OffTopic... doesn't OLX have support for hardware rendering as well? I mean the "Use OpenGL rendering"
It uses OpenGL and thus at some places some hardware blitting instead of software blitting but not to full extend as it would have been possible.
Some preparation was done to extend it even more whereby at some places, some pixel manipulations would still be needed (e.g. particle effects, blood, carving, etc.). Also, since 0.59, much more pixel-based effects has been introduced, e.g. lighting, shadows, map distortion, etc. They are quite hard to replace by OpenGL -- at least some shader programming would be needed. But even then, e.g. you can do pixel effects in your Lua map/mod scripts now, that would be faster if we do it all in software at that level. Or you can even do custom visual map distortion via Lua.
So, the plan was that most of the effects on this level (also blood, carving, etc.) would all be in software and then some clever way to get it from there into the GPU (clever = amount of transfered data is minimized) and then all the other blitting is done there.
I guess this is similar to how Jason did it.