Merge example_web into egui_demo_lib

egui_demo_lib/src/apps/demo/dancing_strings.rs

@@ -0,0 +1,68 @@
+use egui::{containers::*, *};
+
+#[derive(serde::Deserialize, serde::Serialize)]
+#[serde(default)]
+pub struct DancingStrings {}
+
+impl Default for DancingStrings {
+    fn default() -> Self {
+        Self {}
+    }
+}
+
+impl super::Demo for DancingStrings {
+    fn name(&self) -> &str {
+        "♫ Dancing Strings"
+    }
+
+    fn show(&mut self, ctx: &CtxRef, open: &mut bool) {
+        use super::View;
+        Window::new(self.name())
+            .open(open)
+            .default_size(vec2(512.0, 256.0))
+            .scroll(false)
+            .show(ctx, |ui| self.ui(ui));
+    }
+}
+
+impl super::View for DancingStrings {
+    fn ui(&mut self, ui: &mut Ui) {
+        Frame::dark_canvas(ui.style()).show(ui, |ui| {
+            ui.ctx().request_repaint();
+            let time = ui.input().time;
+
+            let desired_size = ui.available_width() * vec2(1.0, 0.35);
+            let (_id, rect) = ui.allocate_space(desired_size);
+
+            let mut cmds = vec![];
+
+            for &mode in &[2, 3, 5] {
+                let mode = mode as f32;
+                let n = 120;
+                let speed = 1.5;
+
+                let points: Vec<Pos2> = (0..=n)
+                    .map(|i| {
+                        let t = i as f32 / (n as f32);
+                        let amp = (time as f32 * speed * mode).sin() / mode;
+                        let y = amp * (t * std::f32::consts::TAU / 2.0 * mode).sin();
+
+                        pos2(
+                            lerp(rect.x_range(), t),
+                            remap(y, -1.0..=1.0, rect.y_range()),
+                        )
+                    })
+                    .collect();
+
+                let thickness = 10.0 / mode;
+                cmds.push(paint::PaintCmd::line(
+                    points,
+                    Stroke::new(thickness, Srgba::additive_luminance(196)),
+                ));
+            }
+
+            ui.painter().extend(cmds);
+        });
+        ui.add(crate::__egui_github_link_file!());
+    }
+}