GLAPI/glDrawBuffer: Difference between revisions

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== Function Definition ==
== Function Definition ==


   void '''glDrawBuffer'''(GLenum ''mode'');
   void '''glDrawBuffer'''(GLenum {{param|mode}});


; mode
; mode
: Specifies up to four color buffers to be drawn into. Symbolic constants {{code|GL_NONE}}, {{code|GL_FRONT_LEFT}}, {{code|GL_FRONT_RIGHT}}, {{code|GL_BACK_LEFT}}, {{code|GL_BACK_RIGHT}}, {{code|GL_FRONT}}, {{code|GL_BACK}}, {{code|GL_LEFT}}, {{code|GL_RIGHT}}, and {{code|GL_FRONT_AND_BACK}} are accepted. The initial value is {{code|GL_FRONT}} for single-buffered contexts, and {{code|GL_BACK}} for double-buffered contexts.
: Specifies up to four color buffers to be drawn into. Symbolic constants {{enum|GL_NONE}}, {{enum|GL_FRONT_LEFT}}, {{enum|GL_FRONT_RIGHT}}, {{enum|GL_BACK_LEFT}}, {{enum|GL_BACK_RIGHT}}, {{enum|GL_FRONT}}, {{enum|GL_BACK}}, {{enum|GL_LEFT}}, {{enum|GL_RIGHT}}, and {{enum|GL_FRONT_AND_BACK}} are accepted. The initial value is {{enum|GL_FRONT}} for single-buffered contexts, and {{enum|GL_BACK}} for double-buffered contexts.


== Description ==
== Description ==
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When colors are written to the frame buffer, they are written into the color buffers specified by '''glDrawBuffer'''. The specifications are as follows:
When colors are written to the frame buffer, they are written into the color buffers specified by '''glDrawBuffer'''. The specifications are as follows:


; {{code|GL_NONE}}
; {{enum|GL_NONE}}
: No color buffers are written.
: No color buffers are written.
; {{code|GL_FRONT_LEFT}}
; {{enum|GL_FRONT_LEFT}}
: Only the front left color buffer is written.
: Only the front left color buffer is written.
; {{code|GL_FRONT_RIGHT}}
; {{enum|GL_FRONT_RIGHT}}
: Only the front right color buffer is written.
: Only the front right color buffer is written.
; {{code|GL_BACK_LEFT}}
; {{enum|GL_BACK_LEFT}}
: Only the back left color buffer is written.
: Only the back left color buffer is written.
; {{code|GL_BACK_RIGHT}}
; {{enum|GL_BACK_RIGHT}}
: Only the back right color buffer is written.
: Only the back right color buffer is written.
; {{code|GL_FRONT}}
; {{enum|GL_FRONT}}
: Only the front left and front right color buffers are written. If there is no front right color buffer, only the front left color buffer is written.
: Only the front left and front right color buffers are written. If there is no front right color buffer, only the front left color buffer is written.
; {{code|GL_BACK}}
; {{enum|GL_BACK}}
: Only the back left and back right color buffers are written. If there is no back right color buffer, only the back left color buffer is written.
: Only the back left and back right color buffers are written. If there is no back right color buffer, only the back left color buffer is written.
; {{code|GL_LEFT}}
; {{enum|GL_LEFT}}
: Only the front left and back left color buffers are written. If there is no back left color buffer, only the front left color buffer is written.
: Only the front left and back left color buffers are written. If there is no back left color buffer, only the front left color buffer is written.
; {{code|GL_RIGHT}}
; {{enum|GL_RIGHT}}
: Only the front right and back right color buffers are written. If there is no back right color buffer, only the front right color buffer is written.
: Only the front right and back right color buffers are written. If there is no back right color buffer, only the front right color buffer is written.
; {{code|GL_FRONT_AND_BACK}}
; {{enum|GL_FRONT_AND_BACK}}
: All the front and back color buffers (front left, front right, back left, back right) are written. If there are no back color buffers, only the front left and front right color buffers are written. If there are no right color buffers, only the front left and back left color buffers are written. If there are no right or back color buffers, only the front left color buffer is written.
: All the front and back color buffers (front left, front right, back left, back right) are written. If there are no back color buffers, only the front left and front right color buffers are written. If there are no right color buffers, only the front left and back left color buffers are written. If there are no right or back color buffers, only the front left color buffer is written.
If more than one color buffer is selected for drawing, then blending or logical operations are computed and applied independently for each color buffer and can produce different results in each buffer.
If more than one color buffer is selected for drawing, then blending or logical operations are computed and applied independently for each color buffer and can produce different results in each buffer.
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== Errors ==
== Errors ==


{{code|GL_INVALID_ENUM}} is generated if ''mode'' is not an accepted value.
{{enum|GL_INVALID_ENUM}} is generated if {{param|mode}} is not an accepted value.


