Wish List: Frame Counter

Would be great, to expose the current frame. Something like a counter that starts, once the animation is running and increases on every draw call.

Variable name could be `i` or `f`.

I'd suggest to start with `i=0`, so people can use it to initialize globals on the first run.

No file or test is named. Start by locating the animation loop and its draw-call entry point; implement the requested exposed counter with an initial value of 0 that increases on each draw. Done means demos can read the current frame while the animation runs.

Written by the indexing model from the issue text.