Question

I’m drawing a line using OpenGL on the iPhone. I used GLView and GLKView delegates to draw the line. But now I want to set a background image to GLKViewController, and on the background image, I want to draw the line. I have tried to set a background image using UIImageView, but the image is appearing above on the (GLKView) drawn line.

How can I set a background image to the GLKViewController?

Answer 1

The easiest way should be to add additional view with background image (such as you proposed – but you need to set it behind OpenGL view). Try this:

[RootViewController.view addSubview: BackgroundView belowSubview: OpenGLView];
OpenGLView.opaque = NO;

But this will bring some FPS penalty (Apple recommends to use opaque OpenGL view for performance reason). More correct approach is to draw background via OpenGL as fullscreen quad.