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pub use grid_2d::{Coord, Grid, Size}; use rand::Rng; #[derive(Debug, Clone, Copy)] enum WallDirection { East, South, } #[derive(Debug, Clone, Copy)] struct Wall { coord: Coord, direction: WallDirection, } impl Wall { fn walls_around(coord: Coord) -> [Wall; 4] { [ Wall { coord, direction: WallDirection::East, }, Wall { coord, direction: WallDirection::South, }, Wall { coord: coord - Coord::new(1, 0), direction: WallDirection::East, }, Wall { coord: coord - Coord::new(0, 1), direction: WallDirection::South, }, ] } fn coords(&self) -> [Coord; 2] { [ self.coord, match self.direction { WallDirection::East => self.coord + Coord::new(1, 0), WallDirection::South => self.coord + Coord::new(0, 1), }, ] } } struct Walls { east: bool, south: bool, } impl Walls { fn get_mut(&mut self, direction: WallDirection) -> &mut bool { match direction { WallDirection::East => &mut self.east, WallDirection::South => &mut self.south, } } } struct GenerationCell { in_maze: bool, seen_walls: Walls, passages: Walls, } impl Default for GenerationCell { fn default() -> Self { Self { in_maze: false, seen_walls: Walls { east: false, south: false, }, passages: Walls { east: false, south: false, }, } } } #[derive(Debug, Clone, Copy)] pub enum MazeCell { Wall, Passage, } pub struct MazeGenerator { grid: Grid<GenerationCell>, walls_to_visit: Vec<Wall>, } impl MazeGenerator { pub fn new(size: Size) -> Self { Self { grid: Grid::new_default(size), walls_to_visit: Vec::new(), } } fn add_wall(&mut self, wall: Wall) { if let Some(cell) = self.grid.get_mut(wall.coord) { let seen = cell.seen_walls.get_mut(wall.direction); if !*seen { *seen = true; self.walls_to_visit.push(wall); } } } fn add_cell_at(&mut self, coord: Coord) { if let Some(cell) = self.grid.get_mut(coord) { if !cell.in_maze { cell.in_maze = true; for &wall in Wall::walls_around(coord).iter() { self.add_wall(wall); } } } } fn add_passage(&mut self, wall: Wall) { if let Some(cell) = self.grid.get_mut(wall.coord) { let passage = cell.passages.get_mut(wall.direction); *passage = true; } } fn process_wall(&mut self, wall: Wall) -> Option<()> { let [coord_a, coord_b] = wall.coords(); let in_maze_a = self.grid.get(coord_a)?.in_maze; let in_maze_b = self.grid.get(coord_b)?.in_maze; if in_maze_a { if in_maze_b { return None; } else { self.add_cell_at(coord_b); } } else { if in_maze_b { self.add_cell_at(coord_a); } else { return None; } } self.add_passage(wall); Some(()) } fn remove_random_wall<R: Rng>(&mut self, rng: &mut R) -> Option<Wall> { if self.walls_to_visit.is_empty() { None } else { let index = rng.gen_range(0..self.walls_to_visit.len()); Some(self.walls_to_visit.swap_remove(index)) } } fn build_maze(&self) -> Grid<MazeCell> { let size = self.grid.size() * 2 - Size::new(1, 1); let mut maze = Grid::new_clone(size, MazeCell::Wall); for (coord, cell) in self.grid.enumerate() { let maze_cell_coord = coord * 2; if cell.in_maze { if let Some(maze_cell) = maze.get_mut(maze_cell_coord) { *maze_cell = MazeCell::Passage; } } if cell.passages.east { let coord = maze_cell_coord + Coord::new(1, 0); if let Some(maze_cell) = maze.get_mut(coord) { *maze_cell = MazeCell::Passage; } } if cell.passages.south { let coord = maze_cell_coord + Coord::new(0, 1); if let Some(maze_cell) = maze.get_mut(coord) { *maze_cell = MazeCell::Passage; } } } maze } pub fn generate<R: Rng>(&mut self, start: Coord, rng: &mut R) -> Grid<MazeCell> { for cell in self.grid.iter_mut() { *cell = GenerationCell::default(); } self.add_cell_at(start); while let Some(wall) = self.remove_random_wall(rng) { self.process_wall(wall); } self.build_maze() } }