path: root/src/main.rs

mod camera;
mod config;
mod renderer;
mod sim;

use futures::executor;
use rand::random_range;
use std::{collections::VecDeque, sync::Arc, time::Instant};
use winit::{
    application::ApplicationHandler,
    event::{
        ElementState, KeyEvent, MouseButton,
        WindowEvent::{self},
    },
    event_loop::{ActiveEventLoop, ControlFlow, EventLoop},
    keyboard::{KeyCode, PhysicalKey},
    window::Window,
};

use crate::{
    camera::Camera,
    config::{SIM_FPS, WINDOW_TITLE},
    renderer::RendererState,
    sim::{cell::Cell, materials::MaterialId, sim::sim_tick, world::World},
};

pub type Error = Box<dyn std::error::Error>;
pub type Result<T> = std::result::Result<T, Error>;

struct Config {
    brush_radius: u8,
    brush_material: MaterialId,
    use_threading: bool,
}

struct Input {
    last_mouse_pos_on_screen: Option<(f64, f64)>,
    last_mouse_pos_on_board: Option<(i32, i32)>,
    is_lmb_pressed: bool,

    // keybindings
    is_up_pressed: bool,
    is_left_pressed: bool,
    is_down_pressed: bool,
    is_right_pressed: bool,
}

struct Diagnostics {
    frame_times: VecDeque<f32>,
    fps: f32,
}

struct App {
    window: Option<Arc<Window>>,
    renderer_state: Option<RendererState>,

    input: Input,

    camera: Option<Camera>,

    world: Option<World>,

    // sim state
    // the last/current (not yet completed) seqno
    sim_seqno: u64,
    sim_paused: bool,
    ignore_pause_next_tick: bool,

    // used to compute delta_time
    last_sim_tick: Instant,
    sim_ticks_due: f32,
    last_render: Instant,

    config: Config,
    diagnostics: Diagnostics,
}

impl Default for App {
    fn default() -> Self {
        Self {
            window: None,
            renderer_state: None,

            input: Input {
                last_mouse_pos_on_screen: None,
                last_mouse_pos_on_board: None,

                is_lmb_pressed: false,
                is_up_pressed: false,
                is_left_pressed: false,
                is_down_pressed: false,
                is_right_pressed: false,
            },

            camera: None,

            world: Some(World::from_default_size()),

            sim_seqno: 0,
            sim_paused: false,
            ignore_pause_next_tick: false,

            last_sim_tick: Instant::now(),
            sim_ticks_due: 0.,
            last_render: Instant::now(),

            config: Config {
                use_threading: true,
                brush_radius: 10,
                brush_material: MaterialId::Sand,
            },
            diagnostics: Diagnostics {
                fps: 0.0,
                frame_times: VecDeque::new(),
            },
        }
    }
}

impl ApplicationHandler for App {
    fn resumed(&mut self, event_loop: &ActiveEventLoop) {
        let window = Arc::new(
            event_loop
                .create_window(Window::default_attributes().with_title(WINDOW_TITLE))
                .unwrap(),
        );

        self.window = Some(window.clone());
        self.renderer_state = Some(executor::block_on(RendererState::new(window.clone())));

        let size = window.inner_size();
        self.camera = Some(Camera::new((size.width as i32, size.height as i32)));

        // let surface = SurfaceTexture::new(size.width, size.height, window_ref);

        // let mut pixels = Pixels::new(PIXEL_BUFFER_WIDTH, PIXEL_BUFFER_HEIGHT, surface).unwrap();

        // pixels.set_scaling_mode(ScalingMode::Fill);
    }

    fn window_event(
        &mut self,
        event_loop: &ActiveEventLoop,
        _: winit::window::WindowId,
        event: WindowEvent,
    ) {
        if let Some(window) = &self.window
            && let Some(renderer_state) = &mut self.renderer_state
            && let Some(world) = &mut self.world
            && let Some(camera) = &mut self.camera
        {
            let egui_response = renderer_state.egui_state.on_window_event(window, &event);
            // if egui consumed the event, it means we shouldn't treat any e.g., mouse clicks
            if egui_response.consumed {
                return;
            }

            match event {
                WindowEvent::KeyboardInput {
                    event:
                        KeyEvent {
                            physical_key: PhysicalKey::Code(code),
                            state,
                            ..
                        },
                    ..
                } => {
                    let pressed = state.is_pressed();
                    match code {
                        KeyCode::KeyW => self.input.is_up_pressed = pressed,
                        KeyCode::KeyA => self.input.is_left_pressed = pressed,
                        KeyCode::KeyS => self.input.is_down_pressed = pressed,
                        KeyCode::KeyD => self.input.is_right_pressed = pressed,
                        KeyCode::KeyC => self.world = Some(World::from_default_size()),
                        KeyCode::Space => {
                            if pressed {
                                self.sim_paused = !self.sim_paused
                            }
                        }
                        KeyCode::KeyX => {
                            if pressed {
                                self.ignore_pause_next_tick = true
                            }
                        }
                        _ => {}
                    }
                }
                WindowEvent::CursorMoved { position, .. } => {
                    self.input.last_mouse_pos_on_screen = Some((position.x, position.y));
                    let world_pos =
                        camera.screen_position_to_world(position.x as f32, position.y as f32);
                    self.input.last_mouse_pos_on_board =
                        Some((world_pos.0 as i32, world_pos.1 as i32))
                }
                WindowEvent::MouseInput { state, button, .. } => {
                    if button == MouseButton::Left {
                        self.input.is_lmb_pressed = state == ElementState::Pressed
                    }
                }
                WindowEvent::Resized(size) => {
                    renderer_state.resize(size.width, size.height);
                    camera.resize((size.width as i32, size.height as i32));
                }
                WindowEvent::CloseRequested => {
                    event_loop.exit();
                }
                WindowEvent::RedrawRequested => {
                    #[cfg(feature = "profiler")]
                    puffin::GlobalProfiler::lock().new_frame();

