Difference between revisions of "GLAPI/glReadBuffer"

From OpenGL.org
Jump to: navigation, search
(Improved description.)
m (Link fix.)
(2 intermediate revisions by 2 users not shown)
Line 4: Line 4:
 
}}
 
}}
  
'''glReadBuffer:''' select a color buffer source for pixels
+
'''glReadBuffer:''' select a color buffer source for pixel read operations from the current read framebuffer.
  
 
== Function Definition ==
 
== Function Definition ==
Line 17: Line 17:
 
'''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}}.
 
'''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}}.
  
{{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}} 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.
  
 
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.
 
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.
Line 37: Line 37:
 
== See Also ==
 
== See Also ==
  
{{apifunc|glCopyTexImage1D}}, {{apifunc|glCopyTexImage2D}}, {{apifunc|glCopyTexSubImage1D}}, {{apifunc|glCopyTexSubImage2D}}, {{apifunc|glCopyTexSubImage3D}}, {{apifunc|glDrawBuffer}}, {{apifunc|glReadPixels}}
+
{{apifunc|glBindFramebuffer}}, {{apifunc|glDrawBuffer}}, {{apifunc|glDrawBuffers}}, {{apifunc|glReadPixels}}
  
 
== Copyright ==
 
== Copyright ==

Revision as of 19:14, 13 February 2013

glReadBuffer
Core in version 4.5
Core since version 1.0

glReadBuffer: select a color buffer source for pixel read operations from the current read framebuffer.

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

glBindFramebuffer, glDrawBuffer, glDrawBuffers, 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/.