2.2.7 Cycle 7 - Add Boss Wave

Design

Objectives

In this cycle I aim to add another type of more difficult enemy, that moves faster and adds an extra challenge to the experience. This could be done through an enemy with more health, speed, smaller size etc.

This will add to the challenge of the game, and this will help to make it more challenging.

• Add another enemy

• Add 'waves' so that there's only one type of enemy on the screen at one time

• Make the waves frequent but not irritating

Usability Features

Key Variables

Variable Name	Use
specialEnemies	This is the group that hold each specialEnemy
specialEnemy	This is each individual sprite in the larger group
deployEnemyShips	This is the function that deploys the enemy ships (both special and normal)
specialEnemyXSpawn	This is the variable that defines the base places for the specialEnemies to spawn at

Pseudocode

procedure create
    add specialEnemies to new group
    enable specialEnemies
    create multiple specialEnemies as specialEnemy
    check bound of specialEnemies
    
    if specialEnemies collide with player
        player takes damage
    if specialEnemies collide with laser
        destroy specialEnemy        
end procedure

procedure deployEnemyShips
    ...
    if switchToNewPattern == 30
        run deploySpecialEnemy procedure
end procedure

procedure deploySpecialEnemy
    specialEnemies exists first = false
    
    if specialEnemy = true
        add specialEnemies = specialEnemyXSpawn

Development

Outcome

Game.js

Game.js

function preload(){
  ...
  game.load.image('specialEnemy', 'assets/images/newEnemyShip.gif');
  ...
}

function create(){
  ...
  specialEnemies = game.add.group();
  specialEnemies.enableBody = true;
  game.physics.arcade.enable(specialEnemies, Phaser.Physics.ARCADE);
  specialEnemies.createMultiple(100, 'specialEnemy');
  specialEnemies.setAll('anchor.x', 0.5);
  specialEnemies.setAll('anchor.y', 0.5);
  specialEnemies.setAll('scale.x', 1.3);
  specialEnemies.setAll('scale.y', 1.3);
  specialEnemies.setAll('outOfBoundsKill', true);
  specialEnemies.setAll('checkWorldBounds', true);
  specialEnemies.setAll('angle', 180);

  
  ...
}

let spawnSpecialEnemy = false;
function deployEnemyShips() {
  ...
    } else if (switchToNewPattern === 30) {
      spawnSpecialEnemy = true;
      switchXSpawn = 0;
      switchToNewPattern = 0;
      enemyXSpawn = 200;
      ENEMY_X = 0;

      deploySpecialEnemy();
    }
  }
}

let specialCount = 0;
let specialEnemyXSpawn = 200;
function deploySpecialEnemy() {
  // Figure out how to get rid of normal enemies while special enemy is in play
  if (spawnSpecialEnemy) {
    let specialEnemy = specialEnemies.getFirstExists(false);

    if (specialEnemy && specialCount != 3) {
      specialEnemy.reset(specialEnemyXSpawn, 0);
      specialEnemy.body.velocity.y = 800;
      specialEnemy.body.drag.x = 0;
      game.time.events.add(500, function() {
        deploySpecialEnemy();
        if (specialEnemyXSpawn === 200) {
          specialEnemyXSpawn = 100;
        } else if (specialEnemyXSpawn === 100) {
          specialEnemyXSpawn = 300;
        } else if (specialEnemyXSpawn === 300) {
          specialEnemyXSpawn = 200;
          setInterval(function() {
            deployEnemyShips();
          }, 5000);
        }
      });
    }
    
  }
}

Challenges

The most challenging part of this cycle was figuring out how to get it so that only the special ships would spawn whilst they were being deployed, and so that the normal enemy ships would stop for the duration of the special ships. I was trying to overcomplicate this to begin with, but I realised that I could just defer the function that calls new normal enemy ships by an amount of time so that it wouldn't be called, and this meant that the normal ships wouldn't spawn for the time that the special enemies were.

Testing

Evidence for testing

Tests

Test	Instructions	What I expect	What actually happens	Pass/Fail
1	Simply load the game	The basic enemies move down the screen both randomly and also in set patterns.	As expected	Pass
2	Survive long enough to get the special enemies	The special enemies spawn in, move faster and basic enemies aren't spawned for duration.	As expected	Pass

Evidence

Comparison of normal enemies and bosses

What next?

• Next I want to add the ability to pick up health

• This should enable the player to live for longer