Dice, shapes and colours

Dice

import { dice, d20, d6, coin } from "ransu/dice";

dice("3d6+2"); // 13
dice("d20"); // 17
d6(3); // three six-sided dice, summed
coin(); // 'heads' | 'tails'

dice.detail("4d6+2");
// { total: 17, dice: [5, 2, 6, 2], modifier: 2 }

The notation is the usual one: NdM, with the count and a +K or -K modifier both optional. dice.detail() reports every die, which is what a game log wants. Anything that is not dice notation throws rather than guessing.

Shapes

import { onCircle, inCircle, onSphere, inSphere, inRect, unitVector } from "ransu/geometry";

onCircle(5); // [x, y] on the circumference
inCircle(5); // [x, y] inside the disc
onSphere(1); // [x, y, z] on the surface
inSphere(1); // [x, y, z] inside
inRect({ x: 0, y: 0, width: 800, height: 600 });
unitVector(4); // a uniform direction in four dimensions

Two of these are easy to get wrong by hand.

inCircle takes the square root of a uniform draw. Without it, points bunch up at the centre, because the area available at radius r grows with r. inSphere generalises that to a cube root, and the tests check both by counting what fraction lands inside the half-area and half-volume radius.

unitVector normalises Gaussians rather than normalising a uniform cube point. The cube version concentrates directions toward the corners, and the higher the dimension the worse it gets.

Colours

import { color, rgb, hsl } from "ransu/color";

color(); // '#3f7ac2'
rgb(); // [63, 122, 194, 1]
hsl(); // [214.2, 0.51, 0.5, 1]
color({ alpha: true }); // '#3f7ac2b3'
color({ format: "rgb" }); // 'rgb(63 122 194)'

color({ hue: [200, 260], saturation: [0.6, 0.9] });

Colours are drawn in HSL and converted, not by picking three bytes. A uniform point in the RGB cube is usually a muddy brown, because most of the cube is desaturated. The defaults keep saturation in [0.45, 0.9] and lightness in [0.35, 0.65]; pass the full spans to get the whole gamut back.

Opacity is opt-in. Leave alpha out and colours are opaque with no alpha in the output; pass true for a random one, a number to fix it, or a span to draw from a band. color({ format }) writes hex, rgb() or hsl() notation.