Add conway example

Cargo.toml

@@ -57,6 +57,8 @@ proc-macro2 = "1"
 quote = "1"
 serde = { version = "1", features = ["derive"] }
 serde_json = "1"
+rayon = "1"
+num = "0.4"
 
 [features]
 # Exposes the raw protocol API

examples/conway.rs

@@ -0,0 +1,205 @@
+use std::mem;
+use std::net::SocketAddr;
+use std::sync::atomic::{AtomicUsize, Ordering};
+use std::sync::Mutex;
+
+use log::LevelFilter;
+use num::Integer;
+use rayon::iter::{IndexedParallelIterator, IntoParallelRefMutIterator, ParallelIterator};
+use valence::client::{Event, GameMode};
+use valence::config::{Config, ServerListPing};
+use valence::text::Color;
+use valence::{
+    async_trait, BlockState, Client, DimensionId, Server, ShutdownResult, Text, TextFormat,
+    WorldId, Worlds,
+};
+
+pub fn main() -> ShutdownResult {
+    env_logger::Builder::new()
+        .filter_module("valence", LevelFilter::Trace)
+        .parse_default_env()
+        .init();
+
+    valence::start_server(Game {
+        player_count: AtomicUsize::new(0),
+        state: Mutex::new(State {
+            board: vec![false; SIZE_X * SIZE_Z].into_boxed_slice(),
+            board_buf: vec![false; SIZE_X * SIZE_Z].into_boxed_slice(),
+        }),
+    })
+}
+
+struct Game {
+    player_count: AtomicUsize,
+    state: Mutex<State>,
+}
+
+struct State {
+    board: Box<[bool]>,
+    board_buf: Box<[bool]>,
+}
+
+const MAX_PLAYERS: usize = 10;
+
+const SIZE_X: usize = 100;
+const SIZE_Z: usize = 100;
+const BOARD_Y: i32 = 50;
+
+#[async_trait]
+impl Config for Game {
+    fn max_connections(&self) -> usize {
+        // We want status pings to be successful even if the server is full.
+        MAX_PLAYERS + 64
+    }
+
+    fn online_mode(&self) -> bool {
+        // You'll want this to be true on real servers.
+        false
+    }
+
+    async fn server_list_ping(&self, _server: &Server, _remote_addr: SocketAddr) -> ServerListPing {
+        ServerListPing::Respond {
+            online_players: self.player_count.load(Ordering::SeqCst) as i32,
+            max_players: MAX_PLAYERS as i32,
+            description: "Hello Valence!".color(Color::AQUA),
+            favicon_png: Some(include_bytes!("favicon.png")),
+        }
+    }
+
+    fn join(
+        &self,
+        _server: &Server,
+        _client: &mut Client,
+        worlds: &mut Worlds,
+    ) -> Result<WorldId, Text> {
+        if let Ok(_) = self
+            .player_count
+            .fetch_update(Ordering::SeqCst, Ordering::SeqCst, |count| {
+                (count < MAX_PLAYERS).then(|| count + 1)
+            })
+        {
+            Ok(worlds.iter().next().unwrap().0)
+        } else {
+            Err("The server is full!".into())
+        }
+    }
+
+    fn init(&self, _server: &Server, worlds: &mut Worlds) {
+        let world = worlds.create(DimensionId::default()).1;
+        world.meta.set_flat(true);
+
+        for chunk_z in -2..Integer::div_ceil(&(SIZE_X as i32), &16) + 2 {
+            for chunk_x in -2..Integer::div_ceil(&(SIZE_Z as i32), &16) + 2 {
+                world.chunks.create((chunk_x as i32, chunk_z as i32));
+            }
+        }
+    }
+
+    fn update(&self, server: &Server, worlds: &mut Worlds) {
+        let world = worlds.iter_mut().next().unwrap().1;
+
+        world.clients.retain(|_, client| {
+            if client.created_tick() == server.current_tick() {
+                client.set_game_mode(GameMode::Survival);
+                let spawn_pos = [
+                    SIZE_X as f64 / 2.0,
+                    BOARD_Y as f64 + 1.0,
+                    SIZE_Z as f64 / 2.0,
+                ];
+                client.teleport(spawn_pos, 0.0, 0.0);
+
+                world.meta.player_list_mut().insert(
+                    client.uuid(),
+                    client.username().to_string(),
+                    client.textures().cloned(),
+                    client.game_mode(),
+                    0,
+                    None,
+                );
+
+                client.send_message("Welcome to Conway's game of life in Minecraft!".italic());
+                client.send_message("Hold the left mouse button to bring blocks to life.".italic());
+            }
+
+            if client.is_disconnected() {
+                self.player_count.fetch_sub(1, Ordering::SeqCst);
+                false
+            } else {
+                true
+            }
+        });
+
+        let State { board, board_buf } = &mut *self.state.lock().unwrap();
+
+        for (_, client) in world.clients.iter_mut() {
+            for event in client.events_mut().drain(..) {
+                if let Event::Digging(e) = event {
+                    let pos = e.position;
+
+                    if (0..SIZE_X as i32).contains(&pos.x)
+                        && (0..SIZE_Z as i32).contains(&pos.z)
+                        && pos.y == BOARD_Y
+                    {
+                        board[pos.x as usize + pos.z as usize * SIZE_X] = true;
+                    }
+                }
+            }
+        }
+
+        if server.current_tick() % 4 != 0 {
+            return;
+        }
+
+        board_buf.par_iter_mut().enumerate().for_each(|(i, cell)| {
+            let cx = (i % SIZE_X) as i32;
+            let cz = (i / SIZE_Z) as i32;
+
+            let mut live_count = 0;
+            for z in cz - 1..=cz + 1 {
+                for x in cx - 1..=cx + 1 {
+                    if !(x == cx && z == cz) {
+                        let i = x.rem_euclid(SIZE_X as i32) as usize
+                            + z.rem_euclid(SIZE_Z as i32) as usize * SIZE_X;
+                        if board[i] {
+                            live_count += 1;
+                        }
+                    }
+                }
+            }
+
+            if board[cx as usize + cz as usize * SIZE_X] {
+                *cell = (2..=3).contains(&live_count);
+            } else {
+                *cell = live_count == 3;
+            }
+        });
+
+        mem::swap(board, board_buf);
+
+        let min_y = server.dimensions().next().unwrap().1.min_y;
+
+        for chunk_x in 0..Integer::div_ceil(&SIZE_X, &16) {
+            for chunk_z in 0..Integer::div_ceil(&SIZE_Z, &16) {
+                let chunk = world
+                    .chunks
+                    .get_mut((chunk_x as i32, chunk_z as i32))
+                    .unwrap();
+                for x in 0..16 {
+                    for z in 0..16 {
+                        let cell_x = chunk_x * 16 + x;
+                        let cell_z = chunk_z * 16 + z;
+
+                        if cell_x < SIZE_X && cell_z < SIZE_Z {
+                            let b = if board[cell_x + cell_z * SIZE_X] {
+                                BlockState::WHITE_WOOL
+                            } else {
+                                BlockState::BLACK_WOOL
+                            };
+                            chunk.set_block_state(x, (BOARD_Y - min_y) as usize, z, b);
+                        }
+                    }
+                }
+            }
+        }
+    }
+}