{{code|GL_INVALID_OPERATION}} is generated if none of the buffers indicated by ''mode'' exists.
{{enum|GL_INVALID_OPERATION}} is generated if none of the buffers indicated by {{param|mode}} exists.


== Associated Gets ==
== Associated Gets ==


[[GLAPI/glGet|glGet]] with argument {{code|GL_DRAW_BUFFER}}
{{apifunc|glGet}} with argument {{enum|GL_DRAW_BUFFER}}


== See Also ==
== See Also ==


[[GLAPI/glBlendFunc|glBlendFunc]], [[GLAPI/glColorMask|glColorMask]], [[GLAPI/glDrawBuffers|glDrawBuffers]], [[GLAPI/glLogicOp|glLogicOp]], [[GLAPI/glReadBuffer|glReadBuffer]]
{{apifunc|glBindFramebuffer}}, {{apifunc|glBlendFunc}}, {{apifunc|glColorMask}}, {{apifunc|glDrawBuffers}}, {{apifunc|glLogicOp}}


== Copyright ==
== Copyright ==


Copyright © 1991-2006 Silicon Graphics, Inc. This document is licensed under the SGI Free Software B License. For details, see [http://oss.sgi.com/projects/FreeB/ http://oss.sgi.com/projects/FreeB/].
Copyright © 1991-2006 Silicon Graphics, Inc. This document is licensed under the SGI Free Software B License. For details, see [https://khronos.org/registry/OpenGL-Refpages/LICENSES/LicenseRef-FreeB.txt LicenseRef-FreeB].


[[Category:Core API Ref Framebuffer Objects|DrawBuffer]]
[[Category:Core API Ref Framebuffer Objects|DrawBuffer]]
[[Category:Core API Reference|DrawBuffer]]
[[Category:Core API Reference|DrawBuffer]]
[[Category:Framebuffer Object API State Functions|DrawBuffer]]

Latest revision as of 21:21, 5 February 2021

glDrawBuffer
Core in version 4.6
Core since version 1.0

glDrawBuffer: specify which color buffers are to be drawn into

Function Definition

 void glDrawBuffer(GLenum mode​);
mode
Specifies up to four color buffers to be drawn into. Symbolic constants GL_NONE, GL_FRONT_LEFT, GL_FRONT_RIGHT, GL_BACK_LEFT, GL_BACK_RIGHT, GL_FRONT, GL_BACK, GL_LEFT, GL_RIGHT, and GL_FRONT_AND_BACK are accepted. The initial value is GL_FRONT for single-buffered contexts, and GL_BACK for double-buffered contexts.

Description

When colors are written to the frame buffer, they are written into the color buffers specified by glDrawBuffer. The specifications are as follows:

GL_NONE
No color buffers are written.
GL_FRONT_LEFT
Only the front left color buffer is written.
GL_FRONT_RIGHT
Only the front right color buffer is written.
GL_BACK_LEFT
Only the back left color buffer is written.
GL_BACK_RIGHT
Only the back right color buffer is written.
GL_FRONT
Only the front left and front right color buffers are written. If there is no front right color buffer, only the front left color buffer is written.
GL_BACK
Only the back left and back right color buffers are written. If there is no back right color buffer, only the back left color buffer is written.
GL_LEFT
Only the front left and back left color buffers are written. If there is no back left color buffer, only the front left color buffer is written.
GL_RIGHT
Only the front right and back right color buffers are written. If there is no back right color buffer, only the front right color buffer is written.
GL_FRONT_AND_BACK
All the front and back color buffers (front left, front right, back left, back right) are written. If there are no back color buffers, only the front left and front right color buffers are written. If there are no right color buffers, only the front left and back left color buffers are written. If there are no right or back color buffers, only the front left color buffer is written.

If more than one color buffer is selected for drawing, then blending or logical operations are computed and applied independently for each color buffer and can produce different results in each buffer.

Monoscopic contexts include only left buffers, and stereoscopic contexts include both left and right buffers. Likewise, single-buffered contexts include only front buffers, and double-buffered contexts include both front and back buffers. The context is selected at GL initialization.

Errors

GL_INVALID_ENUM is generated if mode​ is not an accepted value.

GL_INVALID_OPERATION is generated if none of the buffers indicated by mode​ exists.

Associated Gets

glGet with argument GL_DRAW_BUFFER

See Also

glBindFramebuffer, glBlendFunc, glColorMask, glDrawBuffers, glLogicOp

Copyright

Copyright © 1991-2006 Silicon Graphics, Inc. This document is licensed under the SGI Free Software B License. For details, see LicenseRef-FreeB.

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