As I foretold yesterday on my Twitter account (follow me if you didn’t already, to stay up to date), I updated my HTML5 Serious Scramblers prototype, adding a new enemy: the Rotating Saw.
Unlike angry pigs, saws can’t be killed by stomping on them.
Adding rotating saws was not that different than adding angry pigs. Actually it was even easier because I did not have to manage the case of the saw to be killed by the player.
Rotating saws too are managed by object pooling, but first of all let’s have a look at the game:
Tap and hold left or right to move the character left or right. Once you move, platforms will scroll up. Reach the top of the stage, and it’s game over.
Fall from platform to platform without falling too down, if you reach the bottom of the stage, it’s game over.
Touch an enemy, and it’s game over. But you can kill angry pigs by jumping on their head.
The game is made of 12 TypeScript files and one HTML file used in this prototype. Although I made some changes here and there since previous step, I am highlighting the most interesting pieces of code I added in this step.
index.html
The webpage which hosts the game, just the bare bones of HTML and main.ts is called. No changes have been made.
Also look at the thegame div, this is where the game will run.
<!DOCTYPE html>
<html>
<head>
<style type = "text/css">
body {
background: #000000;
padding: 0px;
margin: 0px;
}
</style>
<script src = "scripts/main.ts"></script>
</head>
<body>
<div id = "thegame"></div>
</body>
</html>
main.ts
The main TypeScript file, the one called by index.html.
Here we import most of the game libraries and define both Scale Manager object and Physics object.
Here we also initialize the game itself. No changes have been made
// MAIN GAME FILE
// modules to import
import Phaser from 'phaser';
import { PreloadAssets } from './preloadAssets';
import { PlayGame} from './playGame';
import { GameOptions } from './gameOptions';
// object to initialize the Scale Manager
const scaleObject: Phaser.Types.Core.ScaleConfig = {
mode: Phaser.Scale.FIT,
autoCenter: Phaser.Scale.CENTER_BOTH,
parent: 'thegame',
width: GameOptions.gameSize.width,
height: GameOptions.gameSize.height
}
// object to initialize Arcade physics
const physicsObject: Phaser.Types.Core.PhysicsConfig = {
default: 'arcade',
arcade: {
gravity: {
y: GameOptions.gameGravity
},
// debug: true
}
}
// game configuration object
const configObject: Phaser.Types.Core.GameConfig = {
type: Phaser.AUTO,
backgroundColor:0x444444,
scale: scaleObject,
scene: [PreloadAssets, PlayGame],
physics: physicsObject,
pixelArt: true
}
// the game itself
new Phaser.Game(configObject);
preloadAssets.ts
Class to preload all assets used in the game. This time we also load the rotating saw sprite sheet.
// CLASS TO PRELOAD ASSETS
// this class extends Scene class
export class PreloadAssets extends Phaser.Scene {
// constructor
constructor() {
super({
key: 'PreloadAssets'
});
}
// preload assets
preload(): void {
this.load.image('platform', 'assets/platform.png');
this.load.image('background', 'assets/background.png');
this.load.image('leftplatformedge', 'assets/leftplatformedge.png');
this.load.image('rightplatformedge', 'assets/rightplatformedge.png');
this.load.spritesheet('enemy', 'assets/enemy.png', {
frameWidth: 36,
frameHeight: 30
});
this.load.spritesheet('enemy_hit', 'assets/enemy_hit.png', {
frameWidth: 36,
frameHeight: 30
});
this.load.spritesheet('hero', 'assets/hero.png', {
frameWidth: 32,
frameHeight: 32
});
this.load.spritesheet('hero_run', 'assets/hero_run.png', {
frameWidth: 32,
frameHeight: 32
});
this.load.spritesheet('saw', 'assets/saw.png', {
frameWidth: 38,
frameHeight: 38
});
}
// method to be called once the instance has been created
create(): void {
// call PlayGame class
this.scene.start('PlayGame');
}
}
gameOptions.ts
Game options which can be changed to tune the gameplay are stored in a separate module, ready to be reused.
I added some constants to store values, then changed the way we decide if we have to place an enemy on a platform.
An array called platformStuff is filled with enemy values, then each time a platform is initialized, we pick a random array item.
