Investigating SFML for graphics…

So, recently I bought a new laptop. And with it being a new year and all, I thought this might be a good opportunity to get back to some Knights development (something that, sadly, I haven’t had much time for these last few months). So, I installed the latest Visual Studio onto the laptop, set up the Knights code directory, and prepared to do some coding…

… and immediately hit a problem. The game would not build. Partly this was because the Microsoft compiler now supports C++11 (the latest version of the C++ language), which caused a few incompatibilities with my code (admittedly this was mostly my fault though!). And partly it was because Microsoft have changed the way DirectX works – in particular, “D3DX” is no longer a supported technology. Unfortunately for me, I had some code that was using D3DX… which now no longer compiles. Grr. (At least on Linux, once you get your code working, it tends to stay working… 🙁 )

Well, I could just fix my DirectX code, but I thought it would be better in the long run to bite the bullet and set up a proper cross-platform solution for graphics. (The initial reason why I added DirectX support to Knights was just as a quick way of testing out hardware-accelerated graphics on Windows; it was never meant as a permanent solution.)

So, if one is looking for a modern 2D graphics library there seem to be two choices: SDL2 and SFML. I had a look at both of these, it seems to me that they both do roughly the same thing, but they have different kinds of API – SFML tries to be more modern and object-oriented and so on, while SDL is more “old school” with low-level C-style functions and structs and things. Personally I prefer the former, so I decided to try out SFML.

I have to say, I was not disappointed – SFML was very easy to set up and integrate into the game and seems to work very well. Performance was much faster than software rendering, although admittedly slightly slower than I got from my DirectX code (not sure why this is; presumably it’s just the overhead of having an extra library in between you and the graphics card; in any event, it’s not that big a deal and I think it’s a price worth paying given how easy to work with SFML is).

I also had some small keyboard handling problems with SFML (e.g. it seems the ` key – the “team chat” key in Knights – is not recognized, but I think I can work around that).

Overall, therefore, I hope to have the SFML integration work done in the next few days, which means the next version of Knights will support fast hardware-accelerated graphics in both Windows and Linux. (As a side note, there is also a problem on some Windows machines where the Knights DirectX graphics doesn’t work if you don’t have the right DirectX runtime libraries installed… that should also be fixed by the move to SFML.)

For more information about Knights please visit http://www.knightsgame.org.uk/.