_size: (120.0, 72.0),
                        primary: (60.0, 36.0, 96.0, 52.0, -1.0),
                        zoom_anchor: anchor,
                        ..Default::default()
                    }),
                    ..Default::default()
                },
            ));
            assert_eq!(
                &shader.uniforms()
                    [GLASS_OPTICAL_ZOOM_ANCHOR_UNIFORM..GLASS_OPTICAL_ZOOM_ANCHOR_UNIFORM + 2],
                &[anchor.0, anchor.1]
            );
        }
    }

    #[test]
    fn key_fill_preserves_valid_parameters_and_rejects_invalid_fields() {
        let lighting = GlassKeyFill {
            height_dp: 1.0,
            curvature: 0.8,
            angle_radians: -std::f32::consts::FRAC_PI_4,
            saturation: 1.5,
            luma_gain: 0.4367,
            offset: 1.125,
            scale_with_surface: true,
        };
        for glass in [Glass::regular(), Glass::clear(), Glass::lens()] {
            assert!(glass.key_fill.is_none());
            let material = glass.key_fill(lighting);
            assert_eq!(material.key_fill, Some(lighting));
            let shader = terminal_shader(material.backdrop_effect(
                &light_colors(),
                3.0,
                GlassDynamics::default(),
            ));
            assert_eq!(
                &shader.uniforms()[GLASS_KEY_FILL_UNIFORM..GLASS_KEY_FILL_UNIFORM + 7],
                &lighting.uniforms().unwrap()
            );
        }
        for scale_with_surface in [false, true] {
            let value = GlassKeyFill {
                scale_with_surface,
                ..lighting
            };
            assert_eq!(value.uniforms().unwrap()[6], f32::from(scale_with_surface));
            let layer = cached_glass_layer(Glass::clear().key_fill(value).resolve(&light_colors()))(
                3.0,
                GlassDynamics::default(),
            );
            assert!(!layer.clip);
            assert!(layer.render_effect.is_some());
            assert!(layer.backdrop_effect.is_some());
        }
        for index in 0..6 {
            for invalid in [f32::NAN, f32::INFINITY, f32::NEG_INFINITY] {
                let mut value = lighting;
                match index {
                    0 => value.height_dp = invalid,
                    1 => value.curvature = invalid,
                    2 => value.angle_radians = invalid,
                    3 => value.saturation = invalid,
                    4 => value.luma_gain = invalid,
                    _ => value.offset = invalid,
                }
                let shader = terminal_shader(Glass::clear().key_fill(value).backdrop_effect(
                    &light_colors(),
                    3.0,
                    GlassDynamics::default(),
                ));
                assert_eq!(
                    shader
                        .uniforms()
                        .get(GLASS_KEY_FILL_UNIFORM)
                        .copied()
                        .unwrap_or_default(),
                    0.0
                );
            }
        }
        for invalid in [0.0, -1.0] {
            assert!(
                GlassKeyFill {
                    height_dp: invalid,
                    ..lighting
                }
                .uniforms()
                .is_none()
            );
            assert!(
                GlassKeyFill {
                    curvature: invalid,
                    ..lighting
                }
                .uniforms()
                .is_none()
            );
        }
    }

    #[test]
    fn independent_edge_return_depth_preserves_zero_and_rejects_invalid_values() {
        for depth in [
            None,
            Some(0.0),
            Some(3.5),
            Some(-1.0),
            Some(f32::NAN),
            Some(f32::INFINITY),
        ] {
            let shader = terminal_shader(
                Glass::lens()
                    .edge_refraction(9.0)
                    .refraction_depth_dp(36.0)
                    .backdrop_effect(
                        &light_colors(),
                        3.0,
                        GlassDynamics {
                            edge_return_depth_dp: depth,
                            ..GlassDynamics::default()
                        },
                    ),
            );
            let valid = depth.filter(|value| value.is_finite() && *value >= 0.0);
            assert_eq!(
                shader
                    .uniforms()
                    .get(GLASS_EDGE_RETURN_DEPTH_UNIFORM)
                    .copied()
                    .unwrap_or(0.0),
                valid.unwrap_or(0.0)
            );
            assert_eq!(
                shader
                    .uniforms()
                    .get(GLASS_EDGE_RETURN_DEPTH_UNIFORM + 1)
                    .copied()
                    .unwrap_or(0.0),
                f32::from(valid.is_some())
            );
            assert_eq!(
                shader.uniforms()[GLASS_PHYSICAL_REFRACTION_DEPTH_UNIFORM],
                36.0
            );
        }
    }

