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.TH "icetGLDrawFrame" "3" "September 26, 2014" "\fBIceT \fPReference" "\fBIceT \fPReference"
.SH NAME

\fBicetGLDrawFrame \-\- renders and composites a frame using \fbOpenGL \fP\fP
.PP
.SH Synopsis

.PP
#include <IceTGL.h>
.PP
.TS H
l l l .
void  \fBicetGLDrawFrame\fP( void );
.TE
.PP
.SH Description

.PP
Initiates a frame draw using the current \fbOpenGL \fPtransformation matrices 
(modelview and projection). 
.PP
Before \fBIceT \fPmay render an image, the tiled display needs to be defined 
(using \fBicetAddTile\fP),
the drawing function needs to be set (using 
\fBicetGLDrawCallback\fP),
and composite strategy must be set (using 
\fBicetStrategy\fP).
The single image sub\-strategy may also optionally 
be set (using \fBicetSingleImageStrategy\fP).
.PP
All processes in the current \fBIceT \fPcontext must call 
\fBicetGLDrawFrame\fP
for it to complete. 
.PP
The \fbOpenGL \fPprojection matrix and modelview matrix must be set using 
\fBglLoadMatrix\fP
or a number of other functions. Likewise, 
the \fbOpenGL \fPbackground color must be set with 
\fBglClearColor\fP\&.
\fBIceT \fPwill use the matrices to determine 
what pixels need to be rendered and composited. \fBIceT \fPwill also modify 
the projection matrix to project onto (or in between) tiles. 
.PP
If \fBICET_GL_DISPLAY\fP
is enabled, then the fully composited image 
is written back to the \fbOpenGL \fPframebuffer for display. It is the 
application\&'s responsibility to synchronize the processes and swap front 
and back buffers. If the \fbOpenGL \fPbackground color is set to something 
other than black, \fBICET_GL_DISPLAY_COLORED_BACKGROUND\fP
should 
also be enabled. Displaying with 
\fBICET_GL_DISPLAY_COLORED_BACKGROUND\fP
disabled may be slightly 
faster (depending on graphics hardware) but can result in black 
rectangles in the background. If \fBICET_GL_DISPLAY_INFLATE\fP
is 
enabled and the size of the renderable window (determined by the current 
\fbOpenGL \fPviewport) is greater than that of the tile being displayed, then 
the image will first be ``inflated\&'' to the size of the actual display. 
This inflation will be assisted by texture hardware if 
\fBICET_GL_DISPLAY_INFLATE_WITH_HARDWARE\fP
is on. If 
\fBICET_GL_DISPLAY_INFLATE\fP
is disabled, the image is drawn at its 
original resolution at the lower left corner of the display. 
.PP
The image remaining in the frame buffer is undefined if 
\fBICET_GL_DISPLAY\fP
is disabled or the process is not displaying a 
tile. 
.PP
.SH Errors

.PP
.TP
\fBICET_INVALID_OPERATION\fP
 Raised if the \fBicetGLInitialize\fP
has not been called or if the 
drawing callback has not been set. Also can be raised if 
\fBicetGLDrawFrame\fP
is called recursively, probably from within the 
drawing callback. 
.TP
\fBICET_OUT_OF_MEMORY\fP
 Not enough memory left to hold intermittent frame buffers and other 
temporary data. 
.PP
\fBicetGLDrawFrame\fP
may also indirectly raise an error if there is an 
issue with the strategy or callback. 
.PP
.SH Warnings

.PP
None. 
.PP
.SH Bugs

.PP
If compositing with color blending on, the image returned may have a 
black background instead of the \fIbackground_color\fP
requested. This 
can be corrected by blending the returned image over the desired 
background. This will be done for you if the 
\fBICET_CORRECT_COLORED_BACKGROUND\fP
is on. 
.PP
.SH Copyright

Copyright (C)2003 Sandia Corporation 
.PP
Under the terms of Contract DE\-AC04\-94AL85000 with Sandia Corporation, the 
U.S. Government retains certain rights in this software. 
.PP
This source code is released under the New BSD License. 
.PP
.SH See Also

.PP
\fIicetAddTile\fP(3),
\fIicetBoundingBox\fP(3),
\fIicetBoundingVertices\fP(3),
\fIicetDrawFrame\fP(3),
\fIicetGLDrawCallback\fP(3),
\fIicetSingleImageStrategy\fP(3),
\fIicetStrategy\fP(3)
.PP
.\" NOTE: This file is generated, DO NOT EDIT.