TurtleBrains now with Linux Support

Upon starting TurtleBrains it was planned to support many major platforms. Not so recently Linux support was added, actually TurtleBrains had been compiling on Linux, and even running with #define tb_legacy_gl_forced in tbi_renderer.h (or compilation settings). This of course is not very

user friendly, and it seemed to have a few issues with text so a game was never actually released, nor support claimed.

The issue for several months (probably close to 9 of them) was an inability to create the the OpenGL 3.2 Core context. After combing through the code for two days, and comparing against several tutorials and having help from the #LudumDare irc channel, the issue finally emerged.

[cpp]
int contextAttributes[] = {
GLX_CONTEXT_PROFILE_MASK_ARB, contextProfileBit,
GLX_CONTEXT_MAJOR_VERSION_ARB, glVersion.mMajor,
GLX_CONTEXT_MINOR_VERSION_ARB, glVersion.mMinor,
GLX_NONE //Incorrect. This should be: None, or 0
};
[/cpp]

Not being super familiar with the platform/GLX I had unknowingly used GLX_NONE to represent the end of the contextAttributes array that would be passed to create the 3.2 Core context. The value of GLX_NONE is NOT zero.

I repeat; NOT ZERO

This actually caused a really weird crash that, with CodeLite IDE debugger, (aka GDB), appeared to be an issue calling the glXCreateContextAttribsARB function, and I got hung up thinking the function pointer was invalid. The actual error was attempting to access memory out of bounds since GLX_NONE was not signifying the end of the attributes array.

After fixing this issue I was able to make an experimental Linux build of my LD36 game, Ancient Robots.