Nuclex Signal/Slot Library: Benchmarks

When you’re writing some code that needs to notify code in othe r parts of the program, your weapon of choice is the "signal / slot concept". A signal is a connection point where any interested party can register a callback function to be invoked when the signal emits/fires.

There’s already an ocean of libraries out there providing this functionality to C++, but as you will see in this article, they’re all suffering from performance issues in one way or other. Plus, most don’t compile without warnings, have inconvenient sytax or lack unit tests.

So here’s the signal/slot "library" (it’s just three headers) I wrote to fix those issues for me, together with a summary of my design goals and a comprehensive benchmark on different compilers and CPUs.

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How Many Watts Does a Power Supply Need?

This post has been sitting in my queue for a little too long, but maybe it helps someone out there. In 2016 I last upgraded my PC and went for a beefy system that would speed up my renders and game engine lighting builds (in this case, the more cores, the better).

I went for a dual socket motherboard and two Xeon CPUs rated at 130 Watts each. And I added the back then top-of-the-line GPU, an NVidia GeForce GTX 1080, rated at 180 Watts.

Picture of a dual CPU motherboard with water coolers mounted on a table-like wood construction

So how big should my PSU be?

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Engine Trouble

I’ve known Unity since 2007 but only started using it seriously in 2013. At that time, a hobbyist shopping for quality engines could either go with one of the Open Source projects, UDK (3) or Unity 4.

While the workflow was very unusual for someone used to code-centric engines where your main working environment is an IDE and perhaps a wonky level editor that lets you place things in the world, Unity was a huge productivity gain.

The interface between game code and engine was very tidy (necessarily so because game code is written in .NET rather than the engine’s C++ but the Unity developers also had good taste in API design). Thus I purchased a Unity 4 Pro license for 1500 Euros (it was an early adopter license: use Unity 3 Pro now, switch to Unity 4 Pro as soon as it is released).

Two years later, Unity announced the interation of Enlighten into Unity 5, promising real-time global illumination. I took the early adopter offer again, 600 Euros for a Unity 5 Pro license for existing customers. There were some issues with new lighting system, but overall, the integration is pretty well done.

Screenshot of my Unity licenses, showing two 3.x and one 5.x Pro license

Early Unity

Until this point, I was very happy with Unity’s business model:

  • rather than collect royalties, I paid an (admittedly large) sum of money and never had to worry about sending sales numbers to Unity Technologies or other bureaucracy.

  • major engine versions became (mostly) stable targets to develop against and after feature development ceased, there was still 1+ year of bugfixing going on, leaving those major releases in a pretty robust sunset state.

  • lastly, it was classical business: UT builds the product I want, I pay them to get it. If they want me to pay again, they need to improve their product so I consider it worthwhile to pay for the next version.

Late Unity

Sadly, during the last years, things took a depressing turn towards “Economy 2.0”

  • In late 2013, ex EA CEO Riccitiello joins the board of directors at Unity Technologies. I have seen no public releases revealing who pushed for what in Unity’s board of directors, but I believe to see the EA CEO’s handwriting in many of the changes, resembling directional changes at EA.

  • In early 2014, Unity Technologies acquires Applifier, a company owning a mobile video ad network.

  • Also in 2014, Unity Technologies acquires Playnomics, a company offering telemetry services for software.

  • In late 2014, Riccitiello advanced from board member to CEO of Unity Technologies, replacing CEO David Helgason.

  • Early 2015, Unity suddenly gives away their bread-winning features for free. While many of us Unity users expected a reaction to Epic offering Unreal Engine 4 for merely $20 per month, this was a strange turn, especially since for most of Unity 5’s beta phase, the licensing terms remained in a state of flux.

  • In 2015, Unity Technologies acquired ecommerce business SilkCloud which has had many dealings with EA developing advertising, shop and mobile device account systems.

  • Still 2015, Unity Technologies introduces Unity Analytics, a telemetry solution as a service directly from Unity Technologies.

  • In 2016, Unity enters the certification business, offering paid certificates for Unity developers.

  • Also in 2016, with Unity 5.3, micro-transactions are natively integrated as “Unity IAP.”

