feat(mapgen): add shared carving primitives

src/gen/carve.lua

@@ -0,0 +1,46 @@
+-- Shared carving primitives used by the room, bsp and prefab generators.
+-- Operate on any object exposing set(x, y, glyph); no dependency on Map itself
+-- so the generators can require this without a cycle.
+
+local Tiles = require("tiles")
+
+local Carve = {}
+
+function Carve.rect(map, x, y, w, h, glyph)
+  glyph = glyph or Tiles.FLOOR
+  for cy = y, y + h - 1 do
+    for cx = x, x + w - 1 do
+      map:set(cx, cy, glyph)
+    end
+  end
+end
+
+function Carve.hTunnel(map, x1, x2, y, glyph)
+  glyph = glyph or Tiles.FLOOR
+  for x = math.min(x1, x2), math.max(x1, x2) do
+    map:set(x, y, glyph)
+  end
+end
+
+function Carve.vTunnel(map, y1, y2, x, glyph)
+  glyph = glyph or Tiles.FLOOR
+  for y = math.min(y1, y2), math.max(y1, y2) do
+    map:set(x, y, glyph)
+  end
+end
+
+function Carve.center(room)
+  return room.x + room.w // 2, room.y + room.h // 2
+end
+
+function Carve.corridor(map, ax, ay, bx, by, rng, glyph)
+  if rng:chance(1, 2) then
+    Carve.hTunnel(map, ax, bx, ay, glyph)
+    Carve.vTunnel(map, ay, by, bx, glyph)
+  else
+    Carve.vTunnel(map, ay, by, ax, glyph)
+    Carve.hTunnel(map, ax, bx, by, glyph)
+  end
+end
+
+return Carve