    #[test]
    fn inner_shadow_validates_and_resolves_its_gaussian_profile() {
        let shadow = GlassShadow::new(Color::BLACK.with_alpha(0.12), 3.0, 7.0, 0.0);
        for glass in [Glass::regular(), Glass::clear(), Glass::lens()] {
            assert_eq!(glass.inner_shadow, None);
            let material = glass.inner_shadow(shadow);
            assert_eq!(material.inner_shadow, Some(shadow));
            let shader = terminal_shader(material.backdrop_effect(
                &light_colors(),
                3.0,
                GlassDynamics::default(),
            ));
            assert_eq!(
                &shader.uniforms()[GLASS_INNER_SHADOW_UNIFORM..GLASS_INNER_SHADOW_UNIFORM + 8],
                &shadow.uniforms().unwrap()
            );
        }
        for alpha in [0.0, 1.0] {
            assert!(
                Glass::lens()
                    .inner_shadow(GlassShadow::new(
                        Color::BLACK.with_alpha(alpha),
                        0.0,
                        -2.0,
                        -3.0
                    ))
                    .inner_shadow
                    .is_some()
            );
        }
        for index in 0..7 {
            for value in [f32::NAN, f32::INFINITY, f32::NEG_INFINITY] {
                let mut values = shadow.uniforms().unwrap();
                values[index] = value;
                let invalid = GlassShadow {
                    color: Color(values[0], values[1], values[2], values[3]),
                    radius: values[4],
                    offset_y: values[5],
                    spread: values[6],
                };
                assert_eq!(Glass::lens().inner_shadow(invalid).inner_shadow, None);
                let material = Glass {
                    inner_shadow: Some(invalid),
                    ..Glass::lens()
                };
                let shader = terminal_shader(material.backdrop_effect(
                    &light_colors(),
                    3.0,
                    GlassDynamics::default(),
                ));
                assert_eq!(
                    shader
                        .uniforms()
                        .get(GLASS_INNER_SHADOW_UNIFORM + 7)
                        .copied()
                        .unwrap_or(0.0),
                    0.0
                );
            }
        }
        for invalid in [
            GlassShadow {
                radius: -1.0,
                ..shadow
            },
            GlassShadow {
                color: Color(0.0, 0.0, 0.0, -0.1),
                ..shadow
            },
            GlassShadow {
                color: Color(0.0, 0.0, 0.0, 1.1),
                ..shadow
            },
        ] {
            assert_eq!(Glass::lens().inner_shadow(invalid).inner_shadow, None);
        }
    }

    #[test]
    fn adaptive_tone_resolves_foreground_and_declares_the_shared_mean() {
        use cranpose_ui_graphics::SubstrateSpec;
        for foreground in [Color::BLACK, Color::WHITE, Color(f32::NAN, 0.0, 0.0, 1.0)] {
            let material = Glass::clear().adaptive_tone(foreground);
            assert!(material.adaptive_tone);
            let resolved = material.resolve(&light_colors());
            assert!(resolved.foreground_luma.is_finite());
            let shader = terminal_shader(resolved.backdrop_effect(3.0, GlassDynamics::default()));
            assert_eq!(shader.uniforms()[GLASS_ADAPTIVE_TONE_UNIFORM], 1.0);
            assert_eq!(shader.substrates(), &[SubstrateSpec::Mean]);
            let expected = if foreground.r().is_finite() {
                foreground.r()
            } else {
                0.2126 * light_colors().label.r()
                    + 0.7152 * light_colors().label.g()
                    + 0.0722 * light_colors().label.b()
            };
            assert!((resolved.foreground_luma - expected).abs() < 0.0001);
        }
        assert!(!Glass::clear().adaptive_tone);
        assert!(!Glass::regular().adaptive_tone);
    }

    #[test]
    fn face_response_preserves_valid_ranges_and_rejects_invalid_values() {
        let response = GlassFaceResponse {
            gain: 0.97,
            start_dp: 1.0 / 3.0,
            end_dp: 2.0 / 3.0,
            illumination: 0.05,
        };
        for glass in [Glass::regular(), Glass::clear(), Glass::lens()] {
            assert!(glass.face_response.is_none());
            let material = glass.face_response(response);
            assert_eq!(material.face_response, Some(response));
            let shader = terminal_shader(material.backdrop_effect(
                &light_colors(),
                3.0,
                GlassDynamics::default(),
            ));
            assert_eq!(
                &shader.uniforms()[GLASS_FACE_RESPONSE_UNIFORM..GLASS_FACE_RESPONSE_UNIFORM + 4],
                &response.uniforms().unwrap()
            );
        }
        for gain in [0.0, 1.0] {
            assert!(
                GlassFaceResponse {
                    gain,
                    start_dp: 0.0,
                    end_dp: 0.0,
                    ..response
                }
                .uniforms()
                .is_some()
            );
        }
        let mut invalid = vec![
            GlassFaceResponse {
                gain: -0.1,
                ..response
            },
            GlassFaceResponse {
                gain: 1.1,
                ..response
            },
            GlassFaceResponse {
                start_dp: -1.0,
                ..response
            },
            GlassFaceResponse {
                end_dp: 0.0,
                ..response
            },
        ];
        for value in [f32::NAN, f32::INFINITY, f32::NEG_INFINITY] {
            invalid.extend([
                GlassFaceResponse {
                    gain: value,
                    ..response
                },
                GlassFaceResponse {
                    start_dp: value,
                    ..response
                },
                GlassFaceResponse {
                    end_dp: value,
                    ..response
                },
                GlassFaceResponse {
                    illumination: value,
                    ..response
                },
            ]);
        }
        for response in invalid {
            assert!(response.uniforms().is_none());
            let shader = terminal_shader(Glass::clear().face_response(response).backdrop_effect(
                &light_colors(),
                3.0,
                GlassDynamics::default(),
            ));
            assert!(
                shader
                    .uniforms()
                    .get(GLASS_FACE_RESPONSE_UNIFORM..GLASS_FACE_RESPONSE_UNIFORM + 4)
                    .is_none_or(|values| values.iter().all(|value| *value == 0.0))
            );
        }
    }

