basis for random subsystem

Sources/Voxelotl/CMakeLists.txt

@@ -3,8 +3,6 @@ add_executable(Voxelotl MACOSX_BUNDLE
 
   test.png
 
-  Chunk.swift
-
   shadertypes.h
   shader.metal
 
@@ -14,12 +12,17 @@ add_executable(Voxelotl MACOSX_BUNDLE
   AABB.swift
   Color.swift
 
+  Random/RandomProvider.swift
+  Random/Arc4Random.swift
+
   NSImageLoader.swift
   Renderer.swift
   GameController.swift
+  FPSCalculator.swift
+
+  Chunk.swift
   Camera.swift
   Player.swift
-  FPSCalculator.swift
   GameDelegate.swift
   Application.swift
 
@@ -61,3 +64,4 @@ set_source_files_properties(test.png PROPERTIES MACOSX_PACKAGE_LOCATION Resource
 
 source_group("Resources" FILES Assets.xcassets test.png)
 source_group("Source Files" REGULAR_EXPRESSION "\\.(swift|metal)$")
+source_group("Source Files\\Random" REGULAR_EXPRESSION "Random/")

Sources/Voxelotl/Game.swift

@@ -1,5 +1,4 @@
 import simd
-import Foundation
 
 struct Instance {
   let position: SIMD3<Float>
@@ -26,6 +25,7 @@ class Game: GameDelegate {
   var player = Player()
   var projection: matrix_float4x4 = .identity
   var chunk = Chunk(position: .zero)
+  var random = Arc4Random.instance
 
   init() {
     player.position = SIMD3(0.5, Float(Chunk.chunkSize) + 0.5, 0.5)
@@ -37,8 +37,8 @@ class Game: GameDelegate {
       .magenta, .yellow, .cyan
     ]
     chunk.fill(allBy: {
-      if (arc4random() & 0x1) == 0x1 {
-        .solid(colors[Int(arc4random_uniform(UInt32(colors.count)))])
+      if (random.next() & 0x1) == 0x1 {
+        .solid(colors[random.next(in: 0..<colors.count)])
       } else {
         .air
       }
@@ -86,7 +86,9 @@ class Game: GameDelegate {
           color:    Color<Float16>(color).linear)
       } else { nil }
     }
-    renderer.batch(instances: instances, camera: self.camera)
+    if !instances.isEmpty {
+      renderer.batch(instances: instances, camera: self.camera)
+    }
   }
 
   func resize(_ size: Size<Int>) {

Sources/Voxelotl/Random.swift

@@ -1,8 +0,0 @@
-//
-//  Random.swift
-//  voxelotl
-//
-//  Created by a dinosaur on 20/8/2024.
-//
-
-import Foundation

Sources/Voxelotl/Random/Arc4Random.swift

@@ -0,0 +1,24 @@
+import Foundation
+
+public class Arc4Random: RandomProvider {
+  public typealias Output = UInt32
+
+  public static var min: UInt32 { 0x00000000 }
+  public static var max: UInt32 { 0xFFFFFFFF }
+
+  private init() {}
+  public static let instance = Arc4Random()
+
+  public func stir() {
+    arc4random_stir()
+  }
+
+  public func next() -> UInt32 {
+    arc4random()
+  }
+
+  public func next(in bound: Range<Int>) -> Int {
+    assert(bound.upperBound <= Self.max)
+    return bound.lowerBound + Int(arc4random_uniform(UInt32(bound.upperBound)))
+  }
+}

Sources/Voxelotl/Random/RandomProvider.swift

@@ -0,0 +1,8 @@
+public protocol RandomProvider {
+  associatedtype Output: FixedWidthInteger
+
+  static var min: Output { get }
+  static var max: Output { get }
+
+  mutating func next() -> Output
+}