// CONFIGURABLE GAME OPTIONS
// some constants to store values
export const EMPTY_PLATFORM = 0;
export const ENEMY = 1;
export const SAW = 2;
export const GameOptions = {
// game size, in pixels
gameSize: {
width: 750,
height: 1334
},
// game scale ratio
pixelScale: 3,
// first platform vertical position. 0 = top of the screen, 1 = bottom of the screen
firstPlatformPosition: 4 / 10,
// game gravity, which only affects the hero
gameGravity: 1200,
// hero speed, in pixels per second
heroSpeed: 300,
// platform speed, in pixels per second
platformSpeed: 90,
// platform length range, in pixels
platformLengthRange: [150, 250],
// platform horizontal distance range from the center of the stage, in pixels
platformHorizontalDistanceRange: [0, 250],
// platform vertical distance range, in pixels
platformVerticalDistanceRange: [150, 250],
// platform tint colors
platformColors: [0xffffff, 0xff0000, 0x00ff00],
// bounce velocity when landing on bouncing platform
bounceVelocity: 500,
// disappearing platform time before disappearing, in milliseconds
disappearTime: 1000,
// enemy patrolling speed range, in pixels per second
enemyPatrolSpeedRange: [40, 80],
// saw patrolling speed range, in pixels per second
sawSpeedRange: [10, 30],
// array filled with stuff to be added to the platform. An item is randomly picked each time we need to place some stuff on the platform
platformStuff: [EMPTY_PLATFORM, ENEMY, ENEMY, ENEMY, ENEMY, SAW, SAW, SAW]
}
playGame.ts
The game itself, the biggest class, game logic is stored here.
In this file I added saw creation, management and collisions. It’s not that different than angry pigs management, anyway. It’s even simpler because saws can’t be killed.
// THE GAME ITSELF
// modules to import
import { GameOptions, ENEMY, SAW } from './gameOptions';
import PlayerSprite from './playerSprite';
import PlatformSprite from './platformSprite';
import EnemySprite from './enemySprite';
import PlatformGroup from './platformGroup';
import EnemyGroup from './enemyGroup';
import SawSprite from './sawSprite';
import SawGroup from './sawGroup';
// this class extends Scene class
export class PlayGame extends Phaser.Scene {
// group to contain all platforms
platformGroup: PlatformGroup;
// group to contain all enemies
enemyGroup: EnemyGroup;
// group to contain all saws
sawGroup: SawGroup;
// the hero of the game
hero: PlayerSprite;
// is it the first time player is moving?
firstMove: Boolean;
// enemy pool, built as an array
enemyPool: EnemySprite[];
// saw pool, built as an array
sawPool: SawSprite[];
// just a debug text to print some info
debugText: Phaser.GameObjects.Text;
// background image
backgroundImage: Phaser.GameObjects.TileSprite;
// left edge platform sprite
leftPlatform: Phaser.GameObjects.Sprite;
// right edge platform sprite
rightPlatform: Phaser.GameObjects.Sprite;
// middle platform sprite
middlePlatform: Phaser.GameObjects.Sprite;
// constructor
constructor() {
super({
key: 'PlayGame'
});
}
// method to be called once the class has been created
create(): void {
// method to initialize platform sprites
this.initializePlatformSprites();
// method to inizialize animations
this.initializeAnimations();
// method to place the background image
this.setBackground();
// add the debug text to the game
this.debugText = this.add.text(16, 16, '', {
color: '#000000',
fontFamily: 'monospace',
fontSize: '48px'
});
// initialize enemy pool as an empty array
this.enemyPool = [];
// initialize saw pool as an empty array
this.sawPool = [];
// this is the firt move
this.firstMove = true;
// create a new physics group for the platforms
this.platformGroup = new PlatformGroup(this.physics.world, this);
// create a new physics group for the enemies
this.enemyGroup = new EnemyGroup(this.physics.world, this);
// create a new physics group for the saws
this.sawGroup = new SawGroup(this.physics.world, this);
// let's create ten platforms. They are more than enough
for (let i: number = 0; i < 10; i ++) {
// create a new platform
let platform: PlatformSprite = new PlatformSprite(this, this.platformGroup, this.leftPlatform, this.middlePlatform, this.rightPlatform);
// if it's not the first platform...
