drive-between-the-lines/src/unitBodies.test.ts

import { describe, expect, it } from 'vitest';
import { createUnitBodies } from './unitBodies';
import { createPhysics } from './physics/physics';
import { createUnits, type Unit, type UnitState } from './sim/units';
import { generateWorld } from './sim/world';

const world = generateWorld(1, 0);

function place(state: UnitState, overrides: Partial<Unit>): Unit {
  const unit: Unit = {
    id: state.nextId++,
    kind: 'soldier',
    faction: 'enemy',
    role: 'fighter',
    x: 0,
    z: 0,
    heading: 0,
    speed: 0,
    hp: 30,
    path: [],
    expires: 999,
    assigned: null,
    onStation: 0,
    cooldown: 0,
    elevation: 1.2,
    ...overrides,
  };
  state.units.push(unit);
  return unit;
}

describe('running people over', () => {
  it('puts down someone you drive through at speed', async () => {
    const physics = await createPhysics(world);
    const contacts = createUnitBodies(physics);
    const units = createUnits();
    const victim = place(units, { x: 1, z: 0 });

    const events = contacts.sync(units, { x: 0, z: 0 }, 14, 1 / 60);
    expect(events.ranOver).toContain(victim);
    expect(victim.hp).toBe(0);
  });

  it('does not hurt anyone you creep past', async () => {
    const physics = await createPhysics(world);
    const contacts = createUnitBodies(physics);
    const units = createUnits();
    const bystander = place(units, { x: 1, z: 0 });

    // Walking pace. Brushing past somebody is not running them over.
    const events = contacts.sync(units, { x: 0, z: 0 }, 1.5, 1 / 60);
    expect(events.ranOver).toHaveLength(0);
    expect(bystander.hp).toBe(30);
  });

  it('leaves people you merely drove near alone', async () => {
    const physics = await createPhysics(world);
    const contacts = createUnitBodies(physics);
    const units = createUnits();
    const bystander = place(units, { x: 9, z: 0 });

    expect(contacts.sync(units, { x: 0, z: 0 }, 25, 1 / 60).ranOver).toHaveLength(0);
    expect(bystander.hp).toBe(30);
  });

  it('gives people no collider, so the car is never hung up on a crowd', async () => {
    const physics = await createPhysics(world);
    const contacts = createUnitBodies(physics);
    const units = createUnits();
    for (let i = 0; i < 12; i++) place(units, { x: i * 2, z: 4 });

    contacts.sync(units, { x: 0, z: 0 }, 0, 1 / 60);
    expect(contacts.count).toBe(0);
  });
});

describe('hitting other vehicles', () => {
  const car = (state: UnitState, at: { x: number; z: number }) =>
    place(state, { kind: 'car', role: 'traffic', faction: 'civilian', hp: 60, ...at });

  it('gives nearby vehicles a body to collide with', async () => {
    const physics = await createPhysics(world);
    const contacts = createUnitBodies(physics);
    const units = createUnits();
    car(units, { x: 12, z: 0 });

    const before = physics.rapier.bodies.len();
    contacts.sync(units, { x: 0, z: 0 }, 0, 1 / 60);
    expect(contacts.count).toBe(1);
    expect(physics.rapier.bodies.len()).toBe(before + 1);
  });

  it('damages a vehicle you ram, and not one you pull up behind', async () => {
    const physics = await createPhysics(world);
    const contacts = createUnitBodies(physics);
    const units = createUnits();
    const rammed = car(units, { x: 3, z: 0 });
    const parked = car(units, { x: 60, z: 0 });

    for (let i = 0; i < 30; i++) contacts.sync(units, { x: 0, z: 0 }, 20, 1 / 60);
    expect(rammed.hp).toBeLessThan(60);
    expect(parked.hp).toBe(60);
  });

  it('does not damage a vehicle you are simply sitting next to', async () => {
    const physics = await createPhysics(world);
    const contacts = createUnitBodies(physics);
    const units = createUnits();
    const neighbour = car(units, { x: 3, z: 0 });

    for (let i = 0; i < 60; i++) contacts.sync(units, { x: 0, z: 0 }, 1, 1 / 60);
    expect(neighbour.hp).toBe(60);
  });

  it('takes bodies away again as traffic drives out of range', async () => {
    const physics = await createPhysics(world);
    const contacts = createUnitBodies(physics);
    const units = createUnits();
    const passing = car(units, { x: 20, z: 0 });

    contacts.sync(units, { x: 0, z: 0 }, 0, 1 / 60);
    const withBody = physics.rapier.bodies.len();
    expect(contacts.count).toBe(1);

    passing.x = 900;
    contacts.sync(units, { x: 0, z: 0 }, 0, 1 / 60);
    expect(contacts.count).toBe(0);
    expect(physics.rapier.bodies.len()).toBe(withBody - 1);
  });

  it('does not leak bodies as traffic comes and goes', async () => {
    const physics = await createPhysics(world);
    const contacts = createUnitBodies(physics);
    const units = createUnits();
    const base = physics.rapier.bodies.len();

    for (let cycle = 0; cycle < 5; cycle++) {
      units.units = [];
      for (let i = 0; i < 6; i++) car(units, { x: 10 + i * 6, z: 0 });
      contacts.sync(units, { x: 0, z: 0 }, 0, 1 / 60);
      expect(contacts.count).toBe(6);
      units.units = [];
      contacts.sync(units, { x: 0, z: 0 }, 0, 1 / 60);
      expect(physics.rapier.bodies.len()).toBe(base);
    }
  });
});