  • Also in 2016, Unity introduces more services. You now get “Unity Ads,” “Unity Analytics,” “Unity Cloud Builds,” and “Unity Collaborate” all from one hand.

  • Still in 2016, the future licensing model becomes clearer: perpetual licenses will be discontinued; for $35 monthly (the $600 upgrade to Unity 5 translated into $25 monthly over its 2 year lifecycle) you get saddled with a revenue cap and can’t disable telemetry anymore while having the same feature set as the free version. Major versions are replaced with a rolling release model.

Quo Vadis?

From the business direction, what I am seeing here is:

  • Unity Technologies has quit the traditional economy. Rather than create features (packaged into major versions) and sell them to customers, the customers sign a contract (subscription) and will pay for whatever Unity decides to do or not do.

    It’s not as bad as the Windows 10 business model yet, where Microsoft can essentially do whatever they want to their OS, customers will download it and install it with no choice, but it’s close enough.

  • The basic product is free, revenue now needs to come from taking a share from advertising and micro-transactions (thus the Unity Ads and Unity IAP features) and services sold to developers.

    This way, Unity’s business now squarely depends on the toxic business model of money-grabbing mobile games.

  • For its services, Unity Technologies now has a lot of recurring costs paying for servers (content distribution for video ads, telemetry storage space, beefy cloud build servers, etc.)

Developer PoV

As a game developer, further worries this creates are:

  • The rolling release model is pretty ugly on the Asset Store. There never was support for downloading older versions of assets, but with rolling releases this has become a real problem. If you stay with Unity 5 for example, pretty soon all your script asset purchases are worthless because they all target Unity 2017.

  • Unity always had slight image problem. Not because the engine is bad, but because of the low barrier to entry allowing inexperiences developers to release very poorly made games.

    With Unity being completely free for everyone, this will get worse. With Unity being the engine behind most ad-supported and/or IAP cash-grabs on mobile devices, this will get worse again.

  • I like to pay small development teams for features. What am I paying for when I subscribe for $35 or $125? Will I pay for the development of useful engine features or for server rent to process the IAPs of some poor suckers?

    I hope Unity Technologies will continue to invest in cutting-edge features (like Enlighten was for Unity 5), but I do not see a strong business case for Unity Technologies to do anything more than just stay relevant with their current model.


These two concerns have so far prevented me from upgrading to Unity 2017.

I have purchased a large number of assets on the asset store, so this would be a big loss, but I also don’t feel comfortable with the direction Unity is heading and want to jump ship as soon as possible.

I have been looking into Unreal Engine 4 since 2015. It is capable of flashy results, but the technical foundation looks rather weak (everything is integrated with everything, where does the engine stop and the gameplay framework start? why do assets opaquely store their IDs with their data?).

Furthermore, I ran into real obvious showstopper bugs everywhere as late as 4.14. Lately things have been getting better, however.

So now I’m sitting here, unsure of when would be the right time to abandon Unity. Should I go with the 2017 license for 12 months and then switch.


I’ve also been looking into Open Source engines again.

Ogre3D has taken a nosedive in quality since the original project lead left,
Horde3D looks abandoned,
Atomic Engine is lacking Linux support (for its editor), but
Urho3D is in great shape and
Godot Engine might be a good choice, too.

Running on Bad Memory

Being able to rely on your memory is one of the most important aspects of having a stable PC. Thus, paying extra for premium memory seemed like a wise choice to me.

Yet I have been surprisingly unlucky with my memory.

In this post I’ll show how to identify broken memory cells and how to prevent Windows and Linux from accessing them, resulting in a stable system while discarding only a few Kilobytes of memory.

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Using Wacom Touch Gestures in Unsupported Applications

I’ve recently made the decision to learn some drawing skills. Specifically, I wanted to start with a tablet right away so I could avoid having to re-teach myself to using a tablet instead of paper. However, I still consider it important to be able to shift and rotate the canvas with my hand, so I went for a Wacom tablet with touch.

