Thanks to popcornmix, we found that the if statement dependence was due to optimization in the shader, and the reason for the hanging was a for-loop in the shader which doesn't work nicely with the pi's legacy driver i.e. the shader is too complex. More details https://github.com/raspberrypi/userlan...

Seems it can happen in some android too? https://stackoverflow.com/questions/43740848/after-call-gllinkprogram-the-app-freezes "I experienced the same issue. The Nexus 7 (2013) was freezing when I called gllinkprogram(). I found that this only happened when I had 'if statements' in my shader. I was ...

This is the weirdest most annoying bug I've ever had, mainly because the pi will freeze and be unable to create a new context until it unfreezes (approx 2 minutes). I've narrowed it down to a single line of code with testing over a span of a few days. It's my fragment shader eyes.frag that's doing i...