if (i > 0) {
// place some stuff on it
this.placeStuffOnPlatform(platform);
}
}
// add the hero
this.hero = new PlayerSprite(this);
// input listener to move the hero
this.input.on("pointerdown", this.moveHero, this);
// input listener to stop the hero
this.input.on("pointerup", this.stopHero, this);
}
// method to set background image
setBackground(): void {
// add a tileSprite
this.backgroundImage = this.add.tileSprite(0, 0, GameOptions.gameSize.width / GameOptions.pixelScale, GameOptions.gameSize.height / GameOptions.pixelScale, 'background');
// set background origin to top left corner
this.backgroundImage.setOrigin(0, 0);
// set background scale
this.backgroundImage.scale = GameOptions.pixelScale;
}
// method to inizialize animations
initializeAnimations(): void {
// hero idle animation
this.anims.create({
key: "idle",
frames: this.anims.generateFrameNumbers('hero', {
start: 0,
end: 10
}),
frameRate: 20,
repeat: -1
});
// hero run animation
this.anims.create({
key: "run",
frames: this.anims.generateFrameNumbers('hero_run', {
start: 0,
end: 11
}),
frameRate: 20,
repeat: -1
});
// enemy run animation
this.anims.create({
key: "enemy_run",
frames: this.anims.generateFrameNumbers('enemy', {
start: 0,
end: 11
}),
frameRate: 20,
repeat: -1
});
// enemy falling animation
this.anims.create({
key: "enemy_falling",
frames: this.anims.generateFrameNumbers('enemy_hit', {
start: 0,
end: 2
}),
frameRate: 20
});
// saw animation
this.anims.create({
key: "saw",
frames: this.anims.generateFrameNumbers('saw', {
start: 0,
end: 7
}),
frameRate: 20,
repeat: -1
});
}
// method to inizialize platform sprites
initializePlatformSprites(): void {
// add left platform edge sprite
this.leftPlatform = this.add.sprite(0, 0, 'leftplatformedge');
// set registration point to top left corner
this.leftPlatform.setOrigin(0, 0);
// set sprite to invisible
this.leftPlatform.setVisible(false);
// add right platform edge sprite
this.rightPlatform = this.add.sprite(0, 0, 'rightplatformedge');
// set registration point to top right corner
this.rightPlatform.setOrigin(1, 0);
// set sprite to invisible
this.rightPlatform.setVisible(false);
// add middle platform sprite
this.middlePlatform = this.add.sprite(0, 0, 'platform');
// set registration point to center
this.middlePlatform.setOrigin(0, 0);
// set sprite to invisible
this.middlePlatform.setVisible(false);
}
// method to place stuff on platform
// argument: the platform
placeStuffOnPlatform(platform: PlatformSprite): void {
// pick a random item from platformStuff array
let randomPick: number = Phaser.Utils.Array.GetRandom(GameOptions.platformStuff);
// add stuff according to random pick
switch (randomPick) {
// enemy
case ENEMY: {
// is the enemy pool empty?
if (this.enemyPool.length == 0) {
// create a new enemy sprite
new EnemySprite(this, platform, this.enemyGroup);
}
// enemy pool is not empty
else {
// retrieve an enemy from the enemy pool
let enemy: EnemySprite = this.enemyPool.shift() as EnemySprite;
// move the enemy from the pool to enemy group
enemy.poolToGroup(platform, this.enemyGroup);
}
break;
}
// saw
case SAW: {
// is the saw pool empty?
if (this.sawPool.length == 0) {
// create a new saw sprite
new SawSprite(this, platform, this.sawGroup);
}
// saw pool is not empty
else {
// retrieve a saw from the saw pool
let saw: SawSprite = this.sawPool.shift() as SawSprite;
// move the saw from the pool to saw group
saw.poolToGroup(platform, this.sawGroup);
}
break;
}
}
}
// method to move the hero
// argument: the input pointer
moveHero(e: Phaser.Input.Pointer): void {
// set hero movement according to input position
this.hero.setMovement((e.x > GameOptions.gameSize.width / 2) ? this.hero.RIGHT : this.hero.LEFT);
// is it the first move?