Most artists I knew swear by Paint Tool SAI, but that just happens to be one of the applications not fully supported by Wacom’s drivers (pressure works fine, but touch is a no-go). Luckily, Wacom’s drivers are pretty flexible and you can easily modify them to support your favorite application.

Here’s a guide to enable pinch-zoom, panning and two-finger rotation in Paint Tool SAI and Manga Studio!

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Simple Main Window Class

Here’s another fairly trivial code snippet. I’ve stumbled across some borked attempts at initializing and maintaining rendering windows for games lately. Most failed to properly respond to window messages, either ignoring WM_CLOSE outright or letting DefWindowProc() call DestroyWindow() when WM_CLOSE was received, thereby not giving the rest of the game’s code any time to cleanly shut down before the window handle becomes invalid.

So I’ll provide a clean and well-behaved window class here. It doesn’t use any global variables – in fact, you could create any number of windows from any number of threads. WM_CLOSE simply causes the class’ WasCloseRequested() method to return true, so by polling this method you can first shut down graphics and input devices and then destroy the window in an orderly fashion.

For your convenience I also added some helper methods: one resizes the window in a way that ensures the client area will actually end up with the exact pixel size requested. Another will center the window on the screen without messing up if the user has extended his desktop over multiple monitors.

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Thread-Safe Random Access to Zip Archives

Many games choose to store their resources in packages instead of shipping the potentially thousands of individual files directly. This is sometimes an attempt at tamper-proofing, but mostly it is about performance. Try copying a thousand 1 KiB files from one drive to another, then copy a single 1 MiB file on the same way – the former operation will take many times longer.

A good choice for a package format is the well known .zip archive. It’s not necessarily well-designed, but it decompresses fast and you definitely won’t have any problems finding tools to create, modify and extract .zip archives. Thus, when I started work on a file system abstraction layer for my future games, seamless .zip support was one of my main goals (I may also add 7-Zip at a later time just for fun).

Here is the design I came up with after exploring the file system APIs available on Windows, WinRT and Linux:

UML diagram showing the design of my file system abstraction layer

You may notice some rather radical design choices in my File class: there are no Open() or Close() methods and there is no Seek() method, either – each read or write specifies the absolute position without requiring the file to be opened.

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Ogre 1.8.0 for WinRT/Metro

Ogre 3D Logo

In March I provided some binaries of Ogre 1.8.0 RC1 that were based on Eugene’s Metro port of Ogre, allowing Ogre to run as a native Metro App, using the Direct3D 11 renderer and RTShaderSystem for dynamic shader generation.

Those binaries no longer work with the Windows 8 Release Preview and Visual Studio 2012 RC, so I thought I’d provide an updated package!

Screenshot of Ogre 1.8.0 on Windows 8 Release Preview running as a Metro app

This time I went a bit further: while the last package was compiled with multithreading disabled, I have in the meantime ported Boost 1.50.0 to compile on WinRT (using a slightly modified version of Shawn Hargreaves’ WinRT CreateThread emulation code. Thus, this Ogre build has full support for multithreading and includes Boost!

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Code Better: Headers without Hidden Dependencies

When you work on a larger project, you cannot easily keep track of which header depends on which other header. You can (and should) do your best to keep the number of other headers referenced inside your headers low (to speed up compilation) and move as many header dependencies as you can into your source files, but this still doesn’t prevent you from building headers that implicitly depend on another header being included before them.

Take this example:

#ifndef MAP_H
#define MAP_H
/// <summary>Stores the tiles of a 2D map<summary>
struct Map {};
#endif // MAP_H
#ifndef WORLD_H
#define WORLD_H
#include "Actor.h"
#include <vector>
// Oops, forgot Map.h, but won't notice since World.cpp includes Map.h before World.h
/// <summary>Maintains the state of the entire world<summary>
struct World {
  /// <summary>Stores the map as a grid of 2D tiles</summary>
  public: Map Map;
  /// <summary>Actors (player, monsters, etc.) currently active in the world</summary>
  public: std::vector<Actor *> Actors;
#endif // WORLD_H

Throughout your project, map.h might always end up being included before world.h and you might never notice that if someone included world.h on its own, a nasty compilation error would be the result.

