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GLDRAWBUFFERS(3G)                                OpenGL 3.3                                GLDRAWBUFFERS(3G)



NAME
       glDrawBuffers - Specifies a list of color buffers to be drawn into

C SPECIFICATION
       void glDrawBuffers(GLsizei n, const GLenum *bufs);

PARAMETERS
       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.

DESCRIPTION
       glDrawBuffers defines 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.

       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_ATTACHMENTn
           The fragment shader output value is written into the nth color attachment of the current
           framebuffer.  n may range from 0 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.

NOTES
       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.

ERRORS
       GL_INVALID_ENUM is generated if one of the values in bufs is not an accepted value.

       GL_INVALID_ENUM is generated if the GL is bound 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 GL is bound 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_ATTACHMENTSn 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_VALUE is generated if n is greater than GL_MAX_DRAW_BUFFERS.

ASSOCIATED GETS
       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

SEE ALSO
       glBlendFunc(), glColorMask(), glDrawBuffers(), glLogicOp(), glReadBuffer()


COPYRIGHT
       Copyright (C) 2003-2005 3Dlabs Inc. Ltd. 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/.



OpenGL 3.3                                       03/08/2011                                GLDRAWBUFFERS(3G)