if (this.firstMove) {
// it's no longer the first move
this.firstMove = false;
// move platform group
this.platformGroup.setVelocityY(-GameOptions.platformSpeed);
// move saw group
this.sawGroup.setVelocityY(-GameOptions.platformSpeed);
}
}
// method to stop the hero
stopHero(): void {
// ... just stop the hero :)
this.hero.setMovement(this.hero.STOP);
}
// method to handle collisions between hero and saws
// arguments: the two colliding bodies
handleSawCollision(body1: Phaser.GameObjects.GameObject, body2: Phaser.GameObjects.GameObject): void {
// restart the game
this.scene.start("PlayGame");
}
// method to handle collisions between hero and enemies
// arguments: the two colliding bodies
handleEnemyCollision(body1: Phaser.GameObjects.GameObject, body2: Phaser.GameObjects.GameObject): void {
// first body is the hero
let hero: PlayerSprite = body1 as PlayerSprite;
// second body is the enemy
let enemy: EnemySprite = body2 as EnemySprite;
// the following code will be executed only if the hero touches the enemy on its upper side (STOMP!)
if (hero.body.touching.down && enemy.body.touching.up) {
// move the enemy from enemy group to enemy pool
enemy.groupToPool(this.enemyGroup, this.enemyPool);
// play "enemy_falling" animation
enemy.anims.play('enemy_falling', true);
// flip the enemy vertically
enemy.setFlipY(true);
// make the hero bounce
hero.setVelocityY(GameOptions.bounceVelocity * -1);
}
// hero touched an enemy without stomping it
else {
// restart the game
this.scene.start("PlayGame");
}
}
// method to handle collisions between hero and platforms
// arguments: the two colliding bodies
handlePlatformCollision(body1: Phaser.GameObjects.GameObject, body2: Phaser.GameObjects.GameObject): void {
// first body is the hero
let hero: PlayerSprite = body1 as PlayerSprite;
// second body is the platform
let platform: PlatformSprite = body2 as PlatformSprite;
// the following code will be executed only if the hero touches the platform on its upper side
if (hero.body.touching.down && platform.body.touching.up) {
// different actions according to platform type
switch (platform.platformType) {
// breakable platform
case 1:
// if the platform is not already fading out...
if (!platform.isFadingOut) {
// flag the platform as a fading out platform
platform.isFadingOut = true;
// add a tween to fade the platform out
this.tweens.add({
targets: platform,
alpha: 0,
ease: 'bounce',
duration: GameOptions.disappearTime,
callbackScope: this,
onComplete: function() {
// reset the platform
this.resetPlatform(platform);
}
});
}
break;
// bouncy platform
case 2:
// make the hero jump changing vertical velocity
hero.setVelocityY(GameOptions.bounceVelocity * -1);
break;
}
}
}
// method to reset a platform
// argument: the platform
resetPlatform(platform: PlatformSprite): void {
// recycle the platform
platform.initialize();
// place stuff on platform
this.placeStuffOnPlatform(platform);
}
// method to handle collisions between enemies and platforms
// arguments: the two colliding bodies
handleEnemyPlatformCollision(body1: Phaser.GameObjects.GameObject, body2: Phaser.GameObjects.GameObject): void {
// first body is the enemy
let enemy: EnemySprite = body1 as EnemySprite;
// second body is the platform
let platform: PlatformSprite = body2 as PlatformSprite;
// set the platform to patrol
enemy.platformToPatrol = platform;
}
// method to be executed at each frame
update(): void {
// if the hero is already moving...
if (!this.firstMove) {
// scroll a bit the background texture
this.backgroundImage.tilePositionY += 0.2;
}
// move the hero
this.hero.move();
// handle collision between hero and platforms
this.physics.world.collide(this.hero, this.platformGroup, this.handlePlatformCollision, undefined, this);
// handle collision between enemies and platforms
this.physics.world.collide(this.enemyGroup, this.platformGroup, this.handleEnemyPlatformCollision, undefined, this);
// handle collisions between hero and enemies
this.physics.world.collide(this.hero, this.enemyGroup, this.handleEnemyCollision, undefined, this);
// handle collisions between hero and saws
this.physics.world.collide(this.hero, this.sawGroup, this.handleSawCollision, undefined, this);
// get all platforms
let platforms: PlatformSprite[] = this.platformGroup.getChildren() as PlatformSprite[];
// loop through all platforms
for (let platform of platforms) {
// get platform bounds
let platformBounds: Phaser.Geom.Rectangle = platform.getBounds();
// if a platform leaves the stage to the upper side...
