Add eating animation

Cargo.lock

@@ -246,6 +246,7 @@ version = "0.1.0"
 dependencies = [
  "bevy",
  "bevy_editor_pls",
+ "bevy_tweening",
  "itertools",
  "iyes_loopless",
  "rand",
@@ -880,6 +881,16 @@ dependencies = [
  "bevy_reflect",
 ]
 
+[[package]]
+name = "bevy_tweening"
+version = "0.5.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "164bcb41708fa1aeb435b6bba6cae61777b9f8cf3e18b207bb6209ca5b970e77"
+dependencies = [
+ "bevy",
+ "interpolation",
+]
+
 [[package]]
 name = "bevy_ui"
 version = "0.8.1"
@@ -2012,6 +2023,12 @@ dependencies = [
  "web-sys",
 ]
 
+[[package]]
+name = "interpolation"
+version = "0.2.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d3b7357d2bbc5ee92f8e899ab645233e43d21407573cceb37fed8bc3dede2c02"
+
 [[package]]
 name = "io-kit-sys"
 version = "0.2.0"

Cargo.toml

@@ -11,6 +11,7 @@ itertools = "0.10.3"
 # bevy-inspector-egui = "0.12.1"
 rand = "0.8.5"
 bevy_editor_pls = { git = "https://github.com/jakobhellermann/bevy_editor_pls" }
+bevy_tweening = "0.5.0"
 
 [dependencies.bevy]
 version = "0.8.0"

src/fruit.rs

@@ -29,10 +29,7 @@ fn eaten_event_sent(mut eaten_event_reader: EventReader<EatenEvent>) -> bool {
     eaten_event_reader.iter().count() != 0
 }
 
-fn spawn_fruit_system(
-    mut commands: Commands,
-    coordinate_query: Query<&grid::Coordinate>,
-) {
+fn spawn_fruit_system(mut commands: Commands, coordinate_query: Query<&grid::Coordinate>) {
     fn random_coordinate() -> grid::Coordinate {
         let mut rng = rand::thread_rng();
         let coordinate_range = 0..grid::SIZE;
@@ -49,7 +46,7 @@ fn spawn_fruit_system(
             .any(|&snake_coordinate| snake_coordinate == coordinate)
     };
 
-    let fruit_coordinate = std::iter::repeat(random_coordinate())
+    let fruit_coordinate = std::iter::repeat_with(random_coordinate)
         .find(|&coordinate| !coordinate_in_other_element(coordinate))
         .expect("Should always be found.");
 

src/main.rs

@@ -3,6 +3,7 @@ use bevy::{prelude::*, render::camera::ScalingMode};
 use bevy_editor_pls::prelude::*;
 use grid::{SEGMENT_SIZE, SIZE};
 use iyes_loopless::prelude::*;
+use bevy_tweening::TweeningPlugin;
 
 mod canvas;
 mod fruit;
@@ -35,6 +36,7 @@ fn main() {
         .add_loopless_state(AppState::Begin)
         .add_plugins(DefaultPlugins)
         .add_plugin(EditorPlugin)
+        .add_plugin(TweeningPlugin)
         .add_plugin(TickPlugin)
         .add_plugin(SnakePlugin)
         .add_plugin(FruitPlugin)

src/snake.rs

@@ -1,7 +1,9 @@
 use crate::{fruit, grid, tick::tick_triggered, AppState};
 use bevy::prelude::*;
+use bevy_tweening::{lens::TransformScaleLens, *};
 use itertools::Itertools;
 use iyes_loopless::prelude::*;
+use std::time::Duration;
 
 #[derive(Debug, Clone, PartialEq, Eq, Hash, StageLabel)]
 struct MovementStage;
@@ -17,7 +19,8 @@ impl Plugin for SnakePlugin {
     fn build(&self, app: &mut App) {
         let movement_stage = SystemStage::parallel();
 
-        app.add_startup_system(setup_snake_system)
+        app.insert_resource(BulgePropagationTimer::default())
+            .add_startup_system(setup_snake_system)
             .add_stage_after(CoreStage::Update, MovementStage, movement_stage)
             .add_system_to_stage(
                 MovementStage,
@@ -49,7 +52,10 @@ impl Plugin for SnakePlugin {
             .add_system(add_direction_system.run_in_state(AppState::Begin))
             .add_system(change_direction_system.run_in_state(AppState::InGame))
             .add_system(grid_transform_system.run_in_state(AppState::InGame))
-            .add_system(add_tail_system);
+            .add_system(add_tail_system)
+            .add_system(add_bulge_system)
+            .add_system(propagate_bulge_system)
+            .add_system(animate_bulge_system);
     }
 }
 
@@ -78,6 +84,18 @@ struct Snake;
 #[derive(Component)]
 struct SnakeSegments(Vec<Entity>);
 
+#[derive(Component)]
+#[component(storage = "SparseSet")]
+struct BulgeMarker;
+
+struct BulgePropagationTimer(Timer);
+
+impl Default for BulgePropagationTimer {
+    fn default() -> Self {
+        Self(Timer::new(Duration::from_millis(30), true))
+    }
+}
+
 impl SnakeSegments {
     fn with_head(snake_head: Entity) -> Self {
         Self(vec![snake_head])
@@ -167,6 +185,69 @@ fn add_tail_system(
     }
 }
 
+fn add_bulge_system(
+    mut commands: Commands,
+    mut eaten_event_reader: EventReader<fruit::EatenEvent>,
+    query: Query<Entity, With<SnakeHead>>,
+) {
+    for _ in eaten_event_reader.iter() {
+        let snake_head_entity = query.single();
+        commands.entity(snake_head_entity).insert(BulgeMarker);
+    }
+}
+
+fn propagate_bulge_system(
+    mut commands: Commands,
+    query: Query<(Entity, &Parent), (With<SnakeSegment>, With<BulgeMarker>)>,
+    snake_segments_query: Query<&SnakeSegments>,
+    time: Res<Time>,
+    mut timer: ResMut<BulgePropagationTimer>,
+) {
+    timer.0.tick(time.delta());
+
+    if !timer.0.finished() {
+        return;
+    }
+
+    for (entity, parent) in query.iter() {
+        commands.entity(entity).remove::<BulgeMarker>();
+        let mut segment_iter = snake_segments_query.get(parent.get()).unwrap().0.iter();
+        segment_iter.find(|&&segment_entity| segment_entity == entity);
+
+        if let Some(&segment_entity) = segment_iter.next() {
+            commands.entity(segment_entity).insert(BulgeMarker);
+        }
+    }
+}
+
+fn animate_bulge_system(mut commands: Commands, query: Query<Entity, Added<BulgeMarker>>) {
+    for entity in query.iter() {
+        let tween_to = Tween::new(
+            EaseFunction::CubicInOut,
+            TweeningType::Once,
+            Duration::from_millis(100),
+            TransformScaleLens {
+                start: Vec3::splat(1.0),
+                end: Vec3::splat(1.1),
+            },
+        );
+
+        let tween_back = Tween::new(
+            EaseFunction::CubicInOut,
+            TweeningType::Once,
+            Duration::from_millis(150),
+            TransformScaleLens {
+                start: Vec3::splat(1.1),
+                end: Vec3::splat(1.0),
+            },
+        );
+
+        let tween = tween_to.then(tween_back);
+
+        commands.entity(entity).insert(Animator::new(tween));
+    }
+}
+
 fn update_direction_system(
     mut query: Query<(&mut Direction, &mut DirectionBuffer), With<SnakeHead>>,
 ) {