From c38a8f16294bf65a43ea526fedeecdbff9ef865d Mon Sep 17 00:00:00 2001
From: Timothy Warren <twarren@nabancard.com>
Date: Fri, 3 Dec 2021 10:00:19 -0500
Subject: [PATCH] Implement start of BSP Interior map builder (Section 4.4)

---
 src/map_builders/bsp_dungeon.rs  |   2 +-
 src/map_builders/bsp_interior.rs | 140 +++++++++++++++++++++++++++++++
 src/map_builders/mod.rs          |   2 +
 3 files changed, 143 insertions(+), 1 deletion(-)
 create mode 100644 src/map_builders/bsp_interior.rs

diff --git a/src/map_builders/bsp_dungeon.rs b/src/map_builders/bsp_dungeon.rs
index 33fff2d..362657f 100644
--- a/src/map_builders/bsp_dungeon.rs
+++ b/src/map_builders/bsp_dungeon.rs
@@ -3,7 +3,7 @@ use crate::map_builders::common::apply_room_to_map;
 use crate::spawner;
 use crate::{components::Position, Map, Rect, TileType, SHOW_MAPGEN_VISUALIZER};
 use rltk::RandomNumberGenerator;
-use specs::World;
+use specs::prelude::*;
 
 pub struct BspDungeonBuilder {
     map: Map,
diff --git a/src/map_builders/bsp_interior.rs b/src/map_builders/bsp_interior.rs
new file mode 100644
index 0000000..29b142f
--- /dev/null
+++ b/src/map_builders/bsp_interior.rs
@@ -0,0 +1,140 @@
+use super::MapBuilder;
+use crate::map_builders::common::apply_room_to_map;
+use crate::spawner;
+use crate::{components::Position, Map, Rect, TileType, SHOW_MAPGEN_VISUALIZER};
+use rltk::RandomNumberGenerator;
+use specs::prelude::*;
+
+const MIN_ROOM_SIZE: i32 = 8;
+
+pub struct BspInteriorBuilder {
+    map: Map,
+    starting_position: Position,
+    depth: i32,
+    rooms: Vec<Rect>,
+    history: Vec<Map>,
+    rects: Vec<Rect>,
+}
+
+impl MapBuilder for BspInteriorBuilder {
+    fn get_map(&self) -> Map {
+        self.map.clone()
+    }
+
+    fn get_starting_position(&self) -> Position {
+        self.starting_position.clone()
+    }
+
+    fn get_snapshot_history(&self) -> Vec<Map> {
+        self.history.clone()
+    }
+
+    fn build_map(&mut self) {
+        self.build();
+    }
+
+    fn spawn_entities(&mut self, ecs: &mut World) {
+        for room in self.rooms.iter().skip(1) {
+            spawner::spawn_room(ecs, room, self.depth);
+        }
+    }
+
+    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 BspInteriorBuilder {
+    pub fn new(new_depth: i32) -> BspInteriorBuilder {
+        BspInteriorBuilder {
+            map: Map::new(new_depth),
+            starting_position: Position { x: 0, y: 0 },
+            depth: new_depth,
+            rooms: Vec::new(),
+            history: Vec::new(),
+            rects: Vec::new(),
+        }
+    }
+
+    fn build(&mut self) {
+        let mut rng = RandomNumberGenerator::new();
+
+        self.rects.clear();
+
+        // Start with a single map-sized rectangle
+        self.rects
+            .push(Rect::new(1, 1, self.map.width - 2, self.map.height - 2));
+
+        let first_room = self.rects[0];
+        self.add_subrects(first_room, &mut rng); // Divide the first room
+
+        let rooms = self.rects.clone();
+        for r in rooms.iter() {
+            let room = *r;
+
+            self.rooms.push(room);
+            for y in room.y1..room.y2 {
+                for x in room.x1..room.x2 {
+                    let idx = self.map.xy_idx(x, y);
+                    if idx > 0 && idx < ((self.map.width * self.map.height) - 1) as usize {
+                        self.map.tiles[idx] = TileType::Floor;
+                    }
+                }
+            }
+
+            self.take_snapshot();
+        }
+
+        let start = self.rooms[0].center();
+        self.starting_position = start.into();
+    }
+
+    fn add_subrects(&mut self, rect: Rect, rng: &mut RandomNumberGenerator) {
+        // Remove the last rect from the list
+        if !self.rects.is_empty() {
+            self.rects.remove(self.rects.len() - 1);
+        }
+
+        // Calculate boundaries
+        let width = rect.x2 - rect.x1;
+        let height = rect.y2 - rect.y1;
+        let half_width = width / 2;
+        let half_height = height / 2;
+
+        let split = rng.roll_dice(1, 4);
+
+        if split <= 2 {
+            // Horizontal split
+            let h1 = Rect::new(rect.x1, rect.y1, half_width - 1, height);
+            self.rects.push(h1);
+            if half_width > MIN_ROOM_SIZE {
+                self.add_subrects(h1, rng);
+            }
+
+            let h2 = Rect::new(rect.x1 + half_width, rect.y1, half_width, height);
+            self.rects.push(h2);
+            if half_width > MIN_ROOM_SIZE {
+                self.add_subrects(h2, rng);
+            }
+        } else {
+            // Vertical split
+            let v1 = Rect::new(rect.x1, rect.y1, width, half_height - 1);
+            self.rects.push(v1);
+            if half_height > MIN_ROOM_SIZE {
+                self.add_subrects(v1, rng);
+            }
+
+            let v2 = Rect::new(rect.x1, rect.y1 + half_height, width, half_height);
+            self.rects.push(v2);
+            if half_height > MIN_ROOM_SIZE {
+                self.add_subrects(v2, rng);
+            }
+        }
+    }
+}
diff --git a/src/map_builders/mod.rs b/src/map_builders/mod.rs
index 9ae675b..31a6138 100644
--- a/src/map_builders/mod.rs
+++ b/src/map_builders/mod.rs
@@ -1,9 +1,11 @@
 mod bsp_dungeon;
+mod bsp_interior;
 mod common;
 mod simple_map;
 
 use crate::{Map, Position};
 use bsp_dungeon::BspDungeonBuilder;
+use bsp_interior::BspInteriorBuilder;
 use common::*;
 use simple_map::SimpleMapBuilder;
 use specs::prelude::*;