Debug context flag always set about glfw

[elmindreda]

It's a side-effect of a workaround for the fact that some drivers don't set the debug bit of the context flags even when a debug context was created. The workaround checks for GL_ARB_debug_output if the bit isn't set, as that is the only way to tell on those drivers whether a debug context has been created.

I'll see if I can make a better workaround.

[biller23]

Ah.. now it's clear, thanks. Fine, I was only worried about the possible performance penalty of a debug context.

[elmindreda]

Since you (and therefore GLFW) aren't requesting a debug context, there shouldn't be any penalty. It seems your driver is nice and giving you the option of debug output anyway.

[biller23]

I think you're right. With glfw 2.7.9 and debug context disabled, it's sufficient calling glEnable(GL_DEBUG_OUTPUT) to have all the functionality...

[georgevanvenrooij]

I think the code should be modified to reflect the requested window hint:

So in my opinion, this piece of code (in context.c):

                // HACK: This is a workaround for older drivers (pre KHR_debug)
                // not setting the debug bit in the context flags for debug
                // contexts
                window->glDebug = GL_TRUE;

Should be changed to something like this:

                window->glDebug = <the value of the GLFW_OPENGL_DEBUG_CONTEXT hint>;

This way, GLFW doesn't report "unexpected" debug contexts. If a developer wants to check for the presence of the extension, that's up to him/her then.

Alternative, only check for the GL_ARB_debug_output extension if the window hint has been set to GL_TRUE.

[elmindreda]

@georgevanvenrooij The last option was my plan, but apparently I forgot to implement it. I'll fix it in 3.1. Thank you for the reminder.

[elmindreda]

@georgevanvenrooij Fixed with ae8393c. Thank you!