if (platformBounds.bottom < 0) {
// reset the platform
this.resetPlatform(platform);
}
}
// get all saws
let saws: SawSprite[] = this.sawGroup.getChildren() as SawSprite[];
// loop through all saws
for (let saw of saws) {
// make enemy patrol
saw.patrol();
let sawBounds: Phaser.Geom.Rectangle = saw.getBounds();
// if a saw leaves the stage to the upper side...
if (sawBounds.bottom < 0) {
// move the saw from saw group to saw pool
saw.groupToPool(this.sawGroup, this.sawPool);
}
}
// get all enemies
let enemies: EnemySprite[] = this.enemyGroup.getChildren() as EnemySprite[];
// update debug text
this.debugText.setText("Enemies: group " + enemies.length.toString() + ", pool: " + this.enemyPool.length.toString() + "\nSaws: group " + saws.length.toString() + ", pool: " + this.sawPool.length.toString());
// loop through all enemies in enemyPool array
for (let enemy of this.enemyPool) {
// if the enemy falls down the stage...
if (enemy.y > GameOptions.gameSize.height + 100) {
// set enemy velocity to zero
enemy.setVelocity(0 ,0);
// do not let enemy to be affacted by gravity
enemy.body.setAllowGravity(false);
}
}
// loop through all enemies
for (let enemy of enemies) {
// make enemy patrol
enemy.patrol();
// get enemy bounds
let enemyBounds: Phaser.Geom.Rectangle = enemy.getBounds();
// if the enemy leaves the screen...
if (enemyBounds.bottom < 0) {
// move enemy from enemy group to enemy pool
enemy.groupToPool(this.enemyGroup, this.enemyPool);
// do not show the enemy
enemy.setVisible(false);
}
}
// if the hero falls down or leaves the stage from the top...
if (this.hero.y > GameOptions.gameSize.height || this.hero.y < 0) {
// restart the scene
this.scene.start("PlayGame");
}
}
}
playerSprite.ts
Class to define the player Sprite, the main actor of the game, the one players control.
Did not change.
// PLAYER SPRITE CLASS
// modules to import
import { GameOptions } from './gameOptions';
// player sprite extends Arcade Sprite class
export default class PlayerSprite extends Phaser.Physics.Arcade.Sprite {
// assign LEFT property a -1 value, just like if it were a constant
LEFT: number = -1;
// assign RIGHT property a 1 value, just like if it were a constant
RIGHT: number = 1;
// assign STOP property a 0 value, just like if it were a constant
STOP: number = 0;
// player current movment is STOP
currentMovement: number = this.STOP;
// constructor
// argument: game scene
constructor(scene: Phaser.Scene) {
super(scene, GameOptions.gameSize.width / 2, GameOptions.gameSize.height * GameOptions.firstPlatformPosition - 100, 'hero');
// add the player to the scnee
scene.add.existing(this);
// add physics body to platform
scene.physics.add.existing(this);
// set player scale
this.scale = GameOptions.pixelScale;
// shrink a bit player pyhsics body size to make the game forgive players a bit
this.body.setSize(this.displayWidth / GameOptions.pixelScale * 0.6, this.displayHeight / GameOptions.pixelScale * 0.7, false);
// set player physics body offset. This has to be done manually, no magic formula
this.body.setOffset(7, 9);
}
// method to set player movement
// argument: the new movement
setMovement(n: number): void {
// set currentMovement to n
this.currentMovement = n;
}
// method to move the player
move(): void {
// set player horizontal velocity according to currentMovement value
this.setVelocityX(GameOptions.heroSpeed * this.currentMovement);
// various cases according to player movememt
switch (this.currentMovement) {
// player is moving left
case this.LEFT:
// flip sprite horizontally
this.setFlipX(true);
// play "run" animation
this.anims.play('run', true);
break;
// player is moving right
case this.RIGHT:
// do not flip sprite horizontally
this.setFlipX(false);
// play "run" animation
this.anims.play('run', true);
break;
// player is not moving
case this.STOP:
// play "idle" animation
this.anims.play('idle', true);
break;
}
}
}
platformSprite.ts
Class to define the platforms. Did not change.
