implement on screen virtual controller for iOS

Sources/Voxelotl/Program.swift

@@ -4,14 +4,33 @@ import Foundation
   @objc public static func run() -> Int32 {
     Thread.current.qualityOfService = .userInteractive
 
+    var flags: ApplicationConfiguration.Flags = [ .resizable, .highDPI, .onScreenVirtualController ]
+    if enableFullscreenWindow() {
+      flags = flags.union(.fullscreen)
+    }
+
     let app = Application(
       delegate: Game(),
       configuration: ApplicationConfiguration(
       frame: Size(1280, 720),
       title: "Voxelotl Demo",
-      flags: [ .resizable, .highDPI ],
+      flags: flags,
       vsyncMode: .on(interval: 1)))
 
     return app.run()
   }
+
+  static func enableFullscreenWindow() -> Bool {
+    return Program.isFrontAndCenterGamingDevice()
+  }
+
+  static func isFrontAndCenterGamingDevice() -> Bool {
+#if os(iOS)
+    return !(ProcessInfo.processInfo.isiOSAppOnMac || ProcessInfo.processInfo.isMacCatalystApp)
+#elseif os(tvOS)
+    return true
+#else
+    return false
+#endif
+  }
 }