fable/val Public Public: anyone can read this; nobody can change it.

/**

 * Guns: the damage table and what a shot does with it. Pure functions —

 * nothing here knows about a match.

 *

 * Distance is in world units; fifty units is a metre, so the map is about

 * forty-eight metres across and the Phantom's fifteen-metre falloff lands

 * where it should. The rule that matters: a Vandal head shot kills through

 * full armour at any range, a Phantom head shot does not.

 */

export type WeaponId =

  | "classic"

  | "ghost"

  | "sheriff"

  | "spectre"

  | "phantom"

  | "vandal"

  | "operator";

export type Zone = "head" | "body" | "legs";

export type Band = { upTo: number; head: number; body: number; legs: number };

export type Weapon = {

  id: WeaponId;

  name: string;

  cost: number;

  /** Shots a second. */

  rate: number;

  magazine: number;

  reload: number;

  /** Cone half-angle in radians when standing still, and the walking penalty. */

  spread: number;

  movePenalty: number;

  range: number;

  auto: boolean;

  bands: Band[];

};

const METRE = 50;

export const WEAPONS: Record<WeaponId, Weapon> = {

  classic: {

    id: "classic",

    name: "Classic",

    cost: 0,

    rate: 6.75,

    magazine: 12,

    reload: 1.75,

    spread: 0.022,

    movePenalty: 0.05,

    range: 1600,

    auto: false,

    bands: [{ upTo: Infinity, head: 78, body: 26, legs: 22 }],

  },

  ghost: {

    id: "ghost",

    name: "Ghost",

    cost: 500,

    rate: 6.75,

    magazine: 15,

    reload: 1.5,

    spread: 0.016,

    movePenalty: 0.05,

    range: 1800,

    auto: false,

    bands: [

      { upTo: 30 * METRE, head: 105, body: 30, legs: 26 },

      { upTo: Infinity, head: 88, body: 25, legs: 21 },

    ],

  },

  sheriff: {

    id: "sheriff",

    name: "Sheriff",

    cost: 800,

    rate: 4,

    magazine: 6,

    reload: 2.25,

    spread: 0.02,

    movePenalty: 0.09,

    range: 2000,

    auto: false,

    bands: [

      { upTo: 30 * METRE, head: 159, body: 55, legs: 46 },

      { upTo: Infinity, head: 145, body: 50, legs: 42 },

    ],

  },

  spectre: {

    id: "spectre",

    name: "Spectre",

    cost: 1600,

    rate: 13.33,

    magazine: 30,

    reload: 2.5,

    spread: 0.03,

    movePenalty: 0.03,

    range: 1600,

    auto: true,

    bands: [

      { upTo: 20 * METRE, head: 78, body: 26, legs: 22 },

      { upTo: Infinity, head: 66, body: 22, legs: 18 },

    ],

  },

  phantom: {

    id: "phantom",

    name: "Phantom",

    cost: 2900,

    rate: 11,

    magazine: 30,

    reload: 2.5,

    spread: 0.021,

    movePenalty: 0.06,

    range: 2400,

    auto: true,

    bands: [

      { upTo: 15 * METRE, head: 156, body: 39, legs: 33 },

      { upTo: 30 * METRE, head: 140, body: 35, legs: 29 },

      { upTo: Infinity, head: 124, body: 31, legs: 26 },

    ],

  },

  vandal: {

    id: "vandal",

    name: "Vandal",

    cost: 2900,

    rate: 9.75,

    magazine: 25,

    reload: 2.5,

    spread: 0.024,

    movePenalty: 0.07,

    range: 2400,

    auto: true,

    bands: [{ upTo: Infinity, head: 160, body: 40, legs: 34 }],

  },

  operator: {

    id: "operator",

    name: "Operator",

    cost: 4700,

    rate: 0.6,

    magazine: 5,

    reload: 3.7,

    spread: 0.004,

    movePenalty: 0.2,

    range: 2800,

    auto: false,

    bands: [{ upTo: Infinity, head: 255, body: 150, legs: 120 }],

  },

};

export const weaponIds = (): WeaponId[] => Object.keys(WEAPONS) as WeaponId[];

export const isWeaponId = (value: unknown): value is WeaponId =>

  typeof value === "string" && value in WEAPONS;

/** Raw damage for a hit: the band the distance falls in, by zone. */

export function damage(id: WeaponId, zone: Zone, distance: number): number {

  const weapon = WEAPONS[id];

  const band = weapon.bands.find((b) => distance <= b.upTo) ?? weapon.bands[weapon.bands.length - 1]!;

  return band[zone];

}

/**

 * Armour absorbs point for point — a hundred health behind fifty armour is a

 * hundred and fifty to chew through — but it takes two thirds of each hit,

 * so it runs out before health does.

 */

export function applyDamage(

  hp: number,

  armour: number,

  amount: number,

): { hp: number; armour: number } {

  const toArmour = Math.min(armour, Math.ceil(amount * (2 / 3)));

  return { hp: Math.max(0, hp - (amount - toArmour)), armour: armour - toArmour };

}

/** True when this hit kills outright: the test the Vandal exists to pass. */

export const isLethal = (hp: number, armour: number, amount: number): boolean =>

  applyDamage(hp, armour, amount).hp <= 0;

/**

 * Where a shot lands, from how close the ray passes the target's centre.

 * Top-down has no vertical, so precision stands in for it: dead centre is a

 * head shot, the outer edge is legs.

 */

export function zoneFromMiss(miss: number, radius: number): Zone {

  if (miss <= radius * 0.33) return "head";

  if (miss <= radius * 0.75) return "body";

  return "legs";

}

/** Cone half-angle for a shot: standing still is accurate, running is not. */

export const shotSpread = (id: WeaponId, speedFraction: number): number =>

  WEAPONS[id].spread + WEAPONS[id].movePenalty * Math.min(1, Math.max(0, speedFraction));

export const SHIELD = { light: { cost: 400, armour: 25 }, heavy: { cost: 1000, armour: 50 } };