From fad0358553f9b45f028e9053e5752b078edb3aed Mon Sep 17 00:00:00 2001
From: Dustin Carlino <dabreegster@gmail.com>
Date: Sat, 28 Nov 2020 10:12:00 -0800
Subject: [PATCH] Experiment with animation

---
 experiment/src/animation.rs | 72 +++++++++++++++++++++++++++++++++++++
 experiment/src/game.rs      | 35 ++++++++++++++----
 experiment/src/main.rs      |  1 +
 3 files changed, 101 insertions(+), 7 deletions(-)
 create mode 100644 experiment/src/animation.rs

diff --git a/experiment/src/animation.rs b/experiment/src/animation.rs
new file mode 100644
index 0000000000..d4a8bb4d9c
--- /dev/null
+++ b/experiment/src/animation.rs
@@ -0,0 +1,72 @@
+use geom::{Duration, Pt2D, Time};
+use widgetry::{Drawable, EventCtx, GeomBatch, GfxCtx};
+
+pub struct Animator {
+    time: Time,
+    active: Vec<Effect>,
+    draw_current: Drawable,
+}
+
+struct Effect {
+    start: Time,
+    end: Time,
+    orig: GeomBatch,
+    center: Pt2D,
+    // Scaling is the only transformation for now
+    lerp_scale: (f64, f64),
+}
+
+impl Animator {
+    pub fn new(ctx: &EventCtx) -> Animator {
+        Animator {
+            time: Time::START_OF_DAY,
+            active: Vec::new(),
+            draw_current: Drawable::empty(ctx),
+        }
+    }
+
+    pub fn add(
+        &mut self,
+        duration: Duration,
+        lerp_scale: (f64, f64),
+        center: Pt2D,
+        orig: GeomBatch,
+    ) {
+        self.active.push(Effect {
+            start: self.time,
+            end: self.time + duration,
+            orig,
+            lerp_scale,
+            center,
+        });
+    }
+
+    pub fn event(&mut self, ctx: &mut EventCtx) {
+        if let Some(dt) = ctx.input.nonblocking_is_update_event() {
+            self.time += dt;
+            if self.active.is_empty() {
+                return;
+            }
+            let mut batch = GeomBatch::new();
+            let time = self.time;
+            self.active.retain(|effect| effect.update(time, &mut batch));
+            self.draw_current = ctx.upload(batch);
+        }
+    }
+
+    pub fn draw(&self, g: &mut GfxCtx) {
+        g.redraw(&self.draw_current);
+    }
+}
+
+impl Effect {
+    fn update(&self, time: Time, batch: &mut GeomBatch) -> bool {
+        let pct = (time - self.start) / (self.end - self.start);
+        if pct > 1.0 {
+            return false;
+        }
+        let scale = self.lerp_scale.0 + pct * (self.lerp_scale.1 - self.lerp_scale.0);
+        batch.append(self.orig.clone().scale(scale).centered_on(self.center));
+        true
+    }
+}
diff --git a/experiment/src/game.rs b/experiment/src/game.rs
index add8b0f3f5..5d046530ae 100644
--- a/experiment/src/game.rs
+++ b/experiment/src/game.rs
@@ -10,6 +10,7 @@ use widgetry::{
     Line, Outcome, Panel, State, Text, TextExt, Transition, UpdateType, VerticalAlignment, Widget,
 };
 
+use crate::animation::Animator;
 use crate::controls::{Controller, InstantController, RotateController};
 
 const ZOOM: f64 = 10.0;
@@ -18,6 +19,7 @@ pub struct Game {
     panel: Panel,
     controls: Box<dyn Controller>,
     minimap: SimpleMinimap,
+    animator: Animator,
 
     sleigh: Pt2D,
     state: SleighState,
@@ -71,6 +73,7 @@ impl Game {
             panel,
             controls: Box::new(InstantController::new()),
             minimap: SimpleMinimap::new(ctx, app, with_zorder),
+            animator: Animator::new(ctx),
 
             sleigh,
             state,
@@ -166,15 +169,27 @@ impl State<SimpleApp> for Game {
         }
 
         if let Some(b) = self.over_bldg.key() {
-            if self.state.has_energy() && self.state.present_dropped(ctx, app, b) {
-                self.over_bldg.clear();
-                self.update_panel(ctx);
+            if self.state.has_energy() {
+                if let Some(increase) = self.state.present_dropped(ctx, app, b) {
+                    self.over_bldg.clear();
+                    self.update_panel(ctx);
+                    self.animator.add(
+                        Duration::seconds(0.5),
+                        (1.0, 4.0),
+                        app.map.get_b(b).label_center,
+                        Text::from(Line(format!("+{}", prettyprint_usize(increase))))
+                            .bg(Color::RED)
+                            .render_to_batch(ctx.prerender)
+                            .scale(0.1),
+                    );
+                }
             }
         }
 
         if let Some(t) = self.minimap.event(ctx, app) {
             return t;
         }
+        self.animator.event(ctx);
 
         match self.panel.event(ctx) {
             Outcome::Clicked(x) => match x.as_ref() {
@@ -242,6 +257,7 @@ impl State<SimpleApp> for Game {
             Color::RED,
             Circle::new(self.sleigh, Distance::meters(5.0)).to_polygon(),
         );
+        self.animator.draw(g);
     }
 }
 
@@ -367,16 +383,21 @@ impl SleighState {
         self.draw_all_depots = ctx.upload(batch);
     }
 
-    // True if state change
-    fn present_dropped(&mut self, ctx: &mut EventCtx, app: &SimpleApp, id: BuildingID) -> bool {
+    // If something changed, return the update to the score
+    fn present_dropped(
+        &mut self,
+        ctx: &mut EventCtx,
+        app: &SimpleApp,
+        id: BuildingID,
+    ) -> Option<usize> {
         if let Some(BldgState::Undelivered { score, cost }) = self.houses.get(&id).cloned() {
             self.score += score;
             self.houses.insert(id, BldgState::Done);
             self.energy -= cost;
             self.redraw(ctx, app);
-            return true;
+            return Some(score);
         }
-        false
+        None
     }
 
     // True if state change
diff --git a/experiment/src/main.rs b/experiment/src/main.rs
index da0a5f6889..1a3a34b31e 100644
--- a/experiment/src/main.rs
+++ b/experiment/src/main.rs
@@ -1,3 +1,4 @@
+mod animation;
 mod controls;
 mod game;
 mod upzone;