// PLATFORM SPRITE CLASS
// modules to import
import PlatformGroup from './platformGroup';
import { GameOptions } from './gameOptions';
import { randomValue } from './utils';
// platform sprite extends RenderTexture class
export default class PlatformSprite extends Phaser.GameObjects.RenderTexture {
// platform physics body
body: Phaser.Physics.Arcade.Body;
// platform type
platformType: number = 0;
// is the platform fading out?
isFadingOut: Boolean = false;
// platform group
platformGroup: PlatformGroup;
// the three sprites forming the platform: left edge, middle, and right edge
leftSprite: Phaser.GameObjects.Sprite;
middleSprite: Phaser.GameObjects.Sprite;
rightSprite: Phaser.GameObjects.Sprite;
// constructor
// arguments: the game scene, the platform group, sprite for left edge, sprite for the middle, sprite for the right edge
constructor(scene: Phaser.Scene, group: PlatformGroup, leftSprite: Phaser.GameObjects.Sprite, middleSprite: Phaser.GameObjects.Sprite, rightSprite: Phaser.GameObjects.Sprite) {
super(scene, 0, 0, 1, 16);
// set left, middle and right sprites
this.leftSprite = leftSprite;
this.middleSprite = middleSprite;
this.rightSprite = rightSprite;
// RenderTexture object does not have default origin at 0.5, so we need to set it
this.setOrigin(0.5);
// add the platform to the scnee
scene.add.existing(this);
// add physics body to platform
scene.physics.add.existing(this);
// add the platform to group
group.add(this);
// platform body does not react to collisions
this.body.setImmovable(true);
// platform body is not affected by gravity
this.body.setAllowGravity(false);
// save platform group
this.platformGroup = group;
// let's initialize the platform, with random position, size and so on
this.initialize();
// set platform scale
this.scale = GameOptions.pixelScale;
}
// method to initialize the platform
initialize(): void {
// platform is not fading out
this.isFadingOut = false;
// platform alpha is set to fully opaque
this.alpha = 1;
// get lowest platform Y coordinate
let lowestPlatformY: number = this.platformGroup.getLowestPlatformY();
// is lowest platform Y coordinate zero? (this means there are no platforms yet)
if (lowestPlatformY == 0) {
// position the first platform
this.y = GameOptions.gameSize.height * GameOptions.firstPlatformPosition;
this.x = GameOptions.gameSize.width / 2;
}
else {
// position the platform
this.y = lowestPlatformY + randomValue(GameOptions.platformVerticalDistanceRange);
this.x = GameOptions.gameSize.width / 2 + randomValue(GameOptions.platformHorizontalDistanceRange) * Phaser.Math.RND.sign();
// set a random platform type
this.platformType = 0//Phaser.Math.Between(0, 2);
}
// platform width
let newWidth: number = randomValue(GameOptions.platformLengthRange) / GameOptions.pixelScale;
// set platform size
this.setSize(newWidth, 16);
// set platform body size
this.body.setSize(newWidth, 16);
// set middle sprite display width equal to entire platform width
this.middleSprite.displayWidth = newWidth;
// draw middle sprite
this.draw(this.middleSprite, 0, 0);
// draw left edge sprite
this.draw(this.leftSprite, 0, 0);
// draw right edge sprite
this.draw(this.rightSprite, newWidth, 0);
}
}
platformGroup.ts
Class to define the Phaser Group, dedicated to the group which contains all platforms. Did not change.
// PLATFORM GROUP CLASS
// modules to import
import PlatformSprite from "./platformSprite";
// platform group extends Arcade Group class
export default class PlatformGroup extends Phaser.Physics.Arcade.Group {
// constructor
// arguments: the physics world, the game scene
constructor(world: Phaser.Physics.Arcade.World, scene: Phaser.Scene) {
super(world, scene);
}
// method to get the lowest platform
getLowestPlatformY(): number {
// lowest platform value is initially set to zero
let lowestPlatformY: number = 0;
// get all group children
let platforms: PlatformSprite[] = this.getChildren() as PlatformSprite[];
// loop through all platforms
for (let platform of platforms) {
// get the highest value between lowestPlatform and platform y coordinate
lowestPlatformY = Math.max(lowestPlatformY, platform.y);
};
// return lowest platform coordinate
return lowestPlatformY;
}
}
enemySprite.ts
The class to define the patrolling enemy. Did not change.
