Greetings once more.
Another suggestion which has probably already been implemented by nVidia:
GLboolean glIsDirty(GLbitfield mask)
returns GL_TRUE if the buffer or buffers specified by ‘mask’ have been written to since they were last cleared. If the buffer in question has not been written to since the last clear, returns GL_FALSE.
I’m mentioning this after a moment of dissappointment, when I learned GL_SELECT and GL_FEEDBACK provide results prior to any fragment operations. This functionality would make portal-testing a breeze…
Waiting to be told it’s already out there,