implement grass spread, resolves #9

src/level.rs

@@ -9,7 +9,8 @@ use bevy_reflect::{PartialReflect, Struct};
 use serde::{Deserialize, Serialize};
 
 use crate::{
-	error::GeneralError, packet::server::ServerPacket, player::SavablePlayerData, util::neighbors,
+	error::GeneralError, packet::server::ServerPacket, player::SavablePlayerData,
+	util::neighbors_full,
 };
 
 use self::block::BLOCK_INFO;
@@ -40,7 +41,11 @@ pub struct Level {
 	pub level_rules: LevelRules,
 
 	/// index of blocks which need to be updated in the next tick
+	#[serde(default)]
 	pub awaiting_update: BTreeSet<usize>,
+	/// index of blocks which are eligible for random tick updates
+	#[serde(default)]
+	pub possible_random_updates: Vec<usize>,
 	/// list of updates to apply to the world on the next tick
 	#[serde(skip)]
 	pub updates: Vec<BlockUpdate>,
@@ -62,6 +67,7 @@ impl Level {
 			weather: WeatherType::Sunny,
 			level_rules: Default::default(),
 			awaiting_update: Default::default(),
+			possible_random_updates: Default::default(),
 			updates: Default::default(),
 			save_now: false,
 			player_data: Default::default(),
@@ -106,11 +112,11 @@ impl Level {
 				z: z as i16,
 				block_type: update.block,
 			});
-			for (nx, ny, nz) in neighbors(self, x, y, z) {
+			for (nx, ny, nz) in neighbors_full(self, x, y, z) {
 				let info = BLOCK_INFO
 					.get(&self.get_block(nx, ny, nz))
 					.expect("missing block");
-				if info.block_type.needs_update_when_neighbor_changed() {
+				if info.needs_update_when_neighbor_changed {
 					self.awaiting_update.insert(self.index(nx, ny, nz));
 				}
 			}
@@ -223,7 +229,14 @@ impl From<u8> for WeatherType {
 #[derive(Debug, Clone, Serialize, Deserialize, bevy_reflect::Reflect)]
 pub struct LevelRules {
 	/// whether fluids should spread in the level
+	#[serde(default = "level_rules::fluid_spread")]
 	pub fluid_spread: bool,
+	/// the number of blocks which should receive random tick updates
+	#[serde(default = "level_rules::random_tick_updates")]
+	pub random_tick_updates: u64,
+	/// the chance that grass will spread to an adjacent dirt block when randomly updated
+	#[serde(default = "level_rules::grass_spread_chance")]
+	pub grass_spread_chance: u64,
 }
 
 impl LevelRules {
@@ -251,6 +264,7 @@ impl LevelRules {
 	pub fn set_rule(&mut self, name: &str, value: &str) -> Result<(), String> {
 		let bool_type_id = TypeId::of::<bool>();
 		let f64_type_id = TypeId::of::<f64>();
+		let u64_type_id = TypeId::of::<u64>();
 		let string_type_id = TypeId::of::<String>();
 
 		fn parse_and_apply<T>(value: &str, field_mut: &mut dyn PartialReflect) -> Result<(), String>
@@ -278,6 +292,8 @@ impl LevelRules {
 			parse_and_apply::<bool>(value, field_mut)?;
 		} else if id == f64_type_id {
 			parse_and_apply::<f64>(value, field_mut)?;
+		} else if id == u64_type_id {
+			parse_and_apply::<u64>(value, field_mut)?;
 		} else if id == string_type_id {
 			parse_and_apply::<String>(value, field_mut)?;
 		} else {
@@ -288,8 +304,27 @@ impl LevelRules {
 	}
 }
 
+mod level_rules {
+	pub fn fluid_spread() -> bool {
+		true
+	}
+
+	pub fn random_tick_updates() -> u64 {
+		1000
+	}
+
+	pub fn grass_spread_chance() -> u64 {
+		2048
+	}
+}
+
 impl Default for LevelRules {
 	fn default() -> Self {
-		Self { fluid_spread: true }
+		use level_rules::*;
+		Self {
+			fluid_spread: fluid_spread(),
+			random_tick_updates: random_tick_updates(),
+			grass_spread_chance: grass_spread_chance(),
+		}
 	}
 }

src/level/block.rs

@@ -7,7 +7,10 @@ use crate::player::PlayerType;
 /// the level of custom blocks supported by the server
 pub const CUSTOM_BLOCKS_SUPPORT_LEVEL: u8 = 1;
 