// ENEMY SPRITE CLASS
// modules to import
import EnemyGroup from "./enemyGroup";
import PlatformSprite from "./platformSprite";
import { randomValue } from './utils';
import { GameOptions } from './gameOptions';
// enemy sprite extends Arcade Sprite class
export default class EnemySprite extends Phaser.Physics.Arcade.Sprite {
// the platform where the enemy is patrolling
platformToPatrol: PlatformSprite;
// enemy physics body
body: Phaser.Physics.Arcade.Body;
// constructor
// arguments: the game scene, the platform where the enemy is on, and enemy group
constructor(scene: Phaser.Scene, platform: PlatformSprite, group: EnemyGroup) {
super(scene, platform.x, platform.y - 100, 'enemy');
// add the platform to the scnee
scene.add.existing(this);
// add physics body to platform
scene.physics.add.existing(this);
// set enemy scale
this.scale = GameOptions.pixelScale;
// shrink a bit enemy pyhsics body size to make the game forgive players a bit
this.body.setSize(this.displayWidth / GameOptions.pixelScale * 0.6, this.displayHeight / GameOptions.pixelScale * 0.75, true);
// set enemy physics body offset. This has to be done manually, no magic formula
this.body.setOffset(7, 7)
// the enemy is patrolling the current platform
this.platformToPatrol = platform;
// add the enemy to the group
group.add(this);
// set enemy horizontal speed
this.setVelocityX(randomValue(GameOptions.enemyPatrolSpeedRange) * Phaser.Math.RND.sign());
// play "enemy_run" animation
this.anims.play('enemy_run', true);
}
// method to make the enemy patrol a platform
patrol(): void {
// flip enemy sprite if moving right
this.setFlipX(this.body.velocity.x > 0);
// get platform bounds
let platformBounds: Phaser.Geom.Rectangle = this.platformToPatrol.getBounds();
// get enemy bounds
let enemyBounds: Phaser.Geom.Rectangle = this.getBounds();
// get enemy horizontal speeds
let enemyVelocityX: number = this.body.velocity.x
// if the enemy is moving left and is about to fall down the platform to the left side
// or the enemy is moving right and is about to fall down the platform to the right side
if ((platformBounds.right + 25 < enemyBounds.right && enemyVelocityX > 0) || (platformBounds.left - 25 > enemyBounds.left && enemyVelocityX < 0)) {
// invert enemy horizontal speed
this.setVelocityX(enemyVelocityX * -1);
}
}
// method to remove the enemy from a group and place it into the pool
// arguments: the group and the pool
groupToPool(group: EnemyGroup, pool: EnemySprite[]): void {
// remove enemy from the group
group.remove(this);
// push the enemy in the pool
pool.push(this);
}
// method to remove the enemy from the pool and place it into a group
// arguments: the platform to patrol and the group
poolToGroup(platform: PlatformSprite, group: EnemyGroup): void {
// set the platform to patrol
this.platformToPatrol = platform;
// place the enemy in the center of the platform
this.x = platform.x;
// place the enemy a little above the platform
this.y = platform.y - 120;
// set the enemy visible
this.setVisible(true);
// add the enemy to the group
group.add(this);
// allow gravity to affect the enemy
this.body.setAllowGravity(true);
// set enemy horizontal speed
this.setVelocityX(randomValue(GameOptions.enemyPatrolSpeedRange) * Phaser.Math.RND.sign());
// play "enemy_run" animation
this.anims.play('enemy_run', true);
// do not vertically flip enemy sprite
this.setFlipY(false);
}
}
enemyGroup.ts
Actually this class to extend the Phaser Group which contains all enemies does not add any custom feature, but I preferred to create a custom class like I did with platformGroup.ts. Did not change
// ENEMY GROUP CLASS
// enemy group extends Arcade Group class
export default class EnemyGroup extends Phaser.Physics.Arcade.Group {
// constructor
// arguments: the physics world, the game scene
constructor(world: Phaser.Physics.Arcade.World, scene: Phaser.Scene) {
super(world, scene);
}
}
utils.ts
This file contains only one custom function, but I thought it was useful to group all custom functions in a separate file, to be reused whenever I need them.
