glDrawBuffers, glNamedFramebufferDrawBuffers — Specifies a list of color buffers to be drawn into
void glDrawBuffers(
|
GLsizei n, |
const GLenum *bufs); |
void glNamedFramebufferDrawBuffers(
|
GLuint framebuffer, |
| GLsizei n, | |
const GLenum *bufs); |
framebuffer
Specifies the name of the framebuffer object for
glNamedFramebufferDrawBuffers.
n
Specifies the number of buffers in
bufs.
bufs
Points to an array of symbolic constants specifying the buffers into which fragment colors or data values will be written.
glDrawBuffers and glNamedFramebufferDrawBuffers define an array of buffers into
which outputs from the fragment shader data will be written. If a fragment
shader writes a value to one or more user defined output variables, then
the value of each variable will be written into the buffer specified at a
location within bufs corresponding to the location
assigned to that user defined output. The draw buffer used for user
defined outputs assigned to locations greater than or equal to
n is implicitly set to GL_NONE
and any data written to such an output is discarded.
For glDrawBuffers, the framebuffer object that
is bound to the GL_DRAW_FRAMEBUFFER binding will be
used. For glNamedFramebufferDrawBuffers,
framebuffer is the name of the framebuffer object.
If framebuffer is zero, then the default
framebuffer is affected.
The symbolic constants contained in bufs may
be any of the following:
GL_NONE
The fragment shader output value is not written into any color buffer.
GL_FRONT_LEFT
The fragment shader output value is written into the front left color buffer.
GL_FRONT_RIGHT
The fragment shader output value is written into the front right color buffer.
GL_BACK_LEFT
The fragment shader output value is written into the back left color buffer.
GL_BACK_RIGHT
The fragment shader output value is written into the back right color buffer.
GL_COLOR_ATTACHMENT
n
The fragment shader output value is written into the
nth color attachment of the current
framebuffer. n may range from zero to the value
of GL_MAX_COLOR_ATTACHMENTS.
Except for GL_NONE, the preceding symbolic
constants may not appear more than once in bufs.
The maximum number of draw buffers supported is implementation dependent
and can be queried by calling
glGet
with the argument
GL_MAX_DRAW_BUFFERS.
The symbolic constants GL_FRONT,
GL_BACK, GL_LEFT,
GL_RIGHT, and GL_FRONT_AND_BACK
are not allowed in the bufs array since they may
refer to multiple buffers.
If a fragment shader does not write to a user defined output
variable, the values of the fragment colors following shader execution are
undefined. For each fragment generated in this situation, a different
value may be written into each of the buffers specified by
bufs.
GL_INVALID_OPERATION error is generated by
glNamedFramebufferDrawBuffers if
framebuffer is not zero or the name of an existing
framebuffer object.
GL_INVALID_ENUM is generated if one of the
values in bufs is not an accepted value.
GL_INVALID_ENUM is generated if the API call
refers to the default framebuffer and one or more of the values in
bufs is one of the
GL_COLOR_ATTACHMENTn
tokens.
GL_INVALID_ENUM is generated if the API call
refers to a framebuffer object and one or more of the values in
bufs is anything other than
GL_NONE or one of the
GL_COLOR_ATTACHMENTn
tokens.
GL_INVALID_ENUM is generated if
n is less than 0.
GL_INVALID_OPERATION is generated if a symbolic
constant other than GL_NONE appears more than once in
bufs.
GL_INVALID_OPERATION is generated if any of the
entries in bufs (other than
GL_NONE ) indicates a color buffer that does not
exist in the current GL context.
GL_INVALID_OPERATION is generated if any value
in bufs is GL_BACK, and
n is not one.
GL_INVALID_VALUE is generated if
n is greater than
GL_MAX_DRAW_BUFFERS.
glGet
with argument GL_MAX_DRAW_BUFFERS
glGet
with argument
GL_DRAW_BUFFERi where
i indicates the number of the draw
buffer whose value is to be queried.
| OpenGL Version | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Function / Feature Name | 2.0 | 2.1 | 3.0 | 3.1 | 3.2 | 3.3 | 4.0 | 4.1 | 4.2 | 4.3 | 4.4 | 4.5 |
glDrawBuffers
|
✔ | ✔ | ✔ | ✔ | ✔ | ✔ | ✔ | ✔ | ✔ | ✔ | ✔ | ✔ |
glNamedFramebufferDrawBuffers
|
- | - | - | - | - | - | - | - | - | - | - | ✔ |
glBlendFunc, glColorMask, glDrawBuffers, glLogicOp, glReadBuffer
Copyright © 2003-2005 3Dlabs Inc. Ltd. Copyright © 2010-2014 Khronos Group. This material may be distributed subject to the terms and conditions set forth in the Open Publication License, v 1.0, 8 June 1999. http://opencontent.org/openpub/.