Two ECS-native, deterministic namespaces for 2D motion, driven off the fixed
frame clock so replays and lockstep netcode reproduce every frame and every
eased value exactly. Both are pure computed-inline Q16.16 / integer math (no new
runtime, no heap) — the game stores a timer on a component and calls these each
frame, exactly the way Collision.* / Grid.* are used.
Anim.* — spritesheet frame animation:
- Anim.frame(timer,fps,count) -> int looping frame index
- Anim.once(timer,fps,count) -> int one-shot, clamps on the last frame
- Anim.pingpong(timer,fps,count) -> int bounce 0..count-1..0
- Anim.finished(timer,fps,count) -> bool has a one-shot run past its end?
- Anim.duration(fps,count) -> fixed seconds for one cycle
- Anim.cell_x/cell_y(frame,cols,cell) -> int source rect on a grid sheet
Tween.* — value interpolation over a timeline:
- Tween.progress/loop/yoyo(timer,duration) -> fixed normalized amount
- Tween.done(timer,duration) -> bool
- Tween.ease(t, mode) -> fixed shape by a literal curve 0..6,
the same curves as Ease.* (now
factored into a shared ease_eval)
- Tween.number/round/point/tint(from,to,t) blend a fixed / int / Vector / color
The typed blends reuse the existing fixed / Vector / color helpers, and
Tween.ease shares Ease.*'s exact formulas via the new ease_eval(mode,t) — one
source of truth for every easing curve in the engine.
examples/library/anim.ludic asserts 34 cases (frame math, clamping, ping-pong,
cell geometry, timeline clamp/loop/yoyo, rounding, color/vector blends, and
Ease.in == Tween.ease(.,1)); wired into x test (now 62 passed). Docs: Anim +
Tween sections with 16 per-symbol pages, inventory/coverage green. Seed
reseeded; the C-free bootstrap fixpoint holds.
The stateful sugar the proposal sketches (named clips, Anim.play, fluent
Tween.chain/parallel handles, and an auto-injected advance system) is deliberately
left as a follow-up — this lands the deterministic math core both halves stand on.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
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891 B
| id | name | category | kind | tokens | sig | tip | order | ns | member |
|---|---|---|---|---|---|---|---|---|---|
| anim-cell_x | Anim.cell_x | anim | namespace-method | Anim.cell_x | Anim.cell_x(frame, cols, cell_w) -> int | The source x (pixels) of a frame on a grid spritesheet. | 6 | Anim | cell_x |
Turns a frame index into the left pixel of its cell on a spritesheet laid out as a grid of cols columns: (frame mod cols) * cell_w. Combine with Anim.cell_y to get the top-left source coordinate to blit from.
Parameters:
frame— the frame index (e.g. fromAnim.frame)cols— columns in the sheetcell_w— cell width in pixels
program Demo {
handler Run phase Update {
let f = Anim.frame(fixed(1), 12, 8)
let sx = Anim.cell_x(f, 4, 16)
let sy = Anim.cell_y(f, 4, 16)
print(sx)
print(sy)
}
}