Work on restructuring world generator API

We need to be able to spawn entities from the generator function, both
as level props and as enemies; the previous API makes this impossible,
so I'm working on restructuring it. Not too happy with it yet, still
needs more work.

src/level.rs

@@ -1,22 +1,35 @@
 use std::fmt::Display;
 
 use pancurses::Window;
+use rand::{thread_rng, Rng};
+use specs::prelude::*;
 
-use crate::rooms;
+use crate::{
+    components::{CharRender, Position},
+    rooms,
+};
 
 /// The size of a dungeon level, in tiles.
 pub const LEVEL_SIZE: (usize, usize) = (80, 24);
 
 /// A single level of the dungeon.
+#[derive(Clone)]
 pub struct DungeonLevel {
     /// The tiles at every position in the level.
     tiles: [[DungeonTile; LEVEL_SIZE.0]; LEVEL_SIZE.1],
 
+    /// The locations of the level's exits.
+    exits: LevelExits,
+}
+
+/// The entrances and exits from a level.
+#[derive(Clone)]
+pub struct LevelExits {
     /// The location of each of the up-staircases.
-    upstairs: Vec<(i32, i32)>,
+    pub upstairs: Vec<(i32, i32)>,
 
     /// The location of each of the down-staircases.
-    downstairs: Vec<(i32, i32)>,
+    pub downstairs: Vec<(i32, i32)>,
 }
 
 /// The smallest measurable independent location in the dungeon,
@@ -49,26 +62,45 @@ impl DungeonTile {
 }
 
 impl DungeonLevel {
-    /// Creates a new level in a branch that has the given
-    /// configuration.
-    pub fn new() -> Self {
-        rooms::generate_level(100, &mut rand::thread_rng(), 1, 1)
-    }
-
     /// Creates a new level with the given set of tiles, upstairs, and
     /// downstairs.
-    pub fn from_raw_parts(
+    pub fn new(
         tiles: [[DungeonTile; LEVEL_SIZE.0]; LEVEL_SIZE.1],
         upstairs: Vec<(i32, i32)>,
         downstairs: Vec<(i32, i32)>,
     ) -> Self {
         Self {
             tiles,
-            upstairs,
-            downstairs,
+            exits: LevelExits {
+                upstairs,
+                downstairs,
+            },
         }
     }
 
+    /// Creates a new level and registers it with the given world.
+    pub fn generate_level(world: &mut World) -> LevelExits {
+        let level = rooms::generate_level(100, &mut thread_rng(), 1, 1);
+        world.insert(level.clone()); // inefficient but whatever
+
+        // Spawn some zombies in the world.
+        for _ in 0..20 {
+            let (x, y) = (
+                thread_rng().gen_range(0..LEVEL_SIZE.0 as _),
+                thread_rng().gen_range(0..LEVEL_SIZE.1 as _),
+            );
+            if level.tile(x, y).is_navigable() {
+                world
+                    .create_entity()
+                    .with(Position { x, y })
+                    .with(CharRender { glyph: 'Z' })
+                    .build();
+            }
+        }
+
+        level.exits
+    }
+
     /// Draws a level on the display window.
     pub fn draw(&self, win: &Window) {
         for y in 0..LEVEL_SIZE.1 {
@@ -130,16 +162,6 @@ impl DungeonLevel {
     pub fn tile(&self, x: i32, y: i32) -> &DungeonTile {
         &self.tiles[y as usize][x as usize]
     }
-
-    /// Gets the list of up-stairs.
-    pub fn upstairs(&self) -> &[(i32, i32)] {
-        &self.upstairs
-    }
-
-    /// Gets the list of down-stairs.
-    pub fn downstairs(&self) -> &[(i32, i32)] {
-        &self.downstairs
-    }
 }
 
 impl Display for DungeonLevel {

src/main.rs

@@ -20,8 +20,8 @@ fn main() {
 
     register_all(&mut world);
 
-    let level = DungeonLevel::new();
-    let spawn_pos = level.upstairs()[0];
+    let level = DungeonLevel::generate_level(&mut world);
+    let spawn_pos = level.upstairs[0];
 
     world.insert(level);
 

src/rooms.rs

@@ -93,7 +93,7 @@ pub fn generate_level(
         *slot = value;
     }
 
-    DungeonLevel::from_raw_parts(data, upstairs, downstairs)
+    DungeonLevel::new(data, upstairs, downstairs)
 }
 
 /// The bounding box of a room.