    #[test]
    fn face_lighting_is_explicit_and_preserves_each_material_default() {
        for glass in [Glass::regular(), Glass::clear(), Glass::lens()] {
            assert!(glass.face_lighting);
            for enabled in [false, true] {
                let material = glass.clone().face_lighting(enabled);
                assert_eq!(material.face_lighting, enabled);
                let resolved = material.resolve(&light_colors());
                assert_eq!(resolved.face_lighting, enabled);
                let shader =
                    terminal_shader(resolved.backdrop_effect(3.0, GlassDynamics::default()));
                assert_eq!(
                    shader.uniforms()[GLASS_FACE_LIGHTING_OFF_UNIFORM],
                    f32::from(!enabled)
                );
            }
        }
    }

    #[test]
    fn layer_clipping_has_one_owner_for_material_coverage() {
        for clipped in [false, true] {
            let mut glass = Glass::regular();
            if !clipped {
                glass = glass.no_clip();
            }
            let shader = terminal_shader(glass.backdrop_effect(
                &light_colors(),
                3.0,
                GlassDynamics::default(),
            ));
            assert_eq!(
                shader.uniforms()[GLASS_LAYER_CLIPPED_UNIFORM],
                f32::from(clipped)
            );
        }
    }

    #[test]
    fn touch_radius_preserves_valid_values_and_normalizes_invalid_values() {
        for radius in [
            None,
            Some(-1.0),
            Some(0.0),
            Some(f32::NAN),
            Some(f32::INFINITY),
            Some(f32::NEG_INFINITY),
            Some(0.5),
            Some(144.0),
        ] {
            let expected = radius
                .filter(|value| value.is_finite() && *value > 0.0)
                .unwrap_or(58.0);
            for density in [1.0, 3.0] {
                let shader = terminal_shader(Glass::regular().backdrop_effect(
                    &light_colors(),
                    density,
                    GlassDynamics {
                        touch_radius_dp: radius,
                        ..Default::default()
                    },
                ));
                assert_eq!(shader.uniforms()[GLASS_TOUCH_RADIUS_UNIFORM], expected);
            }
        }
    }

    #[test]
    fn material_instances_share_source_without_sharing_uniforms_or_overrides() {
        let resolved = Glass::regular().resolve(&light_colors());
        let mut first = terminal_shader(resolved.backdrop_effect(2.0, GlassDynamics::default()));
        let untouched = terminal_shader(resolved.backdrop_effect(1.0, GlassDynamics::default()));
        let unused_slot = RuntimeShader::MAX_USER_UNIFORMS - 1;
        first.set_float(unused_slot, 17.0);
        first.set_override("INSTANCE_ONLY", 1.0);
        let second = terminal_shader(resolved.backdrop_effect(1.0, GlassDynamics::default()));
        assert_eq!(second.uniforms(), untouched.uniforms());
        assert_eq!(second.overrides(), untouched.overrides());
        assert_eq!(
            second.uniforms().get(unused_slot).copied().unwrap_or(0.0),
            0.0
        );
        assert!(
            !second
                .overrides()
                .iter()
                .any(|(name, _)| *name == "INSTANCE_ONLY")
        );
        assert_eq!(first.uniforms()[unused_slot], 17.0);
        assert_eq!(first.uniforms()[GLASS_EFFECT_DENSITY_UNIFORM], 2.0);
        assert_eq!(second.uniforms()[GLASS_EFFECT_DENSITY_UNIFORM], 1.0);
        assert_eq!(first.source().as_ptr(), second.source().as_ptr());
    }

