Added ability to define colors at UV coordinates along a path

crates/ecolor/Cargo.toml

@@ -30,7 +30,6 @@ extra_debug_asserts = []
 ## Always enable additional checks.
 extra_asserts = []
 
-
 [dependencies]
 #! ### Optional dependencies
 

crates/egui/src/painter.rs

@@ -7,7 +7,7 @@ use crate::{
 };
 use epaint::{
     text::{Fonts, Galley, LayoutJob},
-    CircleShape, ClippedShape, RectShape, Rounding, Shape, Stroke,
+    CircleShape, ClippedShape, PathStroke, RectShape, Rounding, Shape, Stroke,
 };
 
 /// Helper to paint shapes and text to a specific region on a specific layer.
@@ -280,21 +280,21 @@ impl Painter {
 /// # Paint different primitives
 impl Painter {
     /// Paints a line from the first point to the second.
-    pub fn line_segment(&self, points: [Pos2; 2], stroke: impl Into<Stroke>) -> ShapeIdx {
+    pub fn line_segment(&self, points: [Pos2; 2], stroke: impl Into<PathStroke>) -> ShapeIdx {
         self.add(Shape::LineSegment {
             points,
             stroke: stroke.into(),
         })
     }
 
     /// Paints a horizontal line.
-    pub fn hline(&self, x: impl Into<Rangef>, y: f32, stroke: impl Into<Stroke>) -> ShapeIdx {
-        self.add(Shape::hline(x, y, stroke))
+    pub fn hline(&self, x: impl Into<Rangef>, y: f32, stroke: impl Into<PathStroke>) -> ShapeIdx {
+        self.add(Shape::hline(x, y, stroke.into()))
     }
 
     /// Paints a vertical line.
-    pub fn vline(&self, x: f32, y: impl Into<Rangef>, stroke: impl Into<Stroke>) -> ShapeIdx {
-        self.add(Shape::vline(x, y, stroke))
+    pub fn vline(&self, x: f32, y: impl Into<Rangef>, stroke: impl Into<PathStroke>) -> ShapeIdx {
+        self.add(Shape::vline(x, y, stroke.into()))
     }
 
     pub fn circle(
@@ -513,15 +513,15 @@ impl Painter {
 }
 
 fn tint_shape_towards(shape: &mut Shape, target: Color32) {
-    epaint::shape_transform::adjust_colors(shape, &|color| {
+    epaint::shape_transform::adjust_colors(shape, move |color| {
         if *color != Color32::PLACEHOLDER {
             *color = crate::ecolor::tint_color_towards(*color, target);
         }
     });
 }
 
 fn multiply_opacity(shape: &mut Shape, opacity: f32) {
-    epaint::shape_transform::adjust_colors(shape, &|color| {
+    epaint::shape_transform::adjust_colors(shape, move |color| {
         if *color != Color32::PLACEHOLDER {
             *color = color.gamma_multiply(opacity);
         }

crates/egui_demo_lib/Cargo.toml

@@ -38,10 +38,12 @@ syntect = ["egui_extras/syntect"]
 
 
 [dependencies]
-egui = { workspace = true, default-features = false }
+egui = { workspace = true, default-features = false, features = ["color-hex"] }
 egui_extras = { workspace = true, features = ["default"] }
 egui_plot = { workspace = true, features = ["default"] }
 
+once_cell = "1.19"
+
 log.workspace = true
 unicode_names2 = { version = "0.6.0", default-features = false } # this old version has fewer dependencies
 

crates/egui_demo_lib/src/demo/dancing_strings.rs

@@ -1,9 +1,22 @@
-use egui::{containers::*, *};
+use egui::{containers::*, epaint::PathStroke, *};
+use once_cell::sync::Lazy;
+
+static GRADIENT: Lazy<[Color32; 5]> = Lazy::new(|| {
+    [
+        hex_color!("#5BCEFA"),
+        hex_color!("#F5A9B8"),
+        Color32::WHITE,
+        hex_color!("#F5A9B8"),
+        hex_color!("#5BCEFA"),
+    ]
+});
 
 #[derive(Default)]
 #[cfg_attr(feature = "serde", derive(serde::Deserialize, serde::Serialize))]
 #[cfg_attr(feature = "serde", serde(default))]
-pub struct DancingStrings {}
+pub struct DancingStrings {
+    colors: bool,
+}
 
 impl super::Demo for DancingStrings {
     fn name(&self) -> &'static str {
@@ -28,6 +41,10 @@ impl super::View for DancingStrings {
             Color32::from_black_alpha(240)
         };
 