So what can you do ensure this situation never happens?

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How to Delete Directories Recursively with Win32

Well, while I’m at it, here’s the counterpart to the recursive directory creation function from my last post, a function that recursively deletes a directory and all its contents.

Ordinarily, you could just use the shell API to achieve this on classic Win32:

/// <summary>Deletes a directory and everything in it</summary>
/// <param name="path">Path of the directory that will be deleted</param>
void deleteDirectory(const std::wstring &path) {
  std::vector<std::wstring::value_type> doubleNullTerminatedPath;
  std::copy(path.begin(), path.end(), std::back_inserter(doubleNullTerminatedPath));
  SHFILEOPSTRUCTW fileOperation;
  fileOperation.wFunc = FO_DELETE;
  fileOperation.pFrom = &doubleNullTerminatedPath[0];
  fileOperation.fFlags = FOF_NO_UI | FOF_NOCONFIRMATION;
  int result = ::SHFileOperationW(&fileOperation);
  if(result != 0) {
    throw std::runtime_error("Could not delete directory");

But WinRT/Metro applications cannot use the shell API and have to do it manually. So here’s a piece of code that takes care of directory deletion using nothing but Win32 API calls that are also available to WinRT/Metro applications:

/// <summary>Automatically closes a search handle upon destruction</summary>
class SearchHandleScope {
  /// <summary>Initializes a new search handle closer</summary>
  /// <param name="searchHandle">Search handle that will be closed on destruction</param>
  public: SearchHandleScope(HANDLE searchHandle) :
    searchHandle(searchHandle) {}
  /// <summary>Closes the search handle</summary>
  public: ~SearchHandleScope() {
  /// <summary>Search handle that will be closed when the instance is destroyed</summary>
  private: HANDLE searchHandle;
/// <summary>Recursively deletes the specified directory and all its contents</summary>
/// <param name="path">Absolute path of the directory that will be deleted</param>
/// <remarks>
///   The path must not be terminated with a path separator.
/// </remarks>
void recursiveDeleteDirectory(const std::wstring &path) {
  static const std::wstring allFilesMask(L"\\*");
  WIN32_FIND_DATAW findData;
  // First, delete the contents of the directory, recursively for subdirectories
  std::wstring searchMask = path + allFilesMask;
  HANDLE searchHandle = ::FindFirstFileExW(
    searchMask.c_str(), FindExInfoBasic, &findData, FindExSearchNameMatch, nullptr, 0
  if(searchHandle == INVALID_HANDLE_VALUE) {
    DWORD lastError = ::GetLastError();
      throw std::runtime_error("Could not start directory enumeration");
  // Did this directory have any contents? If so, delete them first
  if(searchHandle != INVALID_HANDLE_VALUE) {
    SearchHandleScope scope(searchHandle);
    for(;;) {
      // Do not process the obligatory '.' and '..' directories
      if(findData.cFileName[0] != '.') {
        bool isDirectory = 
          ((findData.dwFileAttributes & FILE_ATTRIBUTE_DIRECTORY) != 0) ||
          ((findData.dwFileAttributes & FILE_ATTRIBUTE_REPARSE_POINT) != 0);
        // Subdirectories need to be handled by deleting their contents first
        std::wstring filePath = path + L'\\' + findData.cFileName;
        if(isDirectory) {
        } else {
          BOOL result = ::DeleteFileW(filePath.c_str());
          if(result == FALSE) {
            throw std::runtime_error("Could not delete file");
      // Advance to the next file in the directory
      BOOL result = ::FindNextFileW(searchHandle, &findData);
      if(result == FALSE) {
        DWORD lastError = ::GetLastError();
        if(lastError != ERROR_NO_MORE_FILES) {
          throw std::runtime_error("Error enumerating directory");
        break; // All directory contents enumerated and deleted
    } // for
  // The directory is empty, we can now safely remove it
  BOOL result = ::RemoveDirectory(path.c_str());
  if(result == FALSE) {
    throw std::runtime_error("Could not remove directory");

This code is free for the taking and you can use it however you want.