GLXMAKECURRENT(3G)

✨ GLXMAKECURRENT ✨

okay bestie, so this is glXMakeCurrent — the GLX function that attaches a GLX context to a window or a GLX pixmap. it's giving "let me bind this thing to that thing" and honestly it's a whole vibe. it lives in the section 3G manual, and yes, we're doing the full tour, no skipping 💅

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🌸 C SPECIFICATION 🌸

Bool glXMakeCurrent( Display *dpy,
                     GLXDrawable drawable,
                     GLXContext ctx )

delim $$

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🎀 PARAMETERS 🎀

• dpy — the connection to the X server. your little phone line to the server, basically 💖
• drawable — a GLX drawable. it has to be either an X window ID or a GLX pixmap ID, no third option, that's the rule 🦋
• ctx — the GLX rendering context that's getting attached to drawable. the main character, fr 👑

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💫 DESCRIPTION 💫

glXMakeCurrent does two things at once, and she's multitasking:

1. it makes ctx the current GLX rendering context of the calling thread — replacing whatever context was previously current, if there was one
2. it attaches ctx to a GLX drawable, which is either a window or a GLX pixmap

and because of those two little actions, every GL rendering call after this point uses rendering context ctx to modify GLX drawable drawable. iconic behavior ✨

because glXMakeCurrent always replaces the current rendering context with ctx, there can be only one current context per thread. that's not a suggestion, that's the law 🫶

pending commands to the previous context, if there are any, get flushed before it's released. so nothing gets left on read 😭

the first time ctx is made current to any thread, its viewport gets set to the full size of drawable. after that, subsequent calls by any thread to glXMakeCurrent with ctx have no effect on its viewport. one and done, periodt 💅

to release the current context without assigning a new one, call glXMakeCurrent with drawable set to None and ctx set to NULL. free her 🌈

glXMakeCurrent returns True if it's successful, False otherwise. and if False comes back, the previously current rendering context and drawable (if any) remain unchanged — no harm done, everything stays exactly where it was 💜

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🧚 NOTES 🧚

let's get our vocabulary straight, bestie:

• a process is a single-execution environment, implemented in a single address space, consisting of one or more threads.
• a thread is one of a set of subprocesses that share a single address space, but maintain separate program counters, stack spaces, and other related global data. and a thread that is the only member of its subprocess group is equivalent to a process. iykyk 🦋

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💀 ERRORS 💀

these are the ways it can go wrong. read them, love them, respect them.

• BadMatch — generated if drawable was not created with the same X screen and visual as ctx. it's also generated if drawable is None and ctx is not NULL. double duty, lowkey 🙈
• BadAccess — generated if ctx was current to another thread at the time glXMakeCurrent was called. sharing is not caring here 😭
• GLXBadDrawable — generated if drawable is not a valid GLX drawable.
• GLXBadContext — generated if ctx is not a valid GLX context.
• GLXBadContextState — generated if glXMakeCurrent is executed between the execution of glBegin and the corresponding execution of glEnd. finish your sentence before you interrupt, bestie 🎀
• GLXBadContextState — also generated if the rendering context current to the calling thread has GL renderer state GL_FEEDBACK or GL_SELECT.
• GLXBadCurrentWindow — generated if there are pending GL commands for the previous context and the current drawable is a window that is no longer valid.
• BadAlloc — may be generated if the server has delayed allocation of ancillary buffers until glXMakeCurrent is called, only to find that it has insufficient resources to complete the allocation. the server fumbled the bag, not you 🫠

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👑 SEE ALSO 👑

• glXCreateContext
• glXCreateGLXPixmap

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okay that's the whole page, no cap 💖 this was GLXMAKECURRENT() from the GLX manual, section 3G — that's the title up top and the footer down bottom, and now you have both. go forth and bind your contexts, bestie, you're gonna slay 🦋✨🎀