Merge pull request #2055 from matze/perceptual-gradient

Compute gradients in Oklab color space

clippy.toml

@@ -1 +1,2 @@
 too-many-arguments-threshold = 20
+enum-variant-name-threshold = 10

core/Cargo.toml

@@ -15,6 +15,7 @@ bitflags.workspace = true
 log.workspace = true
 thiserror.workspace = true
 twox-hash.workspace = true
+num-traits.workspace = true
 
 palette.workspace = true
 palette.optional = true

core/src/angle.rs

@@ -1,32 +1,72 @@
 use crate::{Point, Rectangle, Vector};
-use std::f32::consts::PI;
 
-#[derive(Debug, Copy, Clone, PartialEq)]
+use std::f32::consts::{FRAC_PI_2, PI};
+use std::ops::RangeInclusive;
+
 /// Degrees
+#[derive(Debug, Copy, Clone, PartialEq, PartialOrd)]
 pub struct Degrees(pub f32);
 
-#[derive(Debug, Copy, Clone, PartialEq)]
 /// Radians
+#[derive(Debug, Copy, Clone, PartialEq, PartialOrd)]
 pub struct Radians(pub f32);
 
+impl Radians {
+    /// The range of radians of a circle.
+    pub const RANGE: RangeInclusive<Radians> = Radians(0.0)..=Radians(2.0 * PI);
+}
+
 impl From<Degrees> for Radians {
     fn from(degrees: Degrees) -> Self {
-        Radians(degrees.0 * PI / 180.0)
+        Self(degrees.0 * PI / 180.0)
+    }
+}
+
+impl From<f32> for Radians {
+    fn from(radians: f32) -> Self {
+        Self(radians)
+    }
+}
+
+impl From<u8> for Radians {
+    fn from(radians: u8) -> Self {
+        Self(f32::from(radians))
+    }
+}
+
+impl From<Radians> for f64 {
+    fn from(radians: Radians) -> Self {
+        Self::from(radians.0)
+    }
+}
+
+impl num_traits::FromPrimitive for Radians {
+    fn from_i64(n: i64) -> Option<Self> {
+        Some(Self(n as f32))
+    }
+
+    fn from_u64(n: u64) -> Option<Self> {
+        Some(Self(n as f32))
+    }
+
+    fn from_f64(n: f64) -> Option<Self> {
+        Some(Self(n as f32))
     }
 }
 
 impl Radians {
     /// Calculates the line in which the [`Angle`] intercepts the `bounds`.
     pub fn to_distance(&self, bounds: &Rectangle) -> (Point, Point) {
-        let v1 = Vector::new(f32::cos(self.0), f32::sin(self.0));
+        let angle = self.0 - FRAC_PI_2;
+        let r = Vector::new(f32::cos(angle), f32::sin(angle));
 
-        let distance_to_rect = f32::min(
-            f32::abs((bounds.y - bounds.center().y) / v1.y),
-            f32::abs(((bounds.x + bounds.width) - bounds.center().x) / v1.x),
+        let distance_to_rect = f32::max(
+            f32::abs(r.x * bounds.width / 2.0),
+            f32::abs(r.y * bounds.height / 2.0),
         );
 
-        let start = bounds.center() + v1 * distance_to_rect;
-        let end = bounds.center() - v1 * distance_to_rect;
+        let start = bounds.center() - r * distance_to_rect;
+        let end = bounds.center() + r * distance_to_rect;
 
         (start, end)
     }

examples/gradient/Cargo.toml

@@ -0,0 +1,8 @@
+[package]
+name = "gradient"
+version = "0.1.0"
+edition = "2021"
+publish = false
+
+[dependencies]
+iced = { path = "../.." }

