Using the same EAGLContext across different ViewControllers/EAGLViews

I'm having some issues using the same EAGLContext across EAGLViews. I have two View Controllers, each one has one EAGLView.

Each View Controller allocates a new EAGLContext, and a subsequent framebuffer/colorbuffer is created for each respective EAGLView, but this is a waste of memory resources.

I know that it is possible to use the same EAGLContext across ViewControllers by simply binding different framebuffers/colorbuffers to different EAGLViews:

Using Multiple OpenGL Views And UIKit

But i didnt manage to achieve that so far.

Any ideas?

Thanks in advance.

Finally managed to solve the problem.

In one of the view controllers i was using:

dispatch_async(openGLESContextQueue, ^{

        [(EAGLView *)self.view setFramebuffer];

        (...opengl draw code...)

        [(EAGLView *)self.view presentFramebuffer];

    });

When using EAGLContext in a multithreading environment one must be cautious to prevent other threads from accessing it at the same time using:

@syncronized(context) { ...opengl drawing here...}

and to drain the current dispatch_queue before passing control to another ViewController (through presentViewController:), using:

dispatch_sync(openGLESContextQueue, ^{});

So, by using these two tricks i was able to just use one EAGLContext across multiple views. One must also pay extra attention to the current state of the EAGLContext. I was having unexpected results because in the first view i had:

glVertexPointer(2, GL_FLOAT, 0, squareVertices);
glEnableClientState(GL_VERTEX_ARRAY);
glColorPointer(4, GL_UNSIGNED_BYTE, 0, squareColors);
glEnableClientState(GL_COLOR_ARRAY);

In the second view i had completely different drawing code, and i forgot to, of course, use:

glDisableClientState(GL_VERTEX_ARRAY);
glDisableClientState(GL_COLOR_ARRAY);

And voilá!

Thanks :)