Ticks per Step

ticks_per_step(cells_per_second, fixed_dt) returns the integer number of ticks between movement steps to achieve the requested cells/sec rate. Designing in cells/sec instead of ticks-per-step decouples timing from grid resolution — change tile size and your movement still feels the same.

import { ticks_per_step } from "@f0rbit/forge/grid";

const every = ticks_per_step(8, ctx.time.fixed_dt);
//   8 cells/sec at fixed_dt = 1/60 → every = 8
//   8 cells/sec at fixed_dt = 1/30 → every = 4

Shape

const ticks_per_step: (cells_per_second: number, fixed_dt: number) => number;

Implementation: Math.max(1, Math.round(1 / (cells_per_second * fixed_dt))). Returns at least 1 — never returns a step gate of 0.

Reference table (fixed_dt = 1/60)

cells_per_second	every (ticks)	Apparent speed
1	60	one cell per second — slow puzzle pace
2	30	two cells per second — turn-based feel
4	15	four cells per second — relaxed roguelike
6	10	six cells per second — dungeon-walk default
8	8	snappy action-roguelike
12	5	fast — twin-stick or shooter
30	2	very fast — bullet/projectile cadence
60	1	one cell per tick — shouldn’t generally need this

Reference table (fixed_dt = 1/30)

cells_per_second	every (ticks)
2	15
4	8
6	5
8	4
15	2
30	1

Pairing with schedule.add

import { ticks_per_step } from "@f0rbit/forge/grid";
import { schedule } from "@f0rbit/forge";

const sch = schedule();
const every = ticks_per_step(8, time.fixed_dt);

sch.add("update", movement_system, { every, name: "movement" });

Pairing with g.move_tile

When you call g.move_tile inside a periodic system, the gate handles cadence — the system body just performs one step:

const movement_system: System = (w) => {
  for (const [id, , d] of w.query([pos_c, dir_c, player_c] as const)) {
    if (d.dx === 0 && d.dy === 0) continue;
    g.move_tile(w, id, d, { blocked_by });
  }
};

sch.add("update", movement_system, { every: ticks_per_step(8, fixed_dt), name: "movement" });