mgd2-tram-championships/src/game/camera.rs

//! Sets up the game's camera controls etc.

use bevy::{
    input::mouse::{AccumulatedMouseMotion, MouseButtonInput},
    prelude::*,
};

use super::GameplaySet;

pub fn plugin(app: &mut App) {
    app.init_resource::<MouseButtonsPressed>().add_systems(
        Update,
        (
            detect_mouse_button_press,
            panning_basic.after(detect_mouse_button_press),
        )
            .in_set(GameplaySet),
    );
}

/// Resource to store current mouse button state.
#[derive(Resource, Default)]
struct MouseButtonsPressed {
    left: bool,
}

/// Detect whether mouse buttons (currently only left) are pressed.
fn detect_mouse_button_press(
    mut button_events: EventReader<MouseButtonInput>,
    mut pressed: ResMut<MouseButtonsPressed>,
) {
    for event in button_events.read() {
        if event.button == MouseButton::Left {
            pressed.left = dbg!(event.state.is_pressed());
        }
    }
}

/// is SUPPOSED to do proper panning
/// i hate 3d math
fn panning_basic(
    accumulated_mouse_motion: Res<AccumulatedMouseMotion>,
    mut cam_transform: Single<&mut Transform, With<Camera>>,
    pressed: Res<MouseButtonsPressed>,
) {
    if pressed.left && accumulated_mouse_motion.delta != Vec2::ZERO {
        let yaw = Quat::from_rotation_y(accumulated_mouse_motion.delta.x / 150.);
        // cam_transform.rotate_around(Vec3::ZERO, yaw);
        cam_transform.rotation *= yaw;

        let pitch = Quat::from_rotation_x(accumulated_mouse_motion.delta.y / 150.);
        let new_rot = cam_transform.rotation * pitch;
        // cam_transform.rotate_around(Vec3::ZERO, pitch);
        // cam_transform.rotation *= pitch;
        let up_vector = new_rot * Vec3::Y;
        if up_vector.y > 0.0 {
            cam_transform.rotation = new_rot;
        }
    }
    // ???????
    // TODO: figure out/understand how they do it https://github.com/The-DevBlog/bevy_third_person_camera/blob/a7c6b458573fcb0730b65eda6507ca27fb58f571/src/mouse.rs#L29-L74
    //
    let rot_matrix = Mat3::from_quat(cam_transform.rotation);
    cam_transform.translation = rot_matrix.mul_vec3(Vec3::new(0.0, 0.0, 20.));
}