I want to read the colour of a single texel in a large GL texture (for diagnostic purposes).
Do I /really/ have to either use glGetTexImage() to copy the /entire/ texture into CPU RAM ;
or render a portion into the frame buffer and use glReadPixels() hoping the render preserved the colour?
Both approaches suck bigtime when all I want to do is peek particular single texel cells. glGetTexSubImage() would do what I want if it existed but it doesn’t seem to be implimented.
Can anybody help? TIA.