    #[test]
    fn resolved_material_packs_wcksrd_and_dynamic_tint() {
        let resolved = Glass::lens()
            .refraction_depth(0.72)
            .refraction_depth_dp(21.0)
            .refraction_curve(0.8)
            .dispersion(0.42)
            .transmission_refraction(0.35)
            .meniscus_absorption(0.3)
            .blur_radius(3.0)
            .tint(Color::BLACK.with_alpha(0.8))
            .resolve(&light_colors());
        let effect = resolved.backdrop_effect(
            2.0,
            GlassDynamics {
                highlight_boost: 0.2,
                saturation_boost: 0.35,
                tint_alpha_multiplier: Some(0.25),
                ..Default::default()
            },
        );
        let RenderEffect::Chain { first, .. } = &effect else {
            panic!("macroscopic frost must precede the wcKSRD optical pass");
        };
        assert!(matches!(
            first.as_ref(),
            RenderEffect::Blur {
                radius_x: 6.0,
                radius_y: 6.0,
                ..
            }
        ));
        let shader = terminal_shader(effect);
        assert_eq!(shader.uniforms()[9], 0.72);
        assert_eq!(
            shader.uniforms()[GLASS_PHYSICAL_REFRACTION_DEPTH_UNIFORM],
            21.0
        );
        assert_eq!(
            shader.uniforms()[GLASS_PHYSICAL_REFRACTION_DEPTH_ENABLED_UNIFORM],
            1.0
        );
        assert_eq!(shader.uniforms()[GLASS_REFRACTION_CURVE_UNIFORM], 0.8);
        assert_eq!(shader.uniforms()[GLASS_DISPERSION_UNIFORM], 0.42);
        assert_eq!(
            shader.uniforms()[GLASS_TRANSMISSION_REFRACTION_UNIFORM],
            0.35
        );
        assert_eq!(shader.uniforms()[GLASS_MENISCUS_ABSORPTION_UNIFORM], 0.3);
        assert_eq!(shader.uniforms()[11], resolved.highlight + 0.2);
        assert_eq!(shader.uniforms()[18], resolved.saturation + 0.35);
        assert!((shader.uniforms()[17] - 0.2).abs() < 1.0e-6);
        assert_eq!(shader.uniforms()[GLASS_BLUR_RADIUS_UNIFORM], 0.0);
        assert_eq!(shader.uniforms()[GLASS_EFFECT_DENSITY_UNIFORM], 2.0);
    }

    #[test]
    fn heavy_backdrop_blur_rides_the_gaussian_pass_alone() {
        let effect = Glass::regular()
            .resolve(&light_colors())
            .backdrop_effect(3.0, GlassDynamics::default());
        let RenderEffect::Chain { first, .. } = &effect else {
            panic!("heavy blur must ride the separable Gaussian pre-pass");
        };
        assert!(matches!(
            first.as_ref(),
            RenderEffect::Blur {
                radius_x: 24.0,
                radius_y: 24.0,
                ..
            }
        ));
        assert_eq!(
            terminal_shader(effect).uniforms()[GLASS_BLUR_RADIUS_UNIFORM],
            0.0
        );
    }

    #[test]
    fn featherweight_backdrop_blur_stays_in_the_optical_tap() {
        let RenderEffect::Shader { shader } = Glass::regular()
            .blur_radius(0.5)
            .resolve(&light_colors())
            .backdrop_effect(3.0, GlassDynamics::default())
        else {
            panic!("a sub-cap blur must not build a Gaussian chain");
        };
        assert_eq!(shader.uniforms()[GLASS_BLUR_RADIUS_UNIFORM], 1.5);
    }

    #[test]
    fn raised_tint_density_stays_premultiplied_alpha_safe() {
        let effect = Glass::lens()
            .tint(Color::WHITE.with_alpha(0.8))
            .resolve(&light_colors())
            .backdrop_effect(
                1.0,
                GlassDynamics {
                    tint_alpha_multiplier: Some(2.0),
                    ..Default::default()
                },
            );
        assert_eq!(terminal_shader(effect).uniforms()[17], 1.0);
    }

    #[test]
    fn optical_activity_reaches_identity_without_removing_the_glass_geometry() {
        let resolved = Glass::lens()
            .refraction_depth(0.72)
            .refraction_curve(0.8)
            .dispersion(0.42)
            .blur_radius(3.0)
            .saturation(1.4)
            .highlight(0.6)
            .lift(0.2)
            .tint(Color::BLACK.with_alpha(0.8))
            .no_clip()
            .resolve(&light_colors());
        let morph = GlassMorph {
            node_size: (120.0, 72.0),
            primary: (60.0, 36.0, 96.0, 52.0, -1.0),
            wobble_amplitude: 3.0,
            bulge_amplitude: 4.0,
            deformation: Some(GlassDeformation::incompressible((1.0, 0.0), 1.25)),
            ..Default::default()
        };

