How do you activate multisampling in OpenGL ES on the iPhone?

Question

I'm experimenting w/ improving the "resolution" of an OpenGL ES based app. Apple mentions here (developer.apple.com) that OpenGL ES in iOS 4 supports multisampling... and this can improve the graphics somewhat. How do you enable multisampling?

Answer 1

The WWDC session 415 video goes over this a bit, so grab and watch that if you can.

Essentially, you create a second framebuffer for msaa rendering using glRenderbufferStorageMultisampleAPPLE for its depth and color buffers. Then you bind this multisample framebuffer, render your scene, then do the multisampling resolve into your main framebuffer:

glBindFramebuffer(GL_READ_FRAMEBUFFER_APPLE, msaaFramebuffer);
glBindFramebuffer(GL_DRAW_FRAMEBUFFER_APPLE, defaultFramebuffer);
glResolveMultisampleFramebufferAPPLE();

then bind your render buffer and present it as you would normally.

I'm still relatively new to OpenGL ES myself, but I hope this helps put you on the right track.

Answer 2

Or just checkout apples documentation the matter: http://developer.apple.com/library/ios/#documentation/3DDrawing/Conceptual/OpenGLES_ProgrammingGuide/WorkingwithEAGLContexts/WorkingwithEAGLContexts.html in the section "Use multisampling..."