refactors mapgen into chained builders

src/map_builders/voronoi_spawning.rs

@@ -0,0 +1,48 @@
+use super::{spawner, BuilderMap, MetaMapBuilder, TileType};
+use rltk::RandomNumberGenerator;
+use std::collections::HashMap;
+
+pub struct VoronoiSpawning {}
+
+impl MetaMapBuilder for VoronoiSpawning {
+    fn build_map(&mut self, rng: &mut rltk::RandomNumberGenerator, build_data: &mut BuilderMap) {
+        self.build(rng, build_data);
+    }
+}
+
+impl VoronoiSpawning {
+    #[allow(dead_code)]
+    pub fn new() -> Box<VoronoiSpawning> {
+        Box::new(VoronoiSpawning {})
+    }
+
+    #[allow(clippy::map_entry)]
+    fn build(&mut self, rng: &mut RandomNumberGenerator, build_data: &mut BuilderMap) {
+        let mut noise_areas: HashMap<i32, Vec<usize>> = HashMap::new();
+        let mut noise = rltk::FastNoise::seeded(rng.roll_dice(1, 65536) as u64);
+        noise.set_noise_type(rltk::NoiseType::Cellular);
+        noise.set_frequency(0.08);
+        noise.set_cellular_distance_function(rltk::CellularDistanceFunction::Manhattan);
+
+        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);
+                if build_data.map.tiles[idx] == TileType::Floor {
+                    let cell_value_f = noise.get_noise(x as f32, y as f32) * 10240.0;
+                    let cell_value = cell_value_f as i32;
+
+                    if noise_areas.contains_key(&cell_value) {
+                        noise_areas.get_mut(&cell_value).unwrap().push(idx);
+                    } else {
+                        noise_areas.insert(cell_value, vec![idx]);
+                    }
+                }
+            }
+        }
+
+        // Spawn the entities
+        for area in noise_areas.iter() {
+            spawner::spawn_region(&build_data.map, rng, area.1, build_data.map.depth, &mut build_data.spawn_list);
+        }
+    }
+}