        let RenderEffect::Shader { shader } = resolved.backdrop_effect(
            2.0,
            GlassDynamics {
                activity: Some(0.0),
                morph: Some(morph),
                ..Default::default()
            },
        ) else {
            panic!("material must resolve to the shared wcKSRD shader");
        };
        let uniforms = shader.uniforms();
        assert_eq!(uniforms[GLASS_ACTIVITY_UNIFORM], 0.0);
        assert_eq!(uniforms[9], 0.0);
        assert_eq!(uniforms[GLASS_REFRACTION_CURVE_UNIFORM], 0.0);
        assert_eq!(uniforms[GLASS_DISPERSION_UNIFORM], 0.0);
        assert_eq!(uniforms[GLASS_TRANSMISSION_REFRACTION_UNIFORM], 0.0);
        assert_eq!(uniforms[11], 0.0);
        assert_eq!(uniforms[17], 0.0);
        assert_eq!(uniforms[18], 1.0);
        assert_eq!(uniforms[20], 0.0);
        assert_eq!(uniforms[21], 0.0);
        assert_eq!(uniforms[24], 1.0);
        assert_eq!(uniforms[28], 0.0);
        assert_eq!(uniforms[GLASS_BLUR_RADIUS_UNIFORM], 0.0);
        assert_eq!(uniforms[91], 0.0);
        assert_eq!(uniforms[102], 0.0);
        assert_eq!(
            &uniforms[GLASS_RESTING_TINT_UNIFORM..GLASS_RESTING_TINT_UNIFORM + 4],
            &[0.0, 0.0, 0.0, 0.0]
        );
        assert_eq!(uniforms[32], 0.0);
        assert_eq!(uniforms[26], 0.0);
        assert_eq!(&uniforms[108..110], &[1.0, 1.0]);
        assert_eq!(&uniforms[2..6], &[60.0, 36.0, 96.0, 52.0]);
    }

    #[test]
    fn surface_refraction_is_explicit_and_reaches_the_shader() {
        for glass in [Glass::regular(), Glass::lens()] {
            assert_eq!(glass.refraction, GlassRefraction::Radial);
            let surface = glass.surface_refraction(31.0);
            assert_eq!(
                surface.refraction,
                GlassRefraction::Surface { reach_dp: 31.0 }
            );
            let shader = terminal_shader(surface.backdrop_effect(
                &light_colors(),
                3.0,
                GlassDynamics::default(),
            ));
            assert_eq!(shader.uniforms()[GLASS_REFRACTION_MODE_UNIFORM], 1.0);
            assert_eq!(shader.uniforms()[GLASS_EDGE_REFRACTION_REACH_UNIFORM], 31.0);
            assert!(
                !shader
                    .overrides()
                    .iter()
                    .any(|(name, value)| *name == "GLASS_DIRECTIONAL_REFRACTION_OFF"
                        && *value != 0.0)
            );
        }
    }

    #[test]
    fn edge_refraction_preserves_face_zoom_and_scales_outward_reach_with_contact() {
        assert_eq!(GlassRefraction::default(), GlassRefraction::Radial);
        let glass = Glass::lens()
            .surface_refraction(31.0)
            .edge_refraction(12.0)
            .optical_zoom(1.2);
        assert_eq!(
            glass.refraction,
            GlassRefraction::EdgeLens { reach_dp: 12.0 }
        );
        for (activity, press, reach) in [(1.0, 1.0, 12.0), (0.5, 0.5, 3.0), (0.0, 1.0, 0.0)] {
            let shader = terminal_shader(glass.backdrop_effect(
                &light_colors(),
                3.0,
                GlassDynamics {
                    activity: Some(activity),
                    press_depth: Some(press),
                    ..Default::default()
                },
            ));
            assert_eq!(shader.uniforms()[GLASS_REFRACTION_MODE_UNIFORM], 2.0);
            assert_eq!(
                shader.uniforms()[GLASS_EDGE_REFRACTION_REACH_UNIFORM],
                reach
            );
            assert_eq!(
                shader.uniforms()[GLASS_OPTICAL_ZOOM_UNIFORM],
                1.0 + 0.2 * activity
            );
        }
        assert_eq!(
            glass.surface_refraction(31.0).refraction,
            GlassRefraction::Surface { reach_dp: 31.0 }
        );
    }

    #[test]
    fn edge_refraction_captures_the_farthest_spectral_ray() {
        for (reach, dispersion, required) in
            [(20.0, 1.0, 101.67), (0.0, 1.0, 42.78), (20.0, 0.0, 60.88)]
        {
            let shader = terminal_shader(
                Glass::lens()
                    .edge_refraction(reach)
                    .dispersion(dispersion)
                    .backdrop_effect(&light_colors(), 3.0, GlassDynamics::default()),
            );
            assert!(shader.input_padding() >= required);
        }
    }

    #[test]
    fn directional_refraction_rejects_invalid_reach_at_both_public_entry_points() {
        for input in [-1.0, f32::NAN, f32::INFINITY, f32::NEG_INFINITY, 0.0, 12.0] {
            let expected = if input.is_finite() {
                input.max(0.0)
            } else {
                0.0
            };
            for (built, direct, normalized) in [
                (
                    Glass::lens().edge_refraction(input),
                    GlassRefraction::EdgeLens { reach_dp: input },
                    GlassRefraction::EdgeLens { reach_dp: expected },
                ),
                (
                    Glass::regular().surface_refraction(input),
                    GlassRefraction::Surface { reach_dp: input },
                    GlassRefraction::Surface { reach_dp: expected },
                ),
            ] {
                assert_eq!(built.refraction, normalized);
                let direct = Glass {
                    refraction: direct,
                    ..built
                };
                let shader = terminal_shader(direct.backdrop_effect(
                    &light_colors(),
                    1.0,
                    GlassDynamics::default(),
                ));
                assert_eq!(
                    shader.uniforms()[GLASS_EDGE_REFRACTION_REACH_UNIFORM],
                    expected
                );
            }
        }
    }

