Complete section 4.7, using maze generation to build a map

src/map_builders/maze.rs

@@ -0,0 +1,274 @@
+use super::MapBuilder;
+use super::{generate_voronoi_spawn_regions, remove_unreachable_areas_returning_most_distant};
+use crate::{spawner, Map, Position, TileType, SHOW_MAPGEN_VISUALIZER};
+use rltk::RandomNumberGenerator;
+use specs::prelude::*;
+use std::cmp::{max, min};
+use std::collections::HashMap;
+
+pub struct MazeBuilder {
+    map: Map,
+    starting_position: Position,
+    depth: i32,
+    history: Vec<Map>,
+    noise_areas: HashMap<i32, Vec<usize>>,
+}
+
+impl MapBuilder for MazeBuilder {
+    fn build_map(&mut self) {
+        self.build();
+    }
+
+    fn spawn_entities(&mut self, ecs: &mut World) {
+        for area in self.noise_areas.iter() {
+            spawner::spawn_region(ecs, area.1, self.depth);
+        }
+    }
+
+    fn get_map(&self) -> Map {
+        self.map.clone()
+    }
+
+    fn get_starting_position(&self) -> Position {
+        self.starting_position
+    }
+
+    fn get_snapshot_history(&self) -> Vec<Map> {
+        self.history.clone()
+    }
+
+    fn take_snapshot(&mut self) {
+        if SHOW_MAPGEN_VISUALIZER {
+            let mut snapshot = self.map.clone();
+            for v in snapshot.revealed_tiles.iter_mut() {
+                *v = true;
+            }
+            self.history.push(snapshot);
+        }
+    }
+}
+
+impl MazeBuilder {
+    pub fn new(new_depth: i32) -> MazeBuilder {
+        MazeBuilder {
+            map: Map::new(new_depth),
+            starting_position: Position { x: 0, y: 0 },
+            depth: new_depth,
+            history: Vec::new(),
+            noise_areas: HashMap::new(),
+        }
+    }
+
+    #[allow(clippy::map_entry)]
+    fn build(&mut self) {
+        let mut rng = RandomNumberGenerator::new();
+
+        // Maze gen
+        let mut maze = Grid::new(
+            (self.map.width / 2) - 2,
+            (self.map.height / 2) - 2,
+            &mut rng,
+        );
+        maze.generate_maze(self);
+
+        self.starting_position = Position { x: 2, y: 2 };
+        let start_idx = self
+            .map
+            .xy_idx(self.starting_position.x, self.starting_position.y);
+        self.take_snapshot();
+
+        // Find all tiles we can reach from the starting point
+        let exit_tile = remove_unreachable_areas_returning_most_distant(&mut self.map, start_idx);
+        self.take_snapshot();
+
+        // Place the stairs
+        self.map.tiles[exit_tile] = TileType::DownStairs;
+        self.take_snapshot();
+
+        // Now we build a noise map for use in spawning entities later
+        self.noise_areas = generate_voronoi_spawn_regions(&self.map, &mut rng);
+    }
+}
+
+const TOP: usize = 0;
+const RIGHT: usize = 1;
+const BOTTOM: usize = 2;
+const LEFT: usize = 3;
+
+#[derive(Copy, Clone)]
+struct Cell {
+    row: i32,
+    column: i32,
+    walls: [bool; 4],
+    visited: bool,
+}
+
+impl Cell {
+    fn new(row: i32, column: i32) -> Cell {
+        Cell {
+            row,
+            column,
+            walls: [true, true, true, true],
+            visited: false,
+        }
+    }
+
+    fn remove_walls(&mut self, next: &mut Cell) {
+        let x = self.column - next.column;
+        let y = self.row - next.row;
+
+        if x == 1 {
+            self.walls[LEFT] = false;
+            next.walls[RIGHT] = false;
+        } else if x == -1 {
+            self.walls[RIGHT] = false;
+            next.walls[LEFT] = false;
+        } else if y == 1 {
+            self.walls[TOP] = false;
+            next.walls[BOTTOM] = false;
+        } else if y == -1 {
+            self.walls[BOTTOM] = false;
+            next.walls[TOP] = false;
+        }
+    }
+}
+
+struct Grid<'a> {
+    width: i32,
+    height: i32,
+    cells: Vec<Cell>,
+    backtrace: Vec<usize>,
+    current: usize,
+    rng: &'a mut RandomNumberGenerator,
+}
+
+impl<'a> Grid<'a> {
+    fn new(width: i32, height: i32, rng: &mut RandomNumberGenerator) -> Grid {
+        let mut grid = Grid {
+            width,
+            height,
+            cells: Vec::new(),
+            backtrace: Vec::new(),
+            current: 0,
+            rng,
+        };
+
+        for row in 0..height {
+            for column in 0..width {
+                grid.cells.push(Cell::new(row, column));
+            }
+        }
+
+        grid
+    }
+
+    fn calculate_index(&self, row: i32, column: i32) -> i32 {
+        if row < 0 || column < 0 || column > self.width - 1 || row > self.height - 1 {
+            -1
+        } else {
+            column + (row * self.width)
+        }
+    }
+
+    fn get_available_neighbors(&self) -> Vec<usize> {
+        let mut neighbors: Vec<usize> = Vec::new();
+
+        let current_row = self.cells[self.current].row;
+        let current_column = self.cells[self.current].column;
+
+        let neighbor_indices: [i32; 4] = [
+            self.calculate_index(current_row - 1, current_column),
+            self.calculate_index(current_row, current_column + 1),
+            self.calculate_index(current_row + 1, current_column),
+            self.calculate_index(current_row, current_column - 1),
+        ];
+
+        for i in neighbor_indices.iter() {
+            if *i != -1 && !self.cells[*i as usize].visited {
+                neighbors.push(*i as usize);
+            }
+        }
+
+        neighbors
+    }
+
+    fn find_next_cell(&mut self) -> Option<usize> {
+        let neighbors = self.get_available_neighbors();
+        if !neighbors.is_empty() {
+            return if neighbors.len() == 1 {
+                Some(neighbors[0])
+            } else {
+                Some(neighbors[(self.rng.roll_dice(1, neighbors.len() as i32) - 1) as usize])
+            };
+        }
+
+        None
+    }
+
+    fn generate_maze(&mut self, generator: &mut MazeBuilder) {
+        let mut i = 0;
+        loop {
+            self.cells[self.current].visited = true;
+
+            match self.find_next_cell() {
+                Some(next) => {
+                    self.cells[next].visited = true;
+                    self.backtrace.push(self.current);
+
+                    //   __lower_part__      __higher_part_
+                    //   /            \      /            \
+                    // --------cell1------ | cell2-----------
+                    let (lower_part, higher_part) =
+                        self.cells.split_at_mut(max(self.current, next));
+                    let cell1 = &mut lower_part[min(self.current, next)];
+                    let cell2 = &mut higher_part[0];
+
+                    cell1.remove_walls(cell2);
+                    self.current = next;
+                }
+                None => {
+                    if !self.backtrace.is_empty() {
+                        self.current = self.backtrace[0];
+                        self.backtrace.remove(0);
+                    } else {
+                        break;
+                    }
+                }
+            }
+
+            if i % 50 == 0 {
+                self.copy_to_map(&mut generator.map);
+                generator.take_snapshot();
+            }
+            i += 1;
+        }
+    }
+
+    fn copy_to_map(&self, map: &mut Map) {
+        // Clear the map
+        for i in map.tiles.iter_mut() {
+            *i = TileType::Wall;
+        }
+
+        for cell in self.cells.iter() {
+            let x = cell.column + 1;
+            let y = cell.row + 1;
+            let idx = map.xy_idx(x * 2, y * 2);
+
+            map.tiles[idx] = TileType::Floor;
+
+            if !cell.walls[TOP] {
+                map.tiles[idx - map.width as usize] = TileType::Floor;
+            }
+            if !cell.walls[RIGHT] {
+                map.tiles[idx + 1] = TileType::Floor
+            }
+            if !cell.walls[BOTTOM] {
+                map.tiles[idx + map.width as usize] = TileType::Floor
+            }
+            if !cell.walls[LEFT] {
+                map.tiles[idx - 1] = TileType::Floor
+            }
+        }
+    }
+}

