enemy-redesign.js

'use strict';

/**
 * Experimenting with building a better grid based entity management system
 * Uses more efficient Map/Set calls, requiring modern browsers / Node.js
 */

const SPAWNS = [
  {x: 1, y: 1},
  {x: 1, y: 2},
  {x: 1, y: 3},
  {x: 7, y: 1},
  {x: 7, y: 2},
  {x: 7, y: 3}
];

const MAX_ENEMY = 100;

let enemies = []; // All enemies, incl unspawned, alive, dead
let spawn_marker = -1;
let locations = new Map();
let spawns = new Set();

// Create Enemies
for (let i = 0; i < MAX_ENEMY; i++) {
  enemies.push({
    id: i,
    alive: null,
    avatar: {
      opacity: 0
    },
    ticks: 0,
    x: -1,
    y: -1
  });
}

// Generated from map data
for (let i = 0; i < SPAWNS.length; i++) {
  spawns.add({x: SPAWNS[i].x, y: SPAWNS[i].y});
}

function spawn(x, y, id) {
  // console.log('spawn()', x, y, id);

  if (locationOccupied({x, y})) {
    // console.error('cannot spawn', x, y, id);
    return null;
  }

  let enemy = enemies[id];
  enemy.alive = true;
  enemy.avatar.opacity = 1;
  enemy.x = x;
  enemy.y = y;
  locationSet(enemy, enemy);

  return enemy;
}

function spawnWave() {
  let ceil = spawn_marker + SPAWNS.length;

  for (let c of spawns) {
    spawn_marker += 1;
    spawn(c.x, c.y, spawn_marker);
  }
}

function tick(fn) {
  // Game gets slightly slower over time
  for (let i = 0; i <= spawn_marker; i++) {
    if (!enemies[i].alive) {
      continue;
    }

    fn(enemies[i]); // Keep tick logic out of library
  }
}

function slay(id) {
  // console.log('slay()', id);
  let enemy = enemies[id];
  locationRemove(enemy);
  enemy.alive = false; // need to skip slain enemies when iterating enemy pool
  enemy.avatar.opacity = 0;
}

function move(dest, id) {
  // console.log('move()', dest, id);
  let enemy = enemies[id];

  if (!locationOccupied(enemy)) {
    // console.error(`move() enemy ${id} doesn't exist in locations`);
    return false;
  }

  if (locationOccupied(dest)) {
    // console.error("move() destination already exists", dest);
    return false;
  }

  locationRemove(enemy);
  enemy.x = dest.x;
  enemy.y = dest.y;
  locationSet(dest, enemy);

  return true;
}

function locationOccupied(loc) {
  return locations.has(`${loc.x},${loc.y}`);
}

function locationRemove(loc) {
  return locations.delete(`${loc.x},${loc.y}`);
}

function locationSet(loc, item) {
  return locations.set(`${loc.x},${loc.y}`, item);
}

function randomCoord() {
  return {
    x: Math.floor(Math.random() * 20),
    y: Math.floor(Math.random() * 20)
  };
}

const start = +(new Date());

spawnWave();
slay(0);
slay(1);
slay(2);
slay(3);
tick(enemy => {
  enemy.ticks++;
});
// slay(4);
move(randomCoord(), 4);
// slay(5);
spawnWave();
move(randomCoord(), 6);
move(randomCoord(), 7);
move(randomCoord(), 8);
move(randomCoord(), 9);
tick(enemy => {
  enemy.ticks++;
});
spawnWave();
spawnWave();
spawnWave();
spawnWave();
spawnWave();
spawnWave();







const end = +(new Date());

console.log(locations);

console.log('TIME', end-start, 'ms');