    #[test]
    fn surface_reach_is_independent_of_depth_and_tracks_contact() {
        for depth in [4.0, 15.5, 30.0] {
            for (activity, press, reach) in [(1.0, 1.0, 31.0), (0.5, 0.5, 7.75), (0.0, 1.0, 0.0)] {
                let shader = terminal_shader(
                    Glass::regular()
                        .surface_refraction(31.0)
                        .refraction_depth_dp(depth)
                        .backdrop_effect(
                            &light_colors(),
                            3.0,
                            GlassDynamics {
                                activity: Some(activity),
                                press_depth: Some(press),
                                ..Default::default()
                            },
                        ),
                );
                assert_eq!(
                    shader.uniforms()[GLASS_EDGE_REFRACTION_REACH_UNIFORM],
                    reach
                );
                assert_eq!(
                    shader.uniforms()[GLASS_PHYSICAL_REFRACTION_DEPTH_UNIFORM],
                    depth * activity * press
                );
                assert!(shader.input_padding() >= 31.0);
            }
        }
    }

    #[test]
    fn resting_surface_tint_survives_zero_optical_activity() {
        let tint = Color::BLACK.with_alpha(0.11);
        let RenderEffect::Shader { shader } = Glass::lens()
            .no_clip()
            .resolve(&light_colors())
            .backdrop_effect(
                1.0,
                GlassDynamics {
                    activity: Some(0.0),
                    resting_tint: Some(tint),
                    ..Default::default()
                },
            )
        else {
            panic!("resting surface must use the shared wcKSRD shader");
        };
        assert_eq!(
            &shader.uniforms()[GLASS_RESTING_TINT_UNIFORM..GLASS_RESTING_TINT_UNIFORM + 4],
            &[tint.r(), tint.g(), tint.b(), tint.a()]
        );
        assert_eq!(shader.uniforms()[GLASS_ACTIVITY_UNIFORM], 0.0);
    }

    #[test]
    fn full_optical_activity_preserves_the_resolved_material() {
        let resolved = Glass::lens()
            .refraction_depth(0.72)
            .refraction_curve(0.8)
            .dispersion(0.42)
            .blur_radius(3.0)
            .resolve(&light_colors());
        let shader = terminal_shader(resolved.backdrop_effect(
            2.0,
            GlassDynamics {
                activity: Some(1.0),
                ..Default::default()
            },
        ));
        let uniforms = shader.uniforms();
        assert_eq!(uniforms[GLASS_ACTIVITY_UNIFORM], 1.0);
        assert_eq!(uniforms[9], 0.72);
        assert_eq!(
            uniforms[GLASS_PHYSICAL_REFRACTION_DEPTH_ENABLED_UNIFORM],
            0.0
        );
        assert_eq!(uniforms[GLASS_REFRACTION_CURVE_UNIFORM], 0.8);
        assert_eq!(uniforms[GLASS_DISPERSION_UNIFORM], 0.42);
        assert_eq!(uniforms[GLASS_TRANSMISSION_REFRACTION_UNIFORM], 1.0);
        assert_eq!(uniforms[GLASS_BLUR_RADIUS_UNIFORM], 0.0);
    }

    #[test]
    fn morph_geometry_and_incompressible_strain_are_packed() {
        let deformation = GlassDeformation::incompressible((0.0, 2.0), 1.25);
        let morph = GlassMorph {
            node_size: (78.0, 59.0),
            primary: (39.0, 29.5, 58.0, 39.0, -1.0),
            shapes: vec![(70.0, 29.5, 40.0, 40.0, -1.0)],
            glue: 8.0,
            wobble_amplitude: 1.0,
            wobble_phase: 0.5,
            bulge_amplitude: 2.0,
            bulge_direction: 0.25,
            ellipse_blend: 0.3,
            capsule_smoothing_dp: 4.0,
            deformation: Some(deformation),
            zoom_anchor: (0.0, 0.0),
        };
        let RenderEffect::Shader { shader } = Glass::lens()
            .no_clip()
            .resolve(&light_colors())
            .backdrop_effect(
                1.0,
                GlassDynamics {
                    morph: Some(morph),
                    ..Default::default()
                },
            )
        else {
            panic!("morph must use the shared wcKSRD shader");
        };
        let uniforms = shader.uniforms();
        assert_eq!(&uniforms[0..6], &[78.0, 59.0, 39.0, 29.5, 58.0, 39.0]);
        assert_eq!(uniforms[30], 1.0);
        assert_eq!(&uniforms[106..110], &[0.0, 1.0, 1.25, 0.8]);
        assert_eq!(uniforms[110], 0.3);
        assert_eq!(
            uniforms[cranpose_ui_graphics::liquid_glass::GLASS_CAPSULE_SMOOTHING_UNIFORM],
            4.0
        );
        assert!(shader.output_padding() > 0.0);
    }

