move_player.rs

use bevy::prelude::*;

struct Player {
  velocity: Vec3,
}

fn main() {
  App::build()
    .add_plugins(DefaultPlugins)
    .add_startup_system(spawn_player.system())
    .add_system(move_player.system());
}

fn spawn_player(mut commands: Commands) {
  commands.spawn((Player, Transform::default());
}

fn move_player(time: Res<Time>, mut query: Query<(&mut Transform, &Player)>) {
  for (mut transform, player) in in query.iter_mut() {
    transform.translation += player.velocity * time.delta_seconds();
  }
}