cyber_rider/src/camera.rs

use bevy::prelude::*;

use crate::{
    action::MovementSettings,
    geometry::{CyberBike, SPAWN_ALTITUDE},
    input::InputState,
};

pub(crate) const CAM_DIST: f32 = 15.0;

#[derive(Component, Debug)]
pub struct CyberCam;

fn setup_cybercam(mut commands: Commands) {
    commands
        .spawn_bundle(PerspectiveCameraBundle {
            transform: Transform::from_xyz(SPAWN_ALTITUDE + CAM_DIST, 0.0, 0.0)
                .looking_at(Vec3::ZERO, Vec3::Y),
            ..Default::default()
        })
        .insert(CyberCam);
}

fn follow_player(
    bike_query: Query<&Transform, (Without<CyberCam>, With<CyberBike>)>,
    mut cam_query: Query<&mut Transform, (With<CyberCam>, Without<CyberBike>)>,
) {
    let bike_xform = bike_query.single();
    let up = bike_xform.translation.normalize();

    let look_at = bike_xform.translation + (bike_xform.forward() * CAM_DIST);
    let cam_pos = bike_xform.translation + (bike_xform.back() * CAM_DIST * 1.5) + (up * CAM_DIST);

    let mut cam_xform = cam_query.single_mut();
    cam_xform.translation = cam_pos;
    cam_xform.look_at(look_at, up);
}

fn player_look(
    settings: Res<MovementSettings>,
    windows: Res<Windows>,
    time: Res<Time>,
    istate: Res<InputState>,
    mut query: Query<&mut Transform, With<CyberBike>>,
) {
    let window = windows.get_primary().unwrap();
    let window_scale = window.height().min(window.width());
    let dt = time.delta_seconds();
    let mut transform = query.single_mut();

    let d_pitch = (settings.sensitivity * dt * window_scale * istate.pitch).to_radians();
    let d_yaw = (settings.sensitivity * dt * window_scale * istate.yaw).to_radians();
    let rotation = Quat::from_axis_angle(transform.local_y(), d_yaw)
        * Quat::from_axis_angle(transform.local_x(), d_pitch);

    transform.rotate(rotation);
}

pub struct CyberCamPlugin;
impl Plugin for CyberCamPlugin {
    fn build(&self, app: &mut bevy::prelude::App) {
        app.add_startup_system(setup_cybercam)
            .add_system(follow_player)
            .add_system(player_look);
    }
}