+pub const ID_AIR: u8 = 0x00;
 pub const ID_STONE: u8 = 0x01;
+pub const ID_GRASS: u8 = 0x02;
+pub const ID_DIRT: u8 = 0x03;
 pub const ID_WATER_FLOWING: u8 = 0x08;
 pub const ID_WATER_STATIONARY: u8 = 0x09;
 pub const ID_LAVA_FLOWING: u8 = 0x0a;
@@ -16,10 +19,21 @@ pub const ID_LAVA_STATIONARY: u8 = 0x0b;
 /// information about all blocks implemented
 pub static BLOCK_INFO: LazyLock<BTreeMap<u8, BlockInfo>> = LazyLock::new(|| {
 	[
-		(0x00, BlockInfo::new("air").block_type(BlockType::NonSolid)),
+		(
+			ID_AIR,
+			BlockInfo::new("air").block_type(BlockType::NonSolid),
+		),
 		(ID_STONE, BlockInfo::new("stone")),
-		(0x02, BlockInfo::new("grass")),
+		(
-		(0x03, BlockInfo::new("dirt")),
+			ID_GRASS,
+			BlockInfo::new("grass")
+				.needs_update_when_neighbor_changed()
+				.may_receive_random_ticks(),
+		),
+		(
+			ID_DIRT,
+			BlockInfo::new("dirt").needs_update_when_neighbor_changed(),
+		),
 		(0x04, BlockInfo::new("cobblestone")),
 		(0x05, BlockInfo::new("planks")),
 		(
@@ -43,7 +57,8 @@ pub static BLOCK_INFO: LazyLock<BTreeMap<u8, BlockInfo>> = LazyLock::new(|| {
 			ID_WATER_STATIONARY,
 			BlockInfo::new("water_stationary")
 				.block_type(BlockType::FluidStationary { moving: 0x08 })
-				.perm(PlayerType::Moderator, PlayerType::Normal),
+				.perm(PlayerType::Moderator, PlayerType::Normal)
+				.needs_update_when_neighbor_changed(),
 		),
 		(
 			ID_LAVA_FLOWING,
@@ -58,7 +73,8 @@ pub static BLOCK_INFO: LazyLock<BTreeMap<u8, BlockInfo>> = LazyLock::new(|| {
 			ID_LAVA_STATIONARY,
 			BlockInfo::new("lava_stationary")
 				.block_type(BlockType::FluidStationary { moving: 0x0a })
-				.perm(PlayerType::Moderator, PlayerType::Normal),
+				.perm(PlayerType::Moderator, PlayerType::Normal)
+				.needs_update_when_neighbor_changed(),
 		),
 		(0x0c, BlockInfo::new("sand")),
 		(0x0d, BlockInfo::new("gravel")),
@@ -169,6 +185,10 @@ pub struct BlockInfo {
 	pub break_permissions: PlayerType,
 	/// the block used as fallback if the client doesn't support it
 	pub fallback: Option<u8>,
+	/// whether this block needs an update when its neighbor is changed
+	pub needs_update_when_neighbor_changed: bool,
+	/// whether this block may receive random ticks
+	pub may_receive_random_ticks: bool,
 }
 
 impl BlockInfo {
@@ -180,6 +200,8 @@ impl BlockInfo {
 			place_permissions: PlayerType::Normal,
 			break_permissions: PlayerType::Normal,
 			fallback: None,
+			needs_update_when_neighbor_changed: false,
+			may_receive_random_ticks: false,
 		}
 	}
 
@@ -202,6 +224,18 @@ impl BlockInfo {
 		self.fallback = Some(fallback);
 		self
 	}
+
+	/// marks this block as needing updates when its neighbor is changed
+	pub const fn needs_update_when_neighbor_changed(mut self) -> Self {
+		self.needs_update_when_neighbor_changed = true;
+		self
+	}
+
+	/// makes this block capable of receiving random ticks and marks it as eligible when placed
+	pub const fn may_receive_random_ticks(mut self) -> Self {
+		self.may_receive_random_ticks = true;
+		self
+	}
 }
 
