iphone - Displaying an EAGLView with transparent background on a UIImageView

Question

I have an EAGLView displaying an OpenGL 3D model, and a UIImageView displaying an image.

What I want is to display EAGLView above that UIImageView with transparent background.

Is there any way to display this 3D model with transparent background, on top of the UIImageView.

Any solution would be appreciated.

Answer 1

For reference, most of the accepted answer is unnecessary. The only key part is this (in the UIViewController - no need to edit or subclass EAGLView / GLKView):

self.view.opaque = NO; // NB: Apple DELETES THIS VALUE FROM NIB
self.view.backgroundColor = [UIColor clearColor]; // Optional: you can do this in NIB instead

You can set the background Color in the NIB - but you CANNOT set the opacity (Apple seems to overwrite this var for GL views at initWithCoder :( )

Plus, of course, in your OpenGL code you need to clear to alpha=0.0. So, wherever your glClear / glClearColor calls are already, replace the clearColor with:

glClearColor( 0, 0, 0, 0.0);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);