rust-rl/src/map_builders/cellular_automata.rs

use super::{ BuilderMap, InitialMapBuilder, MetaMapBuilder, TileType };
use bracket_lib::prelude::*;

pub struct CellularAutomataBuilder {
    floor_tile: TileType,
}

impl InitialMapBuilder for CellularAutomataBuilder {
    #[allow(dead_code)]
    fn build_map(&mut self, rng: &mut RandomNumberGenerator, build_data: &mut BuilderMap) {
        self.build(rng, build_data);
    }
}

impl MetaMapBuilder for CellularAutomataBuilder {
    #[allow(dead_code)]
    fn build_map(&mut self, _rng: &mut RandomNumberGenerator, build_data: &mut BuilderMap) {
        self.apply_iteration(build_data);
    }
}

impl CellularAutomataBuilder {
    #[allow(dead_code)]
    pub fn new() -> Box<CellularAutomataBuilder> {
        Box::new(CellularAutomataBuilder { floor_tile: TileType::Floor })
    }
    pub fn floor(floor_tile: TileType) -> Box<CellularAutomataBuilder> {
        Box::new(CellularAutomataBuilder { floor_tile })
    }

    #[allow(clippy::map_entry)]
    fn build(&mut self, rng: &mut RandomNumberGenerator, build_data: &mut BuilderMap) {
        // First we completely randomize the map, setting 55% of it to be floor.
        for y in 1..build_data.map.height - 1 {
            for x in 1..build_data.map.width - 1 {
                let roll = rng.roll_dice(1, 100);
                let idx = build_data.map.xy_idx(x, y);
                if roll > 55 {
                    build_data.map.tiles[idx] = TileType::Floor;
                } else {
                    build_data.map.tiles[idx] = TileType::Wall;
                }
            }
        }
        build_data.take_snapshot();

        // Now we iteratively apply cellular automata rules
        for _i in 0..15 {
            self.apply_iteration(build_data);
        }
    }

    fn apply_iteration(&mut self, build_data: &mut BuilderMap) {
        let mut newtiles = build_data.map.tiles.clone();

        for y in 1..build_data.map.height - 1 {
            for x in 1..build_data.map.width - 1 {
                let idx = build_data.map.xy_idx(x, y);
                let mut neighbors = 0;
                if build_data.map.tiles[idx - 1] == TileType::Wall {
                    neighbors += 1;
                }
                if build_data.map.tiles[idx + 1] == TileType::Wall {
                    neighbors += 1;
                }
                if build_data.map.tiles[idx - (build_data.map.width as usize)] == TileType::Wall {
                    neighbors += 1;
                }
                if build_data.map.tiles[idx + (build_data.map.width as usize)] == TileType::Wall {
                    neighbors += 1;
                }
                if
                    build_data.map.tiles[idx - ((build_data.map.width as usize) - 1)] ==
                    TileType::Wall
                {
                    neighbors += 1;
                }
                if
                    build_data.map.tiles[idx - ((build_data.map.width as usize) + 1)] ==
                    TileType::Wall
                {
                    neighbors += 1;
                }
                if
                    build_data.map.tiles[idx + ((build_data.map.width as usize) - 1)] ==
                    TileType::Wall
                {
                    neighbors += 1;
                }
                if
                    build_data.map.tiles[idx + ((build_data.map.width as usize) + 1)] ==
                    TileType::Wall
                {
                    neighbors += 1;
                }

                if neighbors > 4 || neighbors == 0 {
                    newtiles[idx] = TileType::Wall;
                } else {
                    newtiles[idx] = self.floor_tile;
                }
            }
        }

        build_data.map.tiles = newtiles.clone();
        build_data.take_snapshot();
    }
}