I want this to be a background in my app for Ipad.
I'm building everything in objective C (native app)

I need a little help figuring out how to animate each of the triangles over the image (overlay) so it fades in and out independently of each other, the goal to make a constant shimmer like effect so the image doesn't feel sos tatic. Do i have to animate each triangle independently? Is there any algorithm that i should be looking at so it seems kinda random but isn't. 

Here is the background image 

![enter image description here](https://i.stack.imgur.com/0D8Si.jpg) 

I need some guidance on where to start and how to approach this problem, and feedback would be appreciated.