sprite-fps

All sprites are 24fps. A sheet's durations are counted in ticks, and one tick is SPRITE_TICK — 1000 / SPRITE_FPS in src/canvas/sprites/sheet.ts. Pokemon sheets, effect and particle atlases and overworld characters all count in that same tick.

Rules

• Never write a frame time as a literal. SPRITE_TICK * frames, not 16.67 * frames, 1000 / 60, or a milliseconds figure worked out by hand. The same goes for tests: assert against SPRITE_TICK, or against the clip's own length/duration.
• Do not confuse it with the battle clock. The engine ticks at 60fps and its timings — cast windows, cooldowns, move delays — are unrelated. A sprite tick is about how a drawing was animated, not how the fight is simulated.
• Clips play at their own speed by default. A hand-drawn clip has a pace, and that pace is most of what it looks like. Play it and let it run.
• Stretch only where something must line up. A caster's throw is fitted to the window its move is in the air, so the gesture ends as the hit lands. That is the exception, not the habit.
• Effects are never stretched. A spark, a shockwave, a puff of smoke plays at its drawn speed. A beat's span says when the next beat starts and how long this one is drawn for; a span longer than the clip holds its last frame rather than slowing the clip down.
• Looping clips repeat rather than stretch — see isLoopingCast. Filling a long window with one slow pass reads as the game hanging.

Why 24

These are hand-drawn animations of a few frames each. Run at the sixty a second the battle ticks at, a ten-frame clip is over in a sixth of a second and reads as a flicker. At 24 the same clip takes 833ms and reads as a movement.

Converting

// Bad — a magic number, and wrong the moment the rate changes
sprite.advance(16.67 * 8);
expect(sprite.duration).toBeCloseTo(650);

// Good — counted in what the sheets are counted in
sprite.advance(SPRITE_TICK * 8);
expect(sprite.duration).toBeCloseTo(sprite.length * SPRITE_TICK);