    #[test]
    fn capsule_smoothing_is_finite_nonnegative_and_invalidates_the_morph() {
        for value in [-1.0, 0.0, 4.0, f32::NAN, f32::INFINITY, f32::NEG_INFINITY] {
            let morph = GlassMorph {
                node_size: (120.0, 80.0),
                primary: (60.0, 40.0, 111.0, 70.0, -1.0),
                capsule_smoothing_dp: value,
                ..Default::default()
            };
            let expected = if value.is_finite() {
                value.max(0.0)
            } else {
                0.0
            };
            let shader = terminal_shader(Glass::lens().backdrop_effect(
                &light_colors(),
                3.0,
                GlassDynamics {
                    morph: Some(morph.clone()),
                    ..Default::default()
                },
            ));
            assert_eq!(
                shader.uniforms()[cranpose_ui_graphics::GLASS_CAPSULE_SMOOTHING_UNIFORM],
                expected
            );
            assert!(glass_morphs_match(&morph, &morph));
            let changed = GlassMorph {
                capsule_smoothing_dp: 5.0,
                ..morph.clone()
            };
            assert!(!glass_morphs_match(&morph, &changed));
        }
    }

    #[test]
    fn optical_builders_hold_their_own_legal_range() {
        let glass = Glass::regular()
            .fold_depth(-4.0)
            .optical_zoom(0.5)
            .rim_reflection(9.0);
        assert_eq!(glass.fold_depth, 0.0, "a fold cannot be negative deep");
        assert_eq!(glass.optical_zoom, 1.0, "a lens never shrinks its face");
        assert_eq!(
            glass.rim_reflection, 2.0,
            "the rim tops out at twice the line"
        );

        let glass = Glass::regular()
            .fold_depth(6.0)
            .optical_zoom(1.4)
            .rim_reflection(0.25);
        assert_eq!(glass.fold_depth, 6.0);
        assert_eq!(glass.optical_zoom, 1.4);
        assert_eq!(glass.rim_reflection, 0.25);
    }

    #[test]
    fn ink_recolor_records_its_color_at_a_clamped_strength() {
        let red = Color::from_rgb_u8(255, 0, 0);
        let glass = Glass::regular().ink_recolor(red, 3.0);
        assert_eq!(glass.ink_recolor, Some((red, 1.0)));

        let glass = Glass::regular().ink_recolor(red, -1.0);
        assert_eq!(glass.ink_recolor, Some((red, 0.0)));
        assert_eq!(Glass::regular().ink_recolor, None, "no recolor by default");
    }

    #[test]
    fn a_touched_up_surface_amplifies_what_it_already_is() {
        let dynamics = GlassDynamics::default().touched_up(1.0, None, (10.0, 4.0));
        assert!(
            dynamics.highlight_boost > 0.0,
            "a pressed surface goes brighter"
        );
        assert!(dynamics.saturation_boost > 0.0, "and more saturated");
        assert_eq!(
            dynamics.touch,
            Some((10.0, 4.0, 1.0)),
            "with no finger the glow sits at the surface's own heart"
        );
        assert_eq!(
            dynamics.resting_tint, None,
            "a touch never repaints the surface with another color"
        );
    }

    #[test]
    fn a_touch_glow_follows_the_finger_and_accumulates_to_full() {
        let dynamics = GlassDynamics::default()
            .touched_up(0.5, Some((3.0, 7.0)), (10.0, 4.0))
            .touched_up(0.8, Some((3.0, 7.0)), (10.0, 4.0));
        let (x, y, intensity) = dynamics.touch.expect("a pressed surface glows");
        assert_eq!(
            (x, y),
            (3.0, 7.0),
            "the glow tracks the finger, not the center"
        );
        assert_eq!(intensity, 1.0, "carried press saturates at full");
    }

    #[test]
    fn an_unpressed_surface_is_left_exactly_as_it_was() {
        let resting = GlassDynamics::default();
        let untouched = resting
            .clone()
            .touched_up(0.0, Some((3.0, 7.0)), (10.0, 4.0));
        assert_eq!(untouched.highlight_boost, resting.highlight_boost);
        assert_eq!(untouched.saturation_boost, resting.saturation_boost);
        assert_eq!(untouched.touch, None, "no press, no glow");
    }

