GUI: First Prototype

After some more work on the GUI system, I decided to capture a little video. Unfortunatley the mouse cursor wasn’t captured, so it may look a bit weird.

Up to now I have implemented Window, Text and Button elements. Windows can be resized and moved at will and may hold any number of the other GUI elements. The Text element supports strings which are formatted with basic HTML syntax. The text can be left, right, top, bottom aligned or centered. Buttons have various attachment points for callbacks which can be either written in C/C++ or Python script.


NX-Engine progress

While still doing some Python integration I started working on several other parts of the engine.

1. Ported from SDL 1.2 to SFML 2.0

Up to now the engine used SDL 1.2 as it’s wrapper around low level stuff like creating windows and getting events. This worked ok so far but had some major drawbacks:

  • SDL is licensed under LGPL. While still an opensource license and far better than GPL, it is only allowed to dynamically link against the library.
  • SDL 1.2 isn’t able to create OpenGL 3+ contexts.
  • The source code isn’t as clean and readable as I would wish. (C code)

I was aware of SFML for quite a while and while the 2.0 version is still in development and has some bugs it offers clear advantages:

  • Lincense is zlib/png which is awesome because it allows dynamic/static linking + pretty much total freedom.
  • It is possible to create OpenGL 3+ contexts.
  • Source code is very nice and clean. (C++ object oriented)

So I got rid of SDL and plugged SFML into the engine. To my suprise this was easier than I thought and the whole process was smoothly done in a few hours. Maybe a sign for a good engine structure? I hope so!

While SFML has it’s benefits there was some drawbacks aswell. 1. Image loading support isn’t as good as SDL_image and 2. SFML doesn’t support condition variables for thread synchronization. I worked around this problems by integrating DevIL for image loading and porting all threading stuff to boost::thread.

DevIL is an excellent library with an absolutley lovely API which is pretty much the same as OpenGL. It offers support for an amazing range of picture formats and perfectly fits the needs of the engine.

2. gDEBugger fun and optimizations

If you haven’t heard of gDEBugger yet, it is an OpenGL profiler, analyzer, debugger with some nice features. It was recently made available for free and every OpenGL programmer should grab a copy immediately. With the help of this program I was able to optimize the renderer in the engine quite a bit by removing redundant GL calls. The results of 1 hour work were an increase of the FPS in valgrind’s memcheck by the factor 2,5x !

3. Actors for the engine

I started to implement some actor stuff in the engine. Up to know this allows the creation and deletion of objects through script. Next steps are moving things around by script commands and coupling of the system with the scene graph.