Growing the snake

This commit is contained in:
Timothy Warren 2020-12-30 10:26:25 -05:00
parent 962e1bfc12
commit 8a713ba685

View File

@ -36,6 +36,11 @@ struct Materials {
struct SnakeMoveTimer(Timer);
struct GrowthEvent;
#[derive(Default)]
struct LastTailPosition(Option<Position>);
struct SnakeSegment;
#[derive(Default)]
@ -125,6 +130,7 @@ fn spawn_segment(
fn snake_movement(
keyboard_input: Res<Input<KeyCode>>,
snake_timer: ResMut<SnakeMoveTimer>,
mut last_tail_position: ResMut<LastTailPosition>,
segments: ResMut<SnakeSegments>,
mut heads: Query<(Entity, &mut SnakeHead)>,
mut positions: Query<&mut Position>,
@ -172,7 +178,45 @@ fn snake_movement(
.zip(segments.0.iter().skip(1))
.for_each(|(pos, segment)| {
*positions.get_mut(*segment).unwrap() = *pos;
})
});
last_tail_position.0 = Some(*segment_positions.last().unwrap());
}
}
fn snake_eating(
commands: &mut Commands,
snake_timer: ResMut<SnakeMoveTimer>,
mut growth_events: ResMut<Events<GrowthEvent>>,
food_positions: Query<(Entity, &Position), With<Food>>,
head_positions: Query<&Position, With<SnakeHead>>,
) {
if !snake_timer.0.finished() {
return;
}
for head_pos in head_positions.iter() {
for (ent, food_pos) in food_positions.iter() {
if food_pos == head_pos {
commands.despawn(ent);
growth_events.send(GrowthEvent);
}
}
}
}
fn snake_growth(
commands: &mut Commands,
last_tail_position: Res<LastTailPosition>,
growth_events: Res<Events<GrowthEvent>>,
mut segments: ResMut<SnakeSegments>,
mut growth_reader: Local<EventReader<GrowthEvent>>,
materials: Res<Materials>,
) {
if growth_reader.iter(&growth_events).next().is_some() {
segments.0.push(spawn_segment(
commands,
&materials.segment_material,
last_tail_position.0.unwrap(),
));
}
}
@ -238,6 +282,8 @@ fn main() {
})
.add_resource(SnakeMoveTimer(Timer::new(Duration::from_millis(150), true)))
.add_resource(SnakeSegments::default())
.add_resource(LastTailPosition::default())
.add_event::<GrowthEvent>()
.add_startup_system(setup.system())
.add_startup_stage("game_setup", SystemStage::single(spawn_snake.system()))
.add_system(snake_movement.system())
@ -245,6 +291,8 @@ fn main() {
.add_system(size_scaling.system())
.add_system(food_spawner.system())
.add_system(snake_timer.system())
.add_system(snake_eating.system())
.add_system(snake_growth.system())
.add_plugins(DefaultPlugins)
.run();
}