Fix the build; test box subdivisions

Terrain.xcodeproj/project.pbxproj

@@ -591,6 +591,7 @@
 					"$(inherited)",
 					"@executable_path/../Frameworks",
 				);
+				MTL_HEADER_SEARCH_PATHS = Terrain2;
 				PRODUCT_BUNDLE_IDENTIFIER = me.erynwells.Terrain2;
 				PRODUCT_NAME = "$(TARGET_NAME)";
 				PROVISIONING_PROFILE_SPECIFIER = "";
@@ -613,6 +614,7 @@
 					"$(inherited)",
 					"@executable_path/../Frameworks",
 				);
+				MTL_HEADER_SEARCH_PATHS = Terrain2;
 				PRODUCT_BUNDLE_IDENTIFIER = me.erynwells.Terrain2;
 				PRODUCT_NAME = "$(TARGET_NAME)";
 				PROVISIONING_PROFILE_SPECIFIER = "";

Terrain2/Algorithms.swift

@@ -132,54 +132,68 @@ public class DiamondSquareAlgorithm: Algorithm {
         let origin: Point
         let size: Size
 
-        public init(origin o: Point, size s: Size) {
+        init(origin o: Point, size s: Size) {
             origin = o
             size = s
         }
 
-        public var corners: [Point] {
+        var corners: [Point] {
             return [northwest, southwest, northeast, northwest]
         }
 
-        public var sideMidpoints: [Point] {
+        var sideMidpoints: [Point] {
             return [north, west, south, east]
         }
 
-        public var north: Point {
+        var north: Point {
             return (x: origin.x + (size.w / 2 + 1), y: origin.y)
         }
 
-        public var west: Point {
+        var west: Point {
             return (x: origin.x, y: origin.y + (size.h / 2 + 1))
         }
 
-        public var south: Point {
+        var south: Point {
             return (x: origin.x + (size.w / 2 + 1), y: origin.y + size.h)
         }
 
-        public var east: Point {
+        var east: Point {
             return (x: origin.x + size.w, y: origin.y + (size.h / 2 + 1))
         }
 
-        public var northwest: Point {
+        var northwest: Point {
             return origin
         }
 
-        public var southwest: Point {
+        var southwest: Point {
             return (x: origin.x, y: origin.y + size.h)
         }
 
-        public var northeast: Point {
+        var northeast: Point {
             return (x: origin.x + size.w, y: origin.y)
         }
 
-        public var southeast: Point {
+        var southeast: Point {
             return (x: origin.x + size.w, y: origin.y + size.h)
         }
 
-        public var midpoint: Point {
+        var midpoint: Point {
             return (x: origin.x + (size.w / 2 + 1), y: origin.y + (size.h / 2 + 1))
         }
+
+        var subdivisions: [Box] {
+            guard size.w > 1 && size.h > 1 else {
+                return []
+            }
+            let midp = midpoint
+            let newSize = (w: midp.x - origin.x, h: midp.y - origin.y)
+            return [
+                Box(origin: origin, size: newSize),
+                Box(origin: (origin.x + newSize.w, origin.y), size: newSize),
+                Box(origin: (origin.x, origin.y + newSize.h), size: newSize),
+                Box(origin: (origin.x + newSize.w, origin.y + newSize.h), size: newSize)
+            ]
+        }
     }
     
     let name = "Diamond-Square"
@@ -278,6 +292,15 @@ public class DiamondSquareAlgorithm: Algorithm {
         texture.replace(region: region, mipmapLevel: 0, withBytes: heightMap, bytesPerRow: MemoryLayout<Float>.stride * size.width)
     }
 
+    private func breadthFirstSearch(ofGridWithSize size: MTLSize, visit: (Box) -> (Void)) {
+        var queue = [Box(origin: (0, 0), size: (size.width, size.height))]
+        while queue.count > 0 {
+            let box = queue.removeFirst()
+            visit(box)
+            queue.append(contentsOf: box.subdivisions)
+        }
+    }
+
     // MARK: Algorithm
 
     var outTexture: MTLTexture {
@@ -291,6 +314,12 @@ public class DiamondSquareAlgorithm: Algorithm {
     }
 }
 
+extension DiamondSquareAlgorithm.Box: Equatable {
+    public static func == (lhs: DiamondSquareAlgorithm.Box, rhs: DiamondSquareAlgorithm.Box) -> Bool {
+        return lhs.origin == rhs.origin && lhs.size == rhs.size
+    }
+}
+
 /// Implementation of the Circles algorithm.
 //class CirclesAlgorithm: Algorithm {
 //    static let name = "Circles"

Terrain2Tests/AlgorithmsTests.swift

@@ -7,7 +7,15 @@
 //
 
 import XCTest
-import Terrain2
+@testable import Terrain2
+
+public typealias Box = DiamondSquareAlgorithm.Box
+public typealias Point = DiamondSquareAlgorithm.Box.Point
+public typealias Size = DiamondSquareAlgorithm.Box.Size
+
+class DiamondSquareBFSTests: XCTestCase {
+
+}
 
 class DiamondSquareBoxTests: XCTestCase {
     func testNorthwest() {
@@ -49,4 +57,14 @@ class DiamondSquareBoxTests: XCTestCase {
         XCTAssertEqual(midpoint.x, 6)
         XCTAssertEqual(midpoint.y, 7)
     }
+
+    func testSubdivision() {
+        let box = Box(origin: (x: 3, y: 4), size: (w: 5, h: 5))
+        let subdivs = box.subdivisions
+        XCTAssertEqual(subdivs.count, 4)
+        XCTAssertEqual(subdivs[0], Box(origin: (x: 3, y: 4), size: (w: 3, h: 3)))
+        XCTAssertEqual(subdivs[1], Box(origin: (x: 6, y: 4), size: (w: 3, h: 3)))
+        XCTAssertEqual(subdivs[2], Box(origin: (x: 3, y: 7), size: (w: 3, h: 3)))
+        XCTAssertEqual(subdivs[3], Box(origin: (x: 6, y: 7), size: (w: 3, h: 3)))
+    }
 }