 /// types of blocks
@@ -233,13 +267,4 @@ impl BlockType {
 			_ => false,
 		}
 	}
-
-	/// gets whether this block type needs an update when one of it's direct neighbors changes
-	#[allow(clippy::match_like_matches_macro)]
-	pub fn needs_update_when_neighbor_changed(&self) -> bool {
-		match self {
-			BlockType::FluidStationary { .. } => true,
-			_ => false,
-		}
-	}
 }

src/server.rs

@@ -3,20 +3,23 @@ pub(crate) mod network;
 
 use std::{path::PathBuf, sync::Arc};
 
+use rand::{seq::SliceRandom, Rng};
 use tokio::{net::TcpListener, sync::RwLock};
 
 use crate::{
 	error::GeneralError,
 	level::{
 		block::{
-			BlockType, BLOCK_INFO, ID_LAVA_FLOWING, ID_LAVA_STATIONARY, ID_STONE, ID_WATER_FLOWING,
+			BlockType, BLOCK_INFO, ID_DIRT, ID_GRASS, ID_LAVA_FLOWING, ID_LAVA_STATIONARY,
-			ID_WATER_STATIONARY,
+			ID_STONE, ID_WATER_FLOWING, ID_WATER_STATIONARY,
 		},
 		BlockUpdate, Level,
 	},
 	packet::server::ServerPacket,
 	player::Player,
-	util::neighbors_minus_up,
+	util::{
+		get_relative_coords, neighbors_full, neighbors_minus_up, neighbors_with_vertical_diagonals,
+	},
 	CONFIG_FILE,
 };
 
@@ -209,12 +212,68 @@ fn tick(data: &mut ServerData, tick: usize) {
 
 	let mut packets = level.apply_updates();
 
+	// apply random tick updates
+	let mut rng = rand::thread_rng();
+	level.possible_random_updates.shuffle(&mut rng);
+	for _ in 0..level.level_rules.random_tick_updates {
+		if let Some(index) = level.possible_random_updates.pop() {
+			level.awaiting_update.insert(index);
+		} else {
+			break;
+		}
+	}
+
 	let awaiting_update = std::mem::take(&mut level.awaiting_update);
 	for index in awaiting_update {
 		let (x, y, z) = level.coordinates(index);
 		let block_id = level.get_block(x, y, z);
 		let block = BLOCK_INFO.get(&block_id).expect("should never fail");
 		match &block.block_type {
+			BlockType::Solid => {
+				if block_id == ID_GRASS {
+					let mut dirt_count = 0;
+					for (nx, ny, nz) in neighbors_with_vertical_diagonals(level, x, y, z) {
+						if level.get_block(nx, ny, nz) == ID_DIRT {
+							// only turn dirt into grass if there's empty space above it
+							if get_relative_coords(level, nx, ny, nz, 0, 1, 0)
+								.map(|(x, y, z)| level.get_block(x, y, z))
+								.is_none_or(|id| id == 0x00)
+							{
+								dirt_count += 1;
+								if rng.gen_range(0..level.level_rules.grass_spread_chance) == 0 {
+									dirt_count -= 1;
+									level.updates.push(BlockUpdate {
+										index: level.index(nx, ny, nz),
+										block: ID_GRASS,
+									});
+								}
+							}
+						}
+					}
+					if get_relative_coords(level, x, y, z, 0, 1, 0)
+						.map(|(x, y, z)| level.get_block(x, y, z))
+						.is_some_and(|id| id != 0x00)
+					{
+						dirt_count += 1;
+						if rng.gen_range(0..level.level_rules.grass_spread_chance) == 0 {
+							dirt_count -= 1;
+							level.updates.push(BlockUpdate {
+								index: level.index(x, y, z),
+								block: ID_DIRT,
+							});
+						}
+					}
+					if dirt_count > 0 {
+						level.possible_random_updates.push(level.index(x, y, z));
+					}
+				} else if block_id == ID_DIRT {
+					for (nx, ny, nz) in neighbors_full(level, x, y, z) {
+						if level.get_block(nx, ny, nz) == ID_GRASS {
+							level.possible_random_updates.push(level.index(nx, ny, nz));
+						}
+					}
+				}
+			}
 			BlockType::FluidFlowing {
 				stationary,
 				ticks_to_spread,

