glReadBuffer

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. Further more, the constants GL_COLOR_ATTACHMENT i may be used to indicate the i 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 .

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.

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.

glGet with argument GL_READ_BUFFER

glCopyTexImage1D , glCopyTexImage2D , glCopyTexSubImage1D , glCopyTexSubImage2D , glCopyTexSubImage3D , glDrawBuffer , glReadPixels

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