+        ui.horizontal(|ui| ui.checkbox(&mut self.colors, "Show Colors"));
+
+        ui.separator();
+
         Frame::canvas(ui.style()).show(ui, |ui| {
             ui.ctx().request_repaint();
             let time = ui.input(|i| i.time);
@@ -55,7 +72,37 @@ impl super::View for DancingStrings {
                     .collect();
 
                 let thickness = 10.0 / mode as f32;
-                shapes.push(epaint::Shape::line(points, Stroke::new(thickness, color)));
+                shapes.push(epaint::Shape::line(
+                    points,
+                    if self.colors {
+                        PathStroke::new_uv(thickness, move |_r, p| {
+                            let time = time / 10.0;
+                            let x = remap(p.x, rect.x_range(), 0.0..=1.0) as f64;
+                            let y = remap(p.y, rect.y_range(), 0.0..=1.0) as f64;
+
+                            let amp = (time * speed * mode).sin() / mode;
+                            let sin = amp * (time * std::f64::consts::TAU / 2.0 * mode).sin();
+
+                            let value = x * sin + y * sin;
+
+                            let color = if value < 0.2 {
+                                GRADIENT[0]
+                            } else if value < 0.4 {
+                                GRADIENT[1]
+                            } else if value < 0.6 {
+                                GRADIENT[2]
+                            } else if value < 0.8 {
+                                GRADIENT[3]
+                            } else {
+                                GRADIENT[4]
+                            };
+
+                            Color32::from_rgba_premultiplied(color[0], color[1], color[2], color[3])
+                        })
+                    } else {
+                        PathStroke::new(thickness, color)
+                    },
+                ));
             }
 
             ui.painter().extend(shapes);

crates/epaint/benches/benchmark.rs

@@ -1,6 +1,6 @@
 use criterion::{black_box, criterion_group, criterion_main, Criterion};
 
-use epaint::*;
+use epaint::{tessellator::Path, *};
 
 fn single_dashed_lines(c: &mut Criterion) {
     c.bench_function("single_dashed_lines", move |b| {
@@ -72,10 +72,74 @@ fn tessellate_circles(c: &mut Criterion) {
     });
 }
 
+fn thick_line_solid(c: &mut Criterion) {
+    c.bench_function("thick_solid_line", move |b| {
+        let line = [pos2(0.0, 0.0), pos2(50.0, 0.0), pos2(100.0, 1.0)];
+        let mut path = Path::default();
+        path.add_open_points(&line);
+
+        b.iter(|| {
+            let mut mesh = Mesh::default();
+            path.stroke_closed(1.5, &Stroke::new(2.0, Color32::RED).into(), &mut mesh);
+
+            black_box(mesh);
+        });
+    });
+}
+
+fn thick_large_line_solid(c: &mut Criterion) {
+    c.bench_function("thick_large_solid_line", move |b| {
+        let line = (0..1000).map(|i| pos2(i as f32, 10.0)).collect::<Vec<_>>();
+        let mut path = Path::default();
+        path.add_open_points(&line);
+
+        b.iter(|| {
+            let mut mesh = Mesh::default();
+            path.stroke_closed(1.5, &Stroke::new(2.0, Color32::RED).into(), &mut mesh);
+
+            black_box(mesh);
+        });
+    });
+}
+
+fn thin_line_solid(c: &mut Criterion) {
+    c.bench_function("thin_solid_line", move |b| {
+        let line = [pos2(0.0, 0.0), pos2(50.0, 0.0), pos2(100.0, 1.0)];
+        let mut path = Path::default();
+        path.add_open_points(&line);
+
+        b.iter(|| {
+            let mut mesh = Mesh::default();
+            path.stroke_closed(1.5, &Stroke::new(0.5, Color32::RED).into(), &mut mesh);
+
+            black_box(mesh);
+        });
+    });
+}
+
+fn thin_large_line_solid(c: &mut Criterion) {
+    c.bench_function("thin_large_solid_line", move |b| {
+        let line = (0..1000).map(|i| pos2(i as f32, 10.0)).collect::<Vec<_>>();
+        let mut path = Path::default();
+        path.add_open_points(&line);
+
+        b.iter(|| {
+            let mut mesh = Mesh::default();
+            path.stroke_closed(1.5, &Stroke::new(0.5, Color32::RED).into(), &mut mesh);
+
+            black_box(mesh);
+        });
+    });
+}
+
 criterion_group!(
     benches,
     single_dashed_lines,
     many_dashed_lines,
-    tessellate_circles
+    tessellate_circles,
+    thick_line_solid,
+    thick_large_line_solid,
+    thin_line_solid,
+    thin_large_line_solid
 );
 criterion_main!(benches);

crates/epaint/src/bezier.rs

@@ -3,15 +3,15 @@
 
 use std::ops::Range;
 
