Interactive debug playback

[mdales]

To help debug effects/demos, it'd be nice to have a way to at least pause things and step frames, and for functional effects also step forward and backward in time.

• Pause - effectively stops tick being called, leaving just the last frame on display
• Step - calls tick once more and keeps things otherwise paused

For functional effects, where the entire logic is defined by t alone and has no other side-effects, you can also step backwards, where you decrement rather than increment the counter before calling tick.

It'd be fun to do this by having an overlay of play/pause/step buttons on the screen that can be clicked, as well as having some key presses. I imagine we'd use a function key to engage this mode.

[bximbo]

Hello @mdales

This seems like it's going to be fun. I'd like to take this up as a challenge. can this be assigned to me?/

If yes, my first question would be about how to get these buttons on the screen. Also, for the key presses, do we permanently allocate them to a particular key? I hope these questions makes sense

[mdales]

This seems like it's going to be fun. I'd like to take this up as a challenge. can this be assigned to me?

Because we have so many people working on Claudius right now, I like to keep it to one ticket per person. Can you finish the examples ticket? That will help you answer some of your questions, as you need to work out how to work with keypresses for that for instance.

[bximbo]

Right! That's makes a lot of sense. Thank you

[bximbo]

Hello @mdales

Can I be assigned to this now?

[mdales]

@bximbo sure, if you're still interested. do you have an idea of how you might go about this, how the interactions with the user would work?

[bximbo]

Hello @mdales

I have given the task some thought and I have a few basic questions.

For the key presses, you mentioned that it would be nice to have both keyboard keys and clickable on-screen buttons but at the same time a function key that would engage this mode. I imagine it would be a debug mode. Would the key presses be dedicated functions for the Pause, Step Forward, Step Backward events? And then the debug mode be for the clickable on screen buttons. I'm having the thought of implementing a video player mode that go on to show progress bar but since a lot of events may be functional. It would just need the debug mode. That being said I think both the key presses and the clickable overlays can just be a debug mode to be first initialized. Maybe a two key/button combination to prevent entering this mode by mistake.

Also, when that is all said and agreed on. Please do you suggest a display style for the overlay elements (maybe all buttons in a block or each button being an island)? And for the key presses, whilst it's tempting to use F7,F8 and F9 for the Step Backward, Pause, and Step Forward, it's not the same configuration for different users. Please what do you suggest?

For my thought process behind solving this. I plan to track the t and the last rendered frame. Since the program runs normally by increment of 1 for t, when paused, I stop calling t and just show the last thing I drew. When step forward event is initiated, we then increase it by +1 (ofc upon key/ click event) and -1 for step back. I plan to integrate this into the base and then add an interactive debug playback module maybe called debug.mli/debug.ml since it would all be optional. I really want to try to avoid affecting existing code . Ofc intercept some key/click inputs. Please what do you think about this?