mirror of
https://github.com/QB64Official/qb64.git
synced 2024-08-22 05:35:08 +00:00
47 lines
2.8 KiB
Text
47 lines
2.8 KiB
Text
'''_glReadBuffer:''' select a color buffer source for pixel read operations from the current read framebuffer.
|
|
|
|
|
|
{{PageSyntax}}
|
|
|
|
SUB _glReadBuffer (BYVAL mode AS _UNSIGNED LONG)
|
|
void '''_glReadBuffer'''(GLenum {{Parameter|mode}});
|
|
|
|
|
|
; mode
|
|
: Specifies a color buffer. Accepted values are {{KW|_GL_FRONT_LEFT}}, {{KW|_GL_FRONT_RIGHT}}, {{KW|_GL_BACK_LEFT}}, {{KW|_GL_BACK_RIGHT}}, {{KW|_GL_FRONT}}, {{KW|_GL_BACK}}, {{KW|_GL_LEFT}}, {{KW|_GL_RIGHT}}, and the constants {{KW|_GL_COLOR_ATTACHMENT''i''}}.
|
|
|
|
|
|
{{PageDescription}}
|
|
|
|
'''_glReadBuffer''' specifies which color buffer within the current bound {{KW|_GL_READ_FRAMEBUFFER}} will be used as the source for pixel reading commands. These commands include: {{KW|_glBlitFramebuffer}}, {{KW|_glReadPixels}}, {{KW|_glCopyTexImage1D}}, {{KW|_glCopyTexImage2D}}, {{KW|_glCopyTexSubImage1D}}, {{KW|_glCopyTexSubImage2D}}, and {{KW|_glCopyTexSubImage3D}}.
|
|
|
|
{{Parameter|mode}} accepts one of twelve or more predefined values. If the [[default framebuffer]] (the zero [[framebuffer object]])is bound to {{KW|_GL_READ_FRAMEBUFFER}}, then the following enumerators can be used: {{KW|_GL_FRONT}}, {{KW|_GL_LEFT}}, and {{KW|_GL_FRONT_LEFT}} all name the front left buffer, {{KW|_GL_FRONT_RIGHT}} and {{KW|_GL_RIGHT}} name the front right buffer, and {{KW|_GL_BACK_LEFT}} and {{KW|_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 {{KW|_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 {{KW|_GL_MAX_COLOR_ATTACHMENTS}} minus one.
|
|
|
|
It is an error to specify a nonexistent buffer to '''_glReadBuffer'''.
|
|
|
|
For the default framebuffer, {{Parameter|mode}} is initially {{KW|_GL_FRONT}} in single-buffered configurations and {{KW|_GL_BACK}} in double-buffered configurations. For framebuffer objects, the default read buffer is {{KW|_GL_COLOR_ATTACHMENT0}}.
|
|
|
|
|
|
{{PageErrors}}
|
|
|
|
{{KW|_GL_INVALID_ENUM}} is generated if {{Parameter|mode}} is not one of the twelve (or more) accepted values.
|
|
|
|
{{KW|_GL_INVALID_OPERATION}} is generated if {{Parameter|mode}} specifies a buffer that does not exist.
|
|
|
|
|
|
{{PageUseWith}}
|
|
|
|
{{KW|_glGet}} with argument {{KW|_GL_READ_BUFFER}}
|
|
|
|
|
|
{{PageSeeAlso}}
|
|
|
|
[[_GL|SUB _GL]]
|
|
{{KW|_glBindFramebuffer}}, {{KW|_glDrawBuffer}}, {{KW|_glDrawBuffers}}, {{KW|_glReadPixels}}
|
|
|
|
|
|
{{PageCopyright}}
|
|
|
|
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/ http://oss.sgi.com/projects/FreeB/].
|