-use crate::{shape::Shape, Color32, PathShape, Stroke};
+use crate::{shape::Shape, Color32, PathShape, PathStroke};
 use emath::*;
 
 // ----------------------------------------------------------------------------
 
 /// A cubic [Bézier Curve](https://en.wikipedia.org/wiki/B%C3%A9zier_curve).
 ///
 /// See also [`QuadraticBezierShape`].
-#[derive(Copy, Clone, Debug, PartialEq)]
+#[derive(Clone, Debug, PartialEq)]
 #[cfg_attr(feature = "serde", derive(serde::Deserialize, serde::Serialize))]
 pub struct CubicBezierShape {
     /// The first point is the starting point and the last one is the ending point of the curve.
@@ -20,7 +20,7 @@ pub struct CubicBezierShape {
     pub closed: bool,
 
     pub fill: Color32,
-    pub stroke: Stroke,
+    pub stroke: PathStroke,
 }
 
 impl CubicBezierShape {
@@ -32,7 +32,7 @@ impl CubicBezierShape {
         points: [Pos2; 4],
         closed: bool,
         fill: Color32,
-        stroke: impl Into<Stroke>,
+        stroke: impl Into<PathStroke>,
     ) -> Self {
         Self {
             points,
@@ -52,7 +52,7 @@ impl CubicBezierShape {
             points,
             closed: self.closed,
             fill: self.fill,
-            stroke: self.stroke,
+            stroke: self.stroke.clone(),
         }
     }
 
@@ -69,7 +69,7 @@ impl CubicBezierShape {
                 points,
                 closed: self.closed,
                 fill: self.fill,
-                stroke: self.stroke,
+                stroke: self.stroke.clone(),
             };
             pathshapes.push(pathshape);
         }
@@ -156,7 +156,7 @@ impl CubicBezierShape {
             points: [d_from, d_ctrl, d_to],
             closed: self.closed,
             fill: self.fill,
-            stroke: self.stroke,
+            stroke: self.stroke.clone(),
         };
         let delta_t = t_range.end - t_range.start;
         let q_start = q.sample(t_range.start);
@@ -168,7 +168,7 @@ impl CubicBezierShape {
             points: [from, ctrl1, ctrl2, to],
             closed: self.closed,
             fill: self.fill,
-            stroke: self.stroke,
+            stroke: self.stroke.clone(),
         }
     }
 
@@ -375,7 +375,7 @@ impl From<CubicBezierShape> for Shape {
 /// A quadratic [Bézier Curve](https://en.wikipedia.org/wiki/B%C3%A9zier_curve).
 ///
 /// See also [`CubicBezierShape`].
-#[derive(Copy, Clone, Debug, PartialEq)]
+#[derive(Clone, Debug, PartialEq)]
 #[cfg_attr(feature = "serde", derive(serde::Deserialize, serde::Serialize))]
 pub struct QuadraticBezierShape {
     /// The first point is the starting point and the last one is the ending point of the curve.
@@ -384,7 +384,7 @@ pub struct QuadraticBezierShape {
     pub closed: bool,
 
     pub fill: Color32,
-    pub stroke: Stroke,
+    pub stroke: PathStroke,
 }
 
 impl QuadraticBezierShape {
@@ -397,7 +397,7 @@ impl QuadraticBezierShape {
         points: [Pos2; 3],
         closed: bool,
         fill: Color32,
-        stroke: impl Into<Stroke>,
+        stroke: impl Into<PathStroke>,
     ) -> Self {
         Self {
             points,
@@ -417,7 +417,7 @@ impl QuadraticBezierShape {
             points,
             closed: self.closed,
             fill: self.fill,
-            stroke: self.stroke,
+            stroke: self.stroke.clone(),
         }
     }
 
@@ -429,7 +429,7 @@ impl QuadraticBezierShape {
             points,
             closed: self.closed,
             fill: self.fill,
-            stroke: self.stroke,
+            stroke: self.stroke.clone(),
         }
     }
 
@@ -688,7 +688,7 @@ fn single_curve_approximation(curve: &CubicBezierShape) -> QuadraticBezierShape
         points: [curve.points[0], c, curve.points[3]],
         closed: curve.closed,
         fill: curve.fill,
-        stroke: curve.stroke,
+        stroke: curve.stroke.clone(),
     }
 }