GLAPI/glReadBuffer: Difference between revisions
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== Description == | == Description == | ||
'''glReadBuffer''' specifies | '''glReadBuffer''' specifies which color buffer within the current bound {{enum|GL_READ_FRAMEBUFFER}} will be used as the source for pixel reading commands. These commands include: {{apifunc|glBlitFramebuffer}}, {{apifunc|glReadPixels}}, {{apifunc|glCopyTexImage1D}}, {{apifunc|glCopyTexImage2D}}, {{apifunc|glCopyTexSubImage1D}}, {{apifunc|glCopyTexSubImage2D}}, and {{apifunc|glCopyTexSubImage3D}}. | ||
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 | {{param|mode}} accepts one of twelve or more predefined values. If the [[default framebuffer]] (the zero [[framebuffer object]])is bound to {{enum|GL_READ_FRAMEBUFFER}}, then the following enumerators can be used: {{enum|GL_FRONT}}, {{enum|GL_LEFT}}, and {{enum|GL_FRONT_LEFT}} all name the front left buffer, {{enum|GL_FRONT_RIGHT}} and {{enum|GL_RIGHT}} name the front right buffer, and {{enum|GL_BACK_LEFT}} and {{enum|GL_BACK}} name the back left buffer. 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. | ||
{{param|mode}} is initially {{enum|GL_FRONT}} in single-buffered configurations and {{enum|GL_BACK}} in double-buffered configurations. | If a non-zero framebuffer object is bound, then the constants {{enum|GL_COLOR_ATTACHMENT''i''}} may be used to indicate the ''i''<sup>th</sup> color attachment, where ''i'' ranges from zero to the value of {{enum|GL_MAX_COLOR_ATTACHMENTS}} minus one. | ||
It is an error to specify a nonexistent buffer to '''glReadBuffer'''. | |||
For the default framebuffer, {{param|mode}} is initially {{enum|GL_FRONT}} in single-buffered configurations and {{enum|GL_BACK}} in double-buffered configurations. For framebuffer objects, the default read buffer is {{enum|GL_COLOR_ATTACHMENT0}}. | |||
== Errors == | == Errors == | ||
Revision as of 17:05, 15 July 2012
| Core in version | 4.6 | |
|---|---|---|
| Core since version | 1.0 | |
glReadBuffer: select a color buffer source for pixels
Function Definition
void glReadBuffer(GLenum mode);
- 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
glReadBuffer specifies which color buffer within the current bound GL_READ_FRAMEBUFFER will be used as the source for pixel reading commands. These commands include: glBlitFramebuffer, glReadPixels, glCopyTexImage1D, glCopyTexImage2D, glCopyTexSubImage1D, glCopyTexSubImage2D, and glCopyTexSubImage3D.
mode accepts one of twelve or more predefined values. If the default framebuffer (the zero framebuffer object)is bound to GL_READ_FRAMEBUFFER, then the following enumerators can be used: 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. 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.
If a non-zero framebuffer object is bound, then 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.
It is an error to specify a nonexistent buffer to glReadBuffer.
For the default framebuffer, mode is initially GL_FRONT in single-buffered configurations and GL_BACK in double-buffered configurations. For framebuffer objects, the default read buffer is GL_COLOR_ATTACHMENT0.
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.
Associated Gets
glGet with argument GL_READ_BUFFER
See Also
glCopyTexImage1D, glCopyTexImage2D, glCopyTexSubImage1D, glCopyTexSubImage2D, glCopyTexSubImage3D, glDrawBuffer, glReadPixels
Copyright
Copyright © 1991-2006 Silicon Graphics, Inc. Copyright © 2011 Khronos Group. This document is licensed under the SGI Free Software B License. For details, see http://oss.sgi.com/projects/FreeB/.