player_movement_system.rs

use crate::entities::player::Player;
use bevy::input::{keyboard::KeyCode, Input};
use bevy::prelude::*;
use bevy::render::camera::Camera;

const PLAYER_SPEED: f32 = 500.0;
const PADDING: f32 = 100.0;

pub fn player_movement_system(
    time: Res<Time>,
    windows: Res<Windows>,
    keyboard_input: Res<Input<KeyCode>>,
    mut player_query: Query<(&Player, &mut Translation)>,
    mut camera_query: Query<(&Camera, &mut Translation)>,
) {
    let (height, width) = {
        let window = windows.get_primary().expect("no window");
        (window.height as f32, window.width as f32)
    };

    for (_player, mut translation) in &mut player_query.iter() {
        let mut direction = Vec3::zero();
        if keyboard_input.pressed(KeyCode::Left) {
            direction -= Vec3::new(1.0, 0.0, 0.0);
        }
        if keyboard_input.pressed(KeyCode::Right) {
            direction += Vec3::new(1.0, 0.0, 0.0);
        }
        if keyboard_input.pressed(KeyCode::Down) {
            direction -= Vec3::new(0.0, 1.0, 0.0);
        }
        if keyboard_input.pressed(KeyCode::Up) {
            direction += Vec3::new(0.0, 1.0, 0.0);
        }

        let delta = time.delta_seconds * direction * PLAYER_SPEED;

        translation.0 += delta;

        // NOTE: This won't work once a UI camera is added
        for (_camera, mut camera_translation) in &mut camera_query.iter() {
            // Left edge
            if translation.0.x() - camera_translation.0.x() < -(width / 2.0) + PADDING {
                camera_translation.0 += delta;
            }

            // Right edge
            if translation.0.x() - camera_translation.0.x() > (width / 2.0) - PADDING {
                camera_translation.0 += delta;
            }

            // Bottom edge
            if translation.0.y() - camera_translation.0.y() < -(height / 2.0) + PADDING {
                camera_translation.0 += delta;
            }

            // Top edge
            if translation.0.y() - camera_translation.0.y() > (height / 2.0) - PADDING {
                camera_translation.0 += delta;
            }
        }
    }
}