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NAME

       glBlitFramebuffer - copy a block of pixels from the read framebuffer to the draw
       framebuffer

C SPECIFICATION

       void glBlitFramebuffer(GLint srcX0, GLint srcY0, GLint srcX1, GLint srcY1, GLint dstX0,
                              GLint dstY0, GLint dstX1, GLint dstY1, GLbitfield mask,
                              GLenum filter);

PARAMETERS

       srcX0, srcY0, srcX1, srcY1
           Specify the bounds of the source rectangle within the read buffer of the read
           framebuffer.

       dstX0, dstY0, dstX1, dstY1
           Specify the bounds of the destination rectangle within the write buffer of the write
           framebuffer.

       mask
           The bitwise OR of the flags indicating which buffers are to be copied. The allowed
           flags are GL_COLOR_BUFFER_BIT, GL_DEPTH_BUFFER_BIT and GL_STENCIL_BUFFER_BIT.

       filter
           Specifies the interpolation to be applied if the image is stretched. Must be
           GL_NEAREST or GL_LINEAR.

DESCRIPTION

       glBlitFramebuffer transfers a rectangle of pixel values from one region of the read
       framebuffer to another region in the draw framebuffer.  mask is the bitwise OR of a number
       of values indicating which buffers are to be copied. The values are GL_COLOR_BUFFER_BIT,
       GL_DEPTH_BUFFER_BIT, and GL_STENCIL_BUFFER_BIT. The pixels corresponding to these buffers
       are copied from the source rectangle bounded by the locations (srcX0; srcY0) and (srcX1;
       srcY1) to the destination rectangle bounded by the locations (dstX0; dstY0) and (dstX1;
       dstY1). The lower bounds of the rectangle are inclusive, while the upper bounds are
       exclusive.

       The actual region taken from the read framebuffer is limited to the intersection of the
       source buffers being transferred, which may include the color buffer selected by the read
       buffer, the depth buffer, and/or the stencil buffer depending on mask. The actual region
       written to the draw framebuffer is limited to the intersection of the destination buffers
       being written, which may include multiple draw buffers, the depth buffer, and/or the
       stencil buffer depending on mask. Whether or not the source or destination regions are
       altered due to these limits, the scaling and offset applied to pixels being transferred is
       performed as though no such limits were present.

       If the sizes of the source and destination rectangles are not equal, filter specifies the
       interpolation method that will be applied to resize the source image , and must be
       GL_NEAREST or GL_LINEAR.  GL_LINEAR is only a valid interpolation method for the color
       buffer. If filter is not GL_NEAREST and mask includes GL_DEPTH_BUFFER_BIT or
       GL_STENCIL_BUFFER_BIT, no data is transferred and a GL_INVALID_OPERATION error is
       generated.

       If filter is GL_LINEAR and the source rectangle would require sampling outside the bounds
       of the source framebuffer, values are read as if the GL_CLAMP_TO_EDGE texture wrapping
       mode were applied.

       When the color buffer is transferred, values are taken from the read buffer of the read
       framebuffer and written to each of the draw buffers of the draw framebuffer.

       If the source and destination rectangles overlap or are the same, and the read and draw
       buffers are the same, the result of the operation is undefined.

ERRORS

       GL_INVALID_OPERATION is generated if mask contains any of the GL_DEPTH_BUFFER_BIT or
       GL_STENCIL_BUFFER_BIT and filter is not GL_NEAREST.

       GL_INVALID_OPERATION is generated if mask contains GL_COLOR_BUFFER_BIT and any of the
       following conditions hold:

       ·   The read buffer contains fixed-point or floating-point values and any draw buffer
           contains neither fixed-point nor floating-point values.

       ·   The read buffer contains unsigned integer values and any draw buffer does not contain
           unsigned integer values.

       ·   The read buffer contains signed integer values and any draw buffer does not contain
           signed integer values.

       GL_INVALID_OPERATION is generated if mask contains GL_DEPTH_BUFFER_BIT or
       GL_STENCIL_BUFFER_BIT and the source and destination depth and stencil formats do not
       match.

       GL_INVALID_OPERATION is generated if filter is GL_LINEAR and the read buffer contains
       integer data.

       GL_INVALID_OPERATION is generated if the value of GL_SAMPLES for the read and draw buffers
       is not identical.

       GL_INVALID_OPERATION is generated if GL_SAMPLE_BUFFERS for both read and draw buffers
       greater than zero and the dimensions of the source and destination rectangles is not
       identical.

       GL_INVALID_FRAMEBUFFER_OPERATION is generated if the objects bound to
       GL_DRAW_FRAMEBUFFER_BINDING or GL_READ_FRAMEBUFFER_BINDING are not framebuffer complete.

SEE ALSO

       glReadPixels()glCheckFramebufferStatus(),
       glGenFramebuffers()glBindFramebuffer()glDeleteFramebuffers()

COPYRIGHT

       Copyright © 2010 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/.

AUTHORS

       opengl.org