On 16 April 2012 09:59, Anuj Phogat <<a href="mailto:anuj.phogat@gmail.com">anuj.phogat@gmail.com</a>> wrote: <div class="gmail_quote"><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"> This is the draft version of test case. Signed-off-by: Anuj Phogat <<a href="mailto:anuj.phogat@gmail.com">anuj.phogat@gmail.com</a>> --- I was developing this test to verify MSAA with FBO. Test output with MSAA is expected to differ along polygon edges when compared to rendering without MSAA. But it seems like no MSAA is happening. Did I miss something while setting up multisample fbo? GPU Info: OpenGL vendor string: Advanced Micro Devices, Inc. OpenGL renderer string: AMD Radeon(TM) HD 6480G OpenGL version string: 4.2.11554 Compatibility Profile Context OpenGL shading language version string: 4.20 Software: Catalyst Version: 12.2 Test output: ./bin/ext_framebuffer_multisample-turn-on-off -auto GL_SAMPLES = 0, GL_SAMPLE_BUFFERS = 0, MSAA = 0 GL_SAMPLES = 8, GL_SAMPLE_BUFFERS = 1, MSAA = 1 PIGLIT: {'result': 'pass' } </blockquote><div> I think you're setting up the framebuffer correctly. The reason the pixels are the same is because all of the shapes you are drawing are rectangles that are aligned to pixel boundaries. To see the effect of MSAA, you either need to draw some rectangles that aren't aligned to pixel boundaries, or you need to draw an image that has diagonal lines in it. By the way, I've had to write a test of my own to help me in prototyping Sandy Bridge MSAA support. We should coordinate to make sure we're not duplicating effort. Briefly, my test is draws a scene twice, once using the GL implementation's MSAA feature, and once without MSAA but at very high (16x) resolution. Then it compares the two images. Each pixel in the MSAA image corresponds to a 16x16 block in the high resolution image. By counting how many pixels are lit in the 16x16 block, the test can figure out how bright the corresponding MSAA pixel would be if the antialiasing were perfect. Then it computes an RMS error between the actual MSAA output and the "perfectly antialiased" reference image. I'll try to get my test posted to the Piglit list today or tomorrow. In the meantime, to give you a better idea of what I'm doing, I'll attach screenshots. In the attached png images, the image on the left is rendered with MSAA, and the image on the right is the "perfectly antialiased" reference image. Paul </div></div>