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use bevy::window::{PresentMode, WindowResolution};
use bevy::{prelude::*, winit::WinitSettings};
#[derive(Component)]
enum Direction {
Up,
Down,
Left,
Right,
None,
}
fn main() {
App::new()
.add_plugins(DefaultPlugins.set(WindowPlugin {
primary_window: Some(Window {
title: "I am a window!".into(),
resolution: WindowResolution::new(500., 300.).with_scale_factor_override(1.0),
present_mode: PresentMode::AutoVsync,
// Tells wasm to resize the window according to the available canvas
fit_canvas_to_parent: true,
// Tells wasm not to override default event handling, like F5, Ctrl+R etc.
prevent_default_event_handling: false,
..default()
}),
..default()
}))
.add_plugins(EnemyPlugin)
.insert_resource(ClearColor(Color::srgb(0.5, 0.5, 0.9)))
.insert_resource(WinitSettings::game())
.add_systems(Startup, setup_player)
.add_systems(Update, player_movements)
.run();
}
fn offset_to_velocity(abs_v: f32, tr: Vec3, tr_target: Vec3) -> Vec2 {
let dx = tr_target.x - tr.x;
let dy = tr_target.y - tr.y;
let v = Vec2 { x: dx, y: dy }.normalize_or_zero();
Vec2 {
x: v.x * abs_v,
y: v.y * abs_v,
}
}
fn map_key_to_movement(key: &KeyCode) -> Direction {
match key {
KeyCode::KeyW => Direction::Up,
KeyCode::KeyS => Direction::Down,
KeyCode::KeyA => Direction::Left,
KeyCode::KeyD => Direction::Right,
_ => Direction::None,
}
}
pub struct EnemyPlugin;
impl Plugin for EnemyPlugin {
fn build(&self, app: &mut App) {
app.add_systems(Startup, setup_enemy)
.add_systems(Update, enemy_follow);
}
fn name(&self) -> &str {
"Enemy plugin"
}
}
#[derive(Debug)]
enum EntityType {
Player,
Enemy,
}
#[derive(Component)]
pub struct Player {
name: String,
}
#[derive(Component)]
pub struct Enemy {
name: String,
}
fn enemy_follow(
time: Res<Time>,
mut enemy: Query<(&Enemy, &Sprite, &mut Transform), (Without<Player>, With<Enemy>)>,
p: Query<(&Player, &Sprite, &Transform), (With<Player>, Without<Enemy>)>,
) {
let ev = 400. * time.delta_secs();
let (pl, ps, pt) = match p.get_single() {
Ok(p) => p,
Err(e) => return,
};
for (e, s, mut t) in &mut enemy {
let dv = offset_to_velocity(ev, t.translation, pt.translation);
let (ex, ey) = (t.translation.x, t.translation.y);
t.translation.x = safe_move(ex, dv.x, -500., 500.);
t.translation.y = safe_move(ey, dv.y, -300., 300.);
println!(
"Moving {} with v: {:?}, to translation: {:?}",
e.name, dv, t.translation
);
}
}
fn setup_enemy(mut commands: Commands) {
let enemy = Sprite::from_color(Color::srgb(0., 0.5, 0.), Vec2 { x: 10., y: 50. });
commands.spawn((
Enemy {
name: "Evil guy".to_string(),
},
enemy,
Transform::from_xyz(0., 0., 0.),
));
}
fn setup_player(mut commands: Commands) {
let s = Sprite::from_color(Color::srgb(1., 1., 1.), Vec2 { x: 10., y: 50. });
commands.spawn(Camera2d);
commands.spawn((
Player {
name: "Person".to_string(),
},
s,
Transform::from_xyz(0., 0., 0.),
));
}
fn safe_move(x: f32, v: f32, bl: f32, br: f32) -> f32 {
if x + v > 0. && x + v > br {
return x;
}
if x + v < 0. && x + v < bl {
return x;
}
x + v
}
/// The sprite is animated by changing its translation depending on the time that has passed since
/// the last frame.
fn player_movements(
time: Res<Time>,
input: Res<ButtonInput<KeyCode>>,
mut ps: Query<(&Player, &Sprite, &mut Transform), (With<Player>, Without<Enemy>)>,
) {
let pv = 750. * time.delta_secs();
let ev = 500. * time.delta_secs();
let movements: Vec<Direction> = input.get_pressed().map(map_key_to_movement).collect();
for (p, s, mut transform) in &mut ps {
let mut pvel_vec = Vec2 { x: 0., y: 0. };
movements.iter().for_each(|m| match m {
Direction::Up => pvel_vec.y = pv,
Direction::Down => pvel_vec.y = -pv,
Direction::Left => pvel_vec.x = -pv,
Direction::Right => pvel_vec.x = pv,
Direction::None => pvel_vec = Vec2 { x: 0., y: 0. },
});
let pvv = pvel_vec.normalize_or_zero();
let nx = safe_move(transform.translation.x, pv * pvv.x, -500., 500.);
let ny = safe_move(transform.translation.y, pv * pvv.y, -300., 300.);
transform.translation.x = nx;
transform.translation.y = ny;
println!(
"Moving {} with v: {:?}, to translation: {:?}",
p.name, pvv, transform.translation
);
}
}
|
