function rval = kPsychUseExternalSinkTextures
% rval = kPsychUseExternalSinkTextures
%
% Return a flag that you can pass to the 'imagingmode' parameter of
% Screen('OpenWindow') together with the 'kPsychNeedFinalizedFBOSinks'
% flag. If this kPsychUseExternalSinkTextures flag is given then the
% OpenGL framebuffer objects which are created and attached as final
% output image sinks due to the 'kPsychNeedFinalizedFBOSinks' flag will
% not use Screen() internally created OpenGL textures as color attachments,
% and thereby as final target of the output images. Instead, externally
% created suitable (color render-to-texture capable) non-power-of-two
% OpenGL textures will get dynamically attached as render targets during
% the relevant render pass. Producers of such external target textures can
% be 3rd party SDKs or runtimes, e.g., the Oculus VR 1.x SDK and runtime
% which would send such textures with the final rendered output images to
% a VR compositor for output on a suitable VR headset. Other applications
% are conceivable, but this is the initial target application of this flag.
%
rval = 2^21;
return