    #[test]
    fn an_off_axis_strain_widens_the_support_by_the_affine_rows_times_the_half_extents() {
        let resolved = Glass::regular()
            .shape(LiquidShape::RoundedRect(0.0))
            .blur_radius(0.0)
            .shadow(false)
            .no_clip()
            .resolve(&light_colors());
        let angle = 22.5f32.to_radians();
        let morph = GlassMorph {
            node_size: (600.0, 600.0),
            primary: (300.0, 300.0, 200.0, 200.0, 0.0),
            deformation: Some(GlassDeformation::incompressible(
                (angle.cos(), angle.sin()),
                2.0,
            )),
            ..Default::default()
        };
        let RenderEffect::Shader { shader } = resolved.backdrop_effect(
            1.0,
            GlassDynamics {
                activity: Some(1.0),
                morph: Some(morph),
                ..Default::default()
            },
        ) else {
            panic!("an unblurred glass is one shader");
        };
        let support = shader
            .output_support()
            .expect("a morphing glass declares its support");
        let half_x = 100.0 * (2.0 * angle.cos().powi(2) + 0.5 * angle.sin().powi(2))
            + 100.0 * (1.5 * angle.sin() * angle.cos());
        assert!(
            (half_x - 231.066).abs() < 0.01,
            "the example's half extent is {half_x}"
        );
        assert!(
            support.x <= 300.0 - half_x && support.x + support.width >= 300.0 + half_x,
            "the support {support:?} must hold the strained square's x extent {half_x}"
        );
        let half_y = 100.0 * (1.5 * angle.sin() * angle.cos())
            + 100.0 * (2.0 * angle.sin().powi(2) + 0.5 * angle.cos().powi(2));
        assert!(
            (half_y - 125.0).abs() < 0.01,
            "the example's y half extent is {half_y}"
        );
        assert!(
            support.y <= 300.0 - half_y && support.y + support.height >= 300.0 + half_y,
            "the support {support:?} must hold the strained square's y extent {half_y}"
        );
    }

    #[test]
    fn a_morphing_glass_declares_its_output_support_around_its_shapes_and_their_reach() {
        let resolved = Glass::regular()
            .shape(LiquidShape::RoundedRect(12.0))
            .blur_radius(0.0)
            .shadow(true)
            .no_clip()
            .resolve(&light_colors());
        let morph = GlassMorph {
            node_size: (280.0, 160.0),
            primary: (140.0, 80.0, 120.0, 40.0, -1.0),
            shapes: vec![(230.0, 80.0, 40.0, 40.0, -1.0)],
            glue: 20.0,
            wobble_amplitude: 3.0,
            bulge_amplitude: 8.0,
            deformation: Some(GlassDeformation::incompressible((1.0, 0.0), 1.25)),
            ..Default::default()
        };
        let dynamics = GlassDynamics {
            activity: Some(1.0),
            morph: Some(morph.clone()),
            ..Default::default()
        };
        let RenderEffect::Shader { shader } = resolved.backdrop_effect(2.0, dynamics) else {
            panic!("an unblurred glass is one shader");
        };
        let support = shader
            .output_support()
            .expect("a morphing glass declares its support");
        let shape_reach = (230.0 + 20.0) - (140.0 + 60.0);
        let shadow_reach = resolved.shadow_radius
            + resolved.shadow_offset_y.abs()
            + resolved.shadow_spread.max(0.0);
        let field_reach = 3.0 * 2.0 + 8.0 + shape_reach + 40.0 + shadow_reach + 4.0;
        let smallest_strain = 0.8;
        let reach = field_reach / smallest_strain;
        let contains = |x: f32, y: f32| {
            support.x <= x
                && support.y <= y
                && support.x + support.width >= x
                && support.y + support.height >= y
        };
        for (cx, cy) in [(-1.0, -1.0), (1.0, -1.0), (-1.0, 1.0), (1.0, 1.0)] {
            let corner = ((60.0 + reach) * cx, (20.0 + reach) * cy);
            let stretched = (140.0 + corner.0 * 1.25, 80.0 + corner.1 * 0.8);
            assert!(
                contains(stretched.0, stretched.1 - resolved.shadow_offset_y.abs())
                    && contains(stretched.0, stretched.1 + resolved.shadow_offset_y.abs()),
                "{support:?} must hold the strained, dilated corner {stretched:?}"
            );
        }
        assert!(
            contains(230.0 + 20.0 + reach, 80.0),
            "the glued shape's reach is inside"
        );
        assert!(shader.output_padding() >= field_reach);

        let RenderEffect::Shader { shader } =
            resolved.backdrop_effect(2.0, GlassDynamics::default())
        else {
            panic!("an unblurred glass is one shader");
        };
        assert_eq!(
            shader.output_support(),
            None,
            "cover-mode glass fills its rect"
        );
    }
}

#[cfg(test)]
mod transparency_tests {
    use super::*;

    #[test]
    fn less_transparency_makes_glass_a_flat_surface() {
        let colors = crate::theme::LiquidColors::light(Color::from_rgb_u8(0, 122, 255));
        let flat = Glass::regular()
            .resolve(&colors)
            .without_transparency(&colors);
        assert_eq!(flat.tint, colors.surface);
        assert_eq!(flat.blur_radius_dp, 0.0);
        assert_eq!(flat.refraction_depth, 0.0);
        assert_eq!(flat.saturation, 1.0);
        assert!(flat.edge_spectrum.is_none());
        let clear = Glass::regular().resolve(&colors);
        assert!(clear.blur_radius_dp > 0.0, "plain glass keeps its blur");
    }
}