GLREADBUFFER(3G)

hiii bestie 💖 welcome to the GLREADBUFFER(3G) page — that's the page for the 3G manual, and the original header's manual-name slot is literally [FIXME: manual] 😭. this one's all about picking which color buffer your pixel reads come from, and honestly it's more iconic than it sounds ✨.

💖 NAME 💖

glReadBuffer, glNamedFramebufferReadBuffer — select a color buffer source for pixels.

✨ C SPECIFICATION ✨

the signatures, exactly as served:

void glReadBuffer(GLenum mode);

void glNamedFramebufferReadBuffer(GLuint framebuffer, GLenum mode);

🎀 PARAMETERS 🎀

• framebuffer — specifies the name of the framebuffer object for the glNamedFramebufferReadBuffer function.
• mode — specifies a color buffer. Accepted values are GL_FRONT_LEFT, GL_FRONT_RIGHT, GL_BACK_LEFT, GL_BACK_RIGHT, GL_FRONT, GL_BACK, GL_LEFT, GL_RIGHT, and the constants GL_COLOR_ATTACHMENTi.

🦋 DESCRIPTION 🦋

okay so glReadBuffer specifies a color buffer as the source for subsequent glReadPixels(), glCopyTexImage1D(), glCopyTexImage2D(), glCopyTexSubImage1D(), glCopyTexSubImage2D(), and glCopyTexSubImage3D() commands. mode accepts one of twelve or more predefined values. In a fully configured system, GL_FRONT, GL_LEFT, and GL_FRONT_LEFT all name the front left buffer, GL_FRONT_RIGHT and GL_RIGHT name the front right buffer, and GL_BACK_LEFT and GL_BACK name the back left buffer. Also, the constants GL_COLOR_ATTACHMENTi may be used to indicate the ith color attachment where i ranges from zero to the value of GL_MAX_COLOR_ATTACHMENTS minus one.

Nonstereo double-buffered configurations have only a front left and a back left buffer. Single-buffered configurations have a front left and a front right buffer if stereo, and only a front left buffer if nonstereo. It is an error to specify a nonexistent buffer to glReadBuffer — lowkey do not do that 🙈.

mode is initially GL_FRONT in single-buffered configurations and GL_BACK in double-buffered configurations.

For glReadBuffer, the target framebuffer object is that bound to GL_READ_FRAMEBUFFER. For glNamedFramebufferReadBuffer, framebuffer must either be zero or the name of the target framebuffer object. If framebuffer is zero, then the default read framebuffer is affected.

💀 ERRORS 💀

• GL_INVALID_ENUM is generated if mode is not one of the twelve (or more) accepted values.
• GL_INVALID_OPERATION is generated if mode specifies a buffer that does not exist.
• GL_INVALID_OPERATION is generated by glNamedFramebufferReadBuffer if framebuffer is not zero or the name of an existing framebuffer object.

🔥 ASSOCIATED GETS 🔥

glGet() with argument GL_READ_BUFFER — that's the associated get, bestie.

🌈 VERSION SUPPORT 🌈

the original table has columns for OpenGL Version and rows for Function / Feature Name, so here's the whole vibe translated into bullets ✨:

• glNamedFramebufferReadBuffer — 2.0 -; 2.1 -; 3.0 -; 3.1 -; 3.2 -; 3.3 -; 4.0 -; 4.1 -; 4.2 -; 4.3 -; 4.4 -; 4.5 ✔
• glReadBuffer — 2.0 ✔; 2.1 ✔; 3.0 ✔; 3.1 ✔; 3.2 ✔; 3.3 ✔; 4.0 ✔; 4.1 ✔; 4.2 ✔; 4.3 ✔; 4.4 ✔; 4.5 ✔

💜 SEE ALSO 💜

• glCopyTexImage1D()
• glCopyTexImage2D()
• glCopyTexSubImage1D()
• glCopyTexSubImage2D()
• glCopyTexSubImage3D()
• glDrawBuffer()
• glReadPixels()

👑 COPYRIGHT 👑

Copyright © 1991-2006 Silicon Graphics, Inc. Copyright © 2011-2014 Khronos Group. This document is licensed under the SGI Free Software B License. For details, see http://oss.sgi.com/projects/FreeB/.

👑 COPYRIGHT (the sequel) 👑

Copyright © 1991-2006 Silicon Graphics, Inc.

Copyright © 2011-2014 Khronos Group

okay bye bestie 🫶 — the original footer says source [FIXME: source], version/date 08/09/2021, and title GLREADBUFFER(3G), so that's the whole page. go forth and select your color buffer 💅✨