Turnframes in GSC

Turnframes occur from motionless states if you don't continue in the direction you are facing; each 'turnframe' is actually 8 frames in length. The game polls for input for 2 frames before restarting motion (regardless of which direction you are facing). Walking 1 tile in the direction you're facing from a motionless state will take 18 frames; walking 1 tile in another direction will take 26 frames. Turning in place can be done in cycles of 10 frames.

From a motionless state, the input that determines your movement direction is the one you hit 8 frames after the first registered directional input. So you could hit left for 1-2 frames (1 sometimes works, 2 always works, not sure why it's variable), nothing for 7 frames, then up for 1 frame, and your character will go up a tile. In any event, it is notoriously easy to get 'stuck' in Gen 2 after a bonk; the easiest way to ensure you do move is to hold the input for at least 10 frames.


Things that put you into motionless state:

- Releasing D-pad input after moving or turning in place
- Menuing
- Wild pokemon & Trainer battles
- Most interactions with overworld (talking to NPC, picking up item, boulder pushing, biking with select, etc.)
- Turning into certain "warp tiles" (lighted cave exits/red carpeted tiles)
- Arriving in new route/area on warp tiles, arriving in overworld post-Flying, arriving in water post-Surfing, etc.
- Bonking (but side-bonking from a moving state is weird, see below)


Things that do not put you into a motionless state:

- Repel wearing off text
- Exiting caves/doors/stairs (game pushes you out 1 tile, during which you're in motion)


Side-bonking (from a moving state) will put you in a motionless state, but it's followed immediately by a turnframe (towards the bonk object) that puts you back in a state of motion during the first bonk. There is actually a 2 frame correction window before the turnframe occurs that allows you to skip it; you'll hear a bonk, but you'll still be facing the same direction you were previously. If you miss the window, but restart movement before the turnframe (8 frame window) is completed, you'll avoid further turnframes. Otherwise, you'll go back to a motionless state again and have another turnframe to deal with.


Miscellaneous

(1) Turnframes eat into encounter immunity steps. Poor choice of movement (e.g. Route 30 to and from Mr. Pokemon / Union Cave [Gold only]) can thus lead to losing far more than just the 8 frames from the turnframe, as it may also mean 1 extra encounter tile.

(2) Corollary of (1), an encounter roll takes place on each turnframe. Continuously turning in place gets encounter rolls every 10 frames, which makes it a more effective method to get a Poliwag/whirl to show up if you need one. Even if you don't do it perfectly (12 frames per encounter roll would still be an average of 3.5 seconds saved vs standard surfing for Poli to show up). See this in practice here: http://www.twitch.tv/entrpntr/v/23095914.

(3) You can't buffer inputs on turnframes. For something like the Przcureberry, you're looking to time your A input 8 frames after your input to turn towards it.