                    puffin::profile_scope!("redraw_requested");
                    // compute FPS diagnostics
                    let now = Instant::now();
                    let secs_since_last_frame = (now - self.last_render).as_secs_f32();
                    self.last_render = now;

                    let delta_time = secs_since_last_frame / (1.0 / 60.0);

                    self.diagnostics
                        .frame_times
                        .push_back(secs_since_last_frame);

                    if self.diagnostics.frame_times.len() > 30 {
                        self.diagnostics.frame_times.pop_front();
                    }

                    let average_frame_time = self.diagnostics.frame_times.iter().sum::<f32>()
                        / self.diagnostics.frame_times.len() as f32;

                    self.diagnostics.fps = 1.0 / average_frame_time;

                    // apply inputs
                    camera.handle_camera_input(&self.input, delta_time);

                    // // --TEST DRAWING--
                    if self.input.is_lmb_pressed
                        && let Some(lm) = self.input.last_mouse_pos_on_board
                    {
                        // start with the bounding box of the drawing brush circle + some margin
                        // clamp the bounding box to the board sie
                        let bb_xl = lm.0 - self.config.brush_radius as i32;
                        let bb_xu = lm.0 + self.config.brush_radius as i32;
                        let bb_yl = lm.1 - self.config.brush_radius as i32;
                        let bb_yu = lm.1 + self.config.brush_radius as i32;

                        // for each point, check if the distance is less than the brush size and write the pixel
                        for x in bb_xl..bb_xu {
                            for y in bb_yl..bb_yu {
                                let r = random_range(0.0..1.0);
                                if ((x - lm.0).pow(2) + (y - lm.1).pow(2))
                                    < (self.config.brush_radius as i32).pow(2)
                                    && r > 0.9
                                {
                                    let mut cell = Cell::from_material(self.config.brush_material);
                                    cell.flags = (self.sim_seqno as u8) & 0b1;
                                    world.set_cell_from_game_position(
                                        x, y, cell, // wake the chunk
                                        false,
                                    );
                                }
                            }
                        }
                    }

                    // SIM logic
                    let secs_since_last_tick = (now - self.last_sim_tick).as_secs_f32();
                    let expected_secs_since_last_tick = 1.0 / SIM_FPS as f32;

                    if self.sim_paused && self.ignore_pause_next_tick {
                        sim_tick(world, self.sim_seqno, self.config.use_threading);
                        self.sim_seqno += 1;
                        self.ignore_pause_next_tick = false;
                    } else if !self.sim_paused {
                        self.sim_ticks_due += secs_since_last_tick / expected_secs_since_last_tick;
                        self.last_sim_tick = now;
                        let mut ticks_done = 0;
                        // don't ever tick more than 3 times per frame, or else we can get a pseudo deadlock
                        while self.sim_ticks_due >= 1.0 && ticks_done < 3 {
                            sim_tick(world, self.sim_seqno, self.config.use_threading);
                            self.sim_seqno += 1;
                            ticks_done += 1;
                        }
                        self.sim_ticks_due -= ticks_done as f32;
                    }

                    renderer_state.render(
                        world,
                        camera,
                        &mut self.config,
                        &self.diagnostics,
                        &mut self.input,
                    );
                }
                _ => {}
            }
        }
    }

    fn about_to_wait(&mut self, _: &ActiveEventLoop) {
        if let Some(window) = &self.window {
            window.request_redraw();
        } else {
            panic!("No window!")
        }
    }
}

#[cfg(feature = "profiler")]
fn start_profiler() {
    let _server = puffin_http::Server::new("127.0.0.1:8585").unwrap();
    puffin::set_scopes_on(true);
    std::mem::forget(_server); // keep serving for the process lifetime

    std::process::Command::new("puffin_viewer")
        .args(["--url", "127.0.0.1:8585"])
        .spawn()
        .ok(); // don't die if it isn't installed
}

fn main() -> Result<()> {
    #[cfg(feature = "profiler")]
    start_profiler();

    let event_loop = EventLoop::new()?;
    event_loop.set_control_flow(ControlFlow::Poll);

    let mut app = App::default();
    event_loop.run_app(&mut app)?;

    Ok(())
}