examples/gradient/src/main.rs

@@ -0,0 +1,99 @@
+use iced::gradient;
+use iced::widget::{column, container, horizontal_space, row, slider, text};
+use iced::{
+    Alignment, Background, Color, Element, Length, Radians, Sandbox, Settings,
+};
+
+pub fn main() -> iced::Result {
+    Gradient::run(Settings::default())
+}
+
+#[derive(Debug, Clone, Copy)]
+struct Gradient {
+    start: Color,
+    end: Color,
+    angle: Radians,
+}
+
+#[derive(Debug, Clone, Copy)]
+enum Message {
+    StartChanged(Color),
+    EndChanged(Color),
+    AngleChanged(Radians),
+}
+
+impl Sandbox for Gradient {
+    type Message = Message;
+
+    fn new() -> Self {
+        Self {
+            start: Color::WHITE,
+            end: Color::new(0.0, 0.0, 1.0, 1.0),
+            angle: Radians(0.0),
+        }
+    }
+
+    fn title(&self) -> String {
+        String::from("Gradient")
+    }
+
+    fn update(&mut self, message: Message) {
+        match message {
+            Message::StartChanged(color) => self.start = color,
+            Message::EndChanged(color) => self.end = color,
+            Message::AngleChanged(angle) => self.angle = angle,
+        }
+    }
+
+    fn view(&self) -> Element<Message> {
+        let Self { start, end, angle } = *self;
+
+        let gradient_box = container(horizontal_space(Length::Fill))
+            .width(Length::Fill)
+            .height(Length::Fill)
+            .style(move |_: &_| {
+                let gradient = gradient::Linear::new(angle)
+                    .add_stop(0.0, start)
+                    .add_stop(1.0, end)
+                    .into();
+
+                container::Appearance {
+                    background: Some(Background::Gradient(gradient)),
+                    ..Default::default()
+                }
+            });
+
+        let angle_picker = row![
+            text("Angle").width(64),
+            slider(Radians::RANGE, self.angle, Message::AngleChanged)
+                .step(0.01)
+        ]
+        .spacing(8)
+        .padding(8)
+        .align_items(Alignment::Center);
+
+        column![
+            color_picker("Start", self.start).map(Message::StartChanged),
+            color_picker("End", self.end).map(Message::EndChanged),
+            angle_picker,
+            gradient_box
+        ]
+        .into()
+    }
+}
+
+fn color_picker(label: &str, color: Color) -> Element<'_, Color> {
+    row![
+        text(label).width(64),
+        slider(0.0..=1.0, color.r, move |r| { Color { r, ..color } })
+            .step(0.01),
+        slider(0.0..=1.0, color.g, move |g| { Color { g, ..color } })
+            .step(0.01),
+        slider(0.0..=1.0, color.b, move |b| { Color { b, ..color } })
+            .step(0.01),
+    ]
+    .spacing(8)
+    .padding(8)
+    .align_items(Alignment::Center)
+    .into()
+}

wgpu/src/quad/gradient.rs

@@ -1,3 +1,4 @@
+use crate::graphics::color;
 use crate::graphics::gradient;
 use crate::quad::{self, Quad};
 use crate::Buffer;
@@ -78,7 +79,23 @@ impl Pipeline {
             device.create_shader_module(wgpu::ShaderModuleDescriptor {
                 label: Some("iced_wgpu.quad.gradient.shader"),
                 source: wgpu::ShaderSource::Wgsl(std::borrow::Cow::Borrowed(
-                    include_str!("../shader/quad.wgsl"),
+                    if color::GAMMA_CORRECTION {
+                        concat!(
+                            include_str!("../shader/quad.wgsl"),
+                            "\n",
+                            include_str!("../shader/quad/gradient.wgsl"),
+                            "\n",
+                            include_str!("../shader/color/oklab.wgsl")
+                        )
+                    } else {
+                        concat!(
+                            include_str!("../shader/quad.wgsl"),
+                            "\n",
+                            include_str!("../shader/quad/gradient.wgsl"),
+                            "\n",
+                            include_str!("../shader/color/linear_rgb.wgsl")
+                        )
+                    },
                 )),
             });
 

wgpu/src/quad/solid.rs

@@ -72,7 +72,11 @@ impl Pipeline {
             device.create_shader_module(wgpu::ShaderModuleDescriptor {
                 label: Some("iced_wgpu.quad.solid.shader"),
                 source: wgpu::ShaderSource::Wgsl(std::borrow::Cow::Borrowed(
-                    include_str!("../shader/quad.wgsl"),
+                    concat!(
+                        include_str!("../shader/quad.wgsl"),
+                        "\n",
+                        include_str!("../shader/quad/solid.wgsl"),
+                    ),
                 )),
             });
 

wgpu/src/shader/color/linear_rgb.wgsl

@@ -0,0 +1,3 @@
+fn interpolate_color(from_: vec4<f32>, to_: vec4<f32>, factor: f32) -> vec4<f32> {
+    return mix(from_, to_, factor);
+}

wgpu/src/shader/color/oklab.wgsl

@@ -0,0 +1,26 @@
+const to_lms = mat3x4<f32>(
+    vec4<f32>(0.4121656120,  0.2118591070,  0.0883097947, 0.0),
+    vec4<f32>(0.5362752080,  0.6807189584,  0.2818474174, 0.0),
+    vec4<f32>(0.0514575653,  0.1074065790,  0.6302613616, 0.0),
+);
+
+const to_rgb = mat3x4<f32>(
+    vec4<f32>( 4.0767245293, -3.3072168827,  0.2307590544, 0.0),
+    vec4<f32>(-1.2681437731,  2.6093323231, -0.3411344290, 0.0),
+    vec4<f32>(-0.0041119885, -0.7034763098,  1.7068625689, 0.0),
+);
+
+fn interpolate_color(from_: vec4<f32>, to_: vec4<f32>, factor: f32) -> vec4<f32> {
+    // To Oklab
+    let lms_a = pow(from_ * to_lms, vec3<f32>(1.0 / 3.0, 1.0 / 3.0, 1.0 / 3.0));
+    let lms_b = pow(to_ * to_lms, vec3<f32>(1.0 / 3.0, 1.0 / 3.0, 1.0 / 3.0));
+    let mixed = mix(lms_a, lms_b, factor);
+
+    // Back to linear RGB
+    var color = to_rgb * (mixed * mixed * mixed);
+
+    // Alpha interpolation
+    color.a = mix(from_.a, to_.a, factor);
+
+    return color;
+}