src/server/network.rs

@@ -14,7 +14,10 @@ use tokio::{
 use crate::{
 	command::Command,
 	error::GeneralError,
-	level::{block::BLOCK_INFO, BlockUpdate, Level},
+	level::{
+		block::{BLOCK_INFO, ID_AIR},
+		BlockUpdate, Level,
+	},
 	packet::{
 		client::ClientPacket, server::ServerPacket, ExtBitmask, PacketWriter, ARRAY_LENGTH,
 		EXTENSION_MAGIC_NUMBER, STRING_LENGTH,
@@ -326,7 +329,7 @@ async fn handle_stream_inner(
 					mode,
 					block_type,
 				} => {
-					let block_type = if mode == 0x00 { 0 } else { block_type };
+					let block_type = if mode == 0x00 { ID_AIR } else { block_type };
 					let mut data = data.write().await;
 
 					// kick players if they attempt to place a block out of bounds
@@ -383,6 +386,9 @@ async fn handle_stream_inner(
 					if new_block_info.block_type.needs_update_on_place() {
 						data.level.awaiting_update.insert(index);
 					}
+					if new_block_info.may_receive_random_ticks {
+						data.level.possible_random_updates.push(index);
+					}
 				}
 				ClientPacket::PositionOrientation {
 					_player_id_or_held_block: _,

src/util.rs

@@ -9,10 +9,10 @@ const NEIGHBORS: &[(isize, isize, isize)] = &[
 	(0, 0, 1),
 ];
 
-/// gets a block's direct neighbors which are in the bounds of the level
+// /// gets a block's direct neighbors which are in the bounds of the level
-pub fn neighbors(level: &Level, x: usize, y: usize, z: usize) -> Vec<(usize, usize, usize)> {
+// pub fn neighbors(level: &Level, x: usize, y: usize, z: usize) -> Vec<(usize, usize, usize)> {
-	get_many_relative_coords(level, x, y, z, NEIGHBORS.iter().copied())
+// 	get_many_relative_coords(level, x, y, z, NEIGHBORS.iter().copied())
-}
+// }
 
 /// gets a blocks direct neighbors (excluding above the block) which are in the bounds of the level
 pub fn neighbors_minus_up(
@@ -24,6 +24,38 @@ pub fn neighbors_minus_up(
 	get_many_relative_coords(level, x, y, z, NEIGHBORS.iter().skip(1).copied())
 }
 
+/// gets a block's neighbors (including vertical diagonals) which are in the bounds of the level, i.e. for grass spread
+pub fn neighbors_with_vertical_diagonals(
+	level: &Level,
+	x: usize,
+	y: usize,
+	z: usize,
+) -> Vec<(usize, usize, usize)> {
+	let down = NEIGHBORS
+		.iter()
+		.skip(2)
+		.copied()
+		.map(|(x, _, z)| (x, -1isize, z));
+	let up = NEIGHBORS
+		.iter()
+		.skip(2)
+		.copied()
+		.map(|(x, _, z)| (x, 1isize, z));
+	get_many_relative_coords(
+		level,
+		x,
+		y,
+		z,
+		NEIGHBORS.iter().skip(2).copied().chain(down).chain(up),
+	)
+}
+
+/// gets a block's neighbors, including all diagonals
+pub fn neighbors_full(level: &Level, x: usize, y: usize, z: usize) -> Vec<(usize, usize, usize)> {
+	let iter = (-1..=1).flat_map(|x| (-1..=1).flat_map(move |y| (-1..=1).map(move |z| (x, y, z))));
+	get_many_relative_coords(level, x, y, z, iter)
+}
+
 /// adds relative coordinates to the given ones, returning `None` if the coordinates would be out of bounds for hte level
 pub fn get_relative_coords(
 	level: &Level,