Did not change.
// function to toss a random value between two elements in an array
// argument: an array with two items
export function randomValue(a: number[]): number {
// return a random integer between the first and the second item of the array
return Phaser.Math.Between(a[0], a[1]);
}
Then, about saw management, I added two new classes:
sawGroup.ts
Actually this class to extend the Phaser Group which contains all saws does not add any custom feature, but I preferred to create a custom class like I did with platformGroup.ts and enemyGroup.ts.
// SAW GROUP CLASS
// saw group extends Arcade Group class
export default class SawGroup extends Phaser.Physics.Arcade.Group {
// constructor
// arguments: the physics world, the game scene
constructor(world: Phaser.Physics.Arcade.World, scene: Phaser.Scene) {
super(world, scene);
}
}
sawSprite.ts
This is the new saw class. Not that different from enemySprite.ts.
// SAW SPRITE CLASS
// modules to import
import PlatformSprite from "./platformSprite";
import { randomValue } from './utils';
import { GameOptions } from './gameOptions';
import SawGroup from "./sawGroup";
// saw sprite extends Arcade Sprite class
export default class SawSprite extends Phaser.Physics.Arcade.Sprite {
// the platform where the saw is patrolling
platformToPatrol: PlatformSprite;
// saw physics body
body: Phaser.Physics.Arcade.Body;
// constructor
// arguments: the game scene, the platform where the saw is on, and saw group
constructor(scene: Phaser.Scene, platform: PlatformSprite, group: SawGroup) {
super(scene, platform.x, platform.y, 'saw');
// add the saw to the scene
scene.add.existing(this);
// add physics body to enemy
scene.physics.add.existing(this);
// set saw scale
this.scale = GameOptions.pixelScale;
// play "saw" animation
this.anims.play('saw', true);
// add the saw to the group
group.add(this);
// determine body size, making it a bit smaller than sprite size
let bodySize: number = this.displayWidth / 2 / this.scale * 0.8;
// set saw body circular, and set some offset, manually unfortunately
this.setCircle(bodySize, 4, 4);
// saw enemy is patrolling the current platform
this.platformToPatrol = platform;
// set saw horizontal speed
this.setVelocityX(randomValue(GameOptions.sawSpeedRange) * Phaser.Math.RND.sign());
// set saw vertical speed
this.setVelocityY(platform.body.velocity.y);
// saw is not affected by gravity
this.body.setAllowGravity(false);
}
// method to remove the saw from a group and place it into the pool
// arguments: the group and the pool
groupToPool(group: SawGroup, pool: SawSprite[]): void {
// set saw velocity to zero
this.setVelocity(0 ,0);
// remove enemy from the group
group.remove(this);
// push the enemy in the pool
pool.push(this);
}
// method to remove the saw from the pool and place it into a group
// arguments: the platform to patrol and the group
poolToGroup(platform: PlatformSprite, group: SawGroup): void {
// set the platform to patrol
this.platformToPatrol = platform;
// place the saw in the center of the platform
this.x = platform.x;
this.y = platform.y;
// add the saw to the group
group.add(this);
// set saw horizontal speed
this.setVelocityX(randomValue(GameOptions.sawSpeedRange) * Phaser.Math.RND.sign());
// set saw vertical speed
this.setVelocityY(platform.body.velocity.y);
}
// method to make the saw patrol a platform
patrol(): void {
// get platform bounds
let platformBounds: Phaser.Geom.Rectangle = this.platformToPatrol.getBounds();
// get saw bounds
let sawBounds: Phaser.Geom.Rectangle = this.getBounds();
// get saw horizontal speed
let sawVelocityX: number = this.body.velocity.x
// if the saw is moving left and is about to fall down the platform to the left side
// or the saw is moving right and is about to fall down the platform to the right side
if ((platformBounds.right + 25 < sawBounds.right && sawVelocityX > 0) || (platformBounds.left - 25 > sawBounds.left && sawVelocityX < 0)) {
// invert saw horizontal speed
this.setVelocityX(sawVelocityX * -1);
}
}
}
And that’s it. Maybe we need another step to let player die properly rather than just restart the game. Download the source code of the entire project.
