_C_ License Applicability. Except to the extent portions of this file are
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_C_ Software License B, Version 1.1 (the "License"), the contents of this
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_C_ Note that, as provided in the License, the Software is distributed on an
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_C_ 
_C_ Original Code. The Original Code is: OpenGL Sample Implementation,
_C_ Version 1.2.1, released January 26, 2000, developed by Silicon Graphics,
_C_ Inc. The Original Code is Copyright (c) 1991-2000 Silicon Graphics, Inc.
_C_ Copyright in any portions created by third parties is as indicated
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_C_ Additional Notice Provisions: The application programming interfaces
_C_ established by SGI in conjunction with the Original Code are The
_C_ OpenGL(R) Graphics System: A Specification (Version 1.2.1), released
_C_ April 1, 1999; The OpenGL(R) Graphics System Utility Library (Version
_C_ 1.3), released November 4, 1998; and OpenGL(R) Graphics with the X
_C_ Window System(R) (Version 1.3), released October 19, 1998. This software
_C_ was created using the OpenGL(R) version 1.2.1 Sample Implementation
_C_ published by SGI, but has not been independently verified as being
_C_ compliant with the OpenGL(R) version 1.2.1 Specification.
_C_
_C_ The first character in this file must be an '_'!
_C_ Anything on a line after _C_ is ignored
_define(_filters,eqn)_C_
_C_      eqn is automatically replaced with neqn for nroff
_header(PassThrough,place a marker in the feedback buffer)
_names(PassThrough)
.SH PARAMETERS
_phead(_param1)
Specifies a marker value to be placed in the feedback buffer
following a _const(PASS_THROUGH_TOKEN).
.SH DESCRIPTION
.P
Feedback is a GL render mode.
The mode is selected by calling
_cmnd(RenderMode) with _const(FEEDBACK).
When the GL is in feedback mode,
no pixels are produced by rasterization.
Instead,
information about primitives that would have been rasterized
is fed back to the application using the GL.
See the _cmnd(FeedbackBuffer) reference page for a description of the
feedback buffer and the values in it.  
.P
_cmnd inserts a user-defined marker in the feedback buffer
when it is executed in feedback mode.  
_param1 is returned as if it were a primitive;
it is indicated with its own unique identifying value:
_const(PASS_THROUGH_TOKEN).
The order of _cmnd commands with respect to the specification
of graphics primitives is maintained.  
.SH NOTES
_cmnd is ignored if the GL is not in feedback mode.
.SH ERRORS
_const(INVALID_OPERATION) is generated if _cmnd is executed between
the execution of _cmnd(Begin) and the corresponding execution of _cmnd(End).
.SH ASSOCIATED GETS
_cmnd(Get) with argument _const(RENDER_MODE)
.SH SEE ALSO
_cmnd(FeedbackBuffer),
_cmnd(RenderMode)
