Fade in title.

src/color.rs

@@ -47,6 +47,9 @@ pub fn set_style_alpha_in_place(style: &mut Style, factor: f32) {
     ] {
         set_widget_alpha_in_place(widget, factor);
     }
+    if let Some(override_text_color) = style.visuals.override_text_color.as_mut() {
+        set_alpha_in_place(override_text_color, factor);
+    }
     set_alpha_in_place(&mut style.visuals.hyperlink_color, factor);
     set_alpha_in_place(&mut style.visuals.faint_bg_color, factor);
     set_alpha_in_place(&mut style.visuals.extreme_bg_color, factor);

src/slide/s1_title.rs

-use crate::egui::Align2;
+use crate::egui::{Align2, Context};
+use crate::fade_in::fade_in;
 use crate::slide::Slide;
 use crate::{ctx_img, Margin};
 use eframe::egui::{Frame, TextureHandle, Ui, Vec2, Window};
@@ -7,9 +8,32 @@ use eframe::egui::{Frame, TextureHandle, Ui, Vec2, Window};
 #[derive(Default)]
 pub struct Title {
     examples: Vec<TextureHandle>,
+    state: TitleState,
+}
+
+#[derive(Default)]
+enum TitleState {
+    #[default]
+    Initial,
+    Title {
+        // When we started fading in the title.
+        fade_start: f64,
+    },
 }
 
 impl Slide for Title {
+    fn transition(&mut self, ctx: &Context) -> bool {
+        match &self.state {
+            TitleState::Initial => {
+                self.state = TitleState::Title {
+                    fade_start: ctx.input().time,
+                }
+            }
+            TitleState::Title { .. } => return true,
+        }
+        false
+    }
+
     fn show(&mut self, ui: &mut Ui) {
         if self.examples.is_empty() {
             // For now, these images are somewhat like placeholders.
@@ -33,17 +57,29 @@ impl Slide for Title {
                 });
         }
 
-        Window::new("title")
-            .title_bar(false)
-            .resizable(false)
-            .anchor(Align2::CENTER_CENTER, Vec2::ZERO)
-            .default_width(400.0)
-            .frame(Frame::window(ui.style()))
-            .show(ui.ctx(), |ui| {
-                ui.vertical_centered(|ui| {
-                    ui.heading("Generative Art");
-                    ui.label("By: Finn, Matthew, Nathan, Owen");
+        if let &TitleState::Title { fade_start } = &self.state {
+            fade_in(ui, fade_start, |ui| {
+                ui.scope(|ui| {
+                    // Extra large margins for title window.
+                    ui.style_mut().spacing.window_margin = Margin::same(20.0);
+
+                    Window::new("title")
+                        .title_bar(false)
+                        .resizable(false)
+                        .anchor(Align2::CENTER_CENTER, Vec2::ZERO)
+                        .default_width(400.0)
+                        .frame(Frame::window(ui.style()))
+                        .show(ui.ctx(), |ui| {
+                            // Nested fade since fade doesn't propagate through window.
+                            fade_in(ui, fade_start, |ui| {
+                                ui.vertical_centered(|ui| {
+                                    ui.heading("Generative Art");
+                                    ui.label("By: Finn, Matthew, Nathan, Owen");
+                                });
+                            });
+                        });
                 });
             });
+        }
     }
 }