>Psychtoolbox>PsychGLImageProcessing

rval = kPsychNeedClientRectNoFitter

Return a flag that you can pass to the ‘imagingmode’ parameter of
Screen(‘OpenWindow’) in order to allow use of the ‘clientRect’ passed
into Screen(‘Openwindow’) without actually using the panel fitter to
process it.

Without this flag, Screen() will automatically enable its builtin
panelfitter if it detects the presence of a usercode provided
‘clientRect’. With this flag, all size reporting functions like
Screen(‘Rect’) and Screen(‘WindowSize’) etc., as well as all builtin
2D drawing functions will act as if the onscreen window had a size
as specified by ‘clientRect’. However, the panel-fitter will be skipped,
so other processing plugins in the imaging pipeline would be responsible
for doing the job of treating the ‘clientRect’ specially. The actual
virtual framebuffer is the full regular window size, just drawing and
reporting is restricted to ‘clientRect’.

The purpose of this flag is to allow to use drawing areas smaller than
the true framebuffer without incurring the overhead of execution of the
panel fitter if some other post-processing step will do the necessary
sampling of the “oversized” input buffer. Main application is currently
VR head mounted display support, e.g., the Oculus VR Rift HMDs.