Posted by gouessej on Nov 04, 2015; 4:24pm
URL: https://forum.jogamp.org/Unable-to-draw-to-GLOffscreenAutoDrawable-on-Raspberry-Pi-2-tp4035723p4035737.html

Your example can't work because the buffers haven't been swapped yet when you call glReadPixels. Just call canvas.display() a second time and you'll see what I mean.