raidillon/engine/src/systems/fps_camera.rs

use crate::system::{System, SystemContext};
use glam::{Quat, Vec3};
use winit::event::DeviceEvent::MouseMotion;
use winit::event::{ElementState, Event, MouseButton, WindowEvent};
use winit::keyboard::{KeyCode, PhysicalKey};
use winit::window::CursorGrabMode;
use raidillon_assets::model_path;
use raidillon_platform::{Camera, PlatformContext};
use crate::input::InputState;
use crate::resources::EngineResources;
use raidillon_core::scene::Scene;

pub struct FPSDebugCameraSystem {
    mouse_delta: (f64, f64),
    mouse_enabled: bool,
    position: Vec3,
    yaw:   f32,
    pitch: f32,
    speed: f32,
    sensitivity: f32,
}

impl Default for FPSDebugCameraSystem {
    fn default() -> Self {
        Self {
            mouse_delta: Default::default(),
            mouse_enabled: Default::default(),
            position: Vec3::new(0.0, 0.0, 2.0),
            yaw: -90.0,
            pitch: 0.0,
            speed: 3.0,
            sensitivity: 0.1,
        }
    }
}

impl System for FPSDebugCameraSystem {
    fn load_world(&mut self, res: &mut EngineResources, scene: &mut Scene) {
        let pctx = res.get::<PlatformContext>().unwrap();
        scene.world.spawn((Camera {
            eye:    Vec3::new(0.0, 0.0, 2.0),
            center: Vec3::ZERO,
            up:     Vec3::Y,
            fovy:   60_f32.to_radians(),
            aspect: pctx.frame_width / pctx.frame_height,
            znear:  0.1,
            zfar:   100.0,
        },));
    }

    fn handle_event(&mut self, res: &mut EngineResources, scene: &mut Scene) {
        let pctx = res.get::<PlatformContext>().unwrap();
        let event2 = pctx.current_event.clone();
        match event2 {
            Event::DeviceEvent { device_id, event} => {
                match event {
                    MouseMotion { delta } => {
                        self.mouse_delta.0 += delta.0;
                        self.mouse_delta.1 += delta.1;
                    },
                    _ => {}
                }
            },
            Event::WindowEvent { event, .. } => match event {
                WindowEvent::MouseInput { state, button, .. } => {
                    if button == MouseButton::Right {
                        // blood and tear
                        let window = pctx.window.lock().unwrap();
                        match state {
                            ElementState::Pressed => {
                                if window
                                    .set_cursor_grab(CursorGrabMode::Confined)
                                    .or_else(|_| window.set_cursor_grab(CursorGrabMode::Locked))
                                    .is_ok()
                                {
                                    window.set_cursor_visible(false);
                                    self.mouse_enabled = true;
                                }
                            }
                            ElementState::Released => {
                                let _ = window.set_cursor_grab(CursorGrabMode::None);
                                window.set_cursor_visible(true);
                                self.mouse_enabled = false;
                            }
                        }
                    }
                }
                _ => {},
            },
            _ => {},
        }
    }

    fn frame_update(&mut self, res: &mut EngineResources, scene: &mut Scene) {
        let pctx = res.get::<PlatformContext>().unwrap();
        let input = res.get::<InputState>().unwrap();

        if self.mouse_enabled {
            self.yaw += self.mouse_delta.0 as f32 * self.sensitivity;
            self.pitch -= self.mouse_delta.1 as f32 * self.sensitivity;
            self.pitch = self.pitch.clamp(-89.0, 89.0);
        }

        let front = self.front();
        let right_vec = front.cross(Vec3::Y).normalize();

        if input.key_held(KeyCode::KeyW) {
            self.position += front * pctx.time_ctx.frame_dt * self.speed;
        }
        if input.key_held(KeyCode::KeyS) {
            self.position -= front * pctx.time_ctx.frame_dt * self.speed;
        }
        if input.key_held(KeyCode::KeyA) {
            self.position -= right_vec * pctx.time_ctx.frame_dt * self.speed;
        }
        if input.key_held(KeyCode::KeyD) {
            self.position += right_vec * pctx.time_ctx.frame_dt * self.speed;
        }

        scene.world.query_mut::<&mut Camera>().into_iter().for_each(|(_, camera)| {
            camera.eye = self.position;
            camera.center = self.position + front;
        });
        self.mouse_delta = (0.0, 0.0);
    }
}

impl FPSDebugCameraSystem {
    pub fn front(&self) -> Vec3 {
        let yaw_rad   = self.yaw.to_radians();
        let pitch_rad = self.pitch.to_radians();
        Vec3::new(
            yaw_rad.cos() * pitch_rad.cos(),
            pitch_rad.sin(),
            yaw_rad.sin() * pitch_rad.cos(),
        ).normalize()
    }
}