Better fractal arrows.

src/slide/s6_fractals.rs

@@ -363,13 +363,16 @@ impl Slide for Fractals {
                             fill: Color32::RED,
                             stroke: Stroke::default(),
                         }));
-                        for pos in mandelbrot_iter(last_pos).take(5) {
+                        for (i, pos) in mandelbrot_iter(last_pos).take(16).enumerate() {
                             Arrow {
                                 origin: to_screen
                                     * ((last_pos.to_vec2() + Vec2::splat(2f32)) * 0.25).to_pos2(),
                                 tip: to_screen
                                     * ((pos.to_vec2() + Vec2::splat(2f32)) * 0.25).to_pos2(),
-                                stroke: Color32::LIGHT_BLUE,
+                                stroke: set_alpha(
+                                    Color32::LIGHT_BLUE,
+                                    1.0 / (1.0 + i as f32 * 0.2),
+                                ),
                                 stroke_width: 4.0,
                                 ..Arrow::default()
                             }