src/map_builders/mod.rs

@@ -3,6 +3,7 @@ mod bsp_interior;
 mod cellular_automata;
 mod common;
 mod drunkard;
+mod maze;
 mod simple_map;
 
 use crate::{Map, Position};
@@ -11,6 +12,7 @@ use bsp_interior::BspInteriorBuilder;
 use cellular_automata::CellularAutomataBuilder;
 use common::*;
 use drunkard::DrunkardsWalkBuilder;
+use maze::MazeBuilder;
 use simple_map::SimpleMapBuilder;
 use specs::prelude::*;
 
@@ -25,13 +27,14 @@ pub trait MapBuilder {
 
 pub fn random_builder(new_depth: i32) -> Box<dyn MapBuilder> {
     let mut rng = rltk::RandomNumberGenerator::new();
-    match rng.roll_dice(1, 7) {
+    match rng.roll_dice(1, 8) {
         1 => Box::new(BspDungeonBuilder::new(new_depth)),
         2 => Box::new(BspInteriorBuilder::new(new_depth)),
         3 => Box::new(CellularAutomataBuilder::new(new_depth)),
         4 => Box::new(DrunkardsWalkBuilder::open_area(new_depth)),
         5 => Box::new(DrunkardsWalkBuilder::open_halls(new_depth)),
         6 => Box::new(DrunkardsWalkBuilder::winding_passages(new_depth)),
+        7 => Box::new(MazeBuilder::new(new_depth)),
         _ => Box::new(SimpleMapBuilder::new(new_depth)),
     }
 }