Random, Math, & More

This page is a grab-bag of “you’ll use these constantly” utilities: RNG, formatting, time, and a few core subsystems that show up in most games.

If you’re looking for arrays/slices, see Arrays and Collections.

Random numbers (RNG)

Random uses an explicit u64 seed. Pass the seed by ref so it updates.

rng: u64 = rng_root_seed();
// or deterministic per-entity:
// rng: u64 = rng_seed(entity.id);

// Range values are inclusive
roll := rng_range_int(ref rng, 1, 10);
chance := rng_range_float(ref rng, 0, 1);

// Random points and shuffling
offset := rng_disk(ref rng, 0.5, 2.0);
spawn_points: [..]v2;
spawn_points.append({0, 0});
spawn_points.append({4, 0});
rng_shuffle(ref rng, spawn_points);

Gameplay randomness must run in the shared predicted gameplay path. Start from rng_root_seed() or another stable seed; do not seed gameplay from local-only data.

Math functions

Common math helpers:

angle_sin := sin(x);
angle_cos := cos(x);
angle := atan2(dir.y, dir.x);
degrees := to_degrees(angle);
radians := to_radians(degrees);

result := pow(2.0, 3.0);   // 8.0
root := sqrt(16.0);        // 4.0

value := lerp(0.0, 100.0, 0.5);  // 50.0
clamped := clamp(value, 0.0, 10.0);
stepped := linear_step(0.0, 1.0, value);

absolute := abs(-5);
minimum := min(5, 10);
maximum := max(5, 10);
direction_sign := sign(-12);

len := length(v);
len_sq := length_squared(v);
normalized := normalize(v);
facing := dot(normalized, {1, 0});

String formatting

Use % placeholders with an argument array:

format_string("Value: %", {42});
format_string("health: 100%");

If you need an argument adjacent to a percent sign (or next to another argument), use %0 as an alias for %:

hp := 67;
format_string("health: %0%%", {hp}); // "health: 67%"

For decimal rounding, use format_float:

value := 3.14159;
format_string("pi: %", {format_float(value, decimals=2)}); // "pi: 3.14"

Common string helpers:

clean := string_trim("  hello  ");
parts := string_split("a,b,c", ",");
name_lower := to_lower(player.get_username());
name_upper := to_upper("ready");
short := string_substring("abcdef", 1, 3); // "bcd"

Logging

Logging follows the same formatting rules:

log_info("Name: %, age: %", {player.get_username(), 12});

Time

current_time := get_time();       // float seconds since game start
frame := get_frame_number();      // current frame number
now_ns := get_nanoseconds_since_epoch();
utc := get_utc_datetime();

SFX

sound := get_asset(SFX_Asset, "sfx/click.wav");

desc := SFX.default_sfx_desc();
desc.entity_to_follow = entity.id;
desc.delay = 0.25;

sound_id := SFX.play(sound, desc);
SFX.stop(sound_id);

Call gameplay sounds from the shared gameplay path. The engine reconciles predicted playback. For a sound that only one player should hear, set desc.specific_to_player = player; do not wrap SFX.play in is_local().

Economy quick start (currencies)

Economy currencies are per-player and automatically persisted.

ao_before_scene_load :: proc() {
    coin_icon := get_asset(Texture_Asset, "ui/coin.png");
    Economy.register_currency("Coins", coin_icon);
}

Economy.deposit_currency(player, "Coins", 10);
coins := Economy.get_balance(player, "Coins");

COST :: 50;
if Economy.can_withdraw_currency(player, "Coins", COST) {
    Economy.withdraw_currency(player, "Coins", COST);
}

Deposit and withdrawal amounts must be non-negative.

See Economy for the full guide.