Hello there all! I'm trying to copy 1 pixel into a PBO from my actual rendering framebuffer with glReadPixels. If I'm correct if I bind a buffer object that is a type of GL_PIXEL_PACK_BUFFER the glReadPixels call should not block! My problem is that it does block (4-10ms) on an integrated Intel HD 4600 igpu on OSX. I tried the code on a windows machine with a dedicated nvidia card (0.02ms) and on that machine everything is fine!
Anyone had a similar problem? Is